JP4499618B2 - Optical transmission system - Google Patents

Optical transmission system Download PDF

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JP4499618B2
JP4499618B2 JP2005167131A JP2005167131A JP4499618B2 JP 4499618 B2 JP4499618 B2 JP 4499618B2 JP 2005167131 A JP2005167131 A JP 2005167131A JP 2005167131 A JP2005167131 A JP 2005167131A JP 4499618 B2 JP4499618 B2 JP 4499618B2
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transmission system
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喬 小谷川
浩次 増田
俊哉 松田
伸治 松岡
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Nippon Telegraph and Telephone Corp
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本発明は、後方ラマン増幅（ＢＲＡ）とエルビウム添加光ファイバ増幅（ＥＤＦＡ）を組み合わせた光伝送システムにおいて、さらに前方ラマン増幅（ＦＲＡ）を組み合わせる光伝送システムに関する。   The present invention relates to an optical transmission system that combines backward Raman amplification (BRA) and erbium-doped optical fiber amplification (EDFA), and further relates to an optical transmission system that combines forward Raman amplification (FRA).

図４は、従来の光伝送システムの構成例を示す（非特許文献１）。図において、光ファイバ伝送路１，２を介して双方向接続されるＡ局およびＢ局は、光ファイバ伝送路１，２に対して信号光と逆方向にラマン励起光を送出する後方ラマン増幅部（ＢＲＡ部）１０と、ラマン増幅後の信号光を増幅するエルビウム添加光ファイバ増幅部（ＥＤＦＡ部）２０を備える。ＥＤＦＡ部２０の後段で光カプラ３１を介して接続される光スペクトラムアナライザ（ＯＳＡ）３２は、ＷＤＭ信号光の平坦性をモニタしてＥＤＦＡ部２０にフィードバックし、ＥＤＦＡ部２０の出力信号光スペクトルを平坦にする制御を行う。また、制御部４０に接続されるＯＳＣ送信部４１およびＯＳＣ受信部４２は、それぞれ光カプラ４３，４４を介してＥＤＦＡ部２０の後段および前段に接続され、局間で制御情報を伝送するためのＯＳＣ光を送受信する。   FIG. 4 shows a configuration example of a conventional optical transmission system (Non-Patent Document 1). In the figure, station A and station B, which are bidirectionally connected via optical fiber transmission lines 1 and 2, send rear Raman amplification light to optical fiber transmission lines 1 and 2 in the opposite direction to the signal light. Unit (BRA unit) 10 and an erbium-doped optical fiber amplification unit (EDFA unit) 20 that amplifies the signal light after Raman amplification. An optical spectrum analyzer (OSA) 32 connected via an optical coupler 31 at the subsequent stage of the EDFA unit 20 monitors the flatness of the WDM signal light and feeds it back to the EDFA unit 20, and outputs the output signal light spectrum of the EDFA unit 20. Control to flatten. An OSC transmission unit 41 and an OSC reception unit 42 connected to the control unit 40 are connected to the subsequent stage and the previous stage of the EDFA unit 20 via optical couplers 43 and 44, respectively, for transmitting control information between stations. Send and receive OSC light.

後方ラマン増幅（ＢＲＡ）は、その利得が大きいほど伝送後の光ＳＮ比が向上する一方で、ＢＲＡ利得が過大になっても非線形効果による波形劣化量は変わらない。したがって、ＢＲＡ利得が過大になることは考慮しなくてもよく、ある規定値（設計値）以上が確保されることが重要になっている。このため、実用化されているＷＤＭ光伝送システムはＢＲＡ利得の最小値を用いて設計されており、ＢＲＡ部１０はＢＲＡ利得を測定せず、ラマン増幅後の出力レベル（ＥＤＦＡ部２０の入力レベル）が一定となる自動出力パワー一定制御（ＡＬＣ）モードが適用されている。   In the backward Raman amplification (BRA), as the gain increases, the optical S / N ratio after transmission improves. On the other hand, even if the BRA gain becomes excessive, the waveform deterioration amount due to the nonlinear effect does not change. Therefore, it is not necessary to consider that the BRA gain becomes excessive, and it is important to ensure a certain specified value (design value) or more. For this reason, the WDM optical transmission system in practical use is designed using the minimum value of the BRA gain, and the BRA unit 10 does not measure the BRA gain, and the output level after Raman amplification (the input level of the EDFA unit 20) The automatic output power constant control (ALC) mode in which) is constant is applied.

ここで、ＢＲＡ部１０におけるＡＬＣモード、ＡＰＣ（自動パワー一定制御）モードおよびＡＣＣ（自動電流一定制御）モードと、ＥＤＦＡ部２０におけるＡＬＣモードおよびＡＧＣ（自動利得一定制御）モードの制御構成について説明する。   Here, the control configuration of the ALC mode, APC (automatic power constant control) mode and ACC (automatic constant current control) mode in the BRA unit 10, and the ALC mode and AGC (automatic gain constant control) mode in the EDFA unit 20 will be described. .

図５は、ＡＬＣ（ＡＰＣ，ＡＣＣ）機能を有するＢＲＡ部１０の構成例を示す。図において、ラマン励起光源１１は、光カプラ１２を介して光ファイバ伝送路１と結合されており、出力されるラマン励起光が信号光と逆方向に光ファイバ伝送路１に送出される。光ファイバ伝送路１でラマン増幅された信号光は、光カプラ１２、光カプラ１３を介して光検出器（ＰＤ）１４に入力され、ＰＤ１４でラマン増幅後の信号光パワーがモニタされる。このモニタ値は制御回路１５に入力され、制御回路１５はモニタ値（信号光パワー）が一定になるようにラマン励起光源１１の電流値を制御する。これにより、ＡＬＣモードによる制御が実現する。   FIG. 5 shows a configuration example of the BRA unit 10 having an ALC (APC, ACC) function. In the figure, a Raman pumping light source 11 is coupled to an optical fiber transmission line 1 via an optical coupler 12, and output Raman pumping light is sent to the optical fiber transmission line 1 in the direction opposite to that of signal light. The signal light Raman-amplified in the optical fiber transmission line 1 is input to the photodetector (PD) 14 through the optical coupler 12 and the optical coupler 13, and the signal light power after Raman amplification is monitored by the PD 14. This monitor value is input to the control circuit 15, and the control circuit 15 controls the current value of the Raman excitation light source 11 so that the monitor value (signal light power) is constant. Thereby, control by ALC mode is realized.

また、ＢＲＡ部１０をＡＰＣモードに設定するには、ラマン励起光源１１の出力部に配置された光カプラ１６から分岐したラマン励起光を光検出器（ＰＤ）１７でモニタし、制御回路１５でラマン励起光パワーが一定になるように制御する。ＢＲＡ部１０をＡＣＣモードに設定するには、モニタ用の光検出器を用いず、単にラマン励起光源１１への印加電流が一定になるように制御する。   In order to set the BRA unit 10 to the APC mode, the Raman pumping light branched from the optical coupler 16 disposed at the output unit of the Raman pumping light source 11 is monitored by the photodetector (PD) 17, and the control circuit 15 The Raman pumping light power is controlled to be constant. In order to set the BRA unit 10 to the ACC mode, the control is simply performed so that the applied current to the Raman excitation light source 11 is constant without using the monitoring photodetector.

図６は、ＡＬＣ（ＡＧＣ）機能を有するＥＤＦＡ部２０の構成例を示す。図において、エルビウム添加光ファイバ増幅器（ＥＤＦＡ）２１は、エルビウム添加光ファイバおよび励起光源を含む構成であり、その後段に光カプラ２２を介して光検出器（ＰＤ）２３を接続し、ＥＤＦＡ２１で増幅された信号光パワーをモニタする。モニタ値は制御回路２４に入力され、モニタ値（信号光パワー）が一定になるようにＥＤＦＡ２１の励起光源の電流値を制御する。これにより、ＡＬＣモードによる制御が実現する。   FIG. 6 shows a configuration example of the EDFA unit 20 having an ALC (AGC) function. In the figure, an erbium-doped optical fiber amplifier (EDFA) 21 includes an erbium-doped optical fiber and a pumping light source. A photodetector (PD) 23 is connected to the subsequent stage via an optical coupler 22 and amplified by the EDFA 21. Monitor the signal light power. The monitor value is input to the control circuit 24, and the current value of the excitation light source of the EDFA 21 is controlled so that the monitor value (signal light power) becomes constant. Thereby, control by ALC mode is realized.

また、ＥＤＦＡ部２０をＡＧＣモードに設定するには、ＥＤＦＡ２１の前段の光カプラ２５を介して光検出器（ＰＤ）２６を接続し、ＥＤＦＡ２１に入力する信号光パワーをモニタし、ＰＤ２３，２６の各モニタ値の比が一定になるようにＥＤＦＡ２１の励起光源の電流値を制御する。   Further, in order to set the EDFA unit 20 to the AGC mode, a photodetector (PD) 26 is connected via the optical coupler 25 in the previous stage of the EDFA 21, the signal light power input to the EDFA 21 is monitored, The current value of the excitation light source of the EDFA 21 is controlled so that the ratio of the monitor values is constant.

ところで、信号光と同方向にラマン励起光を送出する前方ラマン増幅部（ＦＲＡ部）を用いることにより、さらなる伝送距離の長距離化を図ることが検討されている（非特許文献２）。ここで、前方ラマン増幅（ＦＲＡ）を適用する場合には次の点について考慮する必要がある。ＦＲＡは、その利得が大きいほど光ＳＮ比が向上するが、ＢＲＡと異なって非線形効果による波形劣化量が増加する。このため、実システム運用の際には、個々のＦＲＡ部ごとにＦＲＡ利得を測定し、設計値を超えた過剰な波形劣化が生じないように所定のＦＲＡ利得値に制御することが望まれる。
H.Masuda et al.,High-performance distributed Raman amplification systems: Practical aspects and field trial results, OThF5, OFC2005(2005) E.Desurvire,ERBIUM-DOPED FIBER AMPLIFIERS Principles and Applications, JOHN WILEY & SONS,INC,1994 By the way, it has been studied to further increase the transmission distance by using a forward Raman amplification unit (FRA unit) that transmits Raman pumping light in the same direction as the signal light (Non-patent Document 2). Here, when applying forward Raman amplification (FRA), it is necessary to consider the following points. In the FRA, as the gain increases, the optical SN ratio improves, but unlike the BRA, the amount of waveform deterioration due to the nonlinear effect increases. For this reason, in actual system operation, it is desired to measure the FRA gain for each individual FRA unit and control the FRA gain value to a predetermined value so that excessive waveform deterioration exceeding the design value does not occur.
H. Masuda et al., High-performance distributed Raman amplification systems: Practical aspects and field trial results, OThF5, OFC2005 (2005) E.Desurvire, ERBIUM-DOPED FIBER AMPLIFIERS Principles and Applications, JOHN WILEY & SONS, INC, 1994

図４に示す従来の光伝送システムにおけるＢＲＡ部１０の制御は、上記のようにラマン増幅後の出力レベル（ＥＤＦＡ部２０の入力レベル）を一定に制御するＡＬＣモードである。また、ＥＤＦＡ部２０もＡＬＣモードで制御されている。したがって、図４の従来システムにＦＲＡ部を追加した場合、モニタ用の光検出器（例えば図５の１４、図６の２３，２６）やＯＳＡ３２を用いても、ＦＲＡ利得の測定は困難である。 The control of the BRA unit 10 in the conventional optical transmission system shown in FIG. 4 is an ALC mode in which the output level after Raman amplification (the input level of the EDFA unit 20) is controlled to be constant as described above. The EDFA unit 20 is also controlled in the ALC mode. Therefore, when the FRA unit is added to the conventional system of FIG. 4 , it is difficult to measure the FRA gain even if a monitoring photodetector (for example, 14 in FIG. 5, 23 and 26 in FIG. 6) or OSA 32 is used. .

本発明は、各局にＡＬＣモードで制御されるＢＲＡ部およびＥＤＦＡ部を有する光伝送システムにおいて、ＦＲＡを併用する場合にＦＲＡ利得を測定すること、この測定に基づいて、設計値を超えた過剰な波形劣化が生じないような所定のＦＲＡ利得値に制御することができる光伝送システムを提供することを目的とする。 In an optical transmission system having a BRA unit and an EDFA unit controlled in an ALC mode in each station, the present invention measures the FRA gain when using FRA together , and based on this measurement, an excess of the design value is exceeded. An object of the present invention is to provide an optical transmission system that can be controlled to a predetermined FRA gain value that does not cause waveform deterioration.

本発明は、光ファイバ伝送路を介して接続されるＡ局およびＢ局に、信号光および制御信号を伝送するためのＯＳＣ光を双方向に伝送する手段を備え、Ｂ局は、Ａ局からＢ局に伝送される信号光と逆方向に光ファイバ伝送路に対してラマン励起光を送出する後方ラマン増幅部（ＢＲＡ部）と、ＢＲＡ部によるラマン増幅後の信号光を増幅するエルビウム添加光ファイバ増幅部（ＥＤＦＡ部）と、ＥＤＦＡ部で増幅された信号光パワーをモニタする光スペクトラムアナライザ（ＯＳＡ）とを備えた光伝送システムにおいて、Ａ局は、Ａ局からＢ局に伝送される信号光と同方向に光ファイバ伝送路に対してラマン励起光を送出する前方ラマン増幅部（ＦＲＡ部）と、ＦＲＡ部からラマン励起光を送出する前に、ＯＳＣ光を用いて、Ｂ局のＢＲＡ部をラマン励起光のパワーが一定になるように制御するＡＰＣモードまたはラマン励起光源の電流値が一定になるように制御するＡＣＣモードに設定し、Ｂ局のＥＤＦＡ部を入出力信号光のパワー比が一定になるように制御するＡＧＣモードに設定するための制御信号を送信する制御部とを備え、Ｂ局は、ＯＳＣ光を用いて伝送された制御信号に応じて、ＢＲＡ部をＡＰＣモードまたはＡＣＣモードに設定し、ＥＤＦＡ部をＡＧＣモードに設定し、当該モード設定後にＡ局に対してＯＳＣ光を用いてＦＲＡ部の動作を制御する制御信号を送信する制御部を備え、Ａ局の制御部はＢ局から送信された制御信号に応じてＦＲＡ部を動作させ、Ｂ局のＯＳＡおよび制御部は、ＢＲＡ部のＡＰＣモードまたはＡＣＣモードに設定後およびＥＤＦＡ部のＡＧＣモード設定後に、Ａ局のＦＲＡ部からラマン励起光の送出前と送出時のスペクトルデータの差分を検出し、前方ラマン利得（ＦＲＡ利得）の測定を行う構成である（請求項１）。 The present invention comprises means for bidirectionally transmitting OSC light for transmitting signal light and control signals to the A station and the B station connected via the optical fiber transmission line. Rear Raman amplifier (BRA unit) for sending Raman pumping light to the optical fiber transmission line in the opposite direction to the signal light transmitted to station B, and erbium-doped light for amplifying the signal light after Raman amplification by the BRA unit In an optical transmission system including a fiber amplification unit (EDFA unit) and an optical spectrum analyzer (OSA) that monitors the signal light power amplified by the EDFA unit, station A transmits signals from station A to station B The forward Raman amplification unit (FRA unit) that sends Raman pumping light to the optical fiber transmission line in the same direction as the light, and before sending the Raman pumping light from the FRA unit , using the OSC light, the BRA of the B station The APC mode for controlling the power of the Raman pumping light to be constant or the ACC mode for controlling the current value of the Raman pumping light source to be constant, and the EDFA part of the B station is set to the power of the input / output signal light A control unit that transmits a control signal for setting the AGC mode to control the ratio to be constant, and the B station sets the BRA unit in the APC mode according to the control signal transmitted using the OSC light. Alternatively, the control unit is configured to set the ACC mode, set the EDFA unit to the AGC mode, and transmit a control signal for controlling the operation of the FRA unit using the OSC light to the A station after the mode setting. the control unit operates the FRA portion in response to a control signal transmitted from the B station, OSA and control unit of the station B, after setting the APC mode or ACC mode BRA portion and EDFA portion After AGC mode setting, and detecting a difference spectral data at the time of delivery and prior to delivery of the Raman excitation light from FRA portion of A station, a structure for measuring the forward Raman gain (FRA gain) (claim 1).

さらに、Ａ局およびＢ局の制御部は、Ｂ局で測定されるＦＲＡ利得が規定値になるように、Ａ局のＦＲＡ部のラマン励起光パワーを制御する構成である（請求項２）。   Further, the control units of the A station and the B station are configured to control the Raman pumping light power of the FRA unit of the A station so that the FRA gain measured at the B station becomes a specified value (claim 2).

また、信号光は複数の波長の信号チャネルを波長多重したＷＤＭ信号光であり、Ｂ局の制御部またはＯＳＡは、複数の波長の信号チャネルごとのＦＲＡ利得の規定値をテーブルとして備え、Ａ局の制御部は、ＦＲＡ部のラマン励起光源のパワー値または印加電流値を「ＦＲＡパワー情報」としてＢ局の制御部に通知する手段を含み、Ｂ局の制御部は、測定されたＦＲＡ利得とテーブルのＦＲＡ利得の規定値との偏差を算出し、その偏差とＡ局から通知された「ＦＲＡパワー情報」から規定のＦＲＡ利得を設定するためのラマン励起光源のパワー値または印加電流値を「ＦＲＡ利得制御情報」として算出し、Ａ局の制御部に通知する手段を含み、Ａ局の制御部は、Ｂ局から通知された「ＦＲＡ利得制御情報」に基づいてＦＲＡ部のラマン励起光源のパワー値または印加電流値を設定し、規定のＦＲＡ利得が得られるように制御する手段を含む（請求項３）。 The signal light is WDM signal light obtained by wavelength multiplexing a plurality of signal channels having a plurality of wavelengths, and the control unit or OSA of the station B is provided with a specified value of the FRA gain for each signal channel having a plurality of wavelengths as a table. The control unit includes a means for notifying the power value or applied current value of the Raman pumping light source of the FRA unit to the control unit of the B station as “FRA power information”, and the control unit of the B station includes the measured FRA gain and The deviation from the specified value of the FRA gain in the table is calculated, and the power value or applied current value of the Raman excitation light source for setting the specified FRA gain is calculated from the deviation and the “FRA power information” notified from the A station. It includes means for calculating as “FRA gain control information” and notifying the control unit of the A station, and the control unit of the A station determines the Raman pumping light of the FRA unit based on the “FRA gain control information” notified from the B station. Set the power value or applied current value, comprising means for controlling as FRA gain defined is obtained (claim 3).

また、Ａ局およびＢ局の制御部は、Ａ局とＢ局との間でＦＲＡ利得が規定値に制御された後に、Ａ局のＦＲＡ部をＡＰＣモードまたはＡＣＣモードに設定し、さらにＢ局のＢＲＡ部およびＥＤＦＡ部をそれぞれ出力信号光パワーが一定になるように制御するＡＬＣモードに設定する構成である（請求項４）。   Further, the control unit of the A station and the B station sets the FRA unit of the A station to the APC mode or the ACC mode after the FRA gain is controlled to the specified value between the A station and the B station. The BRA unit and the EDFA unit are set to the ALC mode in which the output signal light power is controlled to be constant (claim 4).

また、Ａ局およびＢ局は、Ａ局とＢ局との間で送受信されるＯＳＣ光を用いて、Ａ局とＢ局との間でＦＲＡ利得の制御に用いる「ＦＲＡパワー情報」および「ＦＲＡ利得制御情報」を伝送する手段を備える（請求項５）。 In addition, the A station and the B station use the OSC light transmitted and received between the A station and the B station, and “FRA power information” and “FRA” used for controlling the FRA gain between the A station and the B station. Means for transmitting "gain control information" ( claim 5 ).

また、Ａ局およびＢ局は、Ａ局とＢ局との間で送受信されるＯＳＣ光を用いて、Ｂ局のＢＲＡ部およびＥＤＦＡ部をＡＬＣモードに設定するための制御信号を伝送する手段を備える（請求項６）。 Also, the A station and the B station use the OSC light transmitted and received between the A station and the B station to transmit means for transmitting a control signal for setting the BRA part and the EDFA part of the B station to the ALC mode. ( Claim 6 ).

また、Ｂ局のＢＲＡ部は、ＡＬＣモードと、ＡＰＣモードまたはＡＣＣモードとの切り替えが可能な構成としてもよい（請求項７）。また、Ｂ局のＥＤＦＡ部は、ＡＬＣモードと、ＡＧＣモードとの切り替えが可能な構成としてもよい（請求項８）。また、Ａ局のＦＲＡ部は、ＦＲＡ部から出力されるラマン励起光パワーをモニタする手段およびそのラマン励起光パワーを制御する手段を含み、ＡＰＣモードまたはＡＣＣモードの設定が可能な構成としてもよい（請求項９）。
Further, the BRA unit of the B station may be configured to be able to switch between the ALC mode and the APC mode or the ACC mode ( Claim 7 ). Further, the EDFA section of the B station may be configured to be able to switch between the ALC mode and the AGC mode ( claim 8 ). Further, the FRA section of the A station includes a means for monitoring the Raman pumping light power output from the FRA section and a means for controlling the Raman pumping light power, and may be configured to be able to set the APC mode or the ACC mode. ( Claim 9 ).

本発明は、ＡＬＣモードで制御されるＢＲＡ部およびＥＤＦＡ部を備えた光伝送システムにおいて、ＦＲＡ利得設定時に一時的にＢＲＡ部をＡＰＣモードまたはＡＣＣモードに設定し、ＥＤＦＡ部をＡＧＣモードに設定することにより、各局間でＦＲＡ利得を測定し、各局ごとに規定のＦＲＡ部利得を設定することができる。これにより、過大または過小なＦＲＡ利得による伝送劣化を抑えることができる。   In an optical transmission system including a BRA unit and an EDFA unit controlled in the ALC mode, the present invention temporarily sets the BRA unit to the APC mode or the ACC mode and sets the EDFA unit to the AGC mode when setting the FRA gain. As a result, the FRA gain can be measured between the stations, and the prescribed FRA unit gain can be set for each station. Thereby, it is possible to suppress transmission degradation due to an excessive or excessive FRA gain.

図１は、本発明の光伝送システムの実施形態を示す。
図において、光ファイバ伝送路１，２を介して双方向接続されるＡ局およびＢ局は、光ファイバ伝送路１，２に対して信号光と逆方向にラマン励起光を送出する後方ラマン増幅部（ＢＲＡ部）１０と、ラマン増幅後の信号光を増幅するエルビウム添加光ファイバ増幅部（ＥＤＦＡ部）２０と、光ファイバ伝送路１，２に対して信号光と同方向にラマン励起光を送出する前方ラマン増幅部（ＦＲＡ部）５０を備える。ＥＤＦＡ部２０の後段で光カプラ３１を介して接続される光スペクトラムアナライザ（ＯＳＡ）３３は、信号光スペクトルをモニタし、そのモニタ値を制御部６０に出力する。制御部６０は、ＢＲＡ部１０、ＥＤＦＡ部２０およびＦＲＡ部５０を制御する。また、制御部６０に接続されるＯＳＣ送信部４１およびＯＳＣ受信部４２は、それぞれ光カプラ４３，４４を介してＥＤＦＡ部２０の後段および前段に接続され、局間で制御情報を伝送するためのＯＳＣ光を送受信する。 FIG. 1 shows an embodiment of the optical transmission system of the present invention.
In the figure, station A and station B, which are bidirectionally connected via optical fiber transmission lines 1 and 2, send rear Raman amplification light to optical fiber transmission lines 1 and 2 in the opposite direction to the signal light. Unit (BRA unit) 10, erbium-doped optical fiber amplifier unit (EDFA unit) 20 for amplifying Raman amplified signal light, and Raman pumping light in the same direction as the signal light with respect to optical fiber transmission lines 1 and 2 A forward Raman amplification unit (FRA unit) 50 is provided. An optical spectrum analyzer (OSA) 33 connected after the EDFA unit 20 via the optical coupler 31 monitors the signal light spectrum and outputs the monitored value to the control unit 60. The control unit 60 controls the BRA unit 10, the EDFA unit 20, and the FRA unit 50. The OSC transmission unit 41 and the OSC reception unit 42 connected to the control unit 60 are connected to the subsequent stage and the previous stage of the EDFA unit 20 via optical couplers 43 and 44, respectively, for transmitting control information between stations. Send and receive OSC light.

本構成において、ＢＲＡ部１０およびＥＤＦＡ部２０がＡＬＣモードに設定される場合、ＦＲＡ利得が生じてもＯＳＡ３３でその利得を測定することができない。したがって、本発明の光伝送システムのＡ局およびＢ局の各制御部６０では、Ａ局がＦＲＡ制御を開始する前に、ＢＲＡ部１０をＡＬＣモードからＡＰＣモードまたはＡＣＣモードに切り替え、ＥＤＦＡ部２０をＡＬＣモードからＡＧＣモードに切り替える。次に、Ａ局はＦＲＡ部５０がラマン励起光を出力するＦＲＡ制御を開始し、Ｂ局のＯＳＡ３３ではＡ局のＦＲＡ制御前とＦＲＡ制御時のスペクトル変化からＦＲＡ利得を測定する。さらに、Ｂ局の制御部６０では、得られたＦＲＡ利得が規定値になるようにＡ局のＦＲＡ部５０のラマン励起光パワーを調整するようにＦＲＡ利得制御情報を送る。Ａ局およびＢ局間でＦＲＡ利得が規定値に制御された後に、Ａ局のＦＲＡ部５０をＡＰＣモードまたはＡＣＣモードに設定し、Ｂ局のＢＲＡ部１０およびＥＤＦＡ部２０をそれぞれＡＬＣモードに戻す制御を行う。   In this configuration, when the BRA unit 10 and the EDFA unit 20 are set to the ALC mode, even if the FRA gain is generated, the OSA 33 cannot measure the gain. Therefore, in each control unit 60 of the A station and the B station of the optical transmission system of the present invention, before the A station starts the FRA control, the BRA unit 10 is switched from the ALC mode to the APC mode or the ACC mode, and the EDFA unit 20 Is switched from the ALC mode to the AGC mode. Next, the A station starts FRA control in which the FRA unit 50 outputs Raman pumping light, and the OSA 33 of the B station measures the FRA gain from the spectrum change before and during the FRA control of the A station. Further, the control unit 60 of the B station sends FRA gain control information so as to adjust the Raman pumping light power of the FRA unit 50 of the A station so that the obtained FRA gain becomes a specified value. After the FRA gain is controlled to the specified value between the A station and the B station, the FRA unit 50 of the A station is set to the APC mode or the ACC mode, and the BRA unit 10 and the EDFA unit 20 of the B station are returned to the ALC mode, respectively. Take control.

以下、ＦＲＡ利得制御の処理手順の一例について、図１および図２のシーケンスを参照して詳細に説明する。   Hereinafter, an example of the processing procedure of the FRA gain control will be described in detail with reference to the sequences of FIG. 1 and FIG.

(1) Ａ局の制御部６０は、ＦＲＡ制御を開始する前に、Ｂ局のＢＲＡ部１０およびＥＤＦＡ部２０の制御モードを切り替えるためのモード切替要求をＯＳＣ送信部４１に出力し、ＯＳＣ送信部４１はＯＳＣ光に重畳して光ファイバ伝送路１に送出する。このモード切替要求を含むＯＳＣ光は、Ｂ局のＯＳＣ受信部４２に受信され、制御部６０にモード切替要求が通知される。   (1) Before starting the FRA control, the control unit 60 of the A station outputs a mode switching request for switching the control mode of the BRA unit 10 and the EDFA unit 20 of the B station to the OSC transmission unit 41 and transmits the OSC transmission. The unit 41 superimposes on the OSC light and sends it out to the optical fiber transmission line 1. The OSC light including the mode switching request is received by the OSC receiving unit 42 of the B station, and the control unit 60 is notified of the mode switching request.

(2) Ｂ局の制御部６０は、そのモード切替要求に応じてＢＲＡ部１０をＡＬＣモードからＡＰＣモードまたはＡＣＣモードに切り替え、ＥＤＦＡ部２０をＡＬＣモードからＡＧＣモードに切り替える。ＢＲＡ部１０では、例えば図５に示すように、ラマン励起光源１１から出力されるラマン励起光をＰＤ１７でモニタし、ラマン励起光パワーが一定になるように制御する構成をとることにより、ＡＰＣモードへの切り替えが行われる。あるいは、ＡＣＣモードへの切り替えの場合は、単にラマン励起光源１１への印加電流が一定になるように制御する構成をとる。ＥＤＦＡ部２０では、例えば図６に示すようなＥＤＦＡ２１の後段のＰＤ２３のモニタ値を用いた出力一定制御から、ＥＤＦＡ２１の前後でＰＤ２６，２３のモニタ値を用いた利得制御を行う構成をとることにより、ＡＧＣモードへの切り替えが行われる。   (2) The control unit 60 of the B station switches the BRA unit 10 from the ALC mode to the APC mode or the ACC mode in response to the mode switching request, and switches the EDFA unit 20 from the ALC mode to the AGC mode. For example, as shown in FIG. 5, the BRA unit 10 monitors the Raman pumping light output from the Raman pumping light source 11 with the PD 17 and controls the Raman pumping light power to be constant. Switching to is performed. Alternatively, in the case of switching to the ACC mode, a configuration is employed in which control is performed so that the current applied to the Raman excitation light source 11 is constant. In the EDFA unit 20, for example, the gain control using the monitor values of the PDs 26 and 23 is performed before and after the EDFA 21 from the constant output control using the monitor value of the PD 23 subsequent to the EDFA 21 as shown in FIG. , Switching to the AGC mode is performed.

(3) Ｂ局の制御部６０は、ＢＲＡ部１０がＡＰＣモードまたはＡＣＣモードに切り替わり、ＥＤＦＡ部２０がＡＧＣモードに切り替わった後に、この切り替わりの完了を通知し、かつＡ局におけるＦＲＡ制御の開始を要求するＦＲＡ制御開始要求をＯＳＣ送信部４１に出力し、ＯＳＣ送信部４１はＯＳＣ光に重畳して光ファイバ伝送路２に送出する。このＦＲＡ制御開始要求を含むＯＳＣ光は、Ａ局のＯＳＣ受信部４２に受信され、制御部６０にＦＲＡ制御開始要求が通知される。   (3) After the BRA unit 10 is switched to the APC mode or the ACC mode and the EDFA unit 20 is switched to the AGC mode, the control unit 60 of the B station notifies the completion of the switching and starts the FRA control in the A station. Is output to the OSC transmission unit 41, and the OSC transmission unit 41 superimposes the OSC light on the optical fiber transmission line 2. The OSC light including this FRA control start request is received by the OSC receiving unit 42 of the A station, and the control unit 60 is notified of the FRA control start request.

(4) Ａ局の制御部６０は、ＦＲＡ制御開始要求の通知によりＦＲＡ部５０のラマン励起光源をオンとし、ラマン励起光を光ファイバ伝送路１に送出させる。また、制御部６０は、このときのラマン励起光源のパワー値または印加電流値を「ＦＲＡパワー情報」としてＯＳＣ送信部４１に出力し、ＯＳＣ送信部４１はＯＳＣ光に重畳して光ファイバ伝送路１に送出する。この「ＦＲＡパワー情報」を含むＯＳＣ光は、Ｂ局のＯＳＣ受信部４２に受信され、制御部６０に「ＦＲＡパワー情報」が通知される。   (4) The control unit 60 of the A station turns on the Raman pumping light source of the FRA unit 50 in response to the notification of the FRA control start request, and sends the Raman pumping light to the optical fiber transmission line 1. Further, the control unit 60 outputs the power value or the applied current value of the Raman pumping light source at this time to the OSC transmission unit 41 as “FRA power information”, and the OSC transmission unit 41 is superimposed on the OSC light to be an optical fiber transmission line. 1 to send. The OSC light including the “FRA power information” is received by the OSC receiving unit 42 of the B station, and the control unit 60 is notified of the “FRA power information”.

(5) Ｂ局の制御部６０は、ＯＳＡ３３で測定されるＦＲＡ制御前のスペクトルデータと、ＦＲＡ制御時のスペクトルデータを入力し、その差分からＦＲＡ制御時のＦＲＡ利得を算出する。ここで、ＯＳＡ３３または制御部６０は、各信号チャネルごとのＦＲＡ利得の規定値をテーブルとしてもっている。制御部６０は、測定されたＦＲＡ利得とテーブルのＦＲＡ利得の規定値との偏差を算出し、その偏差とＡ局から通知された「ＦＲＡパワー情報」から、規定のＦＲＡ利得を設定するためのラマン励起光源のパワー値または印加電流値を「ＦＲＡ利得制御情報」として算出する。   (5) The control unit 60 of the B station inputs the spectrum data before FRA control measured by the OSA 33 and the spectrum data at the time of FRA control, and calculates the FRA gain at the time of FRA control from the difference. Here, the OSA 33 or the control unit 60 has a table of prescribed values of the FRA gain for each signal channel. The control unit 60 calculates a deviation between the measured FRA gain and the prescribed value of the FRA gain in the table, and sets the prescribed FRA gain from the deviation and “FRA power information” notified from the A station. The power value or applied current value of the Raman excitation light source is calculated as “FRA gain control information”.

(6) Ｂ局の制御部６０は、測定されるＦＲＡ利得が規定値になっていなければ、算出した「ＦＲＡ利得制御情報」をＯＳＣ送信部４１に出力し、ＯＳＣ送信部４１はＯＳＣ光に重畳して光ファイバ伝送路２に送出する。この「ＦＲＡ利得制御情報」を含むＯＳＣ光は、Ａ局のＯＳＣ受信部４２に受信され、制御部６０に「ＦＲＡ利得制御情報」が通知される。   (6) If the measured FRA gain does not reach the specified value, the control unit 60 of the B station outputs the calculated “FRA gain control information” to the OSC transmission unit 41, and the OSC transmission unit 41 transmits the OSC light to the OSC light. Superposed and sent to the optical fiber transmission line 2. The OSC light including the “FRA gain control information” is received by the OSC receiving unit 42 of the A station, and the control unit 60 is notified of the “FRA gain control information”.

(7) Ａ局の制御部６０は、Ｂ局から通知された「ＦＲＡ利得制御情報」に基づいてＦＲＡ部５０のラマン励起光源のパワー値または印加電流値を設定し、対応するＦＲＡ利得が得られるように制御する。   (7) The control unit 60 of the A station sets the power value or the applied current value of the Raman excitation light source of the FRA unit 50 based on the “FRA gain control information” notified from the B station, and obtains the corresponding FRA gain. To be controlled.

(8) Ｂ局の制御部６０は、 (4)〜(6) の処理を繰り返し、Ｂ局で規定のＦＲＡ利得が得られた場合には、ＦＲＡ利得制御の終了を通知し、かつＡ局のＦＲＡ部５０の制御モードをＡＣＣモードまたはＡＰＣモードに設定するためのモード設定要求をＯＳＣ送信部４１に出力し、ＯＳＣ送信部４１はＯＳＣ光に重畳して光ファイバ伝送路２に送出する。このモード設定要求を含むＯＳＣ光は、Ａ局のＯＳＣ受信部４２に受信され、制御部６０にモード設定要求が通知される。   (8) The control unit 60 of the B station repeats the processes (4) to (6), and when the specified FRA gain is obtained at the B station, notifies the end of the FRA gain control, and the A station A mode setting request for setting the control mode of the FRA unit 50 to the ACC mode or the APC mode is output to the OSC transmission unit 41, and the OSC transmission unit 41 superimposes the OSC light on the optical fiber transmission line 2. The OSC light including this mode setting request is received by the OSC receiving unit 42 of station A, and the mode setting request is notified to the control unit 60.

(9) Ａ局の制御部６０は、モード設定要求の通知によりＦＲＡ部５０の制御モードをＡＣＣモードまたはＡＰＣモードに設定する。ここで、ＦＲＡ部５０をＡＰＣモードに設定するための構成を図３に示す。ＦＲＡ部５０は、ラマン励起光源５１から出力されるラマン励起光を光カプラ５２を介して光ファイバ伝送路１に送出する。また、ラマン励起光は、ラマン励起光源５１の出力部から光カプラ５３を介して光検出器（ＰＤ）５４に入力され、制御回路５５はそのモニタ値が一定になるようにラマン励起光源５１の印加電流を制御する構成である。なお、ＡＣＣモードに設定する場合には、光カプラ５３およびＰＤ５４は不要であり、制御回路５５でラマン励起光源５１の印加電流が一定になるように制御する構成とする。このようなＡＰＣモードまたはＡＣＣモードに設定することにより、ＦＲＡ利得を規定の利得に保持することができる。   (9) The control unit 60 of the A station sets the control mode of the FRA unit 50 to the ACC mode or the APC mode by notifying the mode setting request. A configuration for setting the FRA unit 50 to the APC mode is shown in FIG. The FRA unit 50 sends the Raman pumping light output from the Raman pumping light source 51 to the optical fiber transmission line 1 via the optical coupler 52. Further, the Raman pumping light is input from the output unit of the Raman pumping light source 51 to the photodetector (PD) 54 via the optical coupler 53, and the control circuit 55 controls the Raman pumping light source 51 so that the monitor value becomes constant. In this configuration, the applied current is controlled. Note that when the ACC mode is set, the optical coupler 53 and the PD 54 are unnecessary, and the control circuit 55 controls the application current of the Raman pumping light source 51 to be constant. By setting to such APC mode or ACC mode, the FRA gain can be maintained at a specified gain.

(10)Ａ局の制御部６０は、ＦＲＡ部５０のモード設定を行うとともに、Ｂ局のＢＲＡ部１０およびＥＤＦＡ部２０を元のＡＬＣモードに戻すためのモード切替要求をＯＳＣ送信部４１に出力し、ＯＳＣ送信部４１はＯＳＣ光に重畳して光ファイバ伝送路１に送出する。このモード切替要求を含むＯＳＣ光は、Ｂ局のＯＳＣ受信部４２に受信され、制御部６０にモード切替要求が通知される。   (10) The control unit 60 of the A station sets the mode of the FRA unit 50 and outputs a mode switching request for returning the BRA unit 10 and the EDFA unit 20 of the B station to the original ALC mode to the OSC transmission unit 41. Then, the OSC transmission unit 41 superimposes the OSC light and transmits it to the optical fiber transmission line 1. The OSC light including the mode switching request is received by the OSC receiving unit 42 of the B station, and the control unit 60 is notified of the mode switching request.

(11)Ｂ局の制御部６０は、そのモード切替要求に応じてＢＲＡ部１０をＡＰＣモードまたはＡＣＣモードから初期状態のＡＬＣモードに戻し、ＥＤＦＡ部２０をＡＧＣモードから初期状態のＡＬＣモードに戻す。
なお、Ｂ局のＢＲＡ部１０およびＥＤＦＡ部２０では、Ａ局のＦＲＡ制御によるＦＲＡ利得が発生する前と後では、ＡＬＣモードで一定制御される出力パワーの値が異なるので、初期状態のＡＬＣモードに戻す際にその制御値（目標値）をＦＲＡ制御を考慮した値に変更する。 (11) In response to the mode switching request, the control unit 60 of the B station returns the BRA unit 10 from the APC mode or the ACC mode to the initial ALC mode, and returns the EDFA unit 20 from the AGC mode to the initial ALC mode. .
In the BRA unit 10 and the EDFA unit 20 of the B station, the value of the output power that is constantly controlled in the ALC mode is different before and after the generation of the FRA gain by the FRA control of the A station. When returning to the above, the control value (target value) is changed to a value considering FRA control.

本発明の光伝送システムの実施形態を示す図。The figure which shows embodiment of the optical transmission system of this invention. 制御部６０におけるＦＲＡ利得制御シーケンスを示す図。The figure which shows the FRA gain control sequence in the control part 60. ＦＲＡ部５０の構成例を示す図。The figure which shows the structural example of the FRA part. 従来の光伝送システムの構成例を示す図。The figure which shows the structural example of the conventional optical transmission system. ＡＬＣ（ＡＰＣ，ＡＣＣ）機能を有するＢＲＡ部１０の構成例を示す図。The figure which shows the structural example of the BRA part 10 which has ALC (APC, ACC) function. ＡＬＣ（ＡＧＣ）機能を有するＥＤＦＡ部２０の構成例を示す図。The figure which shows the structural example of the EDFA part 20 which has an ALC (AGC) function.

符号の説明Explanation of symbols

１，２ 光ファイバ伝送路
１０ 後方ラマン増幅部（ＢＲＡ部）
１１ ラマン励起光源
１２，１３，１６ 光カプラ
１４，１７ 光検出器（ＰＤ）
１５ 制御回路
２０ エルビウム添加光ファイバ増幅部（ＥＤＦＡ部）
２１ エルビウム添加光ファイバ増幅器（ＥＤＦＡ）
２２，２５ 光カプラ
２３，２６ 光検出器（ＰＤ）
２４ 制御回路
３１ 光カプラ
３２，３３ 光スペクトラムアナライザ（ＯＳＡ）
４０，６０ 制御部
４１ ＯＳＣ送信部
４２ ＯＳＣ受信部
４３，４４ 光カプラ
５０ 前方ラマン増幅部（ＦＲＡ部）
５１ ラマン励起光源
５２，５３ 光カプラ
５４ 光検出器（ＰＤ）
５５ 制御回路
1, 2 Optical fiber transmission line 10 Rear Raman amplifier (BRA unit)
11 Raman excitation light source 12, 13, 16 Optical coupler 14, 17 Photodetector (PD)
15 Control circuit 20 Erbium-doped optical fiber amplifier (EDFA)
21 Erbium-doped fiber amplifier (EDFA)
22, 25 Optical coupler 23, 26 Photo detector (PD)
24 Control Circuit 31 Optical Coupler 32, 33 Optical Spectrum Analyzer (OSA)
40, 60 Control unit 41 OSC transmission unit 42 OSC reception unit 43, 44 Optical coupler 50 Front Raman amplification unit (FRA unit)
51 Raman Excitation Light Source 52, 53 Optical Coupler 54 Photodetector (PD)
55 Control circuit

Claims (9)

光ファイバ伝送路を介して接続されるＡ局およびＢ局に、信号光および制御信号を伝送するためのＯＳＣ光を双方向に伝送する手段を備え、
前記Ｂ局は、
前記Ａ局から前記Ｂ局に伝送される信号光と逆方向に前記光ファイバ伝送路に対してラマン励起光を送出する後方ラマン増幅部（ＢＲＡ部）と、
前記ＢＲＡ部によるラマン増幅後の信号光を増幅するエルビウム添加光ファイバ増幅部（ＥＤＦＡ部）と、
前記ＥＤＦＡ部で増幅された信号光パワーをモニタする光スペクトラムアナライザ（ＯＳＡ）と
を備えた光伝送システムにおいて、
前記Ａ局は、
前記Ａ局から前記Ｂ局に伝送される信号光と同方向に前記光ファイバ伝送路に対してラマン励起光を送出する前方ラマン増幅部（ＦＲＡ部）と、
前記ＦＲＡ部からラマン励起光を送出する前に、前記ＯＳＣ光を用いて、前記Ｂ局のＢＲＡ部をラマン励起光のパワーが一定になるように制御するＡＰＣモードまたはラマン励起光源の電流値が一定になるように制御するＡＣＣモードに設定し、前記Ｂ局のＥＤＦＡ部を入出力信号光のパワー比が一定になるように制御するＡＧＣモードに設定するための制御信号を送信する制御部とを備え、
前記Ｂ局は、
前記ＯＳＣ光を用いて伝送された前記制御信号に応じて、前記ＢＲＡ部を前記ＡＰＣモードまたは前記ＡＣＣモードに設定し、前記ＥＤＦＡ部を前記ＡＧＣモードに設定し、当該モード設定後に前記Ａ局に対して前記ＯＳＣ光を用いて前記ＦＲＡ部の動作を制御する制御信号を送信する制御部を備え、
前記Ａ局の制御部は前記Ｂ局から送信された前記制御信号に応じて前記ＦＲＡ部を動作させ、前記Ｂ局のＯＳＡおよび制御部は、前記ＢＲＡ部の前記ＡＰＣモードまたは前記ＡＣＣモードに設定後および前記ＥＤＦＡ部の前記ＡＧＣモード設定後に、前記Ａ局のＦＲＡ部からラマン励起光の送出前と送出時のスペクトルデータの差分を検出し、前方ラマン利得（ＦＲＡ利得）の測定を行う構成である
ことを特徴とする光伝送システム。 A means for bidirectionally transmitting OSC light for transmitting signal light and a control signal to the A station and the B station connected via an optical fiber transmission line ,
The station B is
A backward Raman amplification unit (BRA unit) for sending Raman pumping light to the optical fiber transmission line in the opposite direction to the signal light transmitted from the A station to the B station ;
An erbium-doped optical fiber amplifying unit (EDFA unit) for amplifying the signal light after Raman amplification by the BRA unit ;
An optical transmission system comprising: an optical spectrum analyzer (OSA) that monitors the signal light power amplified by the EDFA unit;
The station A is
A forward Raman amplification unit (FRA unit) that sends Raman pumping light to the optical fiber transmission line in the same direction as the signal light transmitted from the A station to the B station ;
Before sending the Raman pump light from the front Symbol FRA unit, using said OSC light, the current value of the APC mode or Raman excitation light source power of Raman excitation light BRA portion of the B station is controlled to be constant A control unit for setting a control signal for setting the EDFA unit of the B station to an AGC mode for controlling the power ratio of input / output signal light to be constant And
The station B is
Depending on the control signal transmitted using the OSC light, the BRA unit is set to the APC mode or the ACC mode, the EDFA unit is set to the AGC mode, and after the mode setting, the station A is set. A control unit that transmits a control signal for controlling the operation of the FRA unit using the OSC light.
The control unit of the A station operates the FRA unit according to the control signal transmitted from the B station, and the OSA and the control unit of the B station are set to the APC mode or the ACC mode of the BRA unit. after and after the AGC mode setting of said EDFA portion, wherein detecting the difference between the spectral data at the time of delivery and prior to delivery of the Raman excitation light from FRA portion of a station, in a configuration for measuring the forward Raman gain (FRA gain) An optical transmission system characterized by that. 請求項１に記載の光伝送システムにおいて、
前記Ａ局および前記Ｂ局の制御部は、前記Ｂ局で測定されるＦＲＡ利得が規定値になるように、前記Ａ局のＦＲＡ部のラマン励起光パワーを制御する構成である
ことを特徴とする光伝送システム。 The optical transmission system according to claim 1,
The control units of the A station and the B station are configured to control the Raman pumping light power of the FRA unit of the A station so that the FRA gain measured at the B station becomes a specified value. Optical transmission system. 請求項２に記載の光伝送システムにおいて、
前記信号光は複数の波長の信号チャネルを波長多重したＷＤＭ信号光であり、
前記Ｂ局の制御部またはＯＳＡは、前記複数の波長の信号チャネルごとのＦＲＡ利得の規定値をテーブルとして備え、
前記Ａ局の制御部は、ＦＲＡ部のラマン励起光源のパワー値または印加電流値を「ＦＲＡパワー情報」として前記Ｂ局の制御部に通知する手段を含み、
前記Ｂ局の制御部は、測定されたＦＲＡ利得と前記テーブルのＦＲＡ利得の規定値との偏差を算出し、その偏差と前記Ａ局から通知された「ＦＲＡパワー情報」から規定のＦＲＡ利得を設定するためのラマン励起光源のパワー値または印加電流値を「ＦＲＡ利得制御情報」として算出し、前記Ａ局の制御部に通知する手段を含み、
前記Ａ局の制御部は、前記Ｂ局から通知された「ＦＲＡ利得制御情報」に基づいてＦＲＡ部のラマン励起光源のパワー値または印加電流値を設定し、規定のＦＲＡ利得が得られるように制御する手段を含む
ことを特徴とする光伝送システム。 The optical transmission system according to claim 2,
The signal light is a WDM signal light obtained by wavelength multiplexing a plurality of wavelength signal channels;
The control unit or OSA of the B station includes, as a table, prescribed values of FRA gains for the signal channels of the plurality of wavelengths ,
The control unit of the A station includes means for notifying the power value or applied current value of the Raman excitation light source of the FRA unit to the control unit of the B station as “FRA power information”,
The control unit of the B station calculates a deviation between the measured FRA gain and the prescribed value of the FRA gain in the table, and obtains the prescribed FRA gain from the deviation and the “FRA power information” notified from the A station. Means for calculating the power value or applied current value of the Raman excitation light source for setting as “FRA gain control information” and notifying the control unit of the A station;
The control unit of the A station sets the power value or the applied current value of the Raman excitation light source of the FRA unit based on the “FRA gain control information” notified from the B station so that a prescribed FRA gain can be obtained. An optical transmission system comprising means for controlling. 請求項２または請求項３に記載の光伝送システムにおいて、
前記Ａ局および前記Ｂ局の制御部は、Ａ局とＢ局との間でＦＲＡ利得が規定値に制御された後に、前記Ａ局のＦＲＡ部を前記ＡＰＣモードまたはＡＣＣモードに設定し、さらに前記Ｂ局のＢＲＡ部およびＥＤＦＡ部をそれぞれ出力信号光パワーが一定になるように制御するＡＬＣモードに設定する構成である
ことを特徴とする光伝送システム。 In the optical transmission system according to claim 2 or 3,
The control unit of the A station and the B station sets the FRA unit of the A station to the APC mode or the ACC mode after the FRA gain is controlled to a specified value between the A station and the B station. An optical transmission system, wherein the BRA unit and the EDFA unit of the B station are each set to an ALC mode for controlling the output signal light power to be constant. 請求項３に記載の光伝送システムにおいて、
前記Ａ局および前記Ｂ局は、Ａ局とＢ局との間で送受信されるＯＳＣ光を用いて、Ａ局とＢ局との間でＦＲＡ利得の制御に用いる「ＦＲＡパワー情報」および「ＦＲＡ利得制御情報」を伝送する手段を備えた
ことを特徴とする光伝送システム。 The optical transmission system according to claim 3.
The A station and the B station use the OSC light transmitted and received between the A station and the B station, and “FRA power information” and “FRA” used for controlling the FRA gain between the A station and the B station. An optical transmission system comprising means for transmitting "gain control information". 請求項４に記載の光伝送システムにおいて、
前記Ａ局および前記Ｂ局は、Ａ局とＢ局との間で送受信されるＯＳＣ光を用いて、Ｂ局のＢＲＡ部およびＥＤＦＡ部をＡＬＣモードに設定するための制御信号を伝送する手段を備えた
ことを特徴とする光伝送システム。 The optical transmission system according to claim 4, wherein
The A station and the B station use the OSC light transmitted and received between the A station and the B station to transmit a control signal for setting the BRA unit and the EDFA unit of the B station to the ALC mode. An optical transmission system characterized by comprising. 請求項４に記載の光伝送システムにおいて、
前記Ｂ局のＢＲＡ部は、前記ＡＬＣモードと、前記ＡＰＣモードまたはＡＣＣモードとの切り替えが可能な構成である
ことを特徴とする光伝送システム。 The optical transmission system according to claim 4, wherein
The BRA unit of the B station is configured to be able to switch between the ALC mode and the APC mode or the ACC mode. 請求項４に記載の光伝送システムにおいて、
前記Ｂ局のＥＤＦＡ部は、前記ＡＬＣモードと、前記ＡＧＣモードとの切り替えが可能な構成である
ことを特徴とする光伝送システム。 The optical transmission system according to claim 4, wherein
The optical transmission system, wherein the EDFA section of the B station is configured to be able to switch between the ALC mode and the AGC mode. 請求項４に記載の光伝送システムにおいて、
前記Ａ局のＦＲＡ部は、ＦＲＡ部から出力されるラマン励起光パワーをモニタする手段およびそのラマン励起光パワーを制御する手段を含み、前記ＡＰＣモードまたはＡＣＣモードの設定が可能な構成である
ことを特徴とする光伝送システム。 The optical transmission system according to claim 4, wherein
The FRA section of the A station includes a means for monitoring the Raman pumping light power output from the FRA section and a means for controlling the Raman pumping light power, and is configured to be able to set the APC mode or the ACC mode. An optical transmission system characterized by
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