CA2098051A1 - Optical transmission system with optical filter for providing protection against giant pulses - Google Patents
Optical transmission system with optical filter for providing protection against giant pulsesInfo
- Publication number
- CA2098051A1 CA2098051A1 CA002098051A CA2098051A CA2098051A1 CA 2098051 A1 CA2098051 A1 CA 2098051A1 CA 002098051 A CA002098051 A CA 002098051A CA 2098051 A CA2098051 A CA 2098051A CA 2098051 A1 CA2098051 A1 CA 2098051A1
- Authority
- CA
- Canada
- Prior art keywords
- optical
- fiber
- wavelength
- transmission system
- optic
- 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
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/29—Repeaters
- H04B10/291—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/29—Repeaters
- H04B10/291—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form
- H04B10/2912—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form characterised by the medium used for amplification or processing
Abstract
Abstract Optical Transmission System with Optical Filter for Providing Protection against Giant Pulses In optical transmission systems with fiber-optic ampli-fiers, an interruption of the fiber-optic link, e.g., due to fiber breakage, may cause a giant pulse to de-velop.
To prevent the giant pulse from propagating in the fiber-optic link, an optical filter (7) which blocks the wavelength region of the pulse is placed in the fiber-optic link. The wavelength of the optical sig-nal must be chosen to lie outside the wavelength re-gion of the maximum gain of the fiber-optic amplifier.
(Fig. 1)
To prevent the giant pulse from propagating in the fiber-optic link, an optical filter (7) which blocks the wavelength region of the pulse is placed in the fiber-optic link. The wavelength of the optical sig-nal must be chosen to lie outside the wavelength re-gion of the maximum gain of the fiber-optic amplifier.
(Fig. 1)
Description
2~98~
- 1 - P 42 Z2 208.7 Optical Transm;ssion System with Optical Filter for Providing Protection agai.nst Giant Pulses . .
The present in~ention relates to an opti.cal communica~
tion system as set forth ;n the preamble of claim 1.
Such systems are known, e.g., from ~. Weddi.ng et al, "10 Gbit/s to 260000 Subscribers Using Optical Amplifier Distribution Network", Contribution for ICC/Supercomm '92, Optical Communications 300 Level Session, "Impact of Optical Ampli.fiers on Network Architectures". The fiber-optic amplifier is shown in detail in EP O 457 349 A2, for example.
In the above system, there is the danger that in the event of a break in the fiber-optic link, e~g~, due to fiber breakage, high-energy pulses w;Ll be em;.tted. These g;ant pulses are caused by the fact that upon interrup-tion of the fiber-optic link, the input power drops to :
zero and the light resulting from the spontaneous emission is reflected at the point of the break.
This can be described in more detail as follows~ Since the pump;ng process ;s ;ndependent of the power input, energy will constantly be pumped into the amplifyi.ng medium even if the power input has dropped, so that complete population inversion will occur. When reflected light passes through the amplifyi.ng section of optical .
. ~ . . . . :
. .. : - , , . : ' -.
20~80~
waveguide, whose active laser medium is in the invert-ed state, the stored energy will be suddenly released.
Giant pulses will be emitted which are a danger to system components, such as photodetectors.
Be;ng comparable to an effect which is well known from solid-state lasers, the giant-pulse emission is also known by the term Q-switching. For semiconductor lasers, this effect is described, for example, by Petermann, U., in "Laser Diode Modulation and Noise", Kluwer Academic Publishers, UT K Scientific Publisher, Tokyo 1988.
It is the object of the ;nvent;on to provide an optical transmission system of the above kind wherein the danger associated with giant pulses is avoided.
To be able to attain this object, the wavelength of the optical signal must be chosen to lie outside the wavelength region of the maximum gain of the fiber-optic amplifier, where the giant-pulse emiss;on occurs.
In pr;or art systems, attempts are frequently made to place the wavelength of the opt;cal signal ;n this wavelength reg;on.
The object ;s attained as set forth ;n cla;m 1. Further advantageous features of the ;nvent;on are def;ned in the subcla;ms.
C .; ~ - .; t ~ r ~ ;J
~he'inventiôn wirl~now be!explained~in~môre det^ail~ fi reference to the accompanying drawing, in which: -F;g. 1 shows one embod;ment of a transmission link with a fiber-optic amplifier and an optical : , - - - . , -, :, - , -' 2~98~1 filter in accordance with the invent;on;
Fig. 2 shows an em;ss;on spectrum of a fiber-optic amplifier;
Fig. 3 shows exemplary spectral characteristics of an optical sharp-cutoff filter and an optical bandpass f;lter, and F;g. 4 shows a wauelength-select;ve fused f;ber coupler with coupling characteristic.
Fig. 1 shows part of an opt;cal transmission link im-plemented w;th an opt;cal waveguide 1, which includes a prior art fiber-optic ampl;fier 6.
In known system representat;ons, an optical isolator 5 is shown at the output of the fiber-optic amplifier.
It protects the fiber-optic amplifier against feedback from the subsequent portion of the fiber-optic link or from the subsequent amplif;er stage. For the ;nvention~
howeYer, this is of no significance~
An optical isolator 4 at the input of the fiber-optic amplifier can prevent the development of giant pulses if the interruption of the fiber-optic link occurs at point 2. In that case, it will prevent amplified spon-taneous em;ssion tASE) propagating from the amplifying section of optical waveguide in a d;rection opposite -to the direction of transmission. Thus, this em;ssion cannot reach the point of the~break ,in the optical waveguide and, hence, will not be reflected. If, however, the optical isolator 4 is omitted on cost grounds, or the interruption occurs at point 3,~reflection of - , ' .: ' .
.
20980~
am.plifi.ed spontaneous emission will occur~ This reflec-tion, as menti.oned above, will initiate the release of the energy stored in the inverted ampli.fying medium.
The higher the rate of change of the reflected power or the faster the formation of the point of reflection, the larger the resulti.ng pulses will be. The nouel sup-plement to the optical transmission system is constitut-ed by an optical filter 7, whose operation will be ex-plained with reference to Fig~ 2~
Fig. 2 shows the recorded ~optical) spectrum of the amplifi.ed spontaneous emissi.on (denoted in ~ig. 2 by "ASE spectrum") with the superposed spectral line of the giant pulse induced by the bac.k reflecti.on. In the . .:
case of the erbium-doped fiber-optic ampli.fier, the maximu~ of the ASE spectrum appears at 1532 nm. It can be seen that the g;ant pulse occurs at the maxi~um. of the ASE spectrum. This is due to the fact that the medi.um has its greatest optical gain there.
Based on recognition that the pulse spectrum has a very narrow ban.dwiclth in the region around 1532 nm, accordi.ng to the invent;on, light of this wavelength region is prevented from propagating in the optical waveguide by means of an optical filter 7. This optical filter has.a stop band in the wavelength region of the maximum gain of the fiber-optic amplifier, i.e., in the region around 1532 nm. Since the pulse spectrum has a very narrow bandwidth, the wavelength Ae will henceforth be assigned to it.
The location of the optical filter depends on which de-vi.ces of the transmission system have to be protected.
.. . . .
. - ~
- .
.
.
~98~
In practice, the fiber-opt;c amplifiers are also used in cascade. To prevent any escalation of the pulse, the optical f;lter 7 can be placed behind each f;ber-optic amplifier. If the photodetector is to be pro-tected, the optical filter 7 must be positioned in the fiber-opt;c link in such a way that the g;ant pulse w;ll not str;ke the photodetector. ~as;cally, the opt;cal f;lter ;s designed to prevent the energy of the g;ant pulse from reach;ng the subsequent system component. The same appl;es analogously ;n the reverse direction if no optical isolator ;s present ~e.g., to protect the opt;cal transm;tter).
Figs. 3 and 4 show embod;ments of an optical f;lter.
Fig. 3 shows the characteristics of an optical sharp-cutoff f;lter and an optical bandpass filter. The pass-band is chosen so that the optical signal of wavelength ~s will be passed, while the wavelength ~e of the pulse will be eliminated~ Examples of such optical filters are Fabry-Pérot filters, etalons, and absorbin~ filters.
The embodiment of an optical filter shown in Fig. 4A
is a wavelength-selective fused fiber coupler. This coupler separates the wavelengths Ae and As so that only the wavelength ~s of the optical signal will be passed on to the receiver.
Fig. 4B is a sketch of the filter characteristic~ It can be seen that the wavelength ~e of the pulse ;s el;minated.
Another possibility of eliminating the pulse wavelength is to place a length of optical waveguide made of an absorbing material with a narrow absorbtion band in the '' .' ~ ~. ' ~ .' ' ' ~ .
.
~Q98~1 fiber-optic link. This may be, for example, a length of a crystalline optical waveguide doped with a rare-earth element, e.g., Er3 . A crystalline, Er3 -doped optical waveguide has a very narrow absorption band in the region around 1530 nm. This is described in the literature, e.g., H. Stange, U. Petermann, G. Huber, E.W. Duczynski, "Continuous Wave 1.6 ~m Laser Action in Er Doped Garnets at Room Temperature", Applied Physics, B 49, 269-272, 1989.
There are applications in which a specific optical fil-ter for suppressing giant pulses is not necessary. In conclusion an example of such an applicat;on is given.
In high-bit-rate digital systems, receiver sens;tivity can be improved by an optical amplifier thenceforth called "preamplifier") ahead of the receiver if a narrow-band optical filter is provided between pre-amplifier and receiver for noise suppression.
The bandwidth of this optical filter should ideally be equal to the signal bandw;dth~ This opt;cal filter can also be used to provide protection against giant pulses if the wavelength ~s of the optical signal does not overlap the wavelength ~e of the pulse. This eliminates the need for an additional optical filter.
., , . , . ~ . .
'' . ' - , :.
: . : : ~ . . . - -.. . . : : -. :: . , . : .. ~
- 1 - P 42 Z2 208.7 Optical Transm;ssion System with Optical Filter for Providing Protection agai.nst Giant Pulses . .
The present in~ention relates to an opti.cal communica~
tion system as set forth ;n the preamble of claim 1.
Such systems are known, e.g., from ~. Weddi.ng et al, "10 Gbit/s to 260000 Subscribers Using Optical Amplifier Distribution Network", Contribution for ICC/Supercomm '92, Optical Communications 300 Level Session, "Impact of Optical Ampli.fiers on Network Architectures". The fiber-optic amplifier is shown in detail in EP O 457 349 A2, for example.
In the above system, there is the danger that in the event of a break in the fiber-optic link, e~g~, due to fiber breakage, high-energy pulses w;Ll be em;.tted. These g;ant pulses are caused by the fact that upon interrup-tion of the fiber-optic link, the input power drops to :
zero and the light resulting from the spontaneous emission is reflected at the point of the break.
This can be described in more detail as follows~ Since the pump;ng process ;s ;ndependent of the power input, energy will constantly be pumped into the amplifyi.ng medium even if the power input has dropped, so that complete population inversion will occur. When reflected light passes through the amplifyi.ng section of optical .
. ~ . . . . :
. .. : - , , . : ' -.
20~80~
waveguide, whose active laser medium is in the invert-ed state, the stored energy will be suddenly released.
Giant pulses will be emitted which are a danger to system components, such as photodetectors.
Be;ng comparable to an effect which is well known from solid-state lasers, the giant-pulse emission is also known by the term Q-switching. For semiconductor lasers, this effect is described, for example, by Petermann, U., in "Laser Diode Modulation and Noise", Kluwer Academic Publishers, UT K Scientific Publisher, Tokyo 1988.
It is the object of the ;nvent;on to provide an optical transmission system of the above kind wherein the danger associated with giant pulses is avoided.
To be able to attain this object, the wavelength of the optical signal must be chosen to lie outside the wavelength region of the maximum gain of the fiber-optic amplifier, where the giant-pulse emiss;on occurs.
In pr;or art systems, attempts are frequently made to place the wavelength of the opt;cal signal ;n this wavelength reg;on.
The object ;s attained as set forth ;n cla;m 1. Further advantageous features of the ;nvent;on are def;ned in the subcla;ms.
C .; ~ - .; t ~ r ~ ;J
~he'inventiôn wirl~now be!explained~in~môre det^ail~ fi reference to the accompanying drawing, in which: -F;g. 1 shows one embod;ment of a transmission link with a fiber-optic amplifier and an optical : , - - - . , -, :, - , -' 2~98~1 filter in accordance with the invent;on;
Fig. 2 shows an em;ss;on spectrum of a fiber-optic amplifier;
Fig. 3 shows exemplary spectral characteristics of an optical sharp-cutoff filter and an optical bandpass f;lter, and F;g. 4 shows a wauelength-select;ve fused f;ber coupler with coupling characteristic.
Fig. 1 shows part of an opt;cal transmission link im-plemented w;th an opt;cal waveguide 1, which includes a prior art fiber-optic ampl;fier 6.
In known system representat;ons, an optical isolator 5 is shown at the output of the fiber-optic amplifier.
It protects the fiber-optic amplifier against feedback from the subsequent portion of the fiber-optic link or from the subsequent amplif;er stage. For the ;nvention~
howeYer, this is of no significance~
An optical isolator 4 at the input of the fiber-optic amplifier can prevent the development of giant pulses if the interruption of the fiber-optic link occurs at point 2. In that case, it will prevent amplified spon-taneous em;ssion tASE) propagating from the amplifying section of optical waveguide in a d;rection opposite -to the direction of transmission. Thus, this em;ssion cannot reach the point of the~break ,in the optical waveguide and, hence, will not be reflected. If, however, the optical isolator 4 is omitted on cost grounds, or the interruption occurs at point 3,~reflection of - , ' .: ' .
.
20980~
am.plifi.ed spontaneous emission will occur~ This reflec-tion, as menti.oned above, will initiate the release of the energy stored in the inverted ampli.fying medium.
The higher the rate of change of the reflected power or the faster the formation of the point of reflection, the larger the resulti.ng pulses will be. The nouel sup-plement to the optical transmission system is constitut-ed by an optical filter 7, whose operation will be ex-plained with reference to Fig~ 2~
Fig. 2 shows the recorded ~optical) spectrum of the amplifi.ed spontaneous emissi.on (denoted in ~ig. 2 by "ASE spectrum") with the superposed spectral line of the giant pulse induced by the bac.k reflecti.on. In the . .:
case of the erbium-doped fiber-optic ampli.fier, the maximu~ of the ASE spectrum appears at 1532 nm. It can be seen that the g;ant pulse occurs at the maxi~um. of the ASE spectrum. This is due to the fact that the medi.um has its greatest optical gain there.
Based on recognition that the pulse spectrum has a very narrow ban.dwiclth in the region around 1532 nm, accordi.ng to the invent;on, light of this wavelength region is prevented from propagating in the optical waveguide by means of an optical filter 7. This optical filter has.a stop band in the wavelength region of the maximum gain of the fiber-optic amplifier, i.e., in the region around 1532 nm. Since the pulse spectrum has a very narrow bandwidth, the wavelength Ae will henceforth be assigned to it.
The location of the optical filter depends on which de-vi.ces of the transmission system have to be protected.
.. . . .
. - ~
- .
.
.
~98~
In practice, the fiber-opt;c amplifiers are also used in cascade. To prevent any escalation of the pulse, the optical f;lter 7 can be placed behind each f;ber-optic amplifier. If the photodetector is to be pro-tected, the optical filter 7 must be positioned in the fiber-opt;c link in such a way that the g;ant pulse w;ll not str;ke the photodetector. ~as;cally, the opt;cal f;lter ;s designed to prevent the energy of the g;ant pulse from reach;ng the subsequent system component. The same appl;es analogously ;n the reverse direction if no optical isolator ;s present ~e.g., to protect the opt;cal transm;tter).
Figs. 3 and 4 show embod;ments of an optical f;lter.
Fig. 3 shows the characteristics of an optical sharp-cutoff f;lter and an optical bandpass filter. The pass-band is chosen so that the optical signal of wavelength ~s will be passed, while the wavelength ~e of the pulse will be eliminated~ Examples of such optical filters are Fabry-Pérot filters, etalons, and absorbin~ filters.
The embodiment of an optical filter shown in Fig. 4A
is a wavelength-selective fused fiber coupler. This coupler separates the wavelengths Ae and As so that only the wavelength ~s of the optical signal will be passed on to the receiver.
Fig. 4B is a sketch of the filter characteristic~ It can be seen that the wavelength ~e of the pulse ;s el;minated.
Another possibility of eliminating the pulse wavelength is to place a length of optical waveguide made of an absorbing material with a narrow absorbtion band in the '' .' ~ ~. ' ~ .' ' ' ~ .
.
~Q98~1 fiber-optic link. This may be, for example, a length of a crystalline optical waveguide doped with a rare-earth element, e.g., Er3 . A crystalline, Er3 -doped optical waveguide has a very narrow absorption band in the region around 1530 nm. This is described in the literature, e.g., H. Stange, U. Petermann, G. Huber, E.W. Duczynski, "Continuous Wave 1.6 ~m Laser Action in Er Doped Garnets at Room Temperature", Applied Physics, B 49, 269-272, 1989.
There are applications in which a specific optical fil-ter for suppressing giant pulses is not necessary. In conclusion an example of such an applicat;on is given.
In high-bit-rate digital systems, receiver sens;tivity can be improved by an optical amplifier thenceforth called "preamplifier") ahead of the receiver if a narrow-band optical filter is provided between pre-amplifier and receiver for noise suppression.
The bandwidth of this optical filter should ideally be equal to the signal bandw;dth~ This opt;cal filter can also be used to provide protection against giant pulses if the wavelength ~s of the optical signal does not overlap the wavelength ~e of the pulse. This eliminates the need for an additional optical filter.
., , . , . ~ . .
'' . ' - , :.
: . : : ~ . . . - -.. . . : : -. :: . , . : .. ~
Claims (3)
1. An optical transmission system for transmitting an optical signal over an optical waveguide containing at least one fiber-optic amplifier (6), c h a r a c t e r i z e d i n that the wavelength of the optical signal lies outside the wavelength region of the maximum gain of the fiber-optic amplifier, and that an optical filter (7) having a stop band in the wavelength region of the maximum gain of the fiber-optic amplifier (6) is provided be-fore or after at least one fiber-optic amplifier (6).
2. An optical transmission system as claimed in claim 1, characterized in that the optical filter (7) is a wavelength-selective fused fiber coupler.
3. An optical transmission system as claimed in claim 1, characterized in that the optical filter (7) is a length of optical waveguide made of an absorbing ma-terial with a narrow absorption band.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4222208.7 | 1992-07-07 | ||
| DE4222208A DE4222208A1 (en) | 1992-07-07 | 1992-07-07 | Optical communication system with optical filter to protect against giant impulses |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2098051A1 true CA2098051A1 (en) | 1994-01-08 |
Family
ID=6462619
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002098051A Abandoned CA2098051A1 (en) | 1992-07-07 | 1993-06-09 | Optical transmission system with optical filter for providing protection against giant pulses |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US5317660A (en) |
| EP (1) | EP0579023B1 (en) |
| JP (1) | JP3336078B2 (en) |
| AU (1) | AU658749B2 (en) |
| CA (1) | CA2098051A1 (en) |
| DE (2) | DE4222208A1 (en) |
| ES (1) | ES2103401T3 (en) |
| NZ (1) | NZ248011A (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5406404A (en) * | 1993-11-02 | 1995-04-11 | At&T Corp. | Method of mitigating gain peaking using a chain of fiber amplifiers |
| JPH08331048A (en) * | 1995-06-05 | 1996-12-13 | Fujitsu Ltd | Optical signal receiver |
| EP0772264B1 (en) * | 1995-10-30 | 2003-05-07 | Nec Corporation | Optical surge preventing method and system for use in a rare earth doped fiber circuit |
| KR100194421B1 (en) * | 1996-01-29 | 1999-06-15 | 윤종용 | Fiber optic amplifier |
| US5801879A (en) * | 1996-10-29 | 1998-09-01 | Corning Incorporated | Device and method to supress Q-switching in an optical amplifying device |
| JP3000948B2 (en) * | 1997-01-16 | 2000-01-17 | 日本電気株式会社 | Optical amplifier |
| DE19723103A1 (en) * | 1997-06-03 | 1998-12-10 | Alsthom Cge Alcatel | Receiver for receiving optical signals from optical communications network |
| US6775484B1 (en) | 1997-06-03 | 2004-08-10 | Alcatel Alsthom Compagnie Generale D'electricite | Receiver for receiving optical signals |
| KR100264469B1 (en) * | 1997-08-12 | 2000-08-16 | 정선종 | Multi-wavelength channel transmission type optic filter |
| US6583899B1 (en) * | 1998-12-31 | 2003-06-24 | Cisco Photonics Italy S.R.L. | Automatic protection system for an optical transmission system |
| DE19934498C2 (en) * | 1999-07-22 | 2001-11-29 | Siemens Ag | Circuit arrangement and method for detecting an interruption in an optical fiber link |
| US6980747B1 (en) * | 2000-11-28 | 2005-12-27 | Harris Corporation | Optically amplified receiver |
| US7525725B2 (en) * | 2002-03-05 | 2009-04-28 | Sumitomo Electric Industries, Ltd. | Optical amplification module, optical amplifier, optical communication system, and white light source |
| US7218442B2 (en) * | 2005-03-04 | 2007-05-15 | Jds Uniphase Corporation | Optical communications system with fiber break detection in the presence of Raman amplification |
| JP2014033098A (en) * | 2012-08-03 | 2014-02-20 | Fujikura Ltd | Fiber laser device |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4947134A (en) * | 1987-10-30 | 1990-08-07 | American Telephone And Telegraph Company | Lightwave systems using optical amplifiers |
| US4900119A (en) * | 1988-04-01 | 1990-02-13 | Canadian Patents & Development Ltd. | Wavelength selective optical devices using optical directional coupler |
| US4881790A (en) * | 1988-04-25 | 1989-11-21 | American Telephone And Telegraph Company, At&T Bell Laboratories | Optical communications system comprising raman amplification means |
| IT1248821B (en) * | 1990-05-25 | 1995-01-30 | Pirelli Cavi Spa | FIBER OPTIC TELECOMMUNICATION LINE WITH ACTIVE FIBER OPTICAL AMPLIFIERS WITH REDUCED REFLECTIONS |
| IT1231208B (en) * | 1989-07-17 | 1991-11-23 | Pirelli Cavi Spa | UNIT FOR THE AMPLIFICATION OF LIGHT SIGNALS IN FIBER OPTIC TRANSMISSION LINES. |
| CA2042697C (en) * | 1990-05-18 | 1994-08-16 | Kenji Tagawa | Fiber optic amplifier |
| US5146517A (en) * | 1991-07-05 | 1992-09-08 | At&T Bell Laboratories | Low distortion all-optical threshold device |
| US5140656A (en) * | 1991-08-12 | 1992-08-18 | At&T Bell Laboratories | Soliton optical fiber communication system |
-
1992
- 1992-07-07 DE DE4222208A patent/DE4222208A1/en not_active Withdrawn
-
1993
- 1993-06-09 CA CA002098051A patent/CA2098051A1/en not_active Abandoned
- 1993-06-21 US US08/080,352 patent/US5317660A/en not_active Expired - Lifetime
- 1993-06-25 AU AU41489/93A patent/AU658749B2/en not_active Ceased
- 1993-06-29 ES ES93110307T patent/ES2103401T3/en not_active Expired - Lifetime
- 1993-06-29 NZ NZ248011A patent/NZ248011A/en unknown
- 1993-06-29 JP JP15932593A patent/JP3336078B2/en not_active Expired - Lifetime
- 1993-06-29 DE DE59306369T patent/DE59306369D1/en not_active Expired - Lifetime
- 1993-06-29 EP EP93110307A patent/EP0579023B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| AU658749B2 (en) | 1995-04-27 |
| JP3336078B2 (en) | 2002-10-21 |
| AU4148993A (en) | 1994-01-13 |
| NZ248011A (en) | 1996-06-25 |
| DE4222208A1 (en) | 1994-01-13 |
| DE59306369D1 (en) | 1997-06-12 |
| EP0579023B1 (en) | 1997-05-07 |
| ES2103401T3 (en) | 1997-09-16 |
| JPH06204947A (en) | 1994-07-22 |
| EP0579023A1 (en) | 1994-01-19 |
| US5317660A (en) | 1994-05-31 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |