CA2011561C - Apparatus and method for making low-loss permanent optical fiber splices - Google Patents
Apparatus and method for making low-loss permanent optical fiber splicesInfo
- Publication number
- CA2011561C CA2011561C CA002011561A CA2011561A CA2011561C CA 2011561 C CA2011561 C CA 2011561C CA 002011561 A CA002011561 A CA 002011561A CA 2011561 A CA2011561 A CA 2011561A CA 2011561 C CA2011561 C CA 2011561C
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- CA
- Canada
- Prior art keywords
- fiber
- fibers
- laser
- acid
- droplets
- 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.)
- Expired - Fee Related
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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
- G02B6/255—Splicing of light guides, e.g. by fusion or bonding
- G02B6/2555—Alignment or adjustment devices for aligning prior to splicing
-
- 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
- G02B6/245—Removing protective coverings of light guides before coupling
-
- 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
- G02B6/255—Splicing of light guides, e.g. by fusion or bonding
- G02B6/2551—Splicing of light guides, e.g. by fusion or bonding using thermal methods, e.g. fusion welding by arc discharge, laser beam, plasma torch
-
- 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
- G02B6/26—Optical coupling means
- G02B6/264—Optical coupling means with optical elements between opposed fibre ends which perform a function other than beam splitting
Abstract
A single laser is used as a heat source to activate droplets of acid applied to two optical fibers for selective stripping of fiber coating, for forming conical sections on the coating adjacent the exposed fiber for improved bonding, and forfusing the fibers together in a splice. An enhanced method for aligning the two fiber ends prior to splicing is also disclosed, consisting of a TV camera scanning of selected cross-sections of both fibers following stripping and cleaving, to develop indicia of the relative location of the fiber cores. Lateral adjustment of a movable chuck responsive to the indicia, brings the prepared fiber ends into precise axial alignment. The method uses a minimum of acid, and constructs low-loss permanent fusion splices without flame or need for skilled operators.
Description
APPARATUS AND METHOD FOR
MAKING LOW-LOSS PERMANENT OPTICAL FIBER SPLICES
Field of the Invention This invention relates to optical fiber splicing techniques; and S particularly to the efficient and reliable realization of permanent splices of a high-strength, low tr~nsmis~ion loss character.
Background of the Invention Most optical fiber splices intenrled for use in an operating environment, should be both strong and of low loss. The latter is a particularly important 10 re(luilelnellt for many systems where any unnecessary signal strength losses cannot be tolerated.
Achieving such fiber splices using technicians who are not required to be skilled or continuously trained, is problematic with existing methodologies, however. In addition, if the working space is confined or unstable as on-board ship, 15 current techniques are not optimal.
Many current optical fiber splicing processes utiliæ a flame as the heat source for melting and fusing of two fiber ends. The flames, however, create thrust against the fibers, which must be considered or countered in order to m~int~in the fibers in their proper pre-splice axial alignment. Additionally, flame heat creates a 20 differential heating of the fiber ends, reslllting in a lelllp~l~ture gradient across the fiber cross-section. The gradient can deflect the fiber interior, which risks a weak and lossy bond at the tr:~n~mitting core. Moreover, flame sources are inherently risky, particularly in confined spaces.
Laser heat sources have been employed in the prior art to avoid the 25 noted problems which attend use of open flame fusion of optical fibers. In particular, low loss splices have been achieved in silica fibers using a pulsed C02 laser inconjunction with fiber-gripping vacuum chucks, one being stationary and the other being manipulable in three dimensions. When the fiber ends are in axial alignment and tightly abutting relation, the laser is applied to effect the fusion.
Conventional high-strength fiber splicing also frequently requires that heated sulfuric acid be employed to strip the fiber coating prior to splicing.
Conventional acid application methods,both horizontal and vertical, require large volumes of heated acid, typically 50 to 100 milliliters. The acid volume poses additional safety and health hazards to splicers. In addition, the conventional acid 35 containment vessel requires a relatively long length of free fiber, ranging from 1 to -2- 20l l 56~
24 inches, which is cumbersome to use.
Objects of the Invention One object of the invention is to achieve permanent optical fiber splices of consistent high strength and low loss, under adverse field conditions.
A further object of the invention is to develop a fiber splicing process which is both technically sound and also safer for users.
A further object of the invention is to provide a fiber splicing methodology which yields consistently satisfactory results with relatively unskilled labor.
S~lmm~ry of the Invention The present invention makes novel and advantageous use of a laser heat source in conjunction with a greatly reduced volume of acid, to strip, shape and, thereafter, fusion-splice two optical fibers.
The present invention further combines the use of laser energy with an enhanced method for ~ligning the two fiber ends prior to splicing. The alignment technique entails TV camera sc~nning of selected cross-sections of both fibers following stripping and cleaving, to develop indicia of the relative location of the fiber cores. Lateral adjustment of the movable chuck by increments proportional to the difference in the location indicia thus generated for the two fiber cores, then brings the prepared ends into precise axial alignment.
The splice is effected with the fiber ends in tight abutting relation, with a "pre-load" applied to the fibers. Specifically, one fiber end is displaced in what is tantamount to an overlapping relation with respect to the second fiver end.
The pre-load is helpful to the reliable achievement of low loss, high strength splices.
In a specific application of the invention, the described process is adapted to creating optical fiber splices with predetermined loss characteristics. A
particular loss level is occasionally desired rather than a relatively loss-free splice for certain applications; and to achieve it, the present inventive process is adaptedO
A
-2a-In accordance with one aspect of the invention there is provided a method for splicing a pair of cladded core, coated optical fibers, comprising the steps of: applying plural droplets of acid to a section of the exterior coating of each said fiber; heating said droplets with a laser beam; stripping said coating from said section by action of said laser beam and said acid; cleaving said fibers at saidsection; positioning the ends of said cleaved fibers in abutting relation; and fusing said fiber ends with said laser beam.
In accordance with another aspect of the invention there is provided apparatus for splicing a pair of cladded core, coated optical fibers, comprising:
means for independently positioning said fibers in planar and parallel relation;means for applying droplets of acid to a section of the exterior coating of each said fiber; a laser; means for directing the beam of said laser onto said droplets; means for varying the energy concentration of the beam of said laser, thereby to heat said droplets, to strip said coating from said section, and to create conical sections of fiber coating by action of said laser beam and said acid; means for cleaving said fibers at said section; means for positioning the ends of said cleaved fivers inabutting relation; and means including said laser with its said beam focused andconcentrated into said abutting fiber ends, for fusing said fiber ends.
The invention, its further objects, features, and advantages, are set forth in the description to follow of an illustrative embodiment thereof.
Description of the Drawin~
FIG. 1 is a schematic diagram of apparatus for practising the process steps of ~ ning the fibers and applying the acid;
FIG.2is a partial sectional side view of a fiber stripped of its coating with the instant invention;
F M.3is a schematic diagram of apparatus for practicing the step of rinsing;
FIG.4is a schematic diagram of apparatus for practicing the step of cleaving;
FIG.Sis a schematic diagram of the splice station chucks following the cleave step;
FIG.6is a schematic diagram of positional sc~nning of the fibers by a 10 TV camera;
FIG.7is a schematic side view of two fibers cleaved and abutted, ready for a fusion splicing;
FIG.8is a schematic diagram of the apparatus for effecting the fusion splicing and for mrlnitoring the results;
FIG.9is a side view of two fibers joined with fusion splices to a transition element; and FIG.lOis a process diagram for the present invention.
Detailed Description of an Illustrative Embodiment As shown in FIG.l, two optical fibers to be spliced, denoted 10, 20 are 20 respectively placed in V-grooves 12,22 of movable chuck 11 and fixed chuck 21.
The chucks are initially po~ition~cl as seen in FIG.4, with the fiber-receiving V-grooves 12, 22 laterally offset so that the core axes of the two fibers are not in alignment.
An acid application station 30is brought into position with respect to the fibers 10, 20, as seen in FIG.l. Station 30 includes a reservoir 14, provided on a dovetail slide which is centered between the chucks. The acid reservoir 14is of ~011561 greatly reduced capacity, having as its main purpose the cont~inmt~nt of any slight residue from the application of acid droplets. A minim~l amount of an acid, such as sulfuric acid, is then applied via an applicator such as dropper 40 to the cleave zone of the two fibers 10,20. The applied acid is denoted 31, and can be as little as two or 5 three droplets instead of the millilit~r quantities used in the acid baths of the prior art.
A lens 17, with a 36 cm focal length, is mounted on a 3-axis micropositioner 32 and placed between the laser and vacuum chucks. Lens 17 is adapted to broaden the beam lS or to focus the beam thereby to concentrate the laser 10 energy. With the acid applied, a laser beam lS from a source 16, is directed onto the acid droplets to commence the stripping of the optical fiber coating 27 in the vicinity of the splice area. The C02 laser advantageously has an operating wavelength of 10.6 microns. From a 10- watt lasers, up to 6 watts of power is available for stripping.
The position viewing system consisting of TV cameras 82, 83 is utilized for inspection of the stripping stage. A binocular microscope (not shown) may alternatively be include~l in the process for ~ ol ing and inspection.
The power density is increased when the beam is focussed to the dimensions of the fiber's ~ meter. The beam lS is diffused or widened by beam 20 focusing mechanism 17, to de-concenll~le the optical energy while retaining its ability to generate substantial heat in objects. At this stage, the beam lS is diffused and utilized to heat the acid droplets 31 to about 200 degrees Centigrade, a tt;lllpe~ c; at which the acidic activity is substantially increased. The laser beam is moved along the axis of the fiber by moving the lens 17 in a direction parallel to the 25 fiber axis. As beam 15 heats the acid it also is directed onto the strip zone to dirr~,r~ ially activate the acid in order to selectively strip the coating. The duration and sweep of beam 15, to effect this step, may be varied to suit the need of theparticular splice.
The selective strip is monitored by the TV camera positional viewing 30 system. The strip results in a set of conically shaped sections of fiber coating, as denoted by numeral 23 in FIG. 2. Tapered ends aid the flow and adhesion of recoat m~tPri~l when recoating is required.
The beam is then blocked with an absorbing brick (not shown). Then, the reservoir 14 is lowered, removing from the work station any slight acid residue 35 that has not clung to the fibers. The fiber stripping steps described require less than 1 inch of exposed fiber and 50 microliters of sulfuric acid. The sulfuric acid which has been found suitable for use in the inventive process, has a 62 percent absorption at 10.6 microns.
At this point, the zone 23 is rinsed with methyl alcohol using a conventional bath station 50. Following the rinse, a cleaving chuck 61 is positioned 5 as shown in FIG. 4, and the fibers 10, 20 are conventir-n~lly cleaved by a head 60.
The two severed ends 63 of the cleaved fibers then are inspected by, for example, in~ r~ etric analysis, to ensure that the cleave is within the required specification, usually 1 degree of the normal.
From their position depicted in FIG. 5 following proper cleaving, the 10 fibers 10, 20 are positioned into rough axial alignm~nt, in which the fiber axes 28 of the core 29 are substantially, but not necessarily fully, coincident. In order, however, for the splice to be as loss- free as possible, it is essential that the two axes 28 be fully coincident.
According to another aspect of the invention, therefore, as depicted in 15 FIG. 6, the fiber ends 70 are moved to within close proximity of each other, and a TV line scan of the two fiber cores 29 is conducted. Several, for example, three, specific lines of a conventional TV raster are scanned across each fiber, the lines being denoted 64, 65, 66, 67, 68, 69 in FIG. 6. Using TV camera 82, seen in FIG. 8, the selected lines are scanned, with each line being separated from the adjacent lines 20 by a distance of about .01 inches. The position of the brightest region along each of the sc~nned lines 64 - 69, with respect to a selected reference plane, is stored in conventional fashion in processor-monitor 81. The several positional readings are then resolved using any of a variety of resolution techniques into a single best fiber position e~limate in the X-Z plane for each fiber core 29; and the two readings 25 colllp~,d. The difference, if any, is reduced to zero by movement of the chuck 13.
Alignment in the X-Y plane may be achieved by similar steps using the TV camera 83.
Next, the movable chuck 13 is moved toward the stationary chuck 26, to bring the fibers 10, 20 first into abutting relation and then to pre-load the fibers in the 30 manner depicted in FIG. 7. Relatively little force, for example, approximately .05 pounds upon fibers of .005 inches outside diameter, is required to effect the needed preload. The purpose to assure that sufficient glass volume is present in the fusion zone for effecting a full fli~m~ter splice.
Next, as depicted in FIG. 8, the lens 17 of the laser 16 is adjusted to 35 concentrate the beam energy in preparation for effecting a fusion splice. Theeffective beam width at the point of the fiber splice is monitored visually using the TV cameras 82 and a monitor, not shown. The fusion splice finally may be inspected either visually using the aforementioned monitor system comprising cameras 82, 83; or by direct optical measu,emellt of tr~n~mis~ion loss through the splice, if such is feasible.
S The invention may be extended to optical tr:~n~mission applications requiring not the low loss result as was just described, but rather requiring creation of a predetermined and controlled loss. The application may be illustrated by reference to an undersea optical receiver example. Certain optical receivers have fixed allowable input signal amplitudes. They consequently have to be fitted with 10 input signal attenuators if the source-to-receiver cable separation decreases to the point where input signal saturation of the receiver occurs.
The described laser splice method and apparatus can be utilized to create intentionally lossy splices, by introducing an undoped glass segment between thefibers 10, 20. The segment, pictured in FIG. 9 and denoted 33, is a fiber lengthlS without a core. Segment 33 is similar to the fibers 10, 20, in that its refractive index is matched to the cladding index of the fibers 10, 20; and that its outside diameter is the same as the fibers 10, 20. Two fusion splices, 34, 35, are constructed as taught by the present inventive method and apparatus, thereby to place the segment 33 in the tr:~n~mi~sion path of the fibers 10, 20.
The optical signal leaves the core 29 of fiber 10, and diverges as it ll~ve,ses the segment 33, as illustrated in FIG. 9, by an amount determined by the length of the segment. Only a fraction of the energy of the signal being received by the fiber 20, depending on the 11im~n~ion "D" shown in FIG. 9.
It is desirable to provide a position control for the cleaving head 60, 25 schem~tic~lly shown in FIG. 4 as control 36. By cleaving the two fibers at two positions sepal~ed by applv~,l"ately the distance "D", room is provided for the segment 33 to be interpo~iti- n~d using, for example, conventional means such asmanipulators (not shown).
Another method for creating a controlled loss splice, especially for the 30 lower ranges of attenuator values (~SdB) is to introduce a core diffusion zone within the fiber, such as fiber 10, by using the present invention to internally heat the fiber core without significantly disturbing the cladding. Heating the core 29 to a~pro~ ately 800 degrees centigrade for from 1 to S seconds with the laser 16, will create an internal lens discontinuity into the core 29, and force cladding mode 35 prop~g~tion to occur in the cladding 37, thus dissipating power.
MAKING LOW-LOSS PERMANENT OPTICAL FIBER SPLICES
Field of the Invention This invention relates to optical fiber splicing techniques; and S particularly to the efficient and reliable realization of permanent splices of a high-strength, low tr~nsmis~ion loss character.
Background of the Invention Most optical fiber splices intenrled for use in an operating environment, should be both strong and of low loss. The latter is a particularly important 10 re(luilelnellt for many systems where any unnecessary signal strength losses cannot be tolerated.
Achieving such fiber splices using technicians who are not required to be skilled or continuously trained, is problematic with existing methodologies, however. In addition, if the working space is confined or unstable as on-board ship, 15 current techniques are not optimal.
Many current optical fiber splicing processes utiliæ a flame as the heat source for melting and fusing of two fiber ends. The flames, however, create thrust against the fibers, which must be considered or countered in order to m~int~in the fibers in their proper pre-splice axial alignment. Additionally, flame heat creates a 20 differential heating of the fiber ends, reslllting in a lelllp~l~ture gradient across the fiber cross-section. The gradient can deflect the fiber interior, which risks a weak and lossy bond at the tr:~n~mitting core. Moreover, flame sources are inherently risky, particularly in confined spaces.
Laser heat sources have been employed in the prior art to avoid the 25 noted problems which attend use of open flame fusion of optical fibers. In particular, low loss splices have been achieved in silica fibers using a pulsed C02 laser inconjunction with fiber-gripping vacuum chucks, one being stationary and the other being manipulable in three dimensions. When the fiber ends are in axial alignment and tightly abutting relation, the laser is applied to effect the fusion.
Conventional high-strength fiber splicing also frequently requires that heated sulfuric acid be employed to strip the fiber coating prior to splicing.
Conventional acid application methods,both horizontal and vertical, require large volumes of heated acid, typically 50 to 100 milliliters. The acid volume poses additional safety and health hazards to splicers. In addition, the conventional acid 35 containment vessel requires a relatively long length of free fiber, ranging from 1 to -2- 20l l 56~
24 inches, which is cumbersome to use.
Objects of the Invention One object of the invention is to achieve permanent optical fiber splices of consistent high strength and low loss, under adverse field conditions.
A further object of the invention is to develop a fiber splicing process which is both technically sound and also safer for users.
A further object of the invention is to provide a fiber splicing methodology which yields consistently satisfactory results with relatively unskilled labor.
S~lmm~ry of the Invention The present invention makes novel and advantageous use of a laser heat source in conjunction with a greatly reduced volume of acid, to strip, shape and, thereafter, fusion-splice two optical fibers.
The present invention further combines the use of laser energy with an enhanced method for ~ligning the two fiber ends prior to splicing. The alignment technique entails TV camera sc~nning of selected cross-sections of both fibers following stripping and cleaving, to develop indicia of the relative location of the fiber cores. Lateral adjustment of the movable chuck by increments proportional to the difference in the location indicia thus generated for the two fiber cores, then brings the prepared ends into precise axial alignment.
The splice is effected with the fiber ends in tight abutting relation, with a "pre-load" applied to the fibers. Specifically, one fiber end is displaced in what is tantamount to an overlapping relation with respect to the second fiver end.
The pre-load is helpful to the reliable achievement of low loss, high strength splices.
In a specific application of the invention, the described process is adapted to creating optical fiber splices with predetermined loss characteristics. A
particular loss level is occasionally desired rather than a relatively loss-free splice for certain applications; and to achieve it, the present inventive process is adaptedO
A
-2a-In accordance with one aspect of the invention there is provided a method for splicing a pair of cladded core, coated optical fibers, comprising the steps of: applying plural droplets of acid to a section of the exterior coating of each said fiber; heating said droplets with a laser beam; stripping said coating from said section by action of said laser beam and said acid; cleaving said fibers at saidsection; positioning the ends of said cleaved fibers in abutting relation; and fusing said fiber ends with said laser beam.
In accordance with another aspect of the invention there is provided apparatus for splicing a pair of cladded core, coated optical fibers, comprising:
means for independently positioning said fibers in planar and parallel relation;means for applying droplets of acid to a section of the exterior coating of each said fiber; a laser; means for directing the beam of said laser onto said droplets; means for varying the energy concentration of the beam of said laser, thereby to heat said droplets, to strip said coating from said section, and to create conical sections of fiber coating by action of said laser beam and said acid; means for cleaving said fibers at said section; means for positioning the ends of said cleaved fivers inabutting relation; and means including said laser with its said beam focused andconcentrated into said abutting fiber ends, for fusing said fiber ends.
The invention, its further objects, features, and advantages, are set forth in the description to follow of an illustrative embodiment thereof.
Description of the Drawin~
FIG. 1 is a schematic diagram of apparatus for practising the process steps of ~ ning the fibers and applying the acid;
FIG.2is a partial sectional side view of a fiber stripped of its coating with the instant invention;
F M.3is a schematic diagram of apparatus for practicing the step of rinsing;
FIG.4is a schematic diagram of apparatus for practicing the step of cleaving;
FIG.Sis a schematic diagram of the splice station chucks following the cleave step;
FIG.6is a schematic diagram of positional sc~nning of the fibers by a 10 TV camera;
FIG.7is a schematic side view of two fibers cleaved and abutted, ready for a fusion splicing;
FIG.8is a schematic diagram of the apparatus for effecting the fusion splicing and for mrlnitoring the results;
FIG.9is a side view of two fibers joined with fusion splices to a transition element; and FIG.lOis a process diagram for the present invention.
Detailed Description of an Illustrative Embodiment As shown in FIG.l, two optical fibers to be spliced, denoted 10, 20 are 20 respectively placed in V-grooves 12,22 of movable chuck 11 and fixed chuck 21.
The chucks are initially po~ition~cl as seen in FIG.4, with the fiber-receiving V-grooves 12, 22 laterally offset so that the core axes of the two fibers are not in alignment.
An acid application station 30is brought into position with respect to the fibers 10, 20, as seen in FIG.l. Station 30 includes a reservoir 14, provided on a dovetail slide which is centered between the chucks. The acid reservoir 14is of ~011561 greatly reduced capacity, having as its main purpose the cont~inmt~nt of any slight residue from the application of acid droplets. A minim~l amount of an acid, such as sulfuric acid, is then applied via an applicator such as dropper 40 to the cleave zone of the two fibers 10,20. The applied acid is denoted 31, and can be as little as two or 5 three droplets instead of the millilit~r quantities used in the acid baths of the prior art.
A lens 17, with a 36 cm focal length, is mounted on a 3-axis micropositioner 32 and placed between the laser and vacuum chucks. Lens 17 is adapted to broaden the beam lS or to focus the beam thereby to concentrate the laser 10 energy. With the acid applied, a laser beam lS from a source 16, is directed onto the acid droplets to commence the stripping of the optical fiber coating 27 in the vicinity of the splice area. The C02 laser advantageously has an operating wavelength of 10.6 microns. From a 10- watt lasers, up to 6 watts of power is available for stripping.
The position viewing system consisting of TV cameras 82, 83 is utilized for inspection of the stripping stage. A binocular microscope (not shown) may alternatively be include~l in the process for ~ ol ing and inspection.
The power density is increased when the beam is focussed to the dimensions of the fiber's ~ meter. The beam lS is diffused or widened by beam 20 focusing mechanism 17, to de-concenll~le the optical energy while retaining its ability to generate substantial heat in objects. At this stage, the beam lS is diffused and utilized to heat the acid droplets 31 to about 200 degrees Centigrade, a tt;lllpe~ c; at which the acidic activity is substantially increased. The laser beam is moved along the axis of the fiber by moving the lens 17 in a direction parallel to the 25 fiber axis. As beam 15 heats the acid it also is directed onto the strip zone to dirr~,r~ ially activate the acid in order to selectively strip the coating. The duration and sweep of beam 15, to effect this step, may be varied to suit the need of theparticular splice.
The selective strip is monitored by the TV camera positional viewing 30 system. The strip results in a set of conically shaped sections of fiber coating, as denoted by numeral 23 in FIG. 2. Tapered ends aid the flow and adhesion of recoat m~tPri~l when recoating is required.
The beam is then blocked with an absorbing brick (not shown). Then, the reservoir 14 is lowered, removing from the work station any slight acid residue 35 that has not clung to the fibers. The fiber stripping steps described require less than 1 inch of exposed fiber and 50 microliters of sulfuric acid. The sulfuric acid which has been found suitable for use in the inventive process, has a 62 percent absorption at 10.6 microns.
At this point, the zone 23 is rinsed with methyl alcohol using a conventional bath station 50. Following the rinse, a cleaving chuck 61 is positioned 5 as shown in FIG. 4, and the fibers 10, 20 are conventir-n~lly cleaved by a head 60.
The two severed ends 63 of the cleaved fibers then are inspected by, for example, in~ r~ etric analysis, to ensure that the cleave is within the required specification, usually 1 degree of the normal.
From their position depicted in FIG. 5 following proper cleaving, the 10 fibers 10, 20 are positioned into rough axial alignm~nt, in which the fiber axes 28 of the core 29 are substantially, but not necessarily fully, coincident. In order, however, for the splice to be as loss- free as possible, it is essential that the two axes 28 be fully coincident.
According to another aspect of the invention, therefore, as depicted in 15 FIG. 6, the fiber ends 70 are moved to within close proximity of each other, and a TV line scan of the two fiber cores 29 is conducted. Several, for example, three, specific lines of a conventional TV raster are scanned across each fiber, the lines being denoted 64, 65, 66, 67, 68, 69 in FIG. 6. Using TV camera 82, seen in FIG. 8, the selected lines are scanned, with each line being separated from the adjacent lines 20 by a distance of about .01 inches. The position of the brightest region along each of the sc~nned lines 64 - 69, with respect to a selected reference plane, is stored in conventional fashion in processor-monitor 81. The several positional readings are then resolved using any of a variety of resolution techniques into a single best fiber position e~limate in the X-Z plane for each fiber core 29; and the two readings 25 colllp~,d. The difference, if any, is reduced to zero by movement of the chuck 13.
Alignment in the X-Y plane may be achieved by similar steps using the TV camera 83.
Next, the movable chuck 13 is moved toward the stationary chuck 26, to bring the fibers 10, 20 first into abutting relation and then to pre-load the fibers in the 30 manner depicted in FIG. 7. Relatively little force, for example, approximately .05 pounds upon fibers of .005 inches outside diameter, is required to effect the needed preload. The purpose to assure that sufficient glass volume is present in the fusion zone for effecting a full fli~m~ter splice.
Next, as depicted in FIG. 8, the lens 17 of the laser 16 is adjusted to 35 concentrate the beam energy in preparation for effecting a fusion splice. Theeffective beam width at the point of the fiber splice is monitored visually using the TV cameras 82 and a monitor, not shown. The fusion splice finally may be inspected either visually using the aforementioned monitor system comprising cameras 82, 83; or by direct optical measu,emellt of tr~n~mis~ion loss through the splice, if such is feasible.
S The invention may be extended to optical tr:~n~mission applications requiring not the low loss result as was just described, but rather requiring creation of a predetermined and controlled loss. The application may be illustrated by reference to an undersea optical receiver example. Certain optical receivers have fixed allowable input signal amplitudes. They consequently have to be fitted with 10 input signal attenuators if the source-to-receiver cable separation decreases to the point where input signal saturation of the receiver occurs.
The described laser splice method and apparatus can be utilized to create intentionally lossy splices, by introducing an undoped glass segment between thefibers 10, 20. The segment, pictured in FIG. 9 and denoted 33, is a fiber lengthlS without a core. Segment 33 is similar to the fibers 10, 20, in that its refractive index is matched to the cladding index of the fibers 10, 20; and that its outside diameter is the same as the fibers 10, 20. Two fusion splices, 34, 35, are constructed as taught by the present inventive method and apparatus, thereby to place the segment 33 in the tr:~n~mi~sion path of the fibers 10, 20.
The optical signal leaves the core 29 of fiber 10, and diverges as it ll~ve,ses the segment 33, as illustrated in FIG. 9, by an amount determined by the length of the segment. Only a fraction of the energy of the signal being received by the fiber 20, depending on the 11im~n~ion "D" shown in FIG. 9.
It is desirable to provide a position control for the cleaving head 60, 25 schem~tic~lly shown in FIG. 4 as control 36. By cleaving the two fibers at two positions sepal~ed by applv~,l"ately the distance "D", room is provided for the segment 33 to be interpo~iti- n~d using, for example, conventional means such asmanipulators (not shown).
Another method for creating a controlled loss splice, especially for the 30 lower ranges of attenuator values (~SdB) is to introduce a core diffusion zone within the fiber, such as fiber 10, by using the present invention to internally heat the fiber core without significantly disturbing the cladding. Heating the core 29 to a~pro~ ately 800 degrees centigrade for from 1 to S seconds with the laser 16, will create an internal lens discontinuity into the core 29, and force cladding mode 35 prop~g~tion to occur in the cladding 37, thus dissipating power.
Claims (12)
1. A method for splicing a pair of cladded core, coated optical fibers, comprising the steps of:
applying plural droplets of acid to a section of the exterior coating of each said fiber;
heating said droplets with a laser beam;
stripping said coating from said section by action of said laser beam and said acid;
cleaving said fibers at said section;
positioning the ends of said cleaved fibers in abutting relation; and fusing said fiber ends with said laser beam.
applying plural droplets of acid to a section of the exterior coating of each said fiber;
heating said droplets with a laser beam;
stripping said coating from said section by action of said laser beam and said acid;
cleaving said fibers at said section;
positioning the ends of said cleaved fibers in abutting relation; and fusing said fiber ends with said laser beam.
2. A method for splicing a pair of cladded core, coated optical fibers, comprising the steps of:
positioning said fiber pair in planar and parallel relation;
applying droplets of acid to a section of the exterior coating of each said fiber;
heating said droplets with a laser having a beam of broadened width;
selectively directing said laser beam on said droplets to create heightened acidic action for stripping of said coating, thereby to expose a section of cladding glass of each said fiber;
cleaving said fibers;
positioning the ends of said cleaved fibers in abutting and pre- loaded relation; and with said laser beam energy focused on the splice zone, fusing said fiber ends to optically splice said fiber pair.
positioning said fiber pair in planar and parallel relation;
applying droplets of acid to a section of the exterior coating of each said fiber;
heating said droplets with a laser having a beam of broadened width;
selectively directing said laser beam on said droplets to create heightened acidic action for stripping of said coating, thereby to expose a section of cladding glass of each said fiber;
cleaving said fibers;
positioning the ends of said cleaved fibers in abutting and pre- loaded relation; and with said laser beam energy focused on the splice zone, fusing said fiber ends to optically splice said fiber pair.
3. A method for splicing a pair of cladded core, coated optical fibers, comprising the steps of:
applying plural droplets of acid to a section of the exterior coating of each said fiber, while said fibers are independently positioned in planar and parallel relation;
heating said droplets with a laser having a beam of broadened width;
selectively directing said laser beam on said droplets to create heightened acidic action for stripping of said coating, thereby to expose a section of cladding glass of each said fiber and to taper the fiber coating adjacent each said exposed glass section;
cleaving said fibers;
positioning the ends of said cleaved fibers in abutting and pre-loaded relation; and with said laser beam energy focused on the splice zone, fusing said fiber ends to optically splice said fiber pair.
applying plural droplets of acid to a section of the exterior coating of each said fiber, while said fibers are independently positioned in planar and parallel relation;
heating said droplets with a laser having a beam of broadened width;
selectively directing said laser beam on said droplets to create heightened acidic action for stripping of said coating, thereby to expose a section of cladding glass of each said fiber and to taper the fiber coating adjacent each said exposed glass section;
cleaving said fibers;
positioning the ends of said cleaved fibers in abutting and pre-loaded relation; and with said laser beam energy focused on the splice zone, fusing said fiber ends to optically splice said fiber pair.
4. The method of claim 1, 2, or 3, wherein the operating wavelength of said laser is selected to coincide with the acid concentration where the absorption of said acid is substantially at its maximum.
5. The method of claim 1, 2, or 3, wherein said laser is a CO2 laser having an operating wavelength of 10.6 microns.
6. The method of claim 5, wherein said acid comprises sulfuric acid having substantially 62% absorption at 10.6 microns.
7. The method of claim 1, 2, or 3, wherein said process further comprises:
line-scanning with a TV camera at selected vertical planes across each said fiber core;
recording the brightest region along each of the scanned lines;
resolving the position of each said brightest region for each said fiber into a single estimate of that fiber's position in a horizontal plane; and moving said fibers in said horizontal plane so that their respective cores are in axial alignment.
line-scanning with a TV camera at selected vertical planes across each said fiber core;
recording the brightest region along each of the scanned lines;
resolving the position of each said brightest region for each said fiber into a single estimate of that fiber's position in a horizontal plane; and moving said fibers in said horizontal plane so that their respective cores are in axial alignment.
8. Apparatus for splicing a pair of cladded core, coated optical fibers, comprising:
means for independently positioning said fibers in planar and parallel relation;
means for applying droplets of acid to a section of the exterior coating of each said fiber;
a laser;
means for directing the beam of said laser onto said droplets;
means for varying the energy concentration of the beam of said laser, thereby toheat said droplets, to strip said coating from said section, and to create conical sections of fiber coating by action of said laser beam and said acid;
means for cleaving said fibers at said section;
means for positioning the ends of said cleaved fibers in abutting relation; and means including said laser with its said beam focused and concentrated into saidabutting fiber ends, for fusing said fiber ends.
means for independently positioning said fibers in planar and parallel relation;
means for applying droplets of acid to a section of the exterior coating of each said fiber;
a laser;
means for directing the beam of said laser onto said droplets;
means for varying the energy concentration of the beam of said laser, thereby toheat said droplets, to strip said coating from said section, and to create conical sections of fiber coating by action of said laser beam and said acid;
means for cleaving said fibers at said section;
means for positioning the ends of said cleaved fibers in abutting relation; and means including said laser with its said beam focused and concentrated into saidabutting fiber ends, for fusing said fiber ends.
9. Apparatus pursuant to claim 8, wherein said positioning means comprises;
a movable chuck and a fixed chuck, each said chuck having a V- groove for receiving one of said fibers; and means for laterally offsetting said movable chuck relative to said fixed chuck, thereby to laterally offset the core axes of the two said fibers.
a movable chuck and a fixed chuck, each said chuck having a V- groove for receiving one of said fibers; and means for laterally offsetting said movable chuck relative to said fixed chuck, thereby to laterally offset the core axes of the two said fibers.
10. Apparatus pursuant to claim 9, wherein:
said laser is a CO2 laser having an operating wavelength of 10.6 microns.; and said acid comprises sulfuric acid having substantially a 62% absorption at 10.6 microns.
said laser is a CO2 laser having an operating wavelength of 10.6 microns.; and said acid comprises sulfuric acid having substantially a 62% absorption at 10.6 microns.
11. Apparatus pursuant to claim 10, wherein:
said varying means comprises a lens having substantially a 36 cm. focal length;
and said apparatus further comprises:
means including a 3-axis micropositioner for mounting said lens; and means responsive to indicia of the position of said fibers relative to said beam for effecting a fusion splice of said fibers
said varying means comprises a lens having substantially a 36 cm. focal length;
and said apparatus further comprises:
means including a 3-axis micropositioner for mounting said lens; and means responsive to indicia of the position of said fibers relative to said beam for effecting a fusion splice of said fibers
12. Apparatus in accordance with claim 11, further comprising:
means for line-scanning in a plurality of planes normal to each of said fibers;
means for determining the position of the brightest region along each of the scanned lines;
means for resolving said positional readings into a single fiber position estimate in the plane of said V-grooves; and means including said movable chuck for moving said fibers in said V-groove plane so that their respective cores are in axial alignment.
means for line-scanning in a plurality of planes normal to each of said fibers;
means for determining the position of the brightest region along each of the scanned lines;
means for resolving said positional readings into a single fiber position estimate in the plane of said V-grooves; and means including said movable chuck for moving said fibers in said V-groove plane so that their respective cores are in axial alignment.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| USS.N.401,215 | 1989-08-31 | ||
| US07/401,215 US4971418A (en) | 1989-08-31 | 1989-08-31 | Apparatus and method for making low-loss permanent optical fiber splices |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2011561A1 CA2011561A1 (en) | 1991-02-28 |
| CA2011561C true CA2011561C (en) | 1995-07-18 |
Family
ID=23586845
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002011561A Expired - Fee Related CA2011561C (en) | 1989-08-31 | 1990-03-06 | Apparatus and method for making low-loss permanent optical fiber splices |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4971418A (en) |
| EP (1) | EP0415516B1 (en) |
| JP (1) | JPH067207B2 (en) |
| AU (1) | AU620983B2 (en) |
| CA (1) | CA2011561C (en) |
| DE (1) | DE69015927T2 (en) |
| ES (1) | ES2066125T3 (en) |
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|---|---|---|---|---|
| GB8820662D0 (en) * | 1988-09-01 | 1988-10-05 | British Telecomm | Optical fibre splice |
| EP0380779A3 (en) * | 1989-02-01 | 1991-10-30 | Leningradskoe Otdelenie Tsentralnogo Nauchno-Issledo-Vatelskogo Instituta Svyazi (Loniis) | Method for determining the optical losses of optical fibres by reflected light |
| US5095519A (en) * | 1990-11-30 | 1992-03-10 | At&T Bell Laboratories | Apparatus and method for producing an in-line optical fiber attenuator |
| GB9117761D0 (en) * | 1991-08-16 | 1991-10-02 | Bicc Plc | Optical fibre splicing |
| SE9200070L (en) * | 1992-01-13 | 1993-06-14 | Televerket | PROCEDURE AND DEVICE FOR SHARPING OF OPTICAL GUIDELINES |
| US5299274A (en) * | 1992-06-25 | 1994-03-29 | Hughes Aircraft Company | Optical fiber laser fusion splicer |
| US5249246A (en) * | 1992-06-29 | 1993-09-28 | Szanto Attila J | Self-contained fiber splicing unit and method for splicing together optical fibers |
| US6017681A (en) * | 1992-11-09 | 2000-01-25 | Fujitsu Limited | Method of coupling optical parts and method of forming a mirror |
| GB2272306B (en) * | 1992-11-09 | 1996-11-20 | Fujitsu Ltd | Coupling of optical parts using a refractive index imaging material |
| DE4304762A1 (en) * | 1993-02-17 | 1994-08-18 | Abb Research Ltd | Sensor head for a fiber optic current measuring device |
| JP3256918B2 (en) * | 1994-01-28 | 2002-02-18 | 古河電気工業株式会社 | Optical component welding fixture |
| US5500917A (en) * | 1994-04-18 | 1996-03-19 | Gould Electronics Inc. | Optical assembly/housing for securing optical fiber components, devices and fibers to the same or to mounting fixtures |
| US5946986A (en) * | 1997-10-23 | 1999-09-07 | Amherst International, Inc. | Optical fiber preparation unit |
| US6023996A (en) * | 1997-10-23 | 2000-02-15 | Amherst International, Inc. | Optical fiber preparation unit |
| US6139196A (en) * | 1998-11-09 | 2000-10-31 | Honeywell, Inc. | Method of preparing optical fiber for fusion splicing and method of forming a fusion splice |
| FR2789495B1 (en) | 1999-02-08 | 2002-04-12 | France Telecom | ONLINE MITIGATION DEVICE FOR SINGLE-MODE FIBER AND MANUFACTURING METHOD THEREOF |
| US6827508B2 (en) * | 2001-05-24 | 2004-12-07 | Fiber Optic Network Solutions Corporation | Optical fiber fusion system |
| GB0129286D0 (en) * | 2001-12-06 | 2002-01-23 | Optek Ltd | Improvements relating to the coupling of optical waveguides |
| US6758610B2 (en) | 2001-12-10 | 2004-07-06 | Jds Uniphase Corporation | Optical component attachment to optoelectronic packages |
| DE10212716A1 (en) * | 2002-03-21 | 2003-10-09 | Ccs Technology Inc | Method and device for splicing optical fibers |
| US7221838B2 (en) * | 2004-06-23 | 2007-05-22 | Furukawa Electric North America, Inc. | Optical fibers with reduced splice loss and methods for making same |
| CN1992461B (en) * | 2005-12-30 | 2010-05-05 | 鸿富锦精密工业（深圳）有限公司 | Apparatus for cutting insulation layer of electric wire |
| JP4967803B2 (en) * | 2006-05-18 | 2012-07-04 | 凸版印刷株式会社 | Method for manufacturing photoelectric composite substrate |
| US20090060427A1 (en) * | 2006-12-01 | 2009-03-05 | Wouters Vincent A | Quick terminated fiber optic termini and fiber optic cable, and method for making |
| US20120055516A1 (en) * | 2010-09-02 | 2012-03-08 | Vytran, Llc | Optical fiber stripper apparatus and method |
| WO2013123025A1 (en) | 2012-02-14 | 2013-08-22 | Vytran, Llc | Optical element cleaver and splicer apparatus and methods |
| CN107037537B (en) * | 2017-05-05 | 2019-10-22 | 北京航天控制仪器研究所 | A kind of method of quick, low damage removal high-temperature resistant optical fiber polyimide coating layer |
| WO2019146713A1 (en) | 2018-01-25 | 2019-08-01 | 住友電気工業株式会社 | Method for manufacturing optical fiber, and optical fiber |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5936721B2 (en) * | 1977-05-04 | 1984-09-05 | 松下電器産業株式会社 | Optical fiber removal method |
| JPS5434250A (en) * | 1977-08-23 | 1979-03-13 | Nippon Telegr & Teleph Corp <Ntt> | Method and apparatus for fusion connecting of optical fibers |
| JPS5975213A (en) * | 1982-10-22 | 1984-04-27 | Sumitomo Electric Ind Ltd | Arc welding connecting method of optical fiber |
| US4729625A (en) * | 1983-07-06 | 1988-03-08 | The United States Of America As Represented By The Secretary Of The Army | Optical fiber splice sled |
| US4585304A (en) * | 1983-09-06 | 1986-04-29 | Virginia | Technique for repairing and joining small diameter optical fiber cables |
| JPS6250487A (en) * | 1985-08-29 | 1987-03-05 | Agency Of Ind Science & Technol | Laser light projector of laser assist chemical etching method |
| CA1245431A (en) * | 1986-02-13 | 1988-11-29 | Helmut H. Lukas | Fusion apparatus for joining two monomode optical fibers |
| GB2201529A (en) * | 1987-02-26 | 1988-09-01 | Bicc Plc | Aligning optical fibres for splicing using video signals |
| US4727237A (en) * | 1987-05-04 | 1988-02-23 | Hewlett-Packard Company | Pyrolysis coated optical fiber splices: apparatus and method |
| JPH01118106A (en) * | 1987-10-30 | 1989-05-10 | Japan Aviation Electron Ind Ltd | Method for centering and fixing optical fiber |
| US4840450A (en) * | 1988-02-03 | 1989-06-20 | General Electric Company | Apparatus and method for optical fiber end positioning for laser injection |
| US4958905A (en) * | 1989-06-19 | 1990-09-25 | Tynes Arthur R | Method and apparatus for forming high strength splices in optical fibers |
-
1989
- 1989-08-31 US US07/401,215 patent/US4971418A/en not_active Expired - Lifetime
-
1990
- 1990-03-06 CA CA002011561A patent/CA2011561C/en not_active Expired - Fee Related
- 1990-04-20 EP EP90304253A patent/EP0415516B1/en not_active Expired - Lifetime
- 1990-04-20 ES ES90304253T patent/ES2066125T3/en not_active Expired - Lifetime
- 1990-04-20 DE DE69015927T patent/DE69015927T2/en not_active Expired - Fee Related
- 1990-04-25 JP JP2107731A patent/JPH067207B2/en not_active Expired - Fee Related
- 1990-04-26 AU AU53962/90A patent/AU620983B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| US4971418A (en) | 1990-11-20 |
| CA2011561A1 (en) | 1991-02-28 |
| EP0415516B1 (en) | 1995-01-11 |
| EP0415516A3 (en) | 1991-11-13 |
| DE69015927D1 (en) | 1995-02-23 |
| ES2066125T3 (en) | 1995-03-01 |
| JPH067207B2 (en) | 1994-01-26 |
| JPH0392802A (en) | 1991-04-18 |
| EP0415516A2 (en) | 1991-03-06 |
| DE69015927T2 (en) | 1995-05-18 |
| AU5396290A (en) | 1991-08-01 |
| AU620983B2 (en) | 1992-02-27 |
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| EEER | Examination request | ||
| MKLA | Lapsed |