CA2261257A1 - Optical amplifier for constantly adjusting per-channel output power and method thereof - Google Patents
Optical amplifier for constantly adjusting per-channel output power and method thereof Download PDFInfo
- Publication number
- CA2261257A1 CA2261257A1 CA002261257A CA2261257A CA2261257A1 CA 2261257 A1 CA2261257 A1 CA 2261257A1 CA 002261257 A CA002261257 A CA 002261257A CA 2261257 A CA2261257 A CA 2261257A CA 2261257 A1 CA2261257 A1 CA 2261257A1
- Authority
- CA
- Canada
- Prior art keywords
- channel
- optical signal
- channels
- output power
- unit
- 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
- H04B10/293—Signal power control
- H04B10/294—Signal power control in a multiwavelength system, e.g. gain equalisation
- H04B10/296—Transient power control, e.g. due to channel add/drop or rapid fluctuations in the input power
-
- 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
- H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
- H01S3/0064—Anti-reflection devices, e.g. optical isolaters
-
- 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
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/13—Stabilisation of laser output parameters, e.g. frequency or amplitude
- H01S3/1301—Stabilisation of laser output parameters, e.g. frequency or amplitude in optical amplifiers
- H01S3/13013—Stabilisation of laser output parameters, e.g. frequency or amplitude in optical amplifiers by controlling the optical 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
- H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
- H01S3/16—Solid materials
- H01S3/1601—Solid materials characterised by an active (lasing) ion
- H01S3/1603—Solid materials characterised by an active (lasing) ion rare earth
- H01S3/1608—Solid materials characterised by an active (lasing) ion rare earth erbium
-
- 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
-
- 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
- H04B10/293—Signal power control
- H04B10/294—Signal power control in a multiwavelength system, e.g. gain equalisation
- H04B10/2942—Signal power control in a multiwavelength system, e.g. gain equalisation using automatic gain control [AGC]
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0221—Power control, e.g. to keep the total optical power constant
-
- 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
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
- H01S3/06754—Fibre amplifiers
-
- 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
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/10007—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers
- H01S3/10015—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers by monitoring or controlling, e.g. attenuating, the input signal
Abstract
An optical amplifier whose output power for each channel is constantly controlled, for amplifying a data channel optical signal when a monitoring channel optical signal and a data channel optical signal comprised of a plurality of channels are input together, the optical amplifier including a channel monitoring unit for separating the monitoring channel optical signal, converting the monitoring channel optical signal into an electrical signal, extracting the number of channels included in the data channel from the converted signal, and outputting the converted signal, an amplification unit for amplifying the data channel optical signal using a predetermined driving source, an amplification control unit for controlling the input of the driving source so that a target output power value of the amplification unit depending on the number of channels is actually equal to a measured output power value of the amplification unit, and a wavelength coupling unit for converting the output signal of the channel monitoring unit into an optical signal and coupling the optical signal to the amplified data channel optical signal.
The gain of the optical amplifier is controlled so that a target value of the amplified data channel optical signal corresponding to the number of channels becomes actually equal to a measured value. Thus, the output power for each channel can be constantly controlled.
The gain of the optical amplifier is controlled so that a target value of the amplified data channel optical signal corresponding to the number of channels becomes actually equal to a measured value. Thus, the output power for each channel can be constantly controlled.
Description
OPTICAL AMPLIFIER FOR CONSTANTLY ADJUSTING PER-CHANNEL
OUTPUT POWER AND METHOD THEREOF
BACKGROUND OF THE INVENTION
1. Field of the Invention s The present invention relates to an optical amplifier for constantly adjusting per-channel output power and a method thereof, and more particularly, to an optical amplifier in a wavelength division multiplexed (WDM) system, whose output power for each channel is constant, and a method thereof.
OUTPUT POWER AND METHOD THEREOF
BACKGROUND OF THE INVENTION
1. Field of the Invention s The present invention relates to an optical amplifier for constantly adjusting per-channel output power and a method thereof, and more particularly, to an optical amplifier in a wavelength division multiplexed (WDM) system, whose output power for each channel is constant, and a method thereof.
2. Description of the Related Art ~o Development of an erbium-doped fiber amplifier (EDFA) as an optical fiber in the 1990's has contributed to an epoch-making progress in the field of optical transmission. A WDM-EDFA has also been developed with a WDM system which can simultaneously transmit 4 through 16 channels as well as a single channel.
A gain-flattened optical amplifier used in a WDM transmission system has ~s an amplification which varies according to a change in the number of channels or the intensity of an input signal. Such a variation in signal amplification according to wavelength degrades the flatness of the gain and generates errors in the system) thus becoming detrimental to long-distance transmission. In the WDM
transmission system adopting the EDFA, it is important to control per-channel zo output power with respect to the number of channels, since output power level transitions of the EDFA occur when the number of channels are changed due to reconfiguration or defects of a network. That is, since the WDM-EDFA must equally amplify the optical signals for a plurality of channels, the gain must be uniformly maintained for each wavelength. Also, the gain of the WDM-EDFA must Zs be controlled to have little change according to a change in the number of channels.
A dynamic gain-controlled erbium-doped fiber amplifier repeater for WDM
networks by C.Konish et al. disclosed in OFC '97 Technical Digest is used to allow an amplifier to output a signal of constant intensity. FIG. 1 is a block diagram of a conventional EDFA comprising an amplification unit 10, first and second couplers 12 and 14, a wavelength monitor unit 16, and a gain control unit 18. The first and second couplers 12 and 14 output part of the output signal of the amplification unit to the wavelength monitor unit 16. The wavelength monitor unit 16 receives s and monitors an amplified signal output from the second coupler 14. The gain control unit 18 controls the gain of the amplification unit 10 in accordance with the results of monitoring. The wavelength monitor unit 16 is comprised of an acoustic-optic tunable filter (AOTF), a photo diode (PD), and a wavelength counter, and counts the number of channels of an optical signal amplified by the amplification unit. The gain control unit 18 controls the intensity of an output signal by adjusting the gain of the amplification unit using a PD or a gain flattener.
However, the conventional structure is very complicated and large and uses many additional optical devices, so that it is difficult to be used in a real system.
Also, the output port of the EDFA directly divides an amplified optical signal, thus ~s having a direct effect on the output of the EDFA.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide an optical amplifier in which the number of channels and the power of an optical signal are checked, and the per-channel output power is constantly zo controlled by adjusting the gain of an EDFA according to the number of channels and the input power, and a method thereof.
Accordingly, to achieve the above objective, there is provided an optical amplifier whose output power for each channel is constantly controlled, for amplifying a data channel optical signal when a monitoring channel optical signal 2s and a data channel optical signal comprised of a plurality of channels are input together, the optical amplifier comprising: a channel monitoring unit for separating the monitoring channel optical signal, converting the monitoring channel optical signal into an electrical signal, extracting the number of channels included in the data channel from the converted signal, and outputting the converted signal;
an 3o amplification unit for amplifying the data channel optical signal using a predetermined driving source; an amplification control unit for controlling the input z of the driving source so that a target output power value of the amplification unit depending on the number of channels is actually equal to a measured output power value of the amplification unit; and a wavelength coupling unit for converting the output signal of the channel monitoring unit into an optical signal and coupling s the optical signal to the amplified data channel optical signal.
To achieve the above objective, there is provided a method of constantly controlling the output power for each channel of an optical amplifier, comprising the steps of: (a) measuring the output power of the optical amplifier while changing the number of channels of a data channel optical signal, and storing the ~o number of channels and the output power values depending on the number of channels, when the power for each channel of the optical amplifier for amplifying the data channel optical signal comprised of a plurality of channels is constantly controlled; (b) interpreting a change in the number of channels of the data channel optical signal included in the input optical signal by measuring the power of the ~s input data channel optical signal, and extracting the number of channels from the data channel optical signal; (c) setting an output power value of the optical amplifier corresponding to the extracted number of channels, among the output power values stored in the step (a)) as a target value; (d) measuring the output power for the input signal light amplified by the optical amplifier; and (e) adjusting 2o the gain of the optical amplifier so that the measured value becomes actually equal to the target value.
BRIEF DESCRIPTION OF THE DRAWINGS
The above objectives and advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with is reference to the attached drawings in which:
FIG. 1 is a block diagram illustrating the configuration of a conventional optical amplifier;
FIG. 2 is a block diagram illustrating the configuration of an optical amplifier for constantly controlling per-channel output power, according to the present so invention;
A gain-flattened optical amplifier used in a WDM transmission system has ~s an amplification which varies according to a change in the number of channels or the intensity of an input signal. Such a variation in signal amplification according to wavelength degrades the flatness of the gain and generates errors in the system) thus becoming detrimental to long-distance transmission. In the WDM
transmission system adopting the EDFA, it is important to control per-channel zo output power with respect to the number of channels, since output power level transitions of the EDFA occur when the number of channels are changed due to reconfiguration or defects of a network. That is, since the WDM-EDFA must equally amplify the optical signals for a plurality of channels, the gain must be uniformly maintained for each wavelength. Also, the gain of the WDM-EDFA must Zs be controlled to have little change according to a change in the number of channels.
A dynamic gain-controlled erbium-doped fiber amplifier repeater for WDM
networks by C.Konish et al. disclosed in OFC '97 Technical Digest is used to allow an amplifier to output a signal of constant intensity. FIG. 1 is a block diagram of a conventional EDFA comprising an amplification unit 10, first and second couplers 12 and 14, a wavelength monitor unit 16, and a gain control unit 18. The first and second couplers 12 and 14 output part of the output signal of the amplification unit to the wavelength monitor unit 16. The wavelength monitor unit 16 receives s and monitors an amplified signal output from the second coupler 14. The gain control unit 18 controls the gain of the amplification unit 10 in accordance with the results of monitoring. The wavelength monitor unit 16 is comprised of an acoustic-optic tunable filter (AOTF), a photo diode (PD), and a wavelength counter, and counts the number of channels of an optical signal amplified by the amplification unit. The gain control unit 18 controls the intensity of an output signal by adjusting the gain of the amplification unit using a PD or a gain flattener.
However, the conventional structure is very complicated and large and uses many additional optical devices, so that it is difficult to be used in a real system.
Also, the output port of the EDFA directly divides an amplified optical signal, thus ~s having a direct effect on the output of the EDFA.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide an optical amplifier in which the number of channels and the power of an optical signal are checked, and the per-channel output power is constantly zo controlled by adjusting the gain of an EDFA according to the number of channels and the input power, and a method thereof.
Accordingly, to achieve the above objective, there is provided an optical amplifier whose output power for each channel is constantly controlled, for amplifying a data channel optical signal when a monitoring channel optical signal 2s and a data channel optical signal comprised of a plurality of channels are input together, the optical amplifier comprising: a channel monitoring unit for separating the monitoring channel optical signal, converting the monitoring channel optical signal into an electrical signal, extracting the number of channels included in the data channel from the converted signal, and outputting the converted signal;
an 3o amplification unit for amplifying the data channel optical signal using a predetermined driving source; an amplification control unit for controlling the input z of the driving source so that a target output power value of the amplification unit depending on the number of channels is actually equal to a measured output power value of the amplification unit; and a wavelength coupling unit for converting the output signal of the channel monitoring unit into an optical signal and coupling s the optical signal to the amplified data channel optical signal.
To achieve the above objective, there is provided a method of constantly controlling the output power for each channel of an optical amplifier, comprising the steps of: (a) measuring the output power of the optical amplifier while changing the number of channels of a data channel optical signal, and storing the ~o number of channels and the output power values depending on the number of channels, when the power for each channel of the optical amplifier for amplifying the data channel optical signal comprised of a plurality of channels is constantly controlled; (b) interpreting a change in the number of channels of the data channel optical signal included in the input optical signal by measuring the power of the ~s input data channel optical signal, and extracting the number of channels from the data channel optical signal; (c) setting an output power value of the optical amplifier corresponding to the extracted number of channels, among the output power values stored in the step (a)) as a target value; (d) measuring the output power for the input signal light amplified by the optical amplifier; and (e) adjusting 2o the gain of the optical amplifier so that the measured value becomes actually equal to the target value.
BRIEF DESCRIPTION OF THE DRAWINGS
The above objectives and advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with is reference to the attached drawings in which:
FIG. 1 is a block diagram illustrating the configuration of a conventional optical amplifier;
FIG. 2 is a block diagram illustrating the configuration of an optical amplifier for constantly controlling per-channel output power, according to the present so invention;
FIG. 3 is a flowchart illustrating a method of constantly controlling per-channel output power of an optical amplifier, according to the present invention;
FIGS. 4A and 4B are graphs showing output for each channel when a two-channel optical signal is input to an optical amplifier according to the present s invention; and FIGS. 5A and 5B are graphs showing output for each channel when a four-channel optical signal is input to an optical amplifier according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 2, an optical amplifier includes a channel monitor unit 200, a first optical coupler 210, a first photo diode (PD) 211, a first isolator 220, an amplification unit 230, an amplification control unit 240, a second isolator 250, a second optical coupler 260, a second PD 261, an external control unit 270, and a wavelength coupling unit 280.
~s The channel monitor unit 200 decouples a monitoring channel optical signal from which information on the number of channels is extracted, when a data channel optical signal and the monitoring channel optical signal for monitoring data channels are coupled to each other and received as input. The channel monitor unit 200 includes a first wavelength selective coupler (WSC) 201, an optical-to-2o electrical converter 202, and a system control unit 203. The first WSC 201 decouples the monitoring channel optical signal from the input optical signals. The optical-to-electrical conversion unit converts the decoupled monitoring channel optical signal into an electrical signal. The system control unit 203 extracts information on the number of channels input to the optical amplifier from the 2s monitoring channel electrical signal. Also, the system control unit 203 adds information on the amplification state of the amplification unit 230 output by the amplification control unit 240 to the monitoring channel electrical signal.
The amplification unit 230 amplifies the data channel optical signal using a driving source. The amplification unit 230 includes a second WSC 231, an so erbium-doped optical fiber (EDF) 233, a third WSC 234, and first and second pumping optical sources 232 and 235 as amplification driving sources for the EDF
FIGS. 4A and 4B are graphs showing output for each channel when a two-channel optical signal is input to an optical amplifier according to the present s invention; and FIGS. 5A and 5B are graphs showing output for each channel when a four-channel optical signal is input to an optical amplifier according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 2, an optical amplifier includes a channel monitor unit 200, a first optical coupler 210, a first photo diode (PD) 211, a first isolator 220, an amplification unit 230, an amplification control unit 240, a second isolator 250, a second optical coupler 260, a second PD 261, an external control unit 270, and a wavelength coupling unit 280.
~s The channel monitor unit 200 decouples a monitoring channel optical signal from which information on the number of channels is extracted, when a data channel optical signal and the monitoring channel optical signal for monitoring data channels are coupled to each other and received as input. The channel monitor unit 200 includes a first wavelength selective coupler (WSC) 201, an optical-to-2o electrical converter 202, and a system control unit 203. The first WSC 201 decouples the monitoring channel optical signal from the input optical signals. The optical-to-electrical conversion unit converts the decoupled monitoring channel optical signal into an electrical signal. The system control unit 203 extracts information on the number of channels input to the optical amplifier from the 2s monitoring channel electrical signal. Also, the system control unit 203 adds information on the amplification state of the amplification unit 230 output by the amplification control unit 240 to the monitoring channel electrical signal.
The amplification unit 230 amplifies the data channel optical signal using a driving source. The amplification unit 230 includes a second WSC 231, an so erbium-doped optical fiber (EDF) 233, a third WSC 234, and first and second pumping optical sources 232 and 235 as amplification driving sources for the EDF
233. The second WSC 231 couples a pumping light of the first pumping optical source 232 to the data channel optical signal, and the third WSC 234 outputs the pumping light of the second pumping optical source 235 to the EDF 233.
The wavelength coupling unit 280 converts the monitoring channel electrical s signal output from the system control unit 203 into an optical signal, couples the converted optical signal to the data channel optical signal amplified by the amplification unit 230, and transmits the resultant signal to the next port.
The wavelength coupling unit 280 includes a fourth WSC 281 and an electrical-to-optical converter 282. The electrical-to-optical converter 282 converts a system-monitoring channel electrical signal output from the system control unit 203 into an optical signal. The fourth WSC 281 couples the amplified data channel optical signal to the monitoring channel optical signal.
The operation of the optical amplifier having such a configuration will now be described. The channel monitoring unit 200 separates a monitoring channel ~s wavelength using the first WSC 201, and converts the monitoring channel optical signal into an electrical signal using the optical-to-electrical converter 202. The system control unit 203 extracts the information on the number of input channels of the current amplification unit from the monitoring channel electrical signal.
The first optical coupler 210 separates about 1 % of the data channel optical 2o signal passed through the first WSC 201. The first PD 211 converts the data channel optical signal into an electrical signal, and outputs the electrical signal to the amplification control unit 240. The second optical coupler 260 separates about 1 % of the data channel optical signal which is amplified by the amplification unit 230 and passed through the second isolator 250. The second PD 261 converts 25 the separated data channel optical signal into an electrical signal, and outputs the electrical signal to the amplification control unit 240.
The amplification control unit 240 checks the power of a data channel optical signal input to the amplification unit 230 from the magnitude of an electrical signal received from the first PD 211, and determines whether data channels are 3o added or dropped. The gain of the amplification unit 230 is controlled by the results of the check on the amplification power. The amplification control unit 240 informs the system control unit 203 of the amplification state of the amplification unit 230.
The external control unit 270 is connected to the amplification control unit 240 via an RS-232C cable, and allows a user to Check the state of the amplification unit 230 from the outside and control the amplification characteristics of the amplification unit 230 by adjusting the parameters of the amplification unit 230.
In the amplification unit 230, the gain is controlled by the pumping power of the first and second pumping optical sources 232 and 235 which are controlled by ~o the amplification control unit 240. The amplification unit 230 amplifies a data channel optical signal by the controlled amplification degree.
Amplification is accomplished as follows. When a pumping light having a center wavelength of 980nm from the first and second pumping sources 232 and 235 is applied to the EDF 233, the implanted pumping light excites erbium ions of a base state in the EDF 233, the EDF being an amplification medium doped with a rare-earth element such as erbium (Er). The data channel optical signal is amplified by stimulated emission of the excited erbium.
The first and second isolators 220 and 250 improve the gain and noise figures of an amplified signal by blocking forward and reverse amplified Zo spontaneous emission generated by the EDF 233 and beams reflected by an optical device connected to each of the isolators 220 and 250.
The wavelength coupling unit 280 converts the monitoring channel electrical signal, in which amplification state data of the amplification unit 230 is contained, to an optical signal using the electrical-to-optical converter 282, recouples the zs amplified data channel optical signal and the monitoring channel optical signals using the fourth WSC 281, and transmits the resultant signal to the next amplification port or receiving port.
FIG. 3 is a flowchart illustrating a method of constantly controlling the per-channel output power of an optical amplifier, according to the present invention.
so The operation of the present invention will now be described referring to FIG. 3.
First, the output for each channel of the amplification unit 230 is constantly controlled, the output values of the second PD 261 which depend on the number of input channels are measured by varying the number of channels between the maximum and minimum number of channels capable of being amplified by the EDF 233. The output values of the second PD 261 according to the number of channels are stored as data in a storage unit (not shown) installed in the s amplification control unit 240) in step 300. Alternatively, the power output for each channel is determined to be a plurality of values, and the output value of the second PD 261 to be measured with respect to each of the determined output values is stored as data in the storage unit installed in the amplification control unit 240. A user can select a desired output value for each channel from values ~o stored in the amplification control unit 240 using the external control unit 270. The external control unit 270 is connected to the amplification control unit 240 via the RS-232 cable.
The first WSC 201 decouples the monitoring channel optical signal from the input optical signals. The optical-to-electrical converter 202 converts the decoupled monitoring channel optical signal into an electrical signal and stores the electrical signal in the system control unit 203. The system control unit 203 extracts the number of channels of a data channel optical signal from a monitoring channel.
The amplification control unit 240 checks the power of an input optical 2o signal received from the first PD 211, interprets a change in the number of channels, and reads the number of channels extracted from the system control unit 203.
The amplification control unit 240 reads a target output value of the second PD 261 depending on the number of channels extracted from data stored in the 2s system control unit 203, in step 302. The amplification control unit 240 measures the output power of a data channel optical signal amplified by the amplification unit 230 by measuring the output value of the second PD 261, in step 304. The amplification control unit 240 compares the target value of the step 302 to the measured value of the step 304, in step 306. If the two values are actually the so same, the information on the current amplification unit 230, e.g., the number of channels, the driven current value of a pumping optical source, etc., is output to the system control unit 203 or the external control unit 270. The system control unit 203 adds amplification state data of the current amplification unit 230 output from the amplification control unit 240 to the monitoring channel data and outputs the result to the electrical-to-optical converter 282. The electrical-to-optical converter 282 converts a monitoring channel electrical signal input from the s system control unit 203 into an optical signal. The fourth WSC 281 couples the monitoring channel optical signal to the data channel optical signal amplified by the amplification unit 230, and transmits the coupled signal to the next amplification port or receiving port, in step 310.
If the target value of the step 302 is actually not equal to the measured value of the step 304, the amplification control unit 240 actually equalizes the two values by controlling the input current of the first and second pumping optical sources 232 and 235 according to the difference between the target value and the measured value) in step 308. If the output value for each channel is misselected by the user or the number of channels are changed, the output value of a new ~s standard of the second PD 261 becomes a target value, and the output for each channel is thus maintained. That is, as described above, when the per-channel output is selected, the gain is controlled by the amplification control unit 240 even when the intensity of an input signal for each channel or the number of channels are changed, so that the per-channel output is constantly maintained. In 2o particular, when the number of channels was changed according to whether channels are coupled or divided, transient overshoot of each channel power is suppressed, so that the output is constantly maintained.
FIGS. 4A and 4B are graphs showing output for each channel when optical signals of two channels having wavelengths of 1542nm and 1560nm respectively, zs are input to an optical amplifier according to the present invention. FIG.
4A refers to the case in which the input power for each channel is -15dBm, and FIG. 4B
refers to the case in which the input power for each channel is -20dBm, each showing a constant output of +SdBm independently of the intensity of input.
Here, a doted line indicates an input waveform, and a solid line indicates an output so waveform.
FIGS. 5A and 5B are graphs showing output for each channel when optical signals of four channels having wavelengths of 1542nm, 1548nm, 1554nm and 1560nm respectively, are input to an optical amplifier according to the present invention. FIG. 5A refers to the case in which the input power for each channel is -15dBm, and FIG. 5B refers to the case in which the input power for each channel is -20dBm, each showing a constant output of +SdBm independent of the intensity s of input. Here, a doted line indicates the input waveform, and a solid line indicates the output waveform.
According to the present invention, when an input optical signal having a plurality of data channels is amplified, the output power for each channel can be maintained constantly by controlling the amplification degree of an amplification unit to make the target value of the output value for each channel actually the same as a real measured value. In particular, the output for each channel can be kept constant even when the intensity of an input signal or the number of channels are changed, so that an optical amplifier according to the present invention can be used in a channel coupling/division system.
Also, many additional optical devices are not necessary, and the optical amplifier has a simple structure, so the optical amplifier is easy to be applied to a real optical communications system.
Furthermore) the output power for each channel is represented as data with respect to optical signals of a plurality of channels, the output power for each 2o channel can be selected from data values by a user. Thus, the output power for each channel required differently according to the structure of a transmission system can be selected.
The wavelength coupling unit 280 converts the monitoring channel electrical s signal output from the system control unit 203 into an optical signal, couples the converted optical signal to the data channel optical signal amplified by the amplification unit 230, and transmits the resultant signal to the next port.
The wavelength coupling unit 280 includes a fourth WSC 281 and an electrical-to-optical converter 282. The electrical-to-optical converter 282 converts a system-monitoring channel electrical signal output from the system control unit 203 into an optical signal. The fourth WSC 281 couples the amplified data channel optical signal to the monitoring channel optical signal.
The operation of the optical amplifier having such a configuration will now be described. The channel monitoring unit 200 separates a monitoring channel ~s wavelength using the first WSC 201, and converts the monitoring channel optical signal into an electrical signal using the optical-to-electrical converter 202. The system control unit 203 extracts the information on the number of input channels of the current amplification unit from the monitoring channel electrical signal.
The first optical coupler 210 separates about 1 % of the data channel optical 2o signal passed through the first WSC 201. The first PD 211 converts the data channel optical signal into an electrical signal, and outputs the electrical signal to the amplification control unit 240. The second optical coupler 260 separates about 1 % of the data channel optical signal which is amplified by the amplification unit 230 and passed through the second isolator 250. The second PD 261 converts 25 the separated data channel optical signal into an electrical signal, and outputs the electrical signal to the amplification control unit 240.
The amplification control unit 240 checks the power of a data channel optical signal input to the amplification unit 230 from the magnitude of an electrical signal received from the first PD 211, and determines whether data channels are 3o added or dropped. The gain of the amplification unit 230 is controlled by the results of the check on the amplification power. The amplification control unit 240 informs the system control unit 203 of the amplification state of the amplification unit 230.
The external control unit 270 is connected to the amplification control unit 240 via an RS-232C cable, and allows a user to Check the state of the amplification unit 230 from the outside and control the amplification characteristics of the amplification unit 230 by adjusting the parameters of the amplification unit 230.
In the amplification unit 230, the gain is controlled by the pumping power of the first and second pumping optical sources 232 and 235 which are controlled by ~o the amplification control unit 240. The amplification unit 230 amplifies a data channel optical signal by the controlled amplification degree.
Amplification is accomplished as follows. When a pumping light having a center wavelength of 980nm from the first and second pumping sources 232 and 235 is applied to the EDF 233, the implanted pumping light excites erbium ions of a base state in the EDF 233, the EDF being an amplification medium doped with a rare-earth element such as erbium (Er). The data channel optical signal is amplified by stimulated emission of the excited erbium.
The first and second isolators 220 and 250 improve the gain and noise figures of an amplified signal by blocking forward and reverse amplified Zo spontaneous emission generated by the EDF 233 and beams reflected by an optical device connected to each of the isolators 220 and 250.
The wavelength coupling unit 280 converts the monitoring channel electrical signal, in which amplification state data of the amplification unit 230 is contained, to an optical signal using the electrical-to-optical converter 282, recouples the zs amplified data channel optical signal and the monitoring channel optical signals using the fourth WSC 281, and transmits the resultant signal to the next amplification port or receiving port.
FIG. 3 is a flowchart illustrating a method of constantly controlling the per-channel output power of an optical amplifier, according to the present invention.
so The operation of the present invention will now be described referring to FIG. 3.
First, the output for each channel of the amplification unit 230 is constantly controlled, the output values of the second PD 261 which depend on the number of input channels are measured by varying the number of channels between the maximum and minimum number of channels capable of being amplified by the EDF 233. The output values of the second PD 261 according to the number of channels are stored as data in a storage unit (not shown) installed in the s amplification control unit 240) in step 300. Alternatively, the power output for each channel is determined to be a plurality of values, and the output value of the second PD 261 to be measured with respect to each of the determined output values is stored as data in the storage unit installed in the amplification control unit 240. A user can select a desired output value for each channel from values ~o stored in the amplification control unit 240 using the external control unit 270. The external control unit 270 is connected to the amplification control unit 240 via the RS-232 cable.
The first WSC 201 decouples the monitoring channel optical signal from the input optical signals. The optical-to-electrical converter 202 converts the decoupled monitoring channel optical signal into an electrical signal and stores the electrical signal in the system control unit 203. The system control unit 203 extracts the number of channels of a data channel optical signal from a monitoring channel.
The amplification control unit 240 checks the power of an input optical 2o signal received from the first PD 211, interprets a change in the number of channels, and reads the number of channels extracted from the system control unit 203.
The amplification control unit 240 reads a target output value of the second PD 261 depending on the number of channels extracted from data stored in the 2s system control unit 203, in step 302. The amplification control unit 240 measures the output power of a data channel optical signal amplified by the amplification unit 230 by measuring the output value of the second PD 261, in step 304. The amplification control unit 240 compares the target value of the step 302 to the measured value of the step 304, in step 306. If the two values are actually the so same, the information on the current amplification unit 230, e.g., the number of channels, the driven current value of a pumping optical source, etc., is output to the system control unit 203 or the external control unit 270. The system control unit 203 adds amplification state data of the current amplification unit 230 output from the amplification control unit 240 to the monitoring channel data and outputs the result to the electrical-to-optical converter 282. The electrical-to-optical converter 282 converts a monitoring channel electrical signal input from the s system control unit 203 into an optical signal. The fourth WSC 281 couples the monitoring channel optical signal to the data channel optical signal amplified by the amplification unit 230, and transmits the coupled signal to the next amplification port or receiving port, in step 310.
If the target value of the step 302 is actually not equal to the measured value of the step 304, the amplification control unit 240 actually equalizes the two values by controlling the input current of the first and second pumping optical sources 232 and 235 according to the difference between the target value and the measured value) in step 308. If the output value for each channel is misselected by the user or the number of channels are changed, the output value of a new ~s standard of the second PD 261 becomes a target value, and the output for each channel is thus maintained. That is, as described above, when the per-channel output is selected, the gain is controlled by the amplification control unit 240 even when the intensity of an input signal for each channel or the number of channels are changed, so that the per-channel output is constantly maintained. In 2o particular, when the number of channels was changed according to whether channels are coupled or divided, transient overshoot of each channel power is suppressed, so that the output is constantly maintained.
FIGS. 4A and 4B are graphs showing output for each channel when optical signals of two channels having wavelengths of 1542nm and 1560nm respectively, zs are input to an optical amplifier according to the present invention. FIG.
4A refers to the case in which the input power for each channel is -15dBm, and FIG. 4B
refers to the case in which the input power for each channel is -20dBm, each showing a constant output of +SdBm independently of the intensity of input.
Here, a doted line indicates an input waveform, and a solid line indicates an output so waveform.
FIGS. 5A and 5B are graphs showing output for each channel when optical signals of four channels having wavelengths of 1542nm, 1548nm, 1554nm and 1560nm respectively, are input to an optical amplifier according to the present invention. FIG. 5A refers to the case in which the input power for each channel is -15dBm, and FIG. 5B refers to the case in which the input power for each channel is -20dBm, each showing a constant output of +SdBm independent of the intensity s of input. Here, a doted line indicates the input waveform, and a solid line indicates the output waveform.
According to the present invention, when an input optical signal having a plurality of data channels is amplified, the output power for each channel can be maintained constantly by controlling the amplification degree of an amplification unit to make the target value of the output value for each channel actually the same as a real measured value. In particular, the output for each channel can be kept constant even when the intensity of an input signal or the number of channels are changed, so that an optical amplifier according to the present invention can be used in a channel coupling/division system.
Also, many additional optical devices are not necessary, and the optical amplifier has a simple structure, so the optical amplifier is easy to be applied to a real optical communications system.
Furthermore) the output power for each channel is represented as data with respect to optical signals of a plurality of channels, the output power for each 2o channel can be selected from data values by a user. Thus, the output power for each channel required differently according to the structure of a transmission system can be selected.
Claims (12)
1. An optical amplifier whose output power for each channel is constantly controlled, for amplifying a data channel optical signal when a monitoring channel optical signal and a data channel optical signal comprised of a plurality of channels are input together, the optical amplifier comprising:
a channel monitoring unit for separating the monitoring channel optical signal, converting the monitoring channel optical signal into an electrical signal, extracting the number of channels included in the data channel from the converted signal, and outputting the converted signal;
an amplification unit for amplifying the data channel optical signal using a predetermined driving source;
an amplification control unit for controlling the input of the driving source so that a target output power value of the amplification unit depending on the number of channels is actually equal to a measured output power value of the amplification unit; and a wavelength coupling unit for converting the output signal of the channel monitoring unit into an optical signal and coupling the optical signal to the amplified data channel optical signal.
a channel monitoring unit for separating the monitoring channel optical signal, converting the monitoring channel optical signal into an electrical signal, extracting the number of channels included in the data channel from the converted signal, and outputting the converted signal;
an amplification unit for amplifying the data channel optical signal using a predetermined driving source;
an amplification control unit for controlling the input of the driving source so that a target output power value of the amplification unit depending on the number of channels is actually equal to a measured output power value of the amplification unit; and a wavelength coupling unit for converting the output signal of the channel monitoring unit into an optical signal and coupling the optical signal to the amplified data channel optical signal.
2. The optical amplifier whose output power for each channel is constantly controlled as claimed in claim 1, further comprising an optical-to-electrical converter interposed between the channel monitoring unit and the amplification control unit for converting part of the data channel optical signal into an electrical signal so that the amplification control unit can interpret a change in the number of channels from the power of the data channel optical signal.
3. The optical amplifier whose output power for each channel is constantly controlled as claimed in claim 1, wherein the amplification control unit comprises a storage unit for storing the number of channels and the measured output values of the amplification unit according to the number of channels when the output of the amplification unit for each channel is constantly controlled.
4. The optical amplifier whose output power for each channel is constantly controlled as claimed in claim 1, wherein the amplification control unit comprises a storage unit for storing the output values of the amplification unit measured according to the number of channels with respect to determined output for each channel when output for each channel is determined as a plurality of values.
5. The optical amplifier whose output power for each channel is constantly controlled as claimed in claim 1, wherein the channel monitoring unit adds amplification state data of the amplification unit, received from the amplification control unit, to the monitoring channel data and outputs the resultant monitoring channel data to the wavelength coupling unit.
6. The optical amplifier whose output power for each channel is constantly controlled as claimed in claim 5, wherein the wavelength coupling unit converts the monitoring channel data, in which the amplification state data of the amplification unit is contained from the monitoring channel unit, to an optical signal and couples the monitoring channel optical signal to the amplified data channel optical signal.
7. The optical amplifier whose output power for each channel is constantly controlled as claimed in claim 1, wherein the channel monitoring unit comprises:
a wavelength selective coupler for decoupling the monitoring channel optical signal from input optical signals;
an optical-to-electrical converter for converting the decoupled monitoring channel optical signal into an electrical signal; and a system control unit for extracting the information on the number of channels from the electrical signal, transmitting the information to the amplification control unit, and outputting the monitoring channel data in which amplification state data of the amplification unit is contained.
a wavelength selective coupler for decoupling the monitoring channel optical signal from input optical signals;
an optical-to-electrical converter for converting the decoupled monitoring channel optical signal into an electrical signal; and a system control unit for extracting the information on the number of channels from the electrical signal, transmitting the information to the amplification control unit, and outputting the monitoring channel data in which amplification state data of the amplification unit is contained.
8. The optical amplifier whose output power for each channel is constantly controlled as claimed in claim 1, wherein the amplification unit comprises:
a driving source whose input value is adjusted by the amplification control unit;
a wavelength selective coupler for coupling the output of the driving source to the data channel optical signal; and an erbium-doped optical fiber whose gain is controlled by the output of the driving source to amplify the data channel optical signal.
a driving source whose input value is adjusted by the amplification control unit;
a wavelength selective coupler for coupling the output of the driving source to the data channel optical signal; and an erbium-doped optical fiber whose gain is controlled by the output of the driving source to amplify the data channel optical signal.
9. The optical amplifier whose output power for each channel is constantly controlled as claimed in claim 8, further comprising:
a first isolator interposed between the amplification unit and the channel monitoring unit for preventing reverse amplified spontaneous emission of the amplification unit from being reflected by the channel monitoring unit and entering the amplification unit; and a second isolator interposed between the amplification unit and the channel monitoring unit for preventing forward amplified spontaneous emission of the amplification unit from being reflected by the wavelength coupling unit and entering the amplification unit
a first isolator interposed between the amplification unit and the channel monitoring unit for preventing reverse amplified spontaneous emission of the amplification unit from being reflected by the channel monitoring unit and entering the amplification unit; and a second isolator interposed between the amplification unit and the channel monitoring unit for preventing forward amplified spontaneous emission of the amplification unit from being reflected by the wavelength coupling unit and entering the amplification unit
10. The optical amplifier whose output power for each channel is constantly controlled as claimed in claim 1, wherein the amplification control unit further comprises an external control unit connected to a serial cable so that a user can select the target output power value from the outside.
11. A method of constantly controlling the output power for each channel of an optical amplifier, comprising the steps of:
(a) measuring the output power of the optical amplifier while changing the number of channels of a data channel optical signal, and storing the number of channels and the output power values depending on the number of channels,
(a) measuring the output power of the optical amplifier while changing the number of channels of a data channel optical signal, and storing the number of channels and the output power values depending on the number of channels,
12 when the power for each channel of the optical amplifier for amplifying the data channel optical signal comprised of a plurality of channels is constantly controlled;
(b) interpreting a change in the number of channels of the data channel optical signal included in the input optical signal by measuring the power of the input data channel optical signal, and extracting the number of channels from the data channel optical signal;
(c) setting an output power value of the optical amplifier corresponding to the extracted number of channels, among the output power values stored in the step (a), as a target value;
(d) measuring the output power for the input signal light amplified by the optical amplifier; and (e) adjusting the gain of the optical amplifier so that the measured value becomes actually equal to the target value.
12. A method of constantly controlling the output power for each channel of an optical amplifier, comprising the steps of:
(a) measuring the output power of the optical amplifier while changing the number of channels of a data channel optical signal, and storing the number of channels and the output power values depending on the number of channels, when per-channel power of the optical amplifier is determined as a plurality of values;
(b) interpreting a change in the number of channels of the data channel optical signal included in the input optical signal by measuring the power of the input data channel optical signal, and extracting the number of channels from the data channel optical signal;
(c) setting an output power value of the optical amplifier corresponding to the extracted number of channels, among the output power values stored in the step (a), as a target value;
(d) measuring the output power for the input signal light amplified by the optical amplifier; and (e) adjusting the gain of the optical amplifier so that the measured value becomes actually equal to the target value.
(b) interpreting a change in the number of channels of the data channel optical signal included in the input optical signal by measuring the power of the input data channel optical signal, and extracting the number of channels from the data channel optical signal;
(c) setting an output power value of the optical amplifier corresponding to the extracted number of channels, among the output power values stored in the step (a), as a target value;
(d) measuring the output power for the input signal light amplified by the optical amplifier; and (e) adjusting the gain of the optical amplifier so that the measured value becomes actually equal to the target value.
12. A method of constantly controlling the output power for each channel of an optical amplifier, comprising the steps of:
(a) measuring the output power of the optical amplifier while changing the number of channels of a data channel optical signal, and storing the number of channels and the output power values depending on the number of channels, when per-channel power of the optical amplifier is determined as a plurality of values;
(b) interpreting a change in the number of channels of the data channel optical signal included in the input optical signal by measuring the power of the input data channel optical signal, and extracting the number of channels from the data channel optical signal;
(c) setting an output power value of the optical amplifier corresponding to the extracted number of channels, among the output power values stored in the step (a), as a target value;
(d) measuring the output power for the input signal light amplified by the optical amplifier; and (e) adjusting the gain of the optical amplifier so that the measured value becomes actually equal to the target value.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019980003502A KR19990069330A (en) | 1998-02-06 | 1998-02-06 | Optical amplifier with constant output power per channel and its method |
| KR98-3502 | 1998-02-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2261257A1 true CA2261257A1 (en) | 1999-08-06 |
Family
ID=19532657
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002261257A Abandoned CA2261257A1 (en) | 1998-02-06 | 1999-02-08 | Optical amplifier for constantly adjusting per-channel output power and method thereof |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPH11275027A (en) |
| KR (1) | KR19990069330A (en) |
| CN (1) | CN1131458C (en) |
| CA (1) | CA2261257A1 (en) |
| FR (1) | FR2777142A1 (en) |
| GB (1) | GB2334397B (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6307670B1 (en) * | 1999-12-14 | 2001-10-23 | Corning Incorporated | Pump power control for optical fiber amplifier |
| AUPQ511700A0 (en) * | 2000-01-17 | 2000-02-10 | University Of Sydney, The | Method and apparatus for monitoring of data channels |
| AU781588B2 (en) * | 2000-01-17 | 2005-06-02 | University Of Sydney, The | Method and apparatus for monitoring of data channels |
| KR100346221B1 (en) * | 2000-09-06 | 2002-08-01 | 삼성전자 주식회사 | Gain control device and method thereof for a erbium doped fiber amplifier |
| US6504989B1 (en) | 2000-10-23 | 2003-01-07 | Onetta, Inc. | Optical equipment and methods for manufacturing optical communications equipment for networks |
| US6498677B1 (en) | 2000-10-23 | 2002-12-24 | Onetta, Inc. | Optical amplifier systems with transient control |
| US6438010B1 (en) | 2001-03-02 | 2002-08-20 | Onetta, Inc. | Drive circuits for microelectromechanical systems devices |
| US6731424B1 (en) | 2001-03-15 | 2004-05-04 | Onetta, Inc. | Dynamic gain flattening in an optical communication system |
| US6529316B1 (en) | 2001-05-03 | 2003-03-04 | Onetta, Inc. | Optical network equipment with optical channel monitor and dynamic spectral filter alarms |
| US6545800B1 (en) | 2001-06-05 | 2003-04-08 | Onetta, Inc. | Depolarizers for optical channel monitors |
| US6483631B1 (en) | 2001-06-05 | 2002-11-19 | Onetta, Inc. | Optical amplifier spectral tilt controllers |
| GB0129717D0 (en) | 2001-12-12 | 2002-01-30 | Marconi Comm Ltd | A method and an apparatus for signal transmission |
| JP4198082B2 (en) * | 2004-03-24 | 2008-12-17 | 富士通株式会社 | Optical amplifier gain monitoring method and apparatus |
| ATE544252T1 (en) * | 2009-06-02 | 2012-02-15 | Alcatel Lucent | METHOD AND DEVICE FOR ADJUSTING POWER GAIN |
| CN103647539B (en) * | 2013-11-08 | 2017-01-11 | 上海华力微电子有限公司 | Switching device and multichannel coupling selector provided with same |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2714982B1 (en) * | 1994-01-13 | 1996-02-02 | Alcatel Nv | Regulated optical amplifier. |
| JP3379052B2 (en) * | 1994-09-26 | 2003-02-17 | 富士通株式会社 | WDM optical amplifier, WDM transmission system, and WDM transmission method |
| US6025947A (en) * | 1996-05-02 | 2000-02-15 | Fujitsu Limited | Controller which controls a variable optical attenuator to control the power level of a wavelength-multiplexed optical signal when the number of channels are varied |
| JPH09321701A (en) * | 1996-05-31 | 1997-12-12 | Fujitsu Ltd | Optical communication system and optical amplifier |
-
1998
- 1998-02-06 KR KR1019980003502A patent/KR19990069330A/en not_active Application Discontinuation
-
1999
- 1999-02-08 GB GB9902566A patent/GB2334397B/en not_active Expired - Fee Related
- 1999-02-08 FR FR9901439A patent/FR2777142A1/en active Pending
- 1999-02-08 JP JP11030656A patent/JPH11275027A/en active Pending
- 1999-02-08 CA CA002261257A patent/CA2261257A1/en not_active Abandoned
- 1999-02-08 CN CN99100602A patent/CN1131458C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| GB2334397B (en) | 2000-11-15 |
| FR2777142A1 (en) | 1999-10-01 |
| CN1241728A (en) | 2000-01-19 |
| JPH11275027A (en) | 1999-10-08 |
| KR19990069330A (en) | 1999-09-06 |
| CN1131458C (en) | 2003-12-17 |
| GB9902566D0 (en) | 1999-03-24 |
| GB2334397A (en) | 1999-08-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0812078B1 (en) | Optical communication system and optical amplifier | |
| CA2154641C (en) | Amplified telecommunication system for wavelength-division multiplexing transmissions, having an equalized reception power | |
| EP1603257B1 (en) | Optical transmission device and optical communication system | |
| US7038841B2 (en) | Fiber amplifier and control method thereof | |
| CA2261257A1 (en) | Optical amplifier for constantly adjusting per-channel output power and method thereof | |
| JP3068500B2 (en) | Optical signal amplification transmission system | |
| US6373625B1 (en) | Method, apparatus, and system for optical amplification | |
| EP1427075B1 (en) | Raman amplifier and optical relay transmission system | |
| KR100277352B1 (en) | 3-stage WDM-EDFA | |
| US6147796A (en) | Method for determining transmission parameters for the data channels of a WDM optical communication system | |
| US20210057869A1 (en) | Optical amplifier and optical amplification method | |
| US20230412297A1 (en) | Optical amplifier, optical amplifier controlling method, and optical transmission system | |
| CA2235915A1 (en) | Optical signal amplification control system | |
| US6747791B1 (en) | Optical amplifier with a spectral gain monitor using a volume phase grating | |
| US20220052502A1 (en) | Bismuth doped fiber amplifier | |
| US6353496B1 (en) | Wavelength division multiplexing erbium doped fiber amplifier which outputs constant power per channel and amplifying method thereof | |
| US6603896B1 (en) | Power fiber amplifier with flat gain | |
| US6483634B1 (en) | Optical amplifier | |
| US7068422B2 (en) | Optical fiber amplification method and apparatus for controlling gain | |
| EP1237238A2 (en) | Gain-clamped optical fibre amplifier | |
| JP2003179290A (en) | Optical amplifier and optical communication system | |
| JP3917605B2 (en) | Optical communication system and optical amplifier | |
| JP2003124891A (en) | Optical amplifier |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |