CA2074813A1 - Optical amplifier - Google Patents
Optical amplifierInfo
- Publication number
- CA2074813A1 CA2074813A1 CA002074813A CA2074813A CA2074813A1 CA 2074813 A1 CA2074813 A1 CA 2074813A1 CA 002074813 A CA002074813 A CA 002074813A CA 2074813 A CA2074813 A CA 2074813A CA 2074813 A1 CA2074813 A1 CA 2074813A1
- Authority
- CA
- Canada
- Prior art keywords
- operating current
- laser
- pump
- optical amplifier
- current
- 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
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/094003—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light the pumped medium being a fibre
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/094003—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light the pumped medium being a fibre
- H01S3/094011—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light the pumped medium being a fibre with bidirectional pumping, i.e. with injection of the pump light from both two ends of the fibre
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/094076—Pulsed or modulated pumping
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/09408—Pump redundancy
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Lasers (AREA)
Abstract
ABSTRACT
OPTICAL AMPLIFIER
Known optical amplifiers, which are used in a light transmis-sion path to amplify the light signals to be transmitted, have the disadvantage that the semiconductor lasers, used as pump lasers therein, are very sensitive to feedback.
According to the invention, the operating current of such pump lasers (4) is modulated at a high frequency, which causes the pump laser to operate in a multi-mode, thereby making it in-sensitive to feedback. For example, the operating current is DC, on which AC is superimposed.
In the event the optical amplifier has two pump lasers, their operating current is also modulated. Both pump lasers are then advantageously alternately switched on and off at a suf-ficiently high switching frequency, which also prevents recip-rocal interference.
Figure 1.
OPTICAL AMPLIFIER
Known optical amplifiers, which are used in a light transmis-sion path to amplify the light signals to be transmitted, have the disadvantage that the semiconductor lasers, used as pump lasers therein, are very sensitive to feedback.
According to the invention, the operating current of such pump lasers (4) is modulated at a high frequency, which causes the pump laser to operate in a multi-mode, thereby making it in-sensitive to feedback. For example, the operating current is DC, on which AC is superimposed.
In the event the optical amplifier has two pump lasers, their operating current is also modulated. Both pump lasers are then advantageously alternately switched on and off at a suf-ficiently high switching frequency, which also prevents recip-rocal interference.
Figure 1.
Description
2~7~13 TRANSLATED FROM GERMAN
OPTICAL AMPLIFIER
Optical amplifiers serve to amplify light signals which are transmitted over a transmission path, in particular a fiber optical waveguide (optical fiber), and are weakened by attenu-ation so that they must be amplified.
An optical amplifier with characteristics according to the introductory clause of patent claim 1 is known e.g. from: M.
Yoshida et al: "Development of Compact Er3+-doped Fiber Ampli-fiers for Practical Applications", Technical Digest on Optical Amplifiers and their Applications 1990 (Optical So~iety of America, Washington, DC 1990), Volume 13, pages 282 to 285.
It is a fiber amplifier with an erbium-doped length of fiber.
Erbium is a laser-active substance, which is excited by a semiconductor laser serving as a pump laser. In this instance, the semiconductor laser emits light at a wavelength of A = 1480 m. This light is introduced into the doped length of fiber by an optical coupler. Direct current is used as the operating current to control the semiconductor laser.
Instead of a single pump laser, as in figure la, two pump lasers as shown in figure lc can also be provided, whose pump light is coupled into each end of the length of fiber.
A disadvantage of this optical amplifier is that the pump light produced by the semiconductor laser i8 reflected back into the semiconductor laser at all points along its propaga-tion path where refractive index skipping occurs (e.g. in the area of the opti~al coupler or in the transition between the optical fiber and the erbium-doped length of fiber). This degrades the efficiency of the semiconductor laser; the re-flected light can cause amplitude fluctuations in the pumplight emitted by the semiconductor laser, because the laser-active layer in the semiconductor laser acts as a laser reso-nator, together with part of the transmission path (i.e. up to ~7'~81~
the area with the refractive index skip). This changes the emission frequency of the semiconductor laser, on the one hand, and subjects the amplitude of the pump light to oscilla-tions, on the other. In particular, the amplifying effect of the length of fiber is temporarily cancelled when the oscilla-tions occur in the low frequency range, e.g. in the kilohertz range; this can interrupt the optical transmission, under certain circumstances.
In the event two pump lasers are present (semiconductor lasers in each instance), the described problem exists for each of the two pump lasers. Furthermore, in that case there is the problem of residual pump light from each pump laser entering the opposite pump laser, which causes optical instabilities, which in turn lead to the above described problems of fluctua-tions in amplification. For that reason, optical isolatorsare presently used before the pump lasers.
It is the task of the invention to produce an optical amplifi-er with one pump laser or two pump lasers, which ensures in-terference-free amplification of the light signals.
The task i~ fulfilled as indicated in patent claim 1.
An advantage of the invention consists in that it makes unnec-essary the costly installation of optical isolators between the optical coupler and the semiconductor laser, immediately before the latter, to prevent the pump light from being re-flected back into the semiconductor laser.
The frequency at which the operating current i5 modulated, isabove the reciprocal lifetime of the excited energy level of the laser-active substance, e.g. erbium, which causes the amplification of the light signals to be transmitted. In this way, the fluctuations in the pump light amplitude are not "perceived" by the laser-active substance, i.e. the length of ~7~
fiber acts as a low-pass filter for the varying component of the pump light signal.
Further advantageous configurations can be found in the subclaims.
The following describes the invention in greater detail by means of drawings representing only one configuration, where:
Figure 1 shows an optical amplifier according to the inven-tion with a single pump laser, and Figure 2 shows an amplifier according to the invention with two pump lasers.
In figure 1, an optical amplifier is inserted into a light waveguide transmission path 1. It has a length of fiber 2, which is doped with a laser-active substance, e.g. erbium.
Light signals are transmitted over the light waveguide trans-mission path 1, and amplified in the length of fiber 2. Thelight signals have a wavelength of A = 1530 - 1570 nm. One end 21 of the length of fiber 2 is connected to a semiconduc-tor laser 4 by an optical coupler 3. The sQmiconductor laser 4 is, for example, an InGaAsP/InP-, an InGaAs/AlGaAs- or a GaAlAs/GaAs-laser, which emits at a wavelength in the range of = 750 - 870 nm, A = 960 - 1000 nm or A = 1460 - 1500 nm. An electrical contact 41 connects it to a DC source 5. So far, the description of the optical amplifier in figure 1 matches the known types.
According to the invention~ the operating current of the laser is not a DC current but a modulated current. For that pur-pose, the semiconductor laser 4 in the configuration in figure 1 has an electrical contact 42, which connects it to an AC
source 6. The AC source 6 produces for example either a si-nus-shaped or a ~quare-shaped alternating current.
207 ~
The AC source 6 produces an alternating current, which, to-gether with the direct current from the DC source, forms the operating current of the semi~onductor laser 4 ~pump laser).
In other words: the operating current is a direct current on which an alternating current has been superimposed, or: the operating current is a (periodically) modulated direct cur-rent.
Instead of an arrangement of DC source S and AC source 6, a modulatable DC source can also be used a~ the operating cur-rent source. Only the operating current must be modulated insome way.
The semiconductor laser 4 emits multi-mode pump light based on the alternating current, i.e. the modulated operating current.
For example, the light from a semiconductor laser emitting at ~ = 1480 nm, which ha~ only a few modes with direct current, is split by the alternating current portion into 20 - 30 modes, which have a mode spacirg of 80 GHz.
The frequency of the AC, i.e. the modulation frequency of the operating current, i8 above the reciprocal lifetime of the excited, laser-active energy level of the erbium in fiber length 2. Since the lifetime of the energy level is in the millisecond range, the AC should be provided with a frequency in the lower megahertz range. This prevents the pump light frequency from modulating the light signals to be transmitted and amplified.
As mentioned in the beginning, there are fiber optic amplifi-ers with two pump lasers on each side of the amplifying length of fiber. The problem of back reflection of pump light into the pump laser can al80 be solved as indicated earlier, by operating the pump laser or lasers with an operating current which is a modulated direct current.
2 ~ 7 ~
Figure 2 shows a configuration example of such a solution.
The left portion of the figure corresponds exactly to figure 1, therefore this portion does not need to be explained again.
The second end 22 of the length of fiber is connected to a second semiconductor laser 8 by an optical coupler 7. The laser has two electrical contacts 81 and 82, which connect it to the DC source 5 or the AC source 6.
Instead of the single AC source 6, each semiconductor laser 4 and 8 may have its own AC source. The same applies to DC
sour~e 5.
An operating current source of the type shown in figure 2, or by other means, as explained above for the instance of a sin-gle pump laser, also provides modulation of the operating current in the case of two pump lasers.
Still, a reciprocal interference effect of the pump laserg cannot be excluded. ~hat i8 why optical isolators are pres-ently placed before the pump lasers. The invention permits omitting the isolators, when the two pump lasers are alter-nately switched on and off, so that only one is active and the other inactive. This represents a modulation of the operating current of each of the two pump lasers, which prevents recip-rocal interference of the semiconductor laser6 4 and 8. The multi-modicity of the lasers i8 automatically ensured by the switching, if the switching frequency is sufficiently high.
If it i8 high enough for the purpose of multi-modicity of the pump laser, it is also practically higher than the reciprocal lifetime of the excited energy level of the laser-active sub-stance in the length of fiber 2, which is required in all instances, as explained earlier.
Although with two alternately switched-on pump lasers, the average pump output in the length of fiber 2 is only as large as that of a single, permanently operating pump laser, the following advantages are found: bidirectional pumping simul-2 ~ 7 /~
taneously achieves both a lower noise factor and a higheroutput. In addition, each laser is only used half of the time, which has a positive effect on reliability.
For example, to supply both pump lasers with alternately switched-on operating current, an ~F generator with two in-verted outlets can be used, one of which always conducts cur-rent while the other conducts no current.
To switch the pump lasers on and off, it is unimportant wheth-er the operating current of one pump laser is fully switched off during its idle phase, or is only lowered under the pump laser's threshold current.
~he alternate on and off switching of the two pump lasers can also be achieved with a device that supplies a square-wave AC
alternately to one and the other pump laser through a switch.
Regardless of how it is produced, the operating current of a pump laser may be a square-shaped DC that is turned on and off. How-ever, it can also be a square-shaped DC that is turned on and off, on which AC is permanently superimposed, or only during the on-phase of the pump laser, 60 that a modulat-ed DC flows as the operating current through the pump laserduring the on-phase itself. This i8 particularly necessary when the switching frequency of the alternate on-switching of the two lasers i8 not high enough to make each of the pump lasers multi-modal during its on-phase. In that instance, the DC modulation supplie6 the multi-modicity during the on-phase.
OPTICAL AMPLIFIER
Optical amplifiers serve to amplify light signals which are transmitted over a transmission path, in particular a fiber optical waveguide (optical fiber), and are weakened by attenu-ation so that they must be amplified.
An optical amplifier with characteristics according to the introductory clause of patent claim 1 is known e.g. from: M.
Yoshida et al: "Development of Compact Er3+-doped Fiber Ampli-fiers for Practical Applications", Technical Digest on Optical Amplifiers and their Applications 1990 (Optical So~iety of America, Washington, DC 1990), Volume 13, pages 282 to 285.
It is a fiber amplifier with an erbium-doped length of fiber.
Erbium is a laser-active substance, which is excited by a semiconductor laser serving as a pump laser. In this instance, the semiconductor laser emits light at a wavelength of A = 1480 m. This light is introduced into the doped length of fiber by an optical coupler. Direct current is used as the operating current to control the semiconductor laser.
Instead of a single pump laser, as in figure la, two pump lasers as shown in figure lc can also be provided, whose pump light is coupled into each end of the length of fiber.
A disadvantage of this optical amplifier is that the pump light produced by the semiconductor laser i8 reflected back into the semiconductor laser at all points along its propaga-tion path where refractive index skipping occurs (e.g. in the area of the opti~al coupler or in the transition between the optical fiber and the erbium-doped length of fiber). This degrades the efficiency of the semiconductor laser; the re-flected light can cause amplitude fluctuations in the pumplight emitted by the semiconductor laser, because the laser-active layer in the semiconductor laser acts as a laser reso-nator, together with part of the transmission path (i.e. up to ~7'~81~
the area with the refractive index skip). This changes the emission frequency of the semiconductor laser, on the one hand, and subjects the amplitude of the pump light to oscilla-tions, on the other. In particular, the amplifying effect of the length of fiber is temporarily cancelled when the oscilla-tions occur in the low frequency range, e.g. in the kilohertz range; this can interrupt the optical transmission, under certain circumstances.
In the event two pump lasers are present (semiconductor lasers in each instance), the described problem exists for each of the two pump lasers. Furthermore, in that case there is the problem of residual pump light from each pump laser entering the opposite pump laser, which causes optical instabilities, which in turn lead to the above described problems of fluctua-tions in amplification. For that reason, optical isolatorsare presently used before the pump lasers.
It is the task of the invention to produce an optical amplifi-er with one pump laser or two pump lasers, which ensures in-terference-free amplification of the light signals.
The task i~ fulfilled as indicated in patent claim 1.
An advantage of the invention consists in that it makes unnec-essary the costly installation of optical isolators between the optical coupler and the semiconductor laser, immediately before the latter, to prevent the pump light from being re-flected back into the semiconductor laser.
The frequency at which the operating current i5 modulated, isabove the reciprocal lifetime of the excited energy level of the laser-active substance, e.g. erbium, which causes the amplification of the light signals to be transmitted. In this way, the fluctuations in the pump light amplitude are not "perceived" by the laser-active substance, i.e. the length of ~7~
fiber acts as a low-pass filter for the varying component of the pump light signal.
Further advantageous configurations can be found in the subclaims.
The following describes the invention in greater detail by means of drawings representing only one configuration, where:
Figure 1 shows an optical amplifier according to the inven-tion with a single pump laser, and Figure 2 shows an amplifier according to the invention with two pump lasers.
In figure 1, an optical amplifier is inserted into a light waveguide transmission path 1. It has a length of fiber 2, which is doped with a laser-active substance, e.g. erbium.
Light signals are transmitted over the light waveguide trans-mission path 1, and amplified in the length of fiber 2. Thelight signals have a wavelength of A = 1530 - 1570 nm. One end 21 of the length of fiber 2 is connected to a semiconduc-tor laser 4 by an optical coupler 3. The sQmiconductor laser 4 is, for example, an InGaAsP/InP-, an InGaAs/AlGaAs- or a GaAlAs/GaAs-laser, which emits at a wavelength in the range of = 750 - 870 nm, A = 960 - 1000 nm or A = 1460 - 1500 nm. An electrical contact 41 connects it to a DC source 5. So far, the description of the optical amplifier in figure 1 matches the known types.
According to the invention~ the operating current of the laser is not a DC current but a modulated current. For that pur-pose, the semiconductor laser 4 in the configuration in figure 1 has an electrical contact 42, which connects it to an AC
source 6. The AC source 6 produces for example either a si-nus-shaped or a ~quare-shaped alternating current.
207 ~
The AC source 6 produces an alternating current, which, to-gether with the direct current from the DC source, forms the operating current of the semi~onductor laser 4 ~pump laser).
In other words: the operating current is a direct current on which an alternating current has been superimposed, or: the operating current is a (periodically) modulated direct cur-rent.
Instead of an arrangement of DC source S and AC source 6, a modulatable DC source can also be used a~ the operating cur-rent source. Only the operating current must be modulated insome way.
The semiconductor laser 4 emits multi-mode pump light based on the alternating current, i.e. the modulated operating current.
For example, the light from a semiconductor laser emitting at ~ = 1480 nm, which ha~ only a few modes with direct current, is split by the alternating current portion into 20 - 30 modes, which have a mode spacirg of 80 GHz.
The frequency of the AC, i.e. the modulation frequency of the operating current, i8 above the reciprocal lifetime of the excited, laser-active energy level of the erbium in fiber length 2. Since the lifetime of the energy level is in the millisecond range, the AC should be provided with a frequency in the lower megahertz range. This prevents the pump light frequency from modulating the light signals to be transmitted and amplified.
As mentioned in the beginning, there are fiber optic amplifi-ers with two pump lasers on each side of the amplifying length of fiber. The problem of back reflection of pump light into the pump laser can al80 be solved as indicated earlier, by operating the pump laser or lasers with an operating current which is a modulated direct current.
2 ~ 7 ~
Figure 2 shows a configuration example of such a solution.
The left portion of the figure corresponds exactly to figure 1, therefore this portion does not need to be explained again.
The second end 22 of the length of fiber is connected to a second semiconductor laser 8 by an optical coupler 7. The laser has two electrical contacts 81 and 82, which connect it to the DC source 5 or the AC source 6.
Instead of the single AC source 6, each semiconductor laser 4 and 8 may have its own AC source. The same applies to DC
sour~e 5.
An operating current source of the type shown in figure 2, or by other means, as explained above for the instance of a sin-gle pump laser, also provides modulation of the operating current in the case of two pump lasers.
Still, a reciprocal interference effect of the pump laserg cannot be excluded. ~hat i8 why optical isolators are pres-ently placed before the pump lasers. The invention permits omitting the isolators, when the two pump lasers are alter-nately switched on and off, so that only one is active and the other inactive. This represents a modulation of the operating current of each of the two pump lasers, which prevents recip-rocal interference of the semiconductor laser6 4 and 8. The multi-modicity of the lasers i8 automatically ensured by the switching, if the switching frequency is sufficiently high.
If it i8 high enough for the purpose of multi-modicity of the pump laser, it is also practically higher than the reciprocal lifetime of the excited energy level of the laser-active sub-stance in the length of fiber 2, which is required in all instances, as explained earlier.
Although with two alternately switched-on pump lasers, the average pump output in the length of fiber 2 is only as large as that of a single, permanently operating pump laser, the following advantages are found: bidirectional pumping simul-2 ~ 7 /~
taneously achieves both a lower noise factor and a higheroutput. In addition, each laser is only used half of the time, which has a positive effect on reliability.
For example, to supply both pump lasers with alternately switched-on operating current, an ~F generator with two in-verted outlets can be used, one of which always conducts cur-rent while the other conducts no current.
To switch the pump lasers on and off, it is unimportant wheth-er the operating current of one pump laser is fully switched off during its idle phase, or is only lowered under the pump laser's threshold current.
~he alternate on and off switching of the two pump lasers can also be achieved with a device that supplies a square-wave AC
alternately to one and the other pump laser through a switch.
Regardless of how it is produced, the operating current of a pump laser may be a square-shaped DC that is turned on and off. How-ever, it can also be a square-shaped DC that is turned on and off, on which AC is permanently superimposed, or only during the on-phase of the pump laser, 60 that a modulat-ed DC flows as the operating current through the pump laserduring the on-phase itself. This i8 particularly necessary when the switching frequency of the alternate on-switching of the two lasers i8 not high enough to make each of the pump lasers multi-modal during its on-phase. In that instance, the DC modulation supplie6 the multi-modicity during the on-phase.
Claims (5)
1. An optical amplifier with a length of fiber (2) that contains a laser-active substance for amplifying light sig-nals, which is coupled to at least one semiconductor laser (4) serving as a pump light source, which is activated by an oper-ating current, characterized in that an operating current source (5, 6) is provided, and produces a modulated operating current for the pump laser or lasers (4, 8), where the modula-tion frequency of the operating current is above the recipro-cal lifetime of the energy level of the laser-active sub-stance, which amplifies the light signals when it decays.
2. An optical amplifier according to claim 1, charac-terized in that the operating current source contains a DC
source (5) and an AC source (6), whose output currents togeth-er form the operating current.
source (5) and an AC source (6), whose output currents togeth-er form the operating current.
3. An optical amplifier according to claim 1, with two semiconductor lasers (4, 8), each connected as a pump light source to one end of the length of fiber (2), characterized in that the operating current source supplies current to the two semiconductor lasers in such a way, that the two semiconductor lasers are alternately switched on and off.
4. An optical amplifier according to claim 3, charac-terized in that the operating current for each of the two alternately switched-on semiconductor lasers (4, 8), is a DC
current that is switched on and off at the named frequency, and is thereby modulated.
current that is switched on and off at the named frequency, and is thereby modulated.
5. An optical amplifier according to claim 3, charac-terized in that the operating current for each of the two alternately switched-on semiconductor lasers (4, 8) is a DC
current that is switched on and off, which is modulated at the named frequency.
current that is switched on and off, which is modulated at the named frequency.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4041760 | 1990-12-24 | ||
| DEP4041760.3 | 1990-12-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2074813A1 true CA2074813A1 (en) | 1992-06-25 |
Family
ID=6421428
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002074813A Abandoned CA2074813A1 (en) | 1990-12-24 | 1991-12-19 | Optical amplifier |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0516843B1 (en) |
| AU (1) | AU648365B2 (en) |
| CA (1) | CA2074813A1 (en) |
| DE (1) | DE59105276D1 (en) |
| ES (1) | ES2074357T3 (en) |
| NZ (1) | NZ240957A (en) |
| WO (1) | WO1992011561A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5434876A (en) * | 1992-10-23 | 1995-07-18 | At&T Bell Laboratories | Article comprising an optical waveguide laser |
| JPH07176813A (en) * | 1993-12-17 | 1995-07-14 | Fujitsu Ltd | Optical fiber amplifier |
| US20030081307A1 (en) * | 2001-09-28 | 2003-05-01 | Fludger Christopher R. | Raman amplification |
| JP2003115799A (en) * | 2001-10-03 | 2003-04-18 | Fujitsu Ltd | Optical transmitter and stimulation control method |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4554510A (en) * | 1983-09-12 | 1985-11-19 | The Board Of Trustees Of Leland Stanford Junior University | Switching fiber optic amplifier |
| FR2608792B1 (en) * | 1986-12-23 | 1989-03-31 | Thomson Csf | DEVICE FOR AMPLIFYING OPTICAL SIGNALS WITH A PHOTOSENSITIVE MEDIUM |
| IT1237980B (en) * | 1990-02-12 | 1993-06-19 | Pirelli Cavi Spa | CURVED SINGLE-MODE ACTIVE FIBER OPTICAL AMPLIFIER |
-
1991
- 1991-12-11 AU AU89601/91A patent/AU648365B2/en not_active Ceased
- 1991-12-12 NZ NZ240957A patent/NZ240957A/en unknown
- 1991-12-19 CA CA002074813A patent/CA2074813A1/en not_active Abandoned
- 1991-12-19 WO PCT/EP1991/002458 patent/WO1992011561A1/en active IP Right Grant
- 1991-12-19 EP EP92906005A patent/EP0516843B1/en not_active Expired - Lifetime
- 1991-12-19 ES ES92906005T patent/ES2074357T3/en not_active Expired - Lifetime
- 1991-12-19 DE DE59105276T patent/DE59105276D1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| AU8960191A (en) | 1992-06-25 |
| WO1992011561A1 (en) | 1992-07-09 |
| NZ240957A (en) | 1994-04-27 |
| ES2074357T3 (en) | 1995-09-01 |
| EP0516843B1 (en) | 1995-04-19 |
| DE59105276D1 (en) | 1995-05-24 |
| AU648365B2 (en) | 1994-04-21 |
| EP0516843A1 (en) | 1992-12-09 |
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