CA2037030A1 - Uptapered single-mode fiber package for optoelectronic components - Google Patents
Uptapered single-mode fiber package for optoelectronic componentsInfo
- Publication number
- CA2037030A1 CA2037030A1 CA002037030A CA2037030A CA2037030A1 CA 2037030 A1 CA2037030 A1 CA 2037030A1 CA 002037030 A CA002037030 A CA 002037030A CA 2037030 A CA2037030 A CA 2037030A CA 2037030 A1 CA2037030 A1 CA 2037030A1
- Authority
- CA
- Canada
- Prior art keywords
- fiber
- uptapered
- lens
- optical fiber
- housing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4219—Mechanical fixtures for holding or positioning the elements relative to each other in the couplings; Alignment methods for the elements, e.g. measuring or observing methods especially used therefor
- G02B6/422—Active alignment, i.e. moving the elements in response to the detected degree of coupling or position of the elements
- G02B6/4221—Active alignment, i.e. moving the elements in response to the detected degree of coupling or position of the elements involving a visual detection of the position of the elements, e.g. by using a microscope or a camera
- G02B6/4224—Active alignment, i.e. moving the elements in response to the detected degree of coupling or position of the elements involving a visual detection of the position of the elements, e.g. by using a microscope or a camera using visual alignment markings, e.g. index methods
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4204—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms
- G02B6/4207—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms with optical elements reducing the sensitivity to optical feedback
- G02B6/4208—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms with optical elements reducing the sensitivity to optical feedback using non-reciprocal elements or birefringent plates, i.e. quasi-isolators
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4204—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms
- G02B6/4207—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms with optical elements reducing the sensitivity to optical feedback
- G02B6/4208—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms with optical elements reducing the sensitivity to optical feedback using non-reciprocal elements or birefringent plates, i.e. quasi-isolators
- G02B6/4209—Optical features
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4219—Mechanical fixtures for holding or positioning the elements relative to each other in the couplings; Alignment methods for the elements, e.g. measuring or observing methods especially used therefor
- G02B6/422—Active alignment, i.e. moving the elements in response to the detected degree of coupling or position of the elements
- G02B6/4225—Active alignment, i.e. moving the elements in response to the detected degree of coupling or position of the elements by a direct measurement of the degree of coupling, e.g. the amount of light power coupled to the fibre or the opto-electronic element
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4219—Mechanical fixtures for holding or positioning the elements relative to each other in the couplings; Alignment methods for the elements, e.g. measuring or observing methods especially used therefor
- G02B6/4228—Passive alignment, i.e. without a detection of the degree of coupling or the position of the elements
- G02B6/423—Passive alignment, i.e. without a detection of the degree of coupling or the position of the elements using guiding surfaces for the alignment
Abstract
UPTAPERED SINGLE-MODE OPTICAL FIBER PACKAGE
FOR OPTOELECTRONIC COMPONENTS
ABSTRACT
A package for an optoelectronic device, such as a laser, having a photo-active element optically coupled to an uptapered single-mode optical fiber which connects said optoelectronic array to an external device includes a housing having a solderable substrate to which the device is secured, a graded index lens also secured to said substrate at a distance calculated to provide a known magnification of light beam emanating from said laser and an uptapered single-mode optical fiber mechanically positioned and actively aligned to said magnified light beam to achieve optimal optical coupling to said optoelectronic device. The package includes a plurality of reference marks and surfaces such that the laser, the lens and the uptapered end of a single-mode optical fiber may be positioned for precise optical coupling using an active alignment for final adjustments. The reference surfaces include a pedestal for the laser and a plurality of stops for the lens integrally formed with the sub-strate. The package also includes a fiber tube and flange for mechanically positioning the uptapered fiber. The precisely calculated spacing based on the spacing of said photo-active element, the magnification of said lens, and the fiber positioning is achieved by mechanical means. A
method of optically coupling the laser to the optical fiber includes securing a graded index lens to a substrate carrier within a housing at a distance calculated to provide a known magnification of a light beam emanating from said element, positioning and actively aligning the fiber to said magnified light beam to achieve optimal optical coupling to said optoelectronic device, and positioning the uptapered fiber securable to a flange.
FOR OPTOELECTRONIC COMPONENTS
ABSTRACT
A package for an optoelectronic device, such as a laser, having a photo-active element optically coupled to an uptapered single-mode optical fiber which connects said optoelectronic array to an external device includes a housing having a solderable substrate to which the device is secured, a graded index lens also secured to said substrate at a distance calculated to provide a known magnification of light beam emanating from said laser and an uptapered single-mode optical fiber mechanically positioned and actively aligned to said magnified light beam to achieve optimal optical coupling to said optoelectronic device. The package includes a plurality of reference marks and surfaces such that the laser, the lens and the uptapered end of a single-mode optical fiber may be positioned for precise optical coupling using an active alignment for final adjustments. The reference surfaces include a pedestal for the laser and a plurality of stops for the lens integrally formed with the sub-strate. The package also includes a fiber tube and flange for mechanically positioning the uptapered fiber. The precisely calculated spacing based on the spacing of said photo-active element, the magnification of said lens, and the fiber positioning is achieved by mechanical means. A
method of optically coupling the laser to the optical fiber includes securing a graded index lens to a substrate carrier within a housing at a distance calculated to provide a known magnification of a light beam emanating from said element, positioning and actively aligning the fiber to said magnified light beam to achieve optimal optical coupling to said optoelectronic device, and positioning the uptapered fiber securable to a flange.
Description
89 ~ 3 ~ 700 ~ 1 ~
r~ r~
.
UPTAPERED SINGLE-MODE OPTICAL EIB~R PACKAGE
FOR OPTOELECTRONIC CO~PONENTS
This invention relates to packaging of optoelectronic components which generate or process ~ignals that pasis through optical fiber~. In particular, it addresi3es the critical need for providing stable, low-cost alignment of single-mode optical fibers to a single packaged device, such as a semiconductor la~er.
An optoelectronic package is a container or housing that provides protection and isupport for both active and passive components contained within it. These components and their interconnection represent an optical-electrical circuit and define the function of the package. The package also includes a means of connecting the internal components with the external environment, usually as electrical feed-through and optical fiber. Our invention is concerned with the optical fiber and how it i8 :,' .
connected to the components within the package.
To make an optical connection between an optical fiber and an optoelectronic component within a package, it is necessary to position or align the optical fiber in a way that allow~ efficient coupling between the optical fiber and the optoelectronic component. The preci~ion needed for the alignment depends on the ~ize of the light-emitting or light receiving elements, the type of optical fiber, and any type of focusing or defocusing elements which may be present. Optical fiber transmiti3 light ~through iti~ inner core, which is much smaller than the diameter of the optical fiber. There are two classes of optical fiber preisently used in packaging eemiconductor devices: single-mode and multi-mode, with typical core diameters of about 10 microns and 50 microns, respectively. Many telecommunication applications use ~ ~ :
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89~3-700 -2- ~ J~
single-mode optical fiber because of the superior band-width arising from its reduction of mode partition noise.
The prior art for packaging semiconductor lasers is predominantly concerned with the easy task of aligning large cored multi-mode optical fiber. Multi-mode optical fiber is of little value for telecommunications because it suffers from mode-partition noise when used for high speed transmissions over a distance.
Laser packaging with single-mode optical fiber has been done with optical fibers which have their ends either cleaved or tapered and lensed. A cleaved optical fiber has an optically flat end, while a tapered and lensed optical fiber is drawn down to a point in a fashion that aids light entering the fiber. Packages incorporating cleaved optical fibers require a separate lens, as does the package of this invention, while packag~s incorporating lensed optical fibers do not.
Packages utilizing cleaved or tapered and lensed optical fibers ~uffer from stability problems associated with lateral movement of the optical fiber with respect to the laser. For this reason, the alignment of the optical fiber with the laser for such packages is u~ually done with expensive piezo-crystal micromanipulators having submicron sensitivity. The optical fiber is fa~tened with expensive laser welding technigues or special solders.
As explained by Rideout, et al, "Improved LED and laser packaging using up-tapered single mode fibers," CLE0 '89, Baltimore, MD, April 25, 1989, the improved lateral -tolerances arise from first magnifying the emitting spot image of the laser. The larger spot is then projected congruently onto the corresponding uptapered optical fib-r. The lateral and angular sensitivities are:
" . .
.
89-3-700 -3~ d, ~, ,, 1 Lateral coupling ~ exp x wOZ :,.
"
Angular decoupling = exp -~2wO2/~2 2 :' where the 9ymbol s mean:
wO = spot radius of the optical fiber;
~ = wavelength ~ = angular misalignment x = lateral misalignment . .
The equations show that the spot radius of the light beam in the optical fiber determines these sensitivities.
Since the spot radiu~ is in the denominator of the lateral decoupling expression above, the benefit of decreased lateral sensitivity occur~ with increased spot size.
Conversely, the angular sensitivity becomes more detrimental since the spot radius is in the numerator of the angular mi~alignment expression above.
When performing optical fiber alignments, the lateral alignment is more difficult to achieve than the angular ;
alignment. Thus, the net effect of u~ing a lens to magnify the spot radius of the light heam for coupling it to~ a larger diameter uptaperQd optical fiber is benefi-cial.
It is worth noting that even though the thick section of the uptapered optical fiber does not qualify as a single-mode optical fiber diameter, it i8 short enough in length that it maintains only the single-mode. Thus, it possible to obtain the advantage of the ease of alignment~of a thick multi-mode optical fiber, while not ; losing the data transmission advantage of a thin single-mode optl~al fiber.
According to one aspect of the invention, there is provided a package for an optoelectronic semiconductor device having a photo-active element optically coupled to an uptapered single-mode optical fiber connecting said optoelectronic device to an external device, comprising:
a housing to enclose the necessary components to convert electrical signals to optical signals; a substrate carrier having a solderable surface within said housing; an :-optoelectronic device having an photo-active element secured to said substrate carrier; a lens, having a numerical aperture sufficient to access optically said photo-active element secured to said carrier a fixed distance from said photo-active element to yield a deæired magnification of a light beam emanating from ~aid photo-active element by expanding the size of said beam;
an uptapered single-mode optical fiber extending from within said housing to the exterior of said housing through a port thereof, said optical fiber being . .
positioned by active alignment; means to secure ~aid uptapered optical fiber to said housing such that the uptapered end of said optical fiber is optically coupled through said lens to said photo-active element and the ~.
opposite end of said optical fiber is outside said ~.
housing; and a plurality of reference means on said housing and said carrier such that said optoelectronic device, said lens and said optical fiber are mechanically positioned with respect to one or more of said reference means; and such that uptapered said optical fiber is ::
externally aligned and ~ecured to said package.
According to another a~pect of the invention, there is provided a method of optically coupling an uptapered ~ingle-mode optical fiber to a spaced-apart photoactive element, said element integrated with a substrate carrier ~: and a lenæ within a housing, comprising the steps o:
spatially positioning aid element with respect to a fir~t pre-existing reference and then securing said spatially '.:
: -..... . .. . .
89-3-700 ~5~ ~ r~ r~ ~ r~
positioned element to said substrate carrier; positioning said lens with respect to a second pre-existing reference and then securing said positioned lens to said substrate ,~
carrier, said lens having a numerical aperture suficient to optically access said photoactive element and yield an appropriate magnification of a light beam emanating from said photoactive element; positioning the uptapered end of said fiber with respect to a third pre-existing reference and then actively aligning said fiber with said magnified light beam such that the uptapered end is optically coupled through said lens to said photoactive element; and securing said actively aligned fiber to said housing. :
Some embodiments of the invention will now be de~cribed, by way of example, with reference to the accompanying drawings in which: -Fig. 1 is a schematic perspective view of a generalized embodiment of an optoelectronic package which illuqtrates a package according to the principles of the invention and the method of packaging an optoelectronic component according to the invention using reference marks to mechanically align an uptapered optical fiber to a semiconductor laser;
Figs. 2a, 2b and 2c are, re~pectively, top, side and end views of the preferred embodiment of an optoelectronic package, according to one embodiment of the invention;
Fig. 3 is a partially cut-away top view o the embodiment of an optoelectronic package of Fig. 2a, ` enlarged to show details of the package; and ;30 ~ Fig.~ 4 i~ a top view of the embodiment of Fig. 2a, - urther enlarged to show details of substrate carrier.
This~ invention pertains to packages for optoeleatronic devices which provide stable alignment, using~a mechanical method for quick and efficient optical coupl~irg~of ~an uptapered slngle-mode optical fiber to th-~ , ' " ~ . . :
:
photo-active spot of the semi-conductor element. The package controls the uptapered fiber optical tolerances, allowing a relaxation of the optical fiber positional tolerance.
The package of this invention use~ a lens, with a sufficient numerical aperature and magnification, in conjunction with uptapered single-mode optical fiber. The alignment technique takes advantage of the relaxed mechanical tolerance and the magnification provided by the lens and the larger cored uptapered fiber optics. Such optical connections then permit independent transfer of telecommunications data and information for the semiconductor element. ` "
Specifically, thi 8 invention provides a new package for optically coupling an uptapered ~ingle-mode optical fiber to a single packaged optoelectronic device u ing a single len~ mechanically aligned with the semiconductor element in order to magnify the spot image of the photo-active element to expand the size of the emitted light beam. This image i8 then coupled to an uptapered optical fiber. This magnification greatly facilitates mechanical alignment and coupling of the semiconductor laser to the a~sociated optical fiber by relaxing mechani- ,`~
cal tolerances associated with the position of the ray of light coming from the laser.
Uptapered optical fibers are used because the effect of magnification increases the size of the beams or spot.
These beams are best collected on the thick end of the uptapered fiber, where the size of the optical fiber best matches the size of the beams. For example, a typical uptapered optical fiber may have a core that is ten times larger on its thick end than the single-mode optical fiber that it tapers down to. This optical fiber is u~ed with a len~ that magnifies the spot size of the beam tenfold.
mis eff~ct facilitates the alignment when assembling an optoelectronic package.
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.
' ''. '. :'.' '~,' ' ' ' ~ . ~ .. . . . . .
~ 3 Mechanical alignment is also possible with thesepackages because the location of the semiconductor beam can be known with high precision relative to the package.
This i8 because the semiconductor photo-active element i~
usually patterned on the semiconductor with photolithography to a high level of precision, about one micron, and the lens projects a precise image of khis pattern towards the fiber. If a lens with known magnification is first positioned rigidly in a specified location, then the location of the projected beam is know.
Alignment to this beam automatically aligns the uptapered optical fiber held in a fixture engineered with the geometry set by the known magnification determined by the lens.
Figure 1 illustrates a generalized package for an optoelectronic component and a method for assembling the package, according to this invention. Package 10,~ shown partially cut-away in Fig. 1, comprises a housing 12, which completely enclo~es the necessary components that convert input electrical signals to optical signals.
Preferably, housing 12 i~ made of brass and has a removable top for access to the interior. A carrier 14 having a surface that is readily solderable, such as gold-plated copper or brass, is used to support the components. A pedestal 16 is secured to a first ma~or , surface of carrier 14 adjacent to a first end wall 15 of hou~ing 12, for mounting and positioning a æemiconductor laser 22 having a photo-active spot 23. Two lateral stops 18~and~ two axial stops 20 are also secured in a central location to the same major~ surface of carrier 14 for positioning a lens 24, which is hard soldered prior to the optical fiber alignment. Preferably carrier 14, pede~tal 16 -nd~stops 18, 20 are integrally formed as a one-piece element. ~A thermoelectric cooler 26 is secured to the second ~ajor surface of carrier 14. A ~econd end wall 28 has a circular opening (not shown in Fig. 1) to permit the insertion of the thick end of uptapered optical fiber 30, which is enclosed in a fiber tube 32 and rigidly held perpendicular to end wall 28 by a large flange 34. The -lens 24 focuses the light from the photoactive spot 23 of laser 22 onto uptapered optical fiber 30.
A plurality of mechanical features, and regi~tration features and/or reference marks are incorporated into housing 12 and carrier 14 so that the total package 10 mechanically controls the uptapered~fiber optical tolerances, thus allowing a relaxation of the uptapered optical fiber positional tolerance. The uptapered-fiber optical tolerances controlled by package 10 are, the semiconductor position, the lens-to-semiconductor distance; the stability of lens attachment; and the tight angular control of the uptapered fiber.
A one-piece carrier 14 holds the laser 22 and the lens 24. Thiæ controls the stability of the lens-to-semiconductor positional tolerance. Semiconductor 22 and lens 24 move in unison, despite shifts in other package parts caused by vibrations or thermal variations.
The lens 24 is hard soldered prior to doing the optical fiber alignment to provide mechanical stability. For thi~
optical element, lens 24, stability is more important than exact positioning. Some misalignment of the lens 24 can be compensated for during alignment of the uptapered optical fiber 30.
The height of pedestal 16 controls the height of laæer 22 (y-axis). The forward edge 36 of pedestal 16 serves as the forward reference mark for la~er 22 3~ (z-axi~). A lateral reference mark 3~ on pede~tal 16 is aligned with an active region reference mark 40 on laser 22~(x-axis) to control the lateral position of la~er 22.
Axial stop~ 20 control the lens-to-semiconductor di~tance, while Iateral stops 18 control the horizontal alignment of the lens 24 to the photo-active spot 23 of laser 22. The relative positioning of the laæer 22 and the lens 24 is ~ -~: '' ~' .
. .
, usually set to a positional accuracy of about one-half mil. This can be done off-line under a stereomicroscope, making use of the reference marks 36, 3~, 40.
The position of the lenæ 24 sets the magnification of the light-emitting area (photo-active spot 23) of laser 22. The magnification is set to best match the projected emitting area size with the core of the uptapered optical fiber 30. The proper magnification position is set by the axial and lateral stops 18, 20, which are registration features on the carrier 14.
The uptapered optical fiber 30, protected by a fiber tube holder 32, is mounted and aligned externally to the package 10. The uptapered end of optical fiber 30 extends inside the package to a fiber tip reference mark 42 on carrier 14, which is a known distance from axial lens stops 20. The package cover (not shown in the figures) is in place, so that the interior of the package is protected from damage. After fiber positioning, using reference marks 42, 20 the uptapered optical fiber 30 is actively aligned, requiring only crude low co~t micro-meters and is secured in position with simple means such a8 epoxy or screws (not shown in Fig. 1). Active alignment mean# the fiber is aligned to maximize the light beam entering the fiber while the laser is operating. The uptapered optical ~` fiber 30 and the fiber tube holder 32 are easily removed and replaced for packages that have suffered fiber damage, be~ause~ interior parts need not be disturbed. The `~
uptapered optical fiber i8 held perpendicular to the pack`age by~a large fiber~ 1ange 34 on the iber tube holder 32. Thi~ controls the angular uptapered optical flber ~optlcal tolerance. It also improves stability be;cause~an~uptapered optical fiber is more sensitive to angular misalignment than a conventional tapered and lensed~or cleaved fiber.
A long focal distance between the lens 24 and the uptapered end of optlcal fiber 30 allows space to , - - . - ., --.. - , , ., , . , , . , ", . .. . ......... .. .. .. ... .... . .. .. . ... .....
q introduce optical elements such as filters and opto-isolators. In this space the light beam is nearly collimated, greatly simplifying the optical designs incorporating these elements.
The carrier 14 supporting the lens 24 and semiconductor 22 could ibe part of a circuit board, multi-chip module, or ~emiconductor waferboard carrying -~
other optical and electro~ic components.
The lens 24 could be either a GRIN type, convex, 10 plano-convex, or combination of several lenses. The only i -requirement is that it provide the necessary magnification to match light spot sizes with the uptapered end of optical fiber 30. -Internal optical elements, such as opto-isolator~ or ~ -filters, can be located in the space between the lens 24 and the fiber 30 in any combination. Optical coatings could also be placed on the lens 24 to provide some of the function of these optical element~.
The registration or reference marks 18, 20, 36, 38, 42 on the carrier can be either mechanical stops, slots, pin~, visual lines, steps or the like. The only requirement i~ that they be part of the carrier 14 and provide half mil or better accuracy for the lens 24 and the semiconductor 22 positions.
Fig. 1 show~ the uptapered-fiber laser package with the lid removed so that the components are vi~ible. This package incorporates an externally aligned uptapered fiber 30, which is aligned and epoxied onto the outside of the package housing 12 at room temperature. This is the only active alignment, and can be performed without piezoelectric ~taging because of the relaxed lateral alignment tolerances. An AR-coated GRIN lens images the laser spot onto the uptapered fiber. Thi~ lens is soldered in place with high temperature ~older for maximum ~ -stability. ~
: : . . .~ . . , . .: . . . : , . .. ~ . , . : . . . .
89-3-700 -11- ' ~
Figures 2a, 2b, 2c, 3 and 4 illustrate details of the preferred embodiment of the uptapered single-mode optical fiber package according to the invention, aæ built and te~ted by the inventors. In these figures, the same reference numbers are used for corresponding parts as were used in Fig. 1. Some elements not part of the invention are shown in the figures and mentioned in the specification without further elaboration.
Figures 2a, 2b and 2c are top, side and end views of the preferred embodiment of package 10, illustrating its assembly. The following items are specific to thiæ
embodiment. A graduated index (GRIN) lens is used for lens 24. A thermo-electric temperature control (TEC) 26 is present. This package is designed for epi-down semiconductor mounting. The carrier 14 doeæ not extend the full length of the housing 12, so the fiber tip reference mark 42 is on the base of the housing. A
precision fiber tube 32 having an epoxy fill tube 60 for securing the optical fiber 30 after alignment holds the uptapered end of the optical fiber. Fiber tube flange 34 surrounding fiber tube 32 is faætened wlth epoxy to the outside of the at epoxy joint 62 to complete the alignment.
A screw mounting slot 50 i 8 present. An SMA
connector socket 54, a high freguency microline 56 connected thereto, and seven d.c. in-line pin outs to provide high æpeed electrical signalæ complete the package~. ~The package housing 12, the fiber tube 32, and the cover (not shown) are preferably, made of brass.
~Carrier~14 is~preferably made of nickel and gold-plated copper. Package 10 in this embodiment is a high speed laser package having the uptapered fiber optical tolerance controls built into the package.
me~ laserc used in this package are 1.3 ~m Vapor-Phase-Regrowth Burled Heterostructure (VPR-BH) lasers whi~h have a demonstrated maximum bandwidth of 22 GHz and typical bandwidths of 15 GHz. Previously developed microstrip techniques are used to preserve the high frequency integrity of the package to 25GHz.S
Measurements of the variation in output power with slight changes in axial position of the uptapered indicate that back reflections which might introduce noise are less than -45 dB.
Excellent packaged coupling efficiencies of approximately 30% are obtained, which compare favorably to the maximum of 35% obtained on the laboratory bench, and 22% which are obtained using standard tapered-and-lensed fibers with a 12 ~m radius tip and a 30 included angle.
The lens 24 used is a SELFOC GRIN lens (model PCH 1.8 - 0.22). The uptapered fiber 3V used was made at GTE
Laboratories Incorporated. It has an uptapered core size of 90 ~ and a single mode fiber core size 9 ~. The fiber has a cut and polished tip to reduce light scattering ~oss.
The features of the package that control the uptapered-fiber optical tolerances are shown in Table I.
Based on measurements of the package, the mechanical optical tolerances are shown in Table I. The use of a one piece carrier 14 eliminates tolerance "stack-up" arising if separate pedestal, lateral, and axial ~tops were bonded to the carrier.
, .
; ~ ', -' Table I. Packaae OPtical Control Tolerance~
Control Point Tolerance fiber tip reference 5.0 mils fiber tube flange 0.5 of arc axial stops 0.5 mils lateral stops 0.5 mil~
pedestal height 0.5 mils active region reference 0.1 mils*
lateral reference 0.5 mils forward reference mark 0.5 mils _ .
*this item is normally defined with photolithography This embodiment uses epi-down lasers. This eliminates the positional tolerance associated with the thicknes~ of the wafer because the light emitting area i~ . -essentially at the pedestal/semiconductor interface. A
reference mark 40 on the laser 22 enables its correct positioning on the pedestal 16 during assembly since the actiYe~region 23 in the semiconductor 22 is on the reverse side and not visible.
The GRIN lens 24 straddles a slot that determines its height`above the carrier and its lateral position. The back edge of the lens registers With a raised edge on the .
carrier 14 that defines the axial stop 20.
Table I compares observed tolerances for the uptapered fiber package with those of a typical ns:ed-and-tapered fiber package. These tolerances represent the measured misalignment which reduces the coupled power ~by about 25%. 2 The mo#t important implications of this table for package design are: 1) -the r-laxed tolerance in~ the uptapered fiber po~ition lateral and transverse)~is responsible for the increased yièld, atability, and ea~e of assembly, 2) Critical tolerances (angular alignment and magnification) are met by built-in alignment marks and stops in the one-piece carrier, fiber flange, and housing, as schematically shown in Figure 1~ The fiber flange was designed to automatically align the uptapered fiber parallel to the beam within 0.5.
Table I: Tolera~ces for Components W thin Package ~-10 AP~roximate UptaperedTapered Tolerance~ Fiberand Len~ed Packaae Fiber Pa~kaqe `:
Fiber position:
axial (parallel to fiber) 125 ~m* 4 ~m ~:
lateral ( 1I to laser) 25 ~m 0.5 ~m transverse (1 to laser) 25 ~m 0.5 ~m ;
Fiber angle 0.5 12 20 GRIN len~ 13 ~mNot Applicable :.
Semiconductor laser 13 ~mNot Applicable *component held to within tolerance by æelf-alignment to package hardware.
: ' Figures 3 and 4 are enlarged top views of the embodiment of Fig. 2a, showing further details of the package feature~ which mechanically control the fiber .
optic tolerances. Referring now to these figures, two 30 optical path distances, Ll (Eig. 4) and L2, (Fig. 3) ~ ;
should:be maintained to achieve the correct magniflcation. .
in the package 10. Ll is the distance between laser 22 and lens 24 while L2 is the distance between lens 24 and uptapered-fiber 50. Distance L1 was 15.5 mils. A ~.
magni~ication of 10 was used to optically match the .-, : ~ ''' -.~..
semiconductor ~pot size 23 with the uptapered core.
Distance Ll can be checked with a low power (30x) stereomicroscope. Distance L2 is controlled by setting the fiber ~ip at the fiber tip reference mark. L2 is 0.475 inches. ~ -For ætability, the GRIN lens 24 is soldered to the carrier 16 with a reasonably hard 52/48 In/Sn 118 C
solder. The solder should be reflowed, and the lens position adjusted along its slot if Ll i~ found incorrect when checked.
Following active alignment, a bead of epoxy is applied to both the fiber tube flange 34 and the tube 32 epoxy fill hole 60. Our package allows its cover to be in place during the alignment.
The fiber tube flange 34 controls the fiber angle at 90. The package normally does not require angular align-ment. Only translational alignment is needed.
Our uptapered fiber 30 requires an angular alignment of one half degree of arc. If the tolerance~ listed in Table I are maintained, and the Ll position is checked and adju~ted properly, the package will achieve this.
If these tolerances are not strictly held, good alignment~ are still possible, but the active alignment process must include angular alignment of the fiber 30 rather than just lateral alignment. This i8 done by varying the angle of the fiber tube 32 slightly about the horizontal and vertical axes. Epoxy may still be u~ed to join 62 the flange to the package.
The completed package offers both temperature and optical power monitoring of the semiconductor 22.
Temperature regulation is provided by the thermoelectric cooler 26 as controlled by the thermistor 30. Optical power monitoring i provided by the rear facet detector 72 that mea#ures the lo~t light emitting from the rear of the -~
laser 22.
-: : ' : .
.... ...... .. .... . .. . .
High frequency capability is provided by several fea-tures. A 50 ohm impedance microstrip line transmits the high speed signal between the laser and an SMA microwave connector 54. A short wirebond between the ~emiconductor -22 and microstrip 56 minimizes parasitic capacitances and inductances. In Figure 2a, the microstrip line 56 opposite the SMA connector 54 provides for only mechanical positioning and serve~ no electrical function.
A second embodiment (not shown) is the same as the first embodiment except that the semiconductor la~er 22 is mounted epi-up. This means that the light emitting region 23 is now near the top surface of the semiconductor die.
The pedestal height 17 must be reduced to of-set the thickneæs of the emiconductor 22 and bring the light-emitting spot 23 back to the axis of the len3 24.
This embodiment offers two advantages over the first embodiment:
The active region 23 feature~ in the -semiconductor are directly visible, allowing more precise alignment to the lateral reference mark 38 on the pedestal 16.
. ,, It allows for epi-up bonding of semiconductor material reducing diebonding yield loss pre~ent with some diebonding æolders and laser structures.
The comparative di~advantage of this design is that 30 the wafer thickne~s now become~ a controlling optical tolerance requiring an additional wafer thinning processing ~tep or alternatively a ~et of calibrated carrier~ with different known pede~tal heights.
It is po~sible to vary the design of package 10 while preserving elements of our invention. Variations could be both internal or external to the package hou~ing. The :'.
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material comprising the package housing 12 may be metal, ceramic or plastic.
External Variations The diameter of the uptapered-fiber 30 may be increased requiring a greater magnification from the lens 24. The greater magnification is achieved by using a different lens or len~ position. This variation, of increasing the magnification, results in further reduction of the lateral positional tolerance.
The length of the thick ~ection of the uptapered-fiber 30 may be altered. A shorter length section would make a more compact package.
The fiber 30 may be held by a variety of different shaped holders but it always needs to be held rigidly. It iB likely that it would always reguire some kind of flange type attachment 34 such as the one in figure 1 to maintain stability.
Some commercial fibers are supplied with flange shaped connectors on the end and it is likely that uptapers will be supplied this way once the uptapers become commercially available. If this happens, the uptapered package may be designed to accommodate the commercial flange rather than have a special package flange.
The mode of fastening the fiber may be varied.
Different types of epoxies, polyesters, solders or welds may be used. In some circumstance~ it may be possible to screw, crimp, or even use an amalgam to attach the fiber 30 holder to the package. :
I nterrlal Variation The package is made more compact by using stronger, shorter focal length lenses. In this case, the end o the upcapered-fiber i~ placed closer to the len~.
In conclusion, we have realized the first la er package to incorporate an uptapered fiber pigtail.
Because of the relaxed alignment tolerances afforded by the uptapered, external alignment and attachment of the fiber can be implemented. The result i~ an easy-to-aæsemble, rugged package that iæ suitable for all local loop applications, and readily lends itself to automated packaging techni~ues.
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.
UPTAPERED SINGLE-MODE OPTICAL EIB~R PACKAGE
FOR OPTOELECTRONIC CO~PONENTS
This invention relates to packaging of optoelectronic components which generate or process ~ignals that pasis through optical fiber~. In particular, it addresi3es the critical need for providing stable, low-cost alignment of single-mode optical fibers to a single packaged device, such as a semiconductor la~er.
An optoelectronic package is a container or housing that provides protection and isupport for both active and passive components contained within it. These components and their interconnection represent an optical-electrical circuit and define the function of the package. The package also includes a means of connecting the internal components with the external environment, usually as electrical feed-through and optical fiber. Our invention is concerned with the optical fiber and how it i8 :,' .
connected to the components within the package.
To make an optical connection between an optical fiber and an optoelectronic component within a package, it is necessary to position or align the optical fiber in a way that allow~ efficient coupling between the optical fiber and the optoelectronic component. The preci~ion needed for the alignment depends on the ~ize of the light-emitting or light receiving elements, the type of optical fiber, and any type of focusing or defocusing elements which may be present. Optical fiber transmiti3 light ~through iti~ inner core, which is much smaller than the diameter of the optical fiber. There are two classes of optical fiber preisently used in packaging eemiconductor devices: single-mode and multi-mode, with typical core diameters of about 10 microns and 50 microns, respectively. Many telecommunication applications use ~ ~ :
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89~3-700 -2- ~ J~
single-mode optical fiber because of the superior band-width arising from its reduction of mode partition noise.
The prior art for packaging semiconductor lasers is predominantly concerned with the easy task of aligning large cored multi-mode optical fiber. Multi-mode optical fiber is of little value for telecommunications because it suffers from mode-partition noise when used for high speed transmissions over a distance.
Laser packaging with single-mode optical fiber has been done with optical fibers which have their ends either cleaved or tapered and lensed. A cleaved optical fiber has an optically flat end, while a tapered and lensed optical fiber is drawn down to a point in a fashion that aids light entering the fiber. Packages incorporating cleaved optical fibers require a separate lens, as does the package of this invention, while packag~s incorporating lensed optical fibers do not.
Packages utilizing cleaved or tapered and lensed optical fibers ~uffer from stability problems associated with lateral movement of the optical fiber with respect to the laser. For this reason, the alignment of the optical fiber with the laser for such packages is u~ually done with expensive piezo-crystal micromanipulators having submicron sensitivity. The optical fiber is fa~tened with expensive laser welding technigues or special solders.
As explained by Rideout, et al, "Improved LED and laser packaging using up-tapered single mode fibers," CLE0 '89, Baltimore, MD, April 25, 1989, the improved lateral -tolerances arise from first magnifying the emitting spot image of the laser. The larger spot is then projected congruently onto the corresponding uptapered optical fib-r. The lateral and angular sensitivities are:
" . .
.
89-3-700 -3~ d, ~, ,, 1 Lateral coupling ~ exp x wOZ :,.
"
Angular decoupling = exp -~2wO2/~2 2 :' where the 9ymbol s mean:
wO = spot radius of the optical fiber;
~ = wavelength ~ = angular misalignment x = lateral misalignment . .
The equations show that the spot radius of the light beam in the optical fiber determines these sensitivities.
Since the spot radiu~ is in the denominator of the lateral decoupling expression above, the benefit of decreased lateral sensitivity occur~ with increased spot size.
Conversely, the angular sensitivity becomes more detrimental since the spot radius is in the numerator of the angular mi~alignment expression above.
When performing optical fiber alignments, the lateral alignment is more difficult to achieve than the angular ;
alignment. Thus, the net effect of u~ing a lens to magnify the spot radius of the light heam for coupling it to~ a larger diameter uptaperQd optical fiber is benefi-cial.
It is worth noting that even though the thick section of the uptapered optical fiber does not qualify as a single-mode optical fiber diameter, it i8 short enough in length that it maintains only the single-mode. Thus, it possible to obtain the advantage of the ease of alignment~of a thick multi-mode optical fiber, while not ; losing the data transmission advantage of a thin single-mode optl~al fiber.
According to one aspect of the invention, there is provided a package for an optoelectronic semiconductor device having a photo-active element optically coupled to an uptapered single-mode optical fiber connecting said optoelectronic device to an external device, comprising:
a housing to enclose the necessary components to convert electrical signals to optical signals; a substrate carrier having a solderable surface within said housing; an :-optoelectronic device having an photo-active element secured to said substrate carrier; a lens, having a numerical aperture sufficient to access optically said photo-active element secured to said carrier a fixed distance from said photo-active element to yield a deæired magnification of a light beam emanating from ~aid photo-active element by expanding the size of said beam;
an uptapered single-mode optical fiber extending from within said housing to the exterior of said housing through a port thereof, said optical fiber being . .
positioned by active alignment; means to secure ~aid uptapered optical fiber to said housing such that the uptapered end of said optical fiber is optically coupled through said lens to said photo-active element and the ~.
opposite end of said optical fiber is outside said ~.
housing; and a plurality of reference means on said housing and said carrier such that said optoelectronic device, said lens and said optical fiber are mechanically positioned with respect to one or more of said reference means; and such that uptapered said optical fiber is ::
externally aligned and ~ecured to said package.
According to another a~pect of the invention, there is provided a method of optically coupling an uptapered ~ingle-mode optical fiber to a spaced-apart photoactive element, said element integrated with a substrate carrier ~: and a lenæ within a housing, comprising the steps o:
spatially positioning aid element with respect to a fir~t pre-existing reference and then securing said spatially '.:
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89-3-700 ~5~ ~ r~ r~ ~ r~
positioned element to said substrate carrier; positioning said lens with respect to a second pre-existing reference and then securing said positioned lens to said substrate ,~
carrier, said lens having a numerical aperture suficient to optically access said photoactive element and yield an appropriate magnification of a light beam emanating from said photoactive element; positioning the uptapered end of said fiber with respect to a third pre-existing reference and then actively aligning said fiber with said magnified light beam such that the uptapered end is optically coupled through said lens to said photoactive element; and securing said actively aligned fiber to said housing. :
Some embodiments of the invention will now be de~cribed, by way of example, with reference to the accompanying drawings in which: -Fig. 1 is a schematic perspective view of a generalized embodiment of an optoelectronic package which illuqtrates a package according to the principles of the invention and the method of packaging an optoelectronic component according to the invention using reference marks to mechanically align an uptapered optical fiber to a semiconductor laser;
Figs. 2a, 2b and 2c are, re~pectively, top, side and end views of the preferred embodiment of an optoelectronic package, according to one embodiment of the invention;
Fig. 3 is a partially cut-away top view o the embodiment of an optoelectronic package of Fig. 2a, ` enlarged to show details of the package; and ;30 ~ Fig.~ 4 i~ a top view of the embodiment of Fig. 2a, - urther enlarged to show details of substrate carrier.
This~ invention pertains to packages for optoeleatronic devices which provide stable alignment, using~a mechanical method for quick and efficient optical coupl~irg~of ~an uptapered slngle-mode optical fiber to th-~ , ' " ~ . . :
:
photo-active spot of the semi-conductor element. The package controls the uptapered fiber optical tolerances, allowing a relaxation of the optical fiber positional tolerance.
The package of this invention use~ a lens, with a sufficient numerical aperature and magnification, in conjunction with uptapered single-mode optical fiber. The alignment technique takes advantage of the relaxed mechanical tolerance and the magnification provided by the lens and the larger cored uptapered fiber optics. Such optical connections then permit independent transfer of telecommunications data and information for the semiconductor element. ` "
Specifically, thi 8 invention provides a new package for optically coupling an uptapered ~ingle-mode optical fiber to a single packaged optoelectronic device u ing a single len~ mechanically aligned with the semiconductor element in order to magnify the spot image of the photo-active element to expand the size of the emitted light beam. This image i8 then coupled to an uptapered optical fiber. This magnification greatly facilitates mechanical alignment and coupling of the semiconductor laser to the a~sociated optical fiber by relaxing mechani- ,`~
cal tolerances associated with the position of the ray of light coming from the laser.
Uptapered optical fibers are used because the effect of magnification increases the size of the beams or spot.
These beams are best collected on the thick end of the uptapered fiber, where the size of the optical fiber best matches the size of the beams. For example, a typical uptapered optical fiber may have a core that is ten times larger on its thick end than the single-mode optical fiber that it tapers down to. This optical fiber is u~ed with a len~ that magnifies the spot size of the beam tenfold.
mis eff~ct facilitates the alignment when assembling an optoelectronic package.
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~ 3 Mechanical alignment is also possible with thesepackages because the location of the semiconductor beam can be known with high precision relative to the package.
This i8 because the semiconductor photo-active element i~
usually patterned on the semiconductor with photolithography to a high level of precision, about one micron, and the lens projects a precise image of khis pattern towards the fiber. If a lens with known magnification is first positioned rigidly in a specified location, then the location of the projected beam is know.
Alignment to this beam automatically aligns the uptapered optical fiber held in a fixture engineered with the geometry set by the known magnification determined by the lens.
Figure 1 illustrates a generalized package for an optoelectronic component and a method for assembling the package, according to this invention. Package 10,~ shown partially cut-away in Fig. 1, comprises a housing 12, which completely enclo~es the necessary components that convert input electrical signals to optical signals.
Preferably, housing 12 i~ made of brass and has a removable top for access to the interior. A carrier 14 having a surface that is readily solderable, such as gold-plated copper or brass, is used to support the components. A pedestal 16 is secured to a first ma~or , surface of carrier 14 adjacent to a first end wall 15 of hou~ing 12, for mounting and positioning a æemiconductor laser 22 having a photo-active spot 23. Two lateral stops 18~and~ two axial stops 20 are also secured in a central location to the same major~ surface of carrier 14 for positioning a lens 24, which is hard soldered prior to the optical fiber alignment. Preferably carrier 14, pede~tal 16 -nd~stops 18, 20 are integrally formed as a one-piece element. ~A thermoelectric cooler 26 is secured to the second ~ajor surface of carrier 14. A ~econd end wall 28 has a circular opening (not shown in Fig. 1) to permit the insertion of the thick end of uptapered optical fiber 30, which is enclosed in a fiber tube 32 and rigidly held perpendicular to end wall 28 by a large flange 34. The -lens 24 focuses the light from the photoactive spot 23 of laser 22 onto uptapered optical fiber 30.
A plurality of mechanical features, and regi~tration features and/or reference marks are incorporated into housing 12 and carrier 14 so that the total package 10 mechanically controls the uptapered~fiber optical tolerances, thus allowing a relaxation of the uptapered optical fiber positional tolerance. The uptapered-fiber optical tolerances controlled by package 10 are, the semiconductor position, the lens-to-semiconductor distance; the stability of lens attachment; and the tight angular control of the uptapered fiber.
A one-piece carrier 14 holds the laser 22 and the lens 24. Thiæ controls the stability of the lens-to-semiconductor positional tolerance. Semiconductor 22 and lens 24 move in unison, despite shifts in other package parts caused by vibrations or thermal variations.
The lens 24 is hard soldered prior to doing the optical fiber alignment to provide mechanical stability. For thi~
optical element, lens 24, stability is more important than exact positioning. Some misalignment of the lens 24 can be compensated for during alignment of the uptapered optical fiber 30.
The height of pedestal 16 controls the height of laæer 22 (y-axis). The forward edge 36 of pedestal 16 serves as the forward reference mark for la~er 22 3~ (z-axi~). A lateral reference mark 3~ on pede~tal 16 is aligned with an active region reference mark 40 on laser 22~(x-axis) to control the lateral position of la~er 22.
Axial stop~ 20 control the lens-to-semiconductor di~tance, while Iateral stops 18 control the horizontal alignment of the lens 24 to the photo-active spot 23 of laser 22. The relative positioning of the laæer 22 and the lens 24 is ~ -~: '' ~' .
. .
, usually set to a positional accuracy of about one-half mil. This can be done off-line under a stereomicroscope, making use of the reference marks 36, 3~, 40.
The position of the lenæ 24 sets the magnification of the light-emitting area (photo-active spot 23) of laser 22. The magnification is set to best match the projected emitting area size with the core of the uptapered optical fiber 30. The proper magnification position is set by the axial and lateral stops 18, 20, which are registration features on the carrier 14.
The uptapered optical fiber 30, protected by a fiber tube holder 32, is mounted and aligned externally to the package 10. The uptapered end of optical fiber 30 extends inside the package to a fiber tip reference mark 42 on carrier 14, which is a known distance from axial lens stops 20. The package cover (not shown in the figures) is in place, so that the interior of the package is protected from damage. After fiber positioning, using reference marks 42, 20 the uptapered optical fiber 30 is actively aligned, requiring only crude low co~t micro-meters and is secured in position with simple means such a8 epoxy or screws (not shown in Fig. 1). Active alignment mean# the fiber is aligned to maximize the light beam entering the fiber while the laser is operating. The uptapered optical ~` fiber 30 and the fiber tube holder 32 are easily removed and replaced for packages that have suffered fiber damage, be~ause~ interior parts need not be disturbed. The `~
uptapered optical fiber i8 held perpendicular to the pack`age by~a large fiber~ 1ange 34 on the iber tube holder 32. Thi~ controls the angular uptapered optical flber ~optlcal tolerance. It also improves stability be;cause~an~uptapered optical fiber is more sensitive to angular misalignment than a conventional tapered and lensed~or cleaved fiber.
A long focal distance between the lens 24 and the uptapered end of optlcal fiber 30 allows space to , - - . - ., --.. - , , ., , . , , . , ", . .. . ......... .. .. .. ... .... . .. .. . ... .....
q introduce optical elements such as filters and opto-isolators. In this space the light beam is nearly collimated, greatly simplifying the optical designs incorporating these elements.
The carrier 14 supporting the lens 24 and semiconductor 22 could ibe part of a circuit board, multi-chip module, or ~emiconductor waferboard carrying -~
other optical and electro~ic components.
The lens 24 could be either a GRIN type, convex, 10 plano-convex, or combination of several lenses. The only i -requirement is that it provide the necessary magnification to match light spot sizes with the uptapered end of optical fiber 30. -Internal optical elements, such as opto-isolator~ or ~ -filters, can be located in the space between the lens 24 and the fiber 30 in any combination. Optical coatings could also be placed on the lens 24 to provide some of the function of these optical element~.
The registration or reference marks 18, 20, 36, 38, 42 on the carrier can be either mechanical stops, slots, pin~, visual lines, steps or the like. The only requirement i~ that they be part of the carrier 14 and provide half mil or better accuracy for the lens 24 and the semiconductor 22 positions.
Fig. 1 show~ the uptapered-fiber laser package with the lid removed so that the components are vi~ible. This package incorporates an externally aligned uptapered fiber 30, which is aligned and epoxied onto the outside of the package housing 12 at room temperature. This is the only active alignment, and can be performed without piezoelectric ~taging because of the relaxed lateral alignment tolerances. An AR-coated GRIN lens images the laser spot onto the uptapered fiber. Thi~ lens is soldered in place with high temperature ~older for maximum ~ -stability. ~
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89-3-700 -11- ' ~
Figures 2a, 2b, 2c, 3 and 4 illustrate details of the preferred embodiment of the uptapered single-mode optical fiber package according to the invention, aæ built and te~ted by the inventors. In these figures, the same reference numbers are used for corresponding parts as were used in Fig. 1. Some elements not part of the invention are shown in the figures and mentioned in the specification without further elaboration.
Figures 2a, 2b and 2c are top, side and end views of the preferred embodiment of package 10, illustrating its assembly. The following items are specific to thiæ
embodiment. A graduated index (GRIN) lens is used for lens 24. A thermo-electric temperature control (TEC) 26 is present. This package is designed for epi-down semiconductor mounting. The carrier 14 doeæ not extend the full length of the housing 12, so the fiber tip reference mark 42 is on the base of the housing. A
precision fiber tube 32 having an epoxy fill tube 60 for securing the optical fiber 30 after alignment holds the uptapered end of the optical fiber. Fiber tube flange 34 surrounding fiber tube 32 is faætened wlth epoxy to the outside of the at epoxy joint 62 to complete the alignment.
A screw mounting slot 50 i 8 present. An SMA
connector socket 54, a high freguency microline 56 connected thereto, and seven d.c. in-line pin outs to provide high æpeed electrical signalæ complete the package~. ~The package housing 12, the fiber tube 32, and the cover (not shown) are preferably, made of brass.
~Carrier~14 is~preferably made of nickel and gold-plated copper. Package 10 in this embodiment is a high speed laser package having the uptapered fiber optical tolerance controls built into the package.
me~ laserc used in this package are 1.3 ~m Vapor-Phase-Regrowth Burled Heterostructure (VPR-BH) lasers whi~h have a demonstrated maximum bandwidth of 22 GHz and typical bandwidths of 15 GHz. Previously developed microstrip techniques are used to preserve the high frequency integrity of the package to 25GHz.S
Measurements of the variation in output power with slight changes in axial position of the uptapered indicate that back reflections which might introduce noise are less than -45 dB.
Excellent packaged coupling efficiencies of approximately 30% are obtained, which compare favorably to the maximum of 35% obtained on the laboratory bench, and 22% which are obtained using standard tapered-and-lensed fibers with a 12 ~m radius tip and a 30 included angle.
The lens 24 used is a SELFOC GRIN lens (model PCH 1.8 - 0.22). The uptapered fiber 3V used was made at GTE
Laboratories Incorporated. It has an uptapered core size of 90 ~ and a single mode fiber core size 9 ~. The fiber has a cut and polished tip to reduce light scattering ~oss.
The features of the package that control the uptapered-fiber optical tolerances are shown in Table I.
Based on measurements of the package, the mechanical optical tolerances are shown in Table I. The use of a one piece carrier 14 eliminates tolerance "stack-up" arising if separate pedestal, lateral, and axial ~tops were bonded to the carrier.
, .
; ~ ', -' Table I. Packaae OPtical Control Tolerance~
Control Point Tolerance fiber tip reference 5.0 mils fiber tube flange 0.5 of arc axial stops 0.5 mils lateral stops 0.5 mil~
pedestal height 0.5 mils active region reference 0.1 mils*
lateral reference 0.5 mils forward reference mark 0.5 mils _ .
*this item is normally defined with photolithography This embodiment uses epi-down lasers. This eliminates the positional tolerance associated with the thicknes~ of the wafer because the light emitting area i~ . -essentially at the pedestal/semiconductor interface. A
reference mark 40 on the laser 22 enables its correct positioning on the pedestal 16 during assembly since the actiYe~region 23 in the semiconductor 22 is on the reverse side and not visible.
The GRIN lens 24 straddles a slot that determines its height`above the carrier and its lateral position. The back edge of the lens registers With a raised edge on the .
carrier 14 that defines the axial stop 20.
Table I compares observed tolerances for the uptapered fiber package with those of a typical ns:ed-and-tapered fiber package. These tolerances represent the measured misalignment which reduces the coupled power ~by about 25%. 2 The mo#t important implications of this table for package design are: 1) -the r-laxed tolerance in~ the uptapered fiber po~ition lateral and transverse)~is responsible for the increased yièld, atability, and ea~e of assembly, 2) Critical tolerances (angular alignment and magnification) are met by built-in alignment marks and stops in the one-piece carrier, fiber flange, and housing, as schematically shown in Figure 1~ The fiber flange was designed to automatically align the uptapered fiber parallel to the beam within 0.5.
Table I: Tolera~ces for Components W thin Package ~-10 AP~roximate UptaperedTapered Tolerance~ Fiberand Len~ed Packaae Fiber Pa~kaqe `:
Fiber position:
axial (parallel to fiber) 125 ~m* 4 ~m ~:
lateral ( 1I to laser) 25 ~m 0.5 ~m transverse (1 to laser) 25 ~m 0.5 ~m ;
Fiber angle 0.5 12 20 GRIN len~ 13 ~mNot Applicable :.
Semiconductor laser 13 ~mNot Applicable *component held to within tolerance by æelf-alignment to package hardware.
: ' Figures 3 and 4 are enlarged top views of the embodiment of Fig. 2a, showing further details of the package feature~ which mechanically control the fiber .
optic tolerances. Referring now to these figures, two 30 optical path distances, Ll (Eig. 4) and L2, (Fig. 3) ~ ;
should:be maintained to achieve the correct magniflcation. .
in the package 10. Ll is the distance between laser 22 and lens 24 while L2 is the distance between lens 24 and uptapered-fiber 50. Distance L1 was 15.5 mils. A ~.
magni~ication of 10 was used to optically match the .-, : ~ ''' -.~..
semiconductor ~pot size 23 with the uptapered core.
Distance Ll can be checked with a low power (30x) stereomicroscope. Distance L2 is controlled by setting the fiber ~ip at the fiber tip reference mark. L2 is 0.475 inches. ~ -For ætability, the GRIN lens 24 is soldered to the carrier 16 with a reasonably hard 52/48 In/Sn 118 C
solder. The solder should be reflowed, and the lens position adjusted along its slot if Ll i~ found incorrect when checked.
Following active alignment, a bead of epoxy is applied to both the fiber tube flange 34 and the tube 32 epoxy fill hole 60. Our package allows its cover to be in place during the alignment.
The fiber tube flange 34 controls the fiber angle at 90. The package normally does not require angular align-ment. Only translational alignment is needed.
Our uptapered fiber 30 requires an angular alignment of one half degree of arc. If the tolerance~ listed in Table I are maintained, and the Ll position is checked and adju~ted properly, the package will achieve this.
If these tolerances are not strictly held, good alignment~ are still possible, but the active alignment process must include angular alignment of the fiber 30 rather than just lateral alignment. This i8 done by varying the angle of the fiber tube 32 slightly about the horizontal and vertical axes. Epoxy may still be u~ed to join 62 the flange to the package.
The completed package offers both temperature and optical power monitoring of the semiconductor 22.
Temperature regulation is provided by the thermoelectric cooler 26 as controlled by the thermistor 30. Optical power monitoring i provided by the rear facet detector 72 that mea#ures the lo~t light emitting from the rear of the -~
laser 22.
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High frequency capability is provided by several fea-tures. A 50 ohm impedance microstrip line transmits the high speed signal between the laser and an SMA microwave connector 54. A short wirebond between the ~emiconductor -22 and microstrip 56 minimizes parasitic capacitances and inductances. In Figure 2a, the microstrip line 56 opposite the SMA connector 54 provides for only mechanical positioning and serve~ no electrical function.
A second embodiment (not shown) is the same as the first embodiment except that the semiconductor la~er 22 is mounted epi-up. This means that the light emitting region 23 is now near the top surface of the semiconductor die.
The pedestal height 17 must be reduced to of-set the thickneæs of the emiconductor 22 and bring the light-emitting spot 23 back to the axis of the len3 24.
This embodiment offers two advantages over the first embodiment:
The active region 23 feature~ in the -semiconductor are directly visible, allowing more precise alignment to the lateral reference mark 38 on the pedestal 16.
. ,, It allows for epi-up bonding of semiconductor material reducing diebonding yield loss pre~ent with some diebonding æolders and laser structures.
The comparative di~advantage of this design is that 30 the wafer thickne~s now become~ a controlling optical tolerance requiring an additional wafer thinning processing ~tep or alternatively a ~et of calibrated carrier~ with different known pede~tal heights.
It is po~sible to vary the design of package 10 while preserving elements of our invention. Variations could be both internal or external to the package hou~ing. The :'.
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material comprising the package housing 12 may be metal, ceramic or plastic.
External Variations The diameter of the uptapered-fiber 30 may be increased requiring a greater magnification from the lens 24. The greater magnification is achieved by using a different lens or len~ position. This variation, of increasing the magnification, results in further reduction of the lateral positional tolerance.
The length of the thick ~ection of the uptapered-fiber 30 may be altered. A shorter length section would make a more compact package.
The fiber 30 may be held by a variety of different shaped holders but it always needs to be held rigidly. It iB likely that it would always reguire some kind of flange type attachment 34 such as the one in figure 1 to maintain stability.
Some commercial fibers are supplied with flange shaped connectors on the end and it is likely that uptapers will be supplied this way once the uptapers become commercially available. If this happens, the uptapered package may be designed to accommodate the commercial flange rather than have a special package flange.
The mode of fastening the fiber may be varied.
Different types of epoxies, polyesters, solders or welds may be used. In some circumstance~ it may be possible to screw, crimp, or even use an amalgam to attach the fiber 30 holder to the package. :
I nterrlal Variation The package is made more compact by using stronger, shorter focal length lenses. In this case, the end o the upcapered-fiber i~ placed closer to the len~.
In conclusion, we have realized the first la er package to incorporate an uptapered fiber pigtail.
Because of the relaxed alignment tolerances afforded by the uptapered, external alignment and attachment of the fiber can be implemented. The result i~ an easy-to-aæsemble, rugged package that iæ suitable for all local loop applications, and readily lends itself to automated packaging techni~ues.
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Claims (47)
1. A package for an optoelectronic semiconductor device having a photo-active element optically coupled to an uptapered single-mode optical fiber connecting said optoelectronic device to an external device, comprising:
a housing to enclose the necessary components to convert electrical signals to optical signals;
a substrate carrier having a solderable surface within said housing;
an optoelectronic device having an photo-active element secured to said substrate carrier;
a lens, having a numerical aperture sufficient to access optically said photo-active element secured to said carrier a fixed distance from said photo-active element to yield a desired magnification of a light beam emanating from said photo-active element by expanding the size of said beam;
an uptapered single-mode optical fiber extending from within said housing to the exterior of said housing through a port thereof, said optical fiber being positioned by active alignment;
means to secure said uptapered optical fiber to said housing such that the uptapered end of said optical fiber is optically coupled through said lens to said photo-active element and the opposite end of said optical fiber is outside said housing; and a plurality of reference means on said housing and said carrier such that said optoelectronic device, said lens and said optical fiber are mechanically positioned with respect to one or more of said reference means; and such that uptapered said optical fiber is externally aligned and secured to said package.
a housing to enclose the necessary components to convert electrical signals to optical signals;
a substrate carrier having a solderable surface within said housing;
an optoelectronic device having an photo-active element secured to said substrate carrier;
a lens, having a numerical aperture sufficient to access optically said photo-active element secured to said carrier a fixed distance from said photo-active element to yield a desired magnification of a light beam emanating from said photo-active element by expanding the size of said beam;
an uptapered single-mode optical fiber extending from within said housing to the exterior of said housing through a port thereof, said optical fiber being positioned by active alignment;
means to secure said uptapered optical fiber to said housing such that the uptapered end of said optical fiber is optically coupled through said lens to said photo-active element and the opposite end of said optical fiber is outside said housing; and a plurality of reference means on said housing and said carrier such that said optoelectronic device, said lens and said optical fiber are mechanically positioned with respect to one or more of said reference means; and such that uptapered said optical fiber is externally aligned and secured to said package.
2. The package of claim 1 wherein:
said substrate carrier includes a pedestal integrally formed with said substrate;
said optoelectronic device is mounted on said pedestal; and said reference means include the upper surface and one side surface of said pedestal, and a reference mark on said upper surface for alignment with a reference mark on said optoelectronic device.
said substrate carrier includes a pedestal integrally formed with said substrate;
said optoelectronic device is mounted on said pedestal; and said reference means include the upper surface and one side surface of said pedestal, and a reference mark on said upper surface for alignment with a reference mark on said optoelectronic device.
3. The package of claim 1 wherein said reference means for mechanically positioning said lens on said carrier comprises:
a pair of spaced apart lateral stops integrally formed with said carrier; and a pair of spaced apart axial stops integrally formed with said carrier;
such that said lens is rigidly positioned between each pair of stops in alignment with said photo-active spot and said uptapered optical fiber.
a pair of spaced apart lateral stops integrally formed with said carrier; and a pair of spaced apart axial stops integrally formed with said carrier;
such that said lens is rigidly positioned between each pair of stops in alignment with said photo-active spot and said uptapered optical fiber.
4. The package of claim 1 wherein said reference means for mechanically positioning said uptapered optical fiber further comprise:
a reference mark within said housing to position the uptapered end of said optical fiber; and a reference surface on the side wall of said housing through which said fiber passes
a reference mark within said housing to position the uptapered end of said optical fiber; and a reference surface on the side wall of said housing through which said fiber passes
5. The package of claim 1 wherein said lens is a graded index lens and is secured to said carrier with a moderate melting point solder.
6. The package of claim 1, further comprising:
a thermoelectric cooler positioned under said substrate carrier within said housing to maintain a stabilized temperature for said optoelectronic device.
a thermoelectric cooler positioned under said substrate carrier within said housing to maintain a stabilized temperature for said optoelectronic device.
7. The package of claim 4 wherein said means to secure said uptapered optical fiber to said housing comprises:
support means for said uptapered optical fiber, said support being positioned and secured at the port of said housing through which said uptapered optical fiber extends.
support means for said uptapered optical fiber, said support being positioned and secured at the port of said housing through which said uptapered optical fiber extends.
8. The package of claim 7 wherein said support means further comprises:
a fiber tube adapted to receive an uptapered optical fiber in a fiber-receiving position which is determined by the photo-active element-to-lens spacing, such that said uptapered optical fiber may be optically coupled to said photo-active element through said lens;
said uptapered optical fiber in said fiber tube being positioned with respect to said reference means, actively aligned with said photo-active element, and secured in an aligned position within said fiber tube;
means to secure said fiber tube to said housing with said fiber in its aligned position.
a fiber tube adapted to receive an uptapered optical fiber in a fiber-receiving position which is determined by the photo-active element-to-lens spacing, such that said uptapered optical fiber may be optically coupled to said photo-active element through said lens;
said uptapered optical fiber in said fiber tube being positioned with respect to said reference means, actively aligned with said photo-active element, and secured in an aligned position within said fiber tube;
means to secure said fiber tube to said housing with said fiber in its aligned position.
9. An uptapered single-mode optical fiber package providing mechanically precise, stable alignment of an uptapered optical fiber with a semiconductor laser having a photo-active element within said package, comprising:
a housing to enclose the necessary components to convert electrical signals to optical signals;
a substrate carrier having a solderable surface within said housing;
a plurality of reference means positioned on said housing and said substrate carrier;
an optoelectronic laser device having a photo-active element and having a reference means, secured to said substrate carrier in alignment with a first set of corresponding reference means;
a graded index lens, having a numerical aperture sufficient to access optically said photo-active element aligned with a second set of reference means and secured to said substrate a fixed distance from said photo-active element to yield a desired magnification of a light beam emanating from said photo-active element;
an uptapered single-mode optical fiber extending from within said housing to the exterior of said housing through a port thereof for connection of said laser to a device external to said housing;
fiber positioning means to mechanically align said uptapered optical fiber with respect to a third set of reference means and to support said uptapered optical fiber in said aligned position, said optical fiber being positioned by active alignment and secured to said fiber positioning means such that the uptapered end of said optical fiber is optically coupled through said lens to said photo-active element of said laser and the opposite end of said optical fiber is outside said housing, and such that the distance between said uptapered end of said optical fiber and said lens and the distance between said lens and said active element is prespecified by said reference means; and said fiber positioning means being secured to said package with said optical fiber in said aligned position.
a housing to enclose the necessary components to convert electrical signals to optical signals;
a substrate carrier having a solderable surface within said housing;
a plurality of reference means positioned on said housing and said substrate carrier;
an optoelectronic laser device having a photo-active element and having a reference means, secured to said substrate carrier in alignment with a first set of corresponding reference means;
a graded index lens, having a numerical aperture sufficient to access optically said photo-active element aligned with a second set of reference means and secured to said substrate a fixed distance from said photo-active element to yield a desired magnification of a light beam emanating from said photo-active element;
an uptapered single-mode optical fiber extending from within said housing to the exterior of said housing through a port thereof for connection of said laser to a device external to said housing;
fiber positioning means to mechanically align said uptapered optical fiber with respect to a third set of reference means and to support said uptapered optical fiber in said aligned position, said optical fiber being positioned by active alignment and secured to said fiber positioning means such that the uptapered end of said optical fiber is optically coupled through said lens to said photo-active element of said laser and the opposite end of said optical fiber is outside said housing, and such that the distance between said uptapered end of said optical fiber and said lens and the distance between said lens and said active element is prespecified by said reference means; and said fiber positioning means being secured to said package with said optical fiber in said aligned position.
10. The package of claim 9 wherein:
said substrate carrier includes a pedestal integrally formed with said substrate;
said optoelectronic device is mounted on said pedestal; and said reference means include the upper surface and one side surface of said pedestal, and a reference mark on said upper surface for alignment with a reference mark on said optoelectronic device.
said substrate carrier includes a pedestal integrally formed with said substrate;
said optoelectronic device is mounted on said pedestal; and said reference means include the upper surface and one side surface of said pedestal, and a reference mark on said upper surface for alignment with a reference mark on said optoelectronic device.
11. The package of claim 9 wherein said reference means for mechanically positioning said lens on said carrier comprises:
a pair of spaced apart lateral stops integrally formed with said carrier; and a pair of spaced apart axial stops integrally formed with said carrier;
such that said lens is rigidly positioned between each pair of stops in alignment with said photo-active spot and said uptapered optical fiber.
a pair of spaced apart lateral stops integrally formed with said carrier; and a pair of spaced apart axial stops integrally formed with said carrier;
such that said lens is rigidly positioned between each pair of stops in alignment with said photo-active spot and said uptapered optical fiber.
12. The package of claim 9 wherein said reference means for mechanically positioning said uptapered optical fiber further comprise:
a reference mark within said housing to position the uptapered end of said optical fiber; and a reference surface on the side wall of said housing through which said fiber passes.
a reference mark within said housing to position the uptapered end of said optical fiber; and a reference surface on the side wall of said housing through which said fiber passes.
13. The package of claim 9 wherein said graded index lens is secured to said substrate with a moderate melting point solder.
14. The package of claim 9, further comprising:
a thermoelectric cooler positioned under said substrate carrier within said housing to maintain a stabilized temperature for said semiconductor laser device.
a thermoelectric cooler positioned under said substrate carrier within said housing to maintain a stabilized temperature for said semiconductor laser device.
15. The package of claim 12 further comprising:
a support means for said uptapered optical fiber, said support means being positioned at the port of said housing through which said optical fiber extends.
a support means for said uptapered optical fiber, said support means being positioned at the port of said housing through which said optical fiber extends.
16. The package of claim 15 support wherein said support means for said uptapered optical fiber comprises:
a fiber tube adapted to receive an uptapered optical fiber in a fiber-receiving position which is determined by the active element-to-lens spacing, such that said uptapered optical fiber may be optically coupled to said active element of said semiconductor laser through said lens;
said optical fiber in said fiber tube being actively aligned with said photo-active element and secured in said aligned position; and a fiber tube flange to secure said fiber tube to said housing with said fiber in alignment with said semiconductor and with said third set of reference means.
a fiber tube adapted to receive an uptapered optical fiber in a fiber-receiving position which is determined by the active element-to-lens spacing, such that said uptapered optical fiber may be optically coupled to said active element of said semiconductor laser through said lens;
said optical fiber in said fiber tube being actively aligned with said photo-active element and secured in said aligned position; and a fiber tube flange to secure said fiber tube to said housing with said fiber in alignment with said semiconductor and with said third set of reference means.
17. An improved package providing for the precise, secure alignment of an uptapered single-mode optical fiber to a single packaged optoelectronic laser device having a light-emitting source, said package including:
a housing to enclose the necessary components to convert electrical signals to optical signals;
a substrate carrier having a solderable surface within said housing;
an optoelectronic laser device having a light-emitting source positioned on and secured to said substrate;
a graded index lens having a numerical aperture sufficiently large to optically access the light-emitting sources of said optoelectronic array; wherein the improvement comprises:
a plurality of reference means located on said housing and said substrate;
a portion of said substrate being adapted to receive said laser and said lens;
said optoelectronic laser device being positioned mechanically with respect to a first set of reference means;
said graded index lens being mechanically positioned with reference to a second set of reference means and secured to said substrate of a fixed distance from said laser such that the light beams from said light-emitting source are magnified and the spacing between said beams is expanded;
said uptapered optical: fiber being mechanically positioned with respect to a: third set of reference means and actively aligned with said light-emitting source by optically coupling the thick end of said untapered single-mode optical fiber to a light beam emanating from said laser after said beam has been magnified by said lens;
and said means to secure said uptapered optical fiber to said package after alignment.
a housing to enclose the necessary components to convert electrical signals to optical signals;
a substrate carrier having a solderable surface within said housing;
an optoelectronic laser device having a light-emitting source positioned on and secured to said substrate;
a graded index lens having a numerical aperture sufficiently large to optically access the light-emitting sources of said optoelectronic array; wherein the improvement comprises:
a plurality of reference means located on said housing and said substrate;
a portion of said substrate being adapted to receive said laser and said lens;
said optoelectronic laser device being positioned mechanically with respect to a first set of reference means;
said graded index lens being mechanically positioned with reference to a second set of reference means and secured to said substrate of a fixed distance from said laser such that the light beams from said light-emitting source are magnified and the spacing between said beams is expanded;
said uptapered optical: fiber being mechanically positioned with respect to a: third set of reference means and actively aligned with said light-emitting source by optically coupling the thick end of said untapered single-mode optical fiber to a light beam emanating from said laser after said beam has been magnified by said lens;
and said means to secure said uptapered optical fiber to said package after alignment.
18. The improved package of claim 17 wherein said alignment further comprises:
a fiber tube adapted to receive said uptapered optical fiber and to position said fiber with reference to said third set of reference means;
said graded index lens having a predetermined magnification factor being positioned and rigidly secured such that a beam between said optoelectronic laser and said optical fiber passes through the center of said lens;
the position of said lens being determined by the precise location of said light-emitting source as determined by said first et of reference means and the precise location of said second set of reference means such that said activated light-emitting sources as magnified by said graded index lens are coupled to said uptapered fiber; and said uptapered optical fiber being secured to said package such that said optical fiber is positioned to be coupled with a beam of known location and size emanating from said activated light-emitting source.
a fiber tube adapted to receive said uptapered optical fiber and to position said fiber with reference to said third set of reference means;
said graded index lens having a predetermined magnification factor being positioned and rigidly secured such that a beam between said optoelectronic laser and said optical fiber passes through the center of said lens;
the position of said lens being determined by the precise location of said light-emitting source as determined by said first et of reference means and the precise location of said second set of reference means such that said activated light-emitting sources as magnified by said graded index lens are coupled to said uptapered fiber; and said uptapered optical fiber being secured to said package such that said optical fiber is positioned to be coupled with a beam of known location and size emanating from said activated light-emitting source.
19. The improved package of claim 18 wherein said optical fiber tube is secured in said aligned position to said housing by a fiber tube flange.
20. The improved package of claim 18 wherein said graded index lens is secured to said substrate with a moderate melting point solder.
21. The improved package of claim 17 further comprising:
a thermoelectric cooler positioned under said substrate carrier within said housing to maintain a stabilized temperature for said optoelectronic laser device.
a thermoelectric cooler positioned under said substrate carrier within said housing to maintain a stabilized temperature for said optoelectronic laser device.
22. The improved package of claim 18 wherein said optical fibers are secured in said fiber tube by a room temperature curing epoxy.
23. The improved package of claim 18 further comprising:
a fiber tube flange adapted to receive an uptapered optical fiber in said a fiber-receiving tube in a position which is determined by the laser-to-lens spacing, such that said uptapered optical fiber may be optically coupled to a correspondingly positioned light-emitting source through said lens;
said uptapered optical fiber in said fiber tube holder being actively aligned with said light-emitting source by the alignment of its optical fiber tube with the corresponding light-emitting source; and said fiber tube holder being secured in its aligned position with epoxy.
a fiber tube flange adapted to receive an uptapered optical fiber in said a fiber-receiving tube in a position which is determined by the laser-to-lens spacing, such that said uptapered optical fiber may be optically coupled to a correspondingly positioned light-emitting source through said lens;
said uptapered optical fiber in said fiber tube holder being actively aligned with said light-emitting source by the alignment of its optical fiber tube with the corresponding light-emitting source; and said fiber tube holder being secured in its aligned position with epoxy.
24. The improved package of claim 17 wherein:
said substrate carrier includes a pedestal integrally formed with said substrate;
said optoelectronic device is mounted on said pedestal; and said reference means include the upper surface and one side surface of said pedestal, and a reference mark on said upper surface for alignment with a reference mark on said optoelectronic device.
said substrate carrier includes a pedestal integrally formed with said substrate;
said optoelectronic device is mounted on said pedestal; and said reference means include the upper surface and one side surface of said pedestal, and a reference mark on said upper surface for alignment with a reference mark on said optoelectronic device.
25. The improved package of claim 17 wherein said reference means for mechanically positioning said lens on said carrier comprises:
a pair of spaced apart lateral stops integrally formed with said carrier; and a pair of spaced apart axial stops integrally formed with said carrier;
such that said lens is rigidly positioned between each pair of stops in alignment with said photo-active spot and said uptapered optical fiber.
a pair of spaced apart lateral stops integrally formed with said carrier; and a pair of spaced apart axial stops integrally formed with said carrier;
such that said lens is rigidly positioned between each pair of stops in alignment with said photo-active spot and said uptapered optical fiber.
26. The improved package of claim 17 wherein said reference means for mechanically positioning said uptapered optical fiber further comprise:
a reference mark within said housing to position the uptapered end of said optical fiber; and a reference surface on the side wall of said housing through which said fiber passes.
a reference mark within said housing to position the uptapered end of said optical fiber; and a reference surface on the side wall of said housing through which said fiber passes.
27. A method of optically coupling an uptapered single-mode optical fiber to a spaced-apart photoactive element, said element integrated with a substrate carrier and a lens within a housing, comprising the steps of:
spatially positioning said element with respect to a first pre-existing reference and then securing said spatially positioned element to said substrate carrier;
positioning said lens with respect to a second pre-existing reference and then securing said positioned lens to said substrate carrier, said lens having a numerical aperture sufficient to optically access said photoactive element and yield an appropriate magnification of a light beam emanating from said photoactive element;
positioning the uptapered end of said fiber with respect to a third pre-existing reference and then actively aligning said fiber with said magnified light beam such that the uptapered end is optically coupled through said lens to said photoactive element; and securing said actively aligned fiber to said housing.
spatially positioning said element with respect to a first pre-existing reference and then securing said spatially positioned element to said substrate carrier;
positioning said lens with respect to a second pre-existing reference and then securing said positioned lens to said substrate carrier, said lens having a numerical aperture sufficient to optically access said photoactive element and yield an appropriate magnification of a light beam emanating from said photoactive element;
positioning the uptapered end of said fiber with respect to a third pre-existing reference and then actively aligning said fiber with said magnified light beam such that the uptapered end is optically coupled through said lens to said photoactive element; and securing said actively aligned fiber to said housing.
28. The method of aligning a fiber as recited in claim 27 wherein securing said photoactive element to said carrier further includes:
mounting said element on a pedestal integrally formed with said substrate, wherein said first set of reference means includes the upper surface and one side of said pedestal, and a reference mark on said upper surface for alignment with a reference mark on said photoactive element.
mounting said element on a pedestal integrally formed with said substrate, wherein said first set of reference means includes the upper surface and one side of said pedestal, and a reference mark on said upper surface for alignment with a reference mark on said photoactive element.
29. The method of aligning a fiber as recited in claim 27 wherein the positioning of said lens further includes:
concurrently positioning said lens between a pair of spaced apart lateral stops integrally formed with said carrier, and between a pair of spaced apart axial stops integrally formed with said carrier.
concurrently positioning said lens between a pair of spaced apart lateral stops integrally formed with said carrier, and between a pair of spaced apart axial stops integrally formed with said carrier.
30. The method of aligning a fiber as recited in claim 27 further includes the step of:
thermoelectrically cooling said housing to maintain a stabilized temperature for said photoactive element.
thermoelectrically cooling said housing to maintain a stabilized temperature for said photoactive element.
31. The method of aligning a fiber as recited in claim 27 wherein securing said lens to said carrier includes:
soldering said lens to said carrier.
soldering said lens to said carrier.
32. The method of aligning a fiber as recited in claim 27 wherein positioning said fiber further includes:
adaptably receiving said optical fiber in a fiber-receiving position through a fiber tube which is securable to said housing.
adaptably receiving said optical fiber in a fiber-receiving position through a fiber tube which is securable to said housing.
33. The method of aligning a fiber as recited in claim 27 wherein a ratio between the core sizes at the uptapered and downtapered ends of said optical fiber ranges from unity to ten.
34. A method of optically coupling an uptapered single-mode optical fiber to a spaced-apart photoactive element, said element integrated with a substrate carrier and a lens within a housing and said fiber having its uptapered end within said housing and its opposite end outside said housing, comprising the steps of:
determining a location for each of a plural set of reference marks within said housing;
spatially positioning said element with respect to a first set of said reference marks and then securing said positioned element to said carrier;
positioning said lens with respect to a second set of said reference marks and then securing said positioned lens to said substrate, said lens having a numerical aperture sufficient to optically access said photoactive element and yield an appropriate magnification of a light beam emanating from said photoactive element;
positioning the uptapered end of said fiber with respect to a third set of said reference marks and then actively aligning said fiber with said magnified light beam such that the uptapered end is optically coupled through said lens to said photoactive element; and securing said actively aligned fiber to said housing.
determining a location for each of a plural set of reference marks within said housing;
spatially positioning said element with respect to a first set of said reference marks and then securing said positioned element to said carrier;
positioning said lens with respect to a second set of said reference marks and then securing said positioned lens to said substrate, said lens having a numerical aperture sufficient to optically access said photoactive element and yield an appropriate magnification of a light beam emanating from said photoactive element;
positioning the uptapered end of said fiber with respect to a third set of said reference marks and then actively aligning said fiber with said magnified light beam such that the uptapered end is optically coupled through said lens to said photoactive element; and securing said actively aligned fiber to said housing.
35. The method of aligning a fiber as recited in claim 34 wherein securing said photoactive element to said carrier further includes:
mounting said element on a pedestal integrally formed with said substrate, wherein said first set of reference means includes the upper surface and one side of said pedestal, and a reference mark on said upper surface for alignment with a reference mark on said photoactive element.
mounting said element on a pedestal integrally formed with said substrate, wherein said first set of reference means includes the upper surface and one side of said pedestal, and a reference mark on said upper surface for alignment with a reference mark on said photoactive element.
36. The method of aligning a fiber as recited in claim 34 wherein the positioning of said lens further includes:
concurrently positioning said lens between a pair of spaced apart lateral stops integrally formed with said carrier, and between a pair of spaced apart axial stops integrally formed with said carrier.
concurrently positioning said lens between a pair of spaced apart lateral stops integrally formed with said carrier, and between a pair of spaced apart axial stops integrally formed with said carrier.
37. The method of aligning a fiber as recited in claim 34 further includes the step of:
thermoelectrically cooling said housing to maintain a stabilized temperature for said photoactive element.
thermoelectrically cooling said housing to maintain a stabilized temperature for said photoactive element.
38. The method of aligning a fiber as recited in claim 34 wherein securing said lens to said carrier includes:
soldering said lens to said carrier.
soldering said lens to said carrier.
39. The method of aligning a fiber as recited in claim 34 wherein positioning said fiber further includes:
adaptably receiving said optical fiber in a fiber-receiving position through a fiber tube which is securable to said housing.
adaptably receiving said optical fiber in a fiber-receiving position through a fiber tube which is securable to said housing.
40. The method of aligning a fiber as recited in claim 34 wherein a ratio between the core sizes at the uptapered and downtapered ends of said optical fiber ranges from unity to ten.
41. A method of optically coupling an uptapered single-mode optical fiber to a spaced-apart photoactive element, said element integrated with a substrate carrier and a lens within a housing and said fiber having its uptapered end within said housing and its opposite end outside said housing, comprising the steps of:
determining a desired positional arrangement of said element, lens, and fiber relative to one another;
determining a location for each of a plural set of reference marks within said housing in accordance with the desired positioning of said element, lens, and fiber;
placing said reference marks within said housing at said respective locations;
spatially positioning said element with respect to a first set of said reference marks and then securing said positioned element to said carrier;
positioning said lens with respect to a second set of said reference marks and then securing said positioned lens to said substrate, said lens having a numerical aperture sufficient to optically access said photoactive element and yield an appropriate magnification of a light beam emanating from said photoactive element;
positioning the uptapered end of said fiber with respect to a third set of said reference marks and then actively aligning said fiber with said magnified light beam such that the uptapered end is optically coupled through said lens to said photoactive element; and securing said actively aligned fiber to said housing.
determining a desired positional arrangement of said element, lens, and fiber relative to one another;
determining a location for each of a plural set of reference marks within said housing in accordance with the desired positioning of said element, lens, and fiber;
placing said reference marks within said housing at said respective locations;
spatially positioning said element with respect to a first set of said reference marks and then securing said positioned element to said carrier;
positioning said lens with respect to a second set of said reference marks and then securing said positioned lens to said substrate, said lens having a numerical aperture sufficient to optically access said photoactive element and yield an appropriate magnification of a light beam emanating from said photoactive element;
positioning the uptapered end of said fiber with respect to a third set of said reference marks and then actively aligning said fiber with said magnified light beam such that the uptapered end is optically coupled through said lens to said photoactive element; and securing said actively aligned fiber to said housing.
42. The method of aligning a fiber as recited in claim 41 wherein securing said photoactive element to said carrier further includes:
mounting said element on a pedestal integrally formed with said substrate, wherein said first set of reference means includes the upper surface and one side of said pedestal, and a reference mark on said upper surface for alignment with a reference mark on said photoactive element.
mounting said element on a pedestal integrally formed with said substrate, wherein said first set of reference means includes the upper surface and one side of said pedestal, and a reference mark on said upper surface for alignment with a reference mark on said photoactive element.
43. The method of aligning a fiber as recited in claim 41 wherein the positioning of said lens further includes:
concurrently positioning said lens between a pair of spaced apart lateral stops integrally formed with said carrier, and between a pair of spaced apart axial stops integrally formed with said barrier.
concurrently positioning said lens between a pair of spaced apart lateral stops integrally formed with said carrier, and between a pair of spaced apart axial stops integrally formed with said barrier.
44. The method of aligning a fiber as recited in claim 41 further includes the step of:
thermoelectrically cooling said housing to maintain a stabilized temperature for said photoactive element.
thermoelectrically cooling said housing to maintain a stabilized temperature for said photoactive element.
45. The method of aligning a fiber as recited in claim 41 wherein securing said lens to said carrier includes:
soldering said lens to said carrier.
soldering said lens to said carrier.
46. The method of aligning a fiber a recited in claim 41 wherein positioning said fiber further includes:
adaptably receiving said optical fiber in a fiber-receiving position through a fiber tube which is securable to said housing.
adaptably receiving said optical fiber in a fiber-receiving position through a fiber tube which is securable to said housing.
47. The method of aligning a fiber as recited in claim 41 wherein a ratio between the core sizes at the uptapered and downtapered ends of said optical fiber ranges from unity to ten.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/487,497 | 1990-03-02 | ||
| US07/487,497 US5011247A (en) | 1990-03-02 | 1990-03-02 | Uptapered single-mode optical fiber package for optoelectronic components |
| US07/526,367 US5018820A (en) | 1990-03-02 | 1990-05-21 | Method of optically coupling an uptapered single-mode optical fiber to optoelectronic components |
| US07/526,367 | 1990-05-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2037030A1 true CA2037030A1 (en) | 1991-09-03 |
Family
ID=27049023
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002037030A Abandoned CA2037030A1 (en) | 1990-03-02 | 1991-02-25 | Uptapered single-mode fiber package for optoelectronic components |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US5018820A (en) |
| EP (1) | EP0444610A3 (en) |
| JP (1) | JPH0792356A (en) |
| CA (1) | CA2037030A1 (en) |
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|---|---|---|---|---|
| GB2242755B (en) * | 1990-03-31 | 1994-07-27 | Plessey Co Ltd | Optical fibre coupling device |
| DE69201705T2 (en) * | 1991-09-19 | 1995-11-09 | Eastman Kodak Co | Laser diode with card edge connector. |
| US5276756A (en) * | 1991-12-06 | 1994-01-04 | Amoco Corporation | High speed electro-optical signal translator |
| US5299272A (en) * | 1993-01-27 | 1994-03-29 | Origin Medststems, Inc. | Method for attaching a gradient index lens to an optical fibre in the course of making an optical instrument |
| US5461692A (en) * | 1993-11-30 | 1995-10-24 | Amoco Corporation | Multimode optical fiber coupling apparatus and method of transmitting laser radiation using same |
| US5857047A (en) * | 1996-03-20 | 1999-01-05 | The Regents Of The University Of California | Automated fiber pigtailing machine |
| US6370290B1 (en) * | 1997-09-19 | 2002-04-09 | Uniphase Corporation | Integrated wavelength-select transmitter |
| US6325551B1 (en) | 1999-12-08 | 2001-12-04 | New Focus, Inc. | Method and apparatus for optically aligning optical fibers with optical devices |
| US20030124336A1 (en) * | 2001-11-30 | 2003-07-03 | Keane James M. | Adhesive system for absorbent structures |
| DE102012102306B4 (en) * | 2012-03-19 | 2021-05-12 | OSRAM Opto Semiconductors Gesellschaft mit beschränkter Haftung | Laser diode device |
| US8867582B2 (en) * | 2012-04-04 | 2014-10-21 | Osram Opto Semiconductors Gmbh | Laser diode assembly |
| US9008138B2 (en) | 2012-04-12 | 2015-04-14 | Osram Opto Semiconductors Gmbh | Laser diode device |
| DE102012103160A1 (en) | 2012-04-12 | 2013-10-17 | Osram Opto Semiconductors Gmbh | laser diode device |
| CN103944062A (en) * | 2014-04-29 | 2014-07-23 | 鞍山创鑫激光技术有限公司 | Semiconductor laser unit of single chip optical fiber coupling output |
| US9869820B2 (en) | 2015-12-09 | 2018-01-16 | Canon U.S.A, Inc. | Optical probe, light intensity detection, imaging method and system |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL180882C (en) * | 1976-05-31 | 1987-05-04 | Philips Nv | OPTICAL COUPLING ELEMENT AND OPTICAL COUPLING DEVICE WITH SUCH COUPLING ELEMENTS. |
| US4237474A (en) * | 1978-10-18 | 1980-12-02 | Rca Corporation | Electroluminescent diode and optical fiber assembly |
| US4737004A (en) * | 1985-10-03 | 1988-04-12 | American Telephone And Telegraph Company, At&T Bell Laboratories | Expanded end optical fiber and associated coupling arrangements |
| US4767171A (en) * | 1986-03-27 | 1988-08-30 | Siemens Aktiengesellschaft | Transmission and reception module for a bidirectional communication network |
| DE3773810D1 (en) * | 1986-09-02 | 1991-11-21 | Amp Inc | OPTOELECTRONIC PACKING UNIT FOR A SEMICONDUCTOR LASER. |
| JPS6365411A (en) * | 1986-09-08 | 1988-03-24 | Matsushita Electric Ind Co Ltd | Fixing method for lens |
| JPH073907B2 (en) * | 1987-07-03 | 1995-01-18 | 株式会社日立製作所 | Dual in-line package type semiconductor laser module |
-
1990
- 1990-05-21 US US07/526,367 patent/US5018820A/en not_active Expired - Lifetime
-
1991
- 1991-02-25 CA CA002037030A patent/CA2037030A1/en not_active Abandoned
- 1991-02-26 EP EP19910102822 patent/EP0444610A3/en not_active Withdrawn
- 1991-02-28 JP JP3055779A patent/JPH0792356A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| EP0444610A2 (en) | 1991-09-04 |
| US5018820A (en) | 1991-05-28 |
| JPH0792356A (en) | 1995-04-07 |
| EP0444610A3 (en) | 1992-08-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |