JP2006032417A

JP2006032417A - Optical amplifier, automatic control method of amplification function thereof, control apparatus, optical communication apparatus, and optical transmission system

Info

Publication number: JP2006032417A
Application number: JP2004204830A
Authority: JP
Inventors: Naoto Ishino; 直人石野
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 2004-07-12
Filing date: 2004-07-12
Publication date: 2006-02-02

Abstract

<P>PROBLEM TO BE SOLVED: To provide the automatic control method of an optical amplifier for detecting withdrawal of an output connector and shutting down the optical amplifier without giving a loss to a main signal light, and without the need for a high output level in a monitor light and a wide dynamic range for a monitor light receiver, and automatically restarting the optical amplifier after a cause to a fault is eliminated; and to provide the optical amplifier adopting the method and an optical transmission system. <P>SOLUTION: The monitor light outputted from a laser diode LD 7 is multiplexed with a signal light output from the optical amplifier 1 at an optical multiplexing/demultiplexing filter 2 via a coupler 4-1. The LD 7 always keeps outputting a light with a wavelength at the outside of the amplification band of the optical amplifier 1. The light multiplexed by the optical multiplexing/demultiplexing filter 2 is outputted through the output connector 3. A photodiode PD 5-1 detects a reflected light in the output connector 3 receiving the light from the LD 7, and a level detector 6-1 outputs an output stop signal 8 to the optical amplifier 1 when the output of the PD 5-1 exceeds a prescribed level. Further, when the output of the PD 5-1 is lower than the prescribed level or a prescribed level separately decided, the level detector 6-1 stops an output of an output stop signal or outputs a restart signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、光増幅器に関し、とくに監視光による反射光検出を常時行って、光増幅器出力光の自動停止及び解除を自動制御する方法を備えた光増幅器およびこれを用いた光伝送システムに関する。 The present invention relates to an optical amplifier, and more particularly, to an optical amplifier having a method of automatically detecting reflected light by monitoring light and automatically controlling the automatic stop and release of output light from the optical amplifier, and an optical transmission system using the optical amplifier.

光増幅器の出力光は高出力であるため、コネクタ外れなどによる出力光ファイバ端面からの反射光が検出されると、警報が発出され、シャットダウンする安全システムが施されている。これは誤って光コネクタや光コードの先端部を作業者が覗きこんだ場合、眼に障害を起こす危険性があるためである。
特許文献１等に開示されている従来の反射光検出方法を図７に示す。光増幅器１０１の出力光はカプラ１０２を経て、出力コネクタ１０３から出力される。出力コネクタ１０３が外れた場合、出力光が光コネクタ端面で反射されて、光増幅器１０１に戻ってくる。カプラ１０２内には、反射光を取り出す分岐路があり、ここで分岐された反射光をフォトダイオードＰＤ１０４が受光し、パワーをモニタする。モニタされたパワーが所定のレベルより大となった場合に、検出器１０５から光増幅器１０１へ出力停止信号１０６が送られ、光増幅器１０１の出力が停止される。
この光増幅器出力のコネクタ端面からの反射光をモニタする構成では、光増幅器１０１からの出力光が強制停止されると、端面からの反射光が無くなるため、光増幅器の停止状態は機械的に解除され再び増幅光が出力されることになる。このため、作業者に思わぬ危害が加わる恐れがある。
光増幅器の安全のための制御回路は、コネクタからの反射が起きていなくても、反射警報の発出をラッチし続けるような判定ロジックにしておく必要がある。また、シャットダウンの解除は、無人によるのではなく、人手によって光コネクタが正しく接続されたことを確認した後警報を解除し、光増幅器を再起動するような手順マニュアルを設けておく必要がある。
そこで、出力コネクタ外れを自動的に検出して光増幅器のシャットダウンを行い、反射警報を発出する原因が取り除かれた後、自動的にシャットダウンを解除する機能が求められる。 Since the output light of the optical amplifier is a high output, when a reflected light from the end face of the output optical fiber due to disconnection of the connector or the like is detected, an alarm is issued and a safety system for shutting down is provided. This is because if an operator mistakenly looks into the tip of the optical connector or the optical cord, there is a risk of causing eye damage.
FIG. 7 shows a conventional reflected light detection method disclosed in Patent Document 1 and the like. The output light of the optical amplifier 101 is output from the output connector 103 via the coupler 102. When the output connector 103 is disconnected, the output light is reflected by the end face of the optical connector and returns to the optical amplifier 101. In the coupler 102, there is a branch path for extracting reflected light. The reflected light branched here is received by the photodiode PD104 and the power is monitored. When the monitored power becomes larger than a predetermined level, the output stop signal 106 is sent from the detector 105 to the optical amplifier 101, and the output of the optical amplifier 101 is stopped.
In the configuration in which the reflected light from the connector end face of the optical amplifier output is monitored, when the output light from the optical amplifier 101 is forcibly stopped, the reflected light from the end face disappears. Then, the amplified light is output again. For this reason, there is a risk of unexpected harm to workers.
The control circuit for safety of the optical amplifier needs to have a determination logic that continues to latch the occurrence of the reflection alarm even if the reflection from the connector does not occur. In addition, it is necessary to provide a procedure manual for releasing the shutdown after restarting the optical amplifier after confirming that the optical connector has been correctly connected by hand, not by unmanned release.
Therefore, there is a need for a function that automatically detects the disconnection of the output connector, shuts down the optical amplifier, removes the cause of issuing the reflection alarm, and automatically cancels the shutdown.

光増幅器が停止状態であっても光コネクタが接続されたことを確実に確認する方法として、信号光とは別に半導体レーザ光を監視光として挿入する光増幅器が、特許文献２に開示されている。光コネクタから反射して戻る光増幅器出力光レベルを受光器がモニタし、出力光ケーブルの光コネクタ外れを検出して、光増幅器をシャットダウンする。その後、光分岐素子を介して監視光を出力光ケーブルに注入する。光分岐素子を通して監視光の光コネクタからの反射光をモニタ受光器が受光し、その強度低下を確認した後に光増幅器を自動的に再起動する。 Patent Document 2 discloses an optical amplifier that inserts semiconductor laser light as monitoring light separately from signal light as a method for reliably confirming that the optical connector is connected even when the optical amplifier is in a stopped state. . The optical receiver outputs the optical amplifier output light level reflected and returned from the optical connector, detects the disconnection of the optical connector of the output optical cable, and shuts down the optical amplifier. Thereafter, monitoring light is injected into the output optical cable via the optical branching element. The monitor light receiver receives the reflected light from the optical connector of the monitoring light through the optical branching element, and after confirming the decrease in the intensity, the optical amplifier is automatically restarted.

特開平８−２９３８３５号公報（第４−５頁、図１）JP-A-8-293835 (page 4-5, FIG. 1) 特開平６−３０２８９０号公報（第４−５頁、図１）JP-A-6-302890 (page 4-5, FIG. 1)

しかしながら、特許文献２に開示されている光増幅器では、モニタ受光器は光増幅器出力光と監視光の両方を受光する必要がある。このため、分岐特性に波長依存性の少ない光分岐素子を信号光のモニタや監視光の挿入及びモニタのために備える必要があって、信号光である光増幅器出力光や監視光に損失をもたらす。
また、モニタ受光器は、高レベルの光増幅器出力光と低レベルの監視光の両方を受光できる広いダイナミックレンジを備える必要があり、装置コストが高くなる。若しくは、監視光出力を光増幅器出力と同レベルに設定する必要があり、出力の高い監視光によるレーザハザードを受ける可能性がある。過負荷をかけることは監視光用半導体レーザの劣化を早めることに繋がる。
このように出力光コネクタ外れの検出と再起動を自動的に行う従来の方法には難点がある。
本発明は、上記の光増幅器の持つ難点に鑑みて成されたものである。その目的とするところは、主信号光に損失を与えず、監視光に高い出力レベルやモニタ受光器に広いダイナミックレンジを必要とせずに、出力コネクタ外れを自動的に検出して光増幅器のシャットダウンを行い、障害の原因が取り除かれた後、自動的にシャットダウンを解除して再起動する自動制御方法、およびこれを備えた光増幅器並びに光伝送システムを提供することにある。 However, in the optical amplifier disclosed in Patent Document 2, the monitor light receiver needs to receive both the optical amplifier output light and the monitoring light. For this reason, it is necessary to provide an optical branching device with little wavelength dependency in the branching characteristics for monitoring the signal light and for inserting and monitoring the monitoring light, which causes a loss in the optical amplifier output light and the monitoring light that are the signal light. .
In addition, the monitor light receiver needs to have a wide dynamic range capable of receiving both the high-level optical amplifier output light and the low-level monitoring light, which increases the device cost. Alternatively, it is necessary to set the monitoring light output to the same level as the output of the optical amplifier, and there is a possibility of receiving a laser hazard due to the monitoring light having a high output. Applying an overload leads to faster deterioration of the monitoring light semiconductor laser.
As described above, the conventional method for automatically detecting and restarting the output optical connector is difficult.
The present invention has been made in view of the difficulties of the optical amplifier described above. The purpose is to shut down the optical amplifier by automatically detecting disconnection of the output connector without losing the main signal light, without requiring a high output level for the monitoring light and a wide dynamic range for the monitor receiver. And providing an automatic control method for automatically canceling and restarting after the cause of the failure is removed, and an optical amplifier and an optical transmission system including the same.

上記の課題を解決するために、本発明の光増幅器は、出力光導波路からのフレネル反射光を検出するために、増幅する信号波長の帯域外に波長を有する監視光を出力導波路の光出力方向に合波する手段を備えることを特徴とする。
また、本発明の光増幅器は、増幅する信号波長帯域外の波長を有する監視光を出力光導波路の光出力方向に合波し、出力光導波路からの監視光のフレネル反射光を分波する手段を備えることを特徴とする。
また、本発明の光増幅器は、増幅する信号波長の帯域外に波長を有する監視光を出力光導波路の光出力方向に合波し、出力光導波路からの監視光のフレネル反射光を分波する手段と、分波したフレネル反射光を検出し、信号増幅の機能を制御する手段を備えることを特徴とする。
また、本発明の光増幅器は、増幅する信号波長の帯域外に波長を有する監視光を出力光導波路の光出力方向に合波し、出力光導波路からの監視光のフレネル反射光を分波する手段と、分波したフレネル反射光のレベルを検出する手段と、検出したレベルに応じて信号増幅の機能を制御する手段を備えることを特徴とする。
また、本発明の光増幅器は、増幅する信号波長の帯域外に波長を有する監視光を出力光導波路の光出力方向に合波し、出力光導波路からの監視光のフレネル反射光を分波する手段と、分波したフレネル反射光のレベルを監視光の出力レベルで除した比を検出する手段と、レベル比に応じて信号増幅の機能を制御する手段を備えることを特徴とする。
制御する信号光増幅の機能は、光増幅の停止及び再起動であってもよい。
検出したレベルまたはレベル比が第１の所定の値を超えた時、増幅を停止し、検出したレベルまたはレベル比が第２の所定の値を下回った時、増幅を再起動してもよい。
監視光は、変調を受けており、フレネル反射光のレベルまたはレベル比を検出する手段が、フレネル反射光の光電変換信号を変調の周波数帯域でフィルタリングして透過する電気的フィルタを備えてもよい。
監視光の光源は、半導体レーザであってもよい。
監視光の光源は、光増幅器への入力光信号から分波して抽出した光信号が占有する波長帯域外の波長有した光信号であってもよい。 In order to solve the above problems, the optical amplifier according to the present invention is configured to detect monitoring light having a wavelength outside the band of the signal wavelength to be amplified in order to detect Fresnel reflected light from the output optical waveguide. It is characterized by comprising means for multiplexing in the direction.
Further, the optical amplifier of the present invention is a means for multiplexing the monitoring light having a wavelength outside the signal wavelength band to be amplified in the light output direction of the output optical waveguide and demultiplexing the Fresnel reflected light of the monitoring light from the output optical waveguide It is characterized by providing.
The optical amplifier of the present invention multiplexes the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide, and demultiplexes the Fresnel reflected light of the monitoring light from the output optical waveguide. And means for detecting the demultiplexed Fresnel reflected light and controlling the function of signal amplification.
The optical amplifier of the present invention multiplexes the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide, and demultiplexes the Fresnel reflected light of the monitoring light from the output optical waveguide. And means for detecting the level of the demultiplexed Fresnel reflected light, and means for controlling the function of signal amplification in accordance with the detected level.
The optical amplifier of the present invention multiplexes the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide, and demultiplexes the Fresnel reflected light of the monitoring light from the output optical waveguide. And means for detecting a ratio obtained by dividing the level of the demultiplexed Fresnel reflected light by the output level of the monitoring light, and means for controlling the function of signal amplification in accordance with the level ratio.
The function of signal light amplification to be controlled may be stop and restart of light amplification.
Amplification may be stopped when the detected level or level ratio exceeds a first predetermined value, and amplification may be restarted when the detected level or level ratio falls below a second predetermined value.
The monitoring light is modulated, and the means for detecting the level or level ratio of the Fresnel reflected light may include an electrical filter that filters and transmits the photoelectric conversion signal of the Fresnel reflected light in the modulation frequency band. .
The light source for the monitoring light may be a semiconductor laser.
The light source of the monitoring light may be an optical signal having a wavelength outside the wavelength band occupied by the optical signal extracted by demultiplexing from the input optical signal to the optical amplifier.

また、本発明の光増幅器の増幅機能自動制御方法は、増幅する信号波長の帯域外に波長を有する監視光を出力光導波路の光出力方向に合波し、前記出力光導波路からの前記監視光のフレネル反射光を分波し、分波した前記フレネル反射光のレベルを検出して前記信号増幅の機能を制御することを特徴とする。
また、本発明の光増幅器の増幅機能自動制御方法は、増幅する信号波長の帯域外に波長を有する監視光を出力光導波路の光出力方向に合波し、出力光導波路からの監視光のフレネル反射光を分波し、分波したフレネル反射光のレベルを検出し、検出したレベルに応じて信号増幅の機能を制御することを特徴とする。
また、本発明の光増幅器の増幅機能自動制御方法は、増幅する信号波長の帯域外に波長を有する監視光を出力光導波路の光出力方向に合波し、出力光導波路からの監視光のフレネル反射光を分波し、分波したフレネル反射光のレベルを監視光の出力レベルで除した比を検出し、レベル比に応じて信号増幅の機能を制御することを特徴とする。
制御する信号光増幅の機能は、光増幅の停止及び再起動であってもよい。
検出したレベルまたはレベル比が第１の所定の値を超えた時、増幅を停止し、検出したレベルまたはレベル比が第２の所定の値を下回った時、増幅を再起動してもよい。
監視光は、変調を受けており、フレネル反射光のレベルまたはレベル比は、フレネル反射光の光電変換信号を変調の周波数帯域でフィルタリングして透過する電気的フィルタを通して検出されてもよい。
監視光の光源は、半導体レーザであってもよい。
監視光の光源は、光増幅器への入力光信号から分波して抽出した光信号が占有する波長帯域外の波長有した光信号であってもよい。 The method for automatically controlling an amplification function of an optical amplifier according to the present invention also combines monitoring light having a wavelength outside the band of a signal wavelength to be amplified in the light output direction of the output optical waveguide, and the monitoring light from the output optical waveguide. The Fresnel reflected light is demultiplexed, and the level of the demultiplexed Fresnel reflected light is detected to control the signal amplification function.
Also, the method for automatically controlling the amplification function of the optical amplifier according to the present invention combines the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide, The reflected light is demultiplexed, the level of the demultiplexed Fresnel reflected light is detected, and the function of signal amplification is controlled according to the detected level.
Also, the method for automatically controlling the amplification function of the optical amplifier according to the present invention combines the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide, The reflected light is demultiplexed, a ratio obtained by dividing the level of the demultiplexed Fresnel reflected light by the output level of the monitoring light is detected, and the function of signal amplification is controlled according to the level ratio.
The function of signal light amplification to be controlled may be stop and restart of light amplification.
Amplification may be stopped when the detected level or level ratio exceeds a first predetermined value, and amplification may be restarted when the detected level or level ratio falls below a second predetermined value.
The monitoring light is modulated, and the level or level ratio of the Fresnel reflected light may be detected through an electrical filter that filters and transmits the photoelectric conversion signal of the Fresnel reflected light in the modulation frequency band.
The light source for the monitoring light may be a semiconductor laser.
The light source of the monitoring light may be an optical signal having a wavelength outside the wavelength band occupied by the optical signal extracted by demultiplexing from the input optical signal to the optical amplifier.

また、本発明の光増幅器の制御装置は、増幅する信号波長の帯域外に波長を有する監視光を出力光導波路の光出力方向に合波し、前記出力光導波路からの前記監視光のフレネル反射光を分波し、分波した前記フレネル反射光のレベルを検出して前記信号増幅の機能を制御することを特徴とする。
また、本発明の光増幅器の制御装置は、増幅する信号波長の帯域外に波長を有する監視光を出力光導波路の光出力方向に合波し、出力光導波路からの監視光のフレネル反射光を分波し、分波したフレネル反射光のレベルを検出し、検出したレベルに応じて信号増幅の機能を制御することを特徴とする。
また、本発明の光増幅器の制御装置は、増幅する信号波長の帯域外に波長を有する監視光を出力光導波路の光出力方向に合波し、出力光導波路からの監視光のフレネル反射光を分波し、分波したフレネル反射光のレベルを監視光の出力レベルで除した比を検出し、レベル比に応じて信号増幅の機能を制御することを特徴とする。
制御する信号光増幅の機能は、光増幅の停止及び再起動であってもよい。
検出したレベルまたはレベル比が第１の所定の値を超えた時、増幅を停止し、検出したレベルまたはレベル比が第２の所定の値を下回った時、増幅を再起動してもよい。
監視光は、変調を受けており、フレネル反射光のレベルまたはレベル比は、フレネル反射光の光電変換信号を変調の周波数帯域でフィルタリングして透過する電気的フィルタを通して検出されてもよい。
監視光の光源は、半導体レーザであってもよい。
監視光の光源は、光増幅器への入力光信号から分波して抽出した光信号が占有する波長帯域外の波長有した光信号であってもよい。
また本発明の光通信装置は、上記いずれかに記載の光増幅器を備えることを特徴とする。
また本発明の光伝送システムは、上記いずれかに記載の光増幅器を備えることを特徴とする。 The control apparatus for an optical amplifier according to the present invention multiplexes the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide, and Fresnel reflection of the monitoring light from the output optical waveguide The light is demultiplexed, and the level of the demultiplexed Fresnel reflected light is detected to control the function of signal amplification.
Also, the control device for the optical amplifier of the present invention combines the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide, and the Fresnel reflected light of the monitoring light from the output optical waveguide. It demultiplexes, detects the level of the demultiplexed Fresnel reflected light, and controls the function of signal amplification according to the detected level.
Further, the control device for the optical amplifier of the present invention combines the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide, and the Fresnel reflected light of the monitoring light from the output optical waveguide. It is characterized by detecting a ratio obtained by demultiplexing and dividing the level of the demultiplexed Fresnel reflected light by the output level of the monitoring light, and controlling the function of signal amplification according to the level ratio.
The function of signal light amplification to be controlled may be stop and restart of light amplification.
Amplification may be stopped when the detected level or level ratio exceeds a first predetermined value, and amplification may be restarted when the detected level or level ratio falls below a second predetermined value.
The monitoring light is modulated, and the level or level ratio of the Fresnel reflected light may be detected through an electrical filter that filters and transmits the photoelectric conversion signal of the Fresnel reflected light in the modulation frequency band.
The light source for the monitoring light may be a semiconductor laser.
The light source for the monitoring light may be an optical signal having a wavelength outside the wavelength band occupied by the optical signal extracted by demultiplexing from the input optical signal to the optical amplifier.
An optical communication apparatus according to the present invention includes any one of the optical amplifiers described above.
An optical transmission system according to the present invention includes any one of the optical amplifiers described above.

本発明の光増幅器によれば、出力光導波路からのフレネル反射光を検出するために、増幅する信号波長の帯域外に波長を有する監視光を出力導波路の光出力方向に合波する手段を備える。このため、光増幅器の稼働・停止に拘わらず、出力光導波路のフレネル反射光を常時検出することができる。
また、本発明の光増幅器の増幅機能自動制御方法及び制御装置は、増幅する信号波長の帯域外に波長を有する監視光を出力光導波路の光出力方向に合波する。そして、出力光導波路からの監視光のフレネル反射光を分波し、分波したフレネル反射光のレベルを検出して信号増幅の機能を制御する。このため反射光が発生していても、自動で停止および復旧することができる。 According to the optical amplifier of the present invention, in order to detect the Fresnel reflected light from the output optical waveguide, means for multiplexing the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the optical output direction of the output waveguide. Prepare. For this reason, it is possible to always detect the Fresnel reflected light of the output optical waveguide regardless of the operation / stop of the optical amplifier.
Also, the amplification function automatic control method and control apparatus for an optical amplifier according to the present invention multiplexes the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide. Then, the Fresnel reflected light of the monitoring light from the output optical waveguide is demultiplexed, and the level of the demultiplexed Fresnel reflected light is detected to control the function of signal amplification. For this reason, even if reflected light is generated, it can be automatically stopped and restored.

本発明の実施の形態について図面を参照して説明する。
［実施例１］
図１は、本発明の第１の実施例の構成を示す図である。図１において、レーザダイオードＬＤ７から出力された監視光は、カプラ４−１を経て、光増幅器１からの信号光出力と合波／分波フィルタ２で合波される。このＬＤ７は光増幅器１の増幅帯域外の波長の光を常に出力し続けている。合波／分波フィルタ２で合波された光は、出力コネクタ３を通じて出力される。フォトダイオードＰＤ５−１は、ＬＤ７の出力コネクタ３からのフレネル反射光を光電変換する。レベル検出器６−１は、ＰＤ５−１の出力を検知し、その出力が所定のレベルを超えた場合に出力停止信号８を光増幅器１に出力する。また、ＰＤ５−１の出力が上記のレベルまたは別に定めた所定のレベルを下回った場合には、出力停止信号の出力を停止するかまたは再起動の信号を出力する。
カプラ４−１は、導波路型方向性結合器や誘電体多層膜や金属半透膜を使ったバルク型の光分岐素子を用いることができる。また、光サーキュレータを用いると監視光の損失は低下する。
また、光分岐素子を用いた場合には、光増幅器１やＬＤ７への反射戻り光を防ぐために、合波／分波フィルタ２と光増幅器との間やカプラ４−１とＬＤ７との間に、必要に応じて光アイソレータを配設してもよい。 Embodiments of the present invention will be described with reference to the drawings.
[Example 1]
FIG. 1 is a diagram showing the configuration of the first exemplary embodiment of the present invention. In FIG. 1, the monitoring light output from the laser diode LD 7 is combined with the signal light output from the optical amplifier 1 by the multiplexing / demultiplexing filter 2 through the coupler 4-1. The LD 7 always outputs light having a wavelength outside the amplification band of the optical amplifier 1. The light combined by the multiplexing / demultiplexing filter 2 is output through the output connector 3. The photodiode PD5-1 photoelectrically converts the Fresnel reflected light from the output connector 3 of the LD7. The level detector 6-1 detects the output of the PD 5-1, and outputs an output stop signal 8 to the optical amplifier 1 when the output exceeds a predetermined level. When the output of the PD 5-1 falls below the above level or a predetermined level determined separately, the output stop signal output is stopped or a restart signal is output.
As the coupler 4-1, a bulk type optical branching element using a waveguide type directional coupler, a dielectric multilayer film, or a metal semi-permeable film can be used. In addition, when an optical circulator is used, the loss of monitoring light is reduced.
Further, when an optical branching element is used, in order to prevent reflected return light to the optical amplifier 1 and the LD 7, between the multiplexing / demultiplexing filter 2 and the optical amplifier or between the coupler 4-1 and the LD 7. An optical isolator may be provided as necessary.

次に図１の動作を説明する。図１において、出力コネクタ３が外れるなどして、端面で反射が起きたとする。この時、反射光は合波／分波フィルタ２でＬＤ７の出力波長の光だけが分岐されて、カプラ４−１に入射される。このカプラ４−１を経て、ＰＤ５−１で反射光を受光する。受光パワーがある閾値を超えると、検出器６−１から光増幅器１へ出力停止信号８が出力される。光増幅器１は、励起用レーザ停止して信号光の増幅出力を停止する。
光増幅器１からの出力光は停止しているが、ＬＤ７からの光は常に出力されているので、この時もコネクタ３での反射は起きている。コネクタ外れによる反射原因がある限り、ＰＤ５−１は反射光を受光し続けている。出力コネクタ３が正常に接続されて、反射原因が除去されると、ＬＤ７からの光はコネクタ端面で反射しないので、ＰＤ５−１で受けていた反射光のパワーも落ちてくる。そのパワーが所定の閾値を下回ると、検出器６−１から光増幅器１へ出力停止信号８が出力されなくなり、光増幅器１の光増幅は自動的に再開される。 Next, the operation of FIG. 1 will be described. In FIG. 1, it is assumed that reflection occurs at the end face due to the output connector 3 being disconnected. At this time, only the light of the output wavelength of the LD 7 is branched by the multiplexing / demultiplexing filter 2 and the reflected light is incident on the coupler 4-1. The reflected light is received by the PD 5-1 through the coupler 4-1. When the received light power exceeds a certain threshold value, an output stop signal 8 is output from the detector 6-1 to the optical amplifier 1. The optical amplifier 1 stops the pumping laser and stops the amplification output of the signal light.
Although the output light from the optical amplifier 1 is stopped, the light from the LD 7 is always output, so that the reflection at the connector 3 still occurs at this time. As long as there is a cause of reflection due to disconnection of the connector, the PD 5-1 continues to receive reflected light. When the output connector 3 is normally connected and the cause of reflection is removed, the light from the LD 7 is not reflected at the end face of the connector, so the power of the reflected light received by the PD 5-1 is also reduced. When the power falls below a predetermined threshold, the output stop signal 8 is not output from the detector 6-1 to the optical amplifier 1, and the optical amplification of the optical amplifier 1 is automatically restarted.

本実施例においては、以下に記載するような効果を奏する。
第１の効果は、光コネクタ外れによってコネクタ端面で反射光が発生していても、光増幅器の増幅動作を自動で停止および復旧することができるので、作業者の安全性を確保できる。
第２に、監視光であるＬＤの発振波長を光増幅器の増幅帯域外の波長に選び、合波／分波フィルタによって信号光との合波／分波を行っているため、信号光や監視光の損失が少ない。このため、分岐素子によって信号光と監視光を合流／分離する従来の方式に比べて、ＰＤ５−１やＬＤ７へ過度な負担が掛からず、装置の信頼性が高まる。 In this embodiment, the following effects can be obtained.
The first effect is that the amplification operation of the optical amplifier can be automatically stopped and restored even if reflected light is generated at the connector end face due to the disconnection of the optical connector, so that the safety of the operator can be ensured.
Second, since the oscillation wavelength of the LD, which is the monitoring light, is selected as a wavelength outside the amplification band of the optical amplifier, and multiplexing / demultiplexing with the signal light is performed by the multiplexing / demultiplexing filter, the signal light and monitoring There is little loss of light. For this reason, compared with the conventional system which joins / separates signal light and monitoring light by a branch element, an excessive burden is not applied to PD5-1 and LD7, and the reliability of an apparatus increases.

［実施例２］
本発明の第２の実施例として、その基本的構成は上記の第１の実施例と同様であるが、反射光の検出方法についてさらに工夫している。その構成を図２に示す。
図２において、光増幅器１からの出力光とＬＤ７からの出力光を合波／分波フィルタ２で合波する。出力コネクタ３が外れるなどして、コネクタ端面で反射が起きたとする。この時、反射光は合波／分波フィルタ２でＬＤ７の出力波長の光だけが分波されて、カプラ４−２に入射される。このカプラ４−２を経て、ＰＤ５−３で反射光を受けて、そのパワーをモニタする。また、ＰＤ５−２でＬＤ７から出力される光のパワーをモニタしている。このとき、比較検出器６−２ではＬＤ出力光とコネクタ端面からの反射光とを比較することによって、コネクタ端面が反射状態であると判断し、出力停止信号８を光増幅器１に出力し、これによって光増幅器１の出力は停止する。
光増幅器１からの出力光は停止しているが、ＬＤ７からの光は常に入力されているので、この時も反射は起きていて、反射原因がある限り、ＰＤ５−３は反射光を受け続けている。出力コネクタ３を正常に接続して、反射原因を除去すると、ＬＤ７からの光は反射しないので、ＰＤ５−３で受けていた反射光のパワーも落ちてくる。反射光レベルとＬＤ出力光レベルとの比較結果がある閾値を下回ると、比較検出器６−２から光増幅器１へ出力停止信号８が出力されなくなり、光増幅器１の出力が自動的に再開される。 [Example 2]
As a second embodiment of the present invention, the basic configuration is the same as that of the first embodiment, but the reflected light detection method is further devised. The configuration is shown in FIG.
In FIG. 2, the output light from the optical amplifier 1 and the output light from the LD 7 are combined by a multiplexing / demultiplexing filter 2. It is assumed that reflection occurs at the connector end surface due to the output connector 3 being disconnected. At this time, only the light having the output wavelength of the LD 7 is demultiplexed by the multiplexing / demultiplexing filter 2 and is incident on the coupler 4-2. The reflected light is received by the PD 5-3 through the coupler 4-2, and its power is monitored. Further, the power of light output from the LD 7 is monitored by the PD 5-2. At this time, the comparison detector 6-2 compares the LD output light and the reflected light from the connector end face to determine that the connector end face is in a reflecting state, and outputs an output stop signal 8 to the optical amplifier 1. As a result, the output of the optical amplifier 1 is stopped.
Although the output light from the optical amplifier 1 is stopped, the light from the LD 7 is always input. Therefore, reflection occurs at this time, and as long as there is a cause of reflection, the PD 5-3 continues to receive the reflected light. ing. When the output connector 3 is normally connected and the cause of reflection is removed, the light from the LD 7 does not reflect, so the power of the reflected light received by the PD 5-3 also decreases. When the comparison result between the reflected light level and the LD output light level falls below a certain threshold value, the output stop signal 8 is not output from the comparison detector 6-2 to the optical amplifier 1, and the output of the optical amplifier 1 is automatically restarted. The

ＬＤ７が劣化して出力パワーが低下したとき、コネクタ端面での反射が起きても第１の実施例の構成ではＰＤ５−１で受けていた反射光のパワーが低くなり、反射状態として検出されない恐れがある。そこで本実施例の構成を採ることによって、入射光と反射光の比較値を見ることで、反射状態を正確に検出することができる。
また、反射光の検知精度が高まるため、コネクタ外れのように比較的反射レベルが高い障害だけではなく、光ファイバの折損のように折点における反射光の反射レベルが小さいような伝送路障害も監視できる可能性がある。
なお、カプラ４−２は、導波路型方向性結合器や誘電体多層膜や金属半透膜を使ったバルク型の光分岐素子を用いることができる。また、光サーキュレータと光分岐素子とを合わせて用いるとLD光、反射光へのカプラ４−２の挿入損失は低下する。 When the output power is reduced due to degradation of the LD 7, even if reflection at the connector end face occurs, the power of the reflected light received by the PD 5-1 in the configuration of the first embodiment is low, and may not be detected as a reflection state. There is. Therefore, by adopting the configuration of the present embodiment, the reflection state can be accurately detected by looking at the comparison value between the incident light and the reflected light.
In addition, since the accuracy of detection of reflected light is increased, not only a failure with a relatively high reflection level such as disconnection of a connector, but also a transmission path failure with a low reflection level of reflected light at a break point such as optical fiber breakage. There is a possibility of monitoring.
The coupler 4-2 may be a bulk type optical branching element using a waveguide type directional coupler, a dielectric multilayer film, or a metal semipermeable film. Further, when the optical circulator and the optical branching element are used in combination, the insertion loss of the coupler 4-2 into the LD light and the reflected light decreases.

［実施例３］
図３に第３の実施例を示す。ＬＤ７の光に光変調器１０で変調をかけた出力光と、光増幅器１からの信号光出力を合波／分波フィルタ２で合波する。出力コネクタ３が外れるなどして、反射が起きたとする。この時、反射光は合波／分波フィルタ２でＬＤ７の出力波長の光だけが分波されて、カプラ４−１に入射する。このカプラ４−１を経て、反射光はＰＤ５−１で電気変換され、帯域通過型の電気フィルタ９−１によって変調周波数成分が抽出される。その振幅レベルをモニタし、反射レベルを検出する。そのレベルがある閾値を超えると、検出器６−１から光増幅器１へ出力停止信号８が出力され、光増幅器１は出力を停止する。
光増幅器１からの出力光は停止しているが、ＬＤ７からの光は常に入力されているので、この時も反射は起きていて、反射原因がある限り、ＰＤ５−１は反射光を受け続けている。出力コネクタ３を正常に接続して、反射原因を除去すると、ＬＤ７からの光は反射しないので、ＰＤ５−１で受けていた反射光のパワーも落ちてくる。そのパワーがある閾値を下回ると、検出器６−１から光増幅器１へ出力停止信号８が出力されなくなり、光増幅器１の出力が自動的に再開される。
本実施例では、監視光に特定の変調信号を重畳することによって、ＰＤ５−１や検出器６−１のアナログ回路が受ける電磁干渉雑音の影響を除去することができ、安定した監視光検出が可能となる。
なお、光変調器を用いずに、ＬＤ駆動電流に電気的に変調信号を重畳しても同じ効果が得られる。 [Example 3]
FIG. 3 shows a third embodiment. The output light obtained by modulating the light of the LD 7 by the optical modulator 10 and the signal light output from the optical amplifier 1 are combined by the multiplexing / demultiplexing filter 2. It is assumed that reflection occurs because the output connector 3 is disconnected. At this time, only the light of the output wavelength of the LD 7 is demultiplexed by the multiplexing / demultiplexing filter 2, and the reflected light enters the coupler 4-1. Through this coupler 4-1, the reflected light is electrically converted by the PD 5-1, and the modulation frequency component is extracted by the band pass type electric filter 9-1. The amplitude level is monitored and the reflection level is detected. When the level exceeds a certain threshold value, the output stop signal 8 is output from the detector 6-1 to the optical amplifier 1, and the optical amplifier 1 stops the output.
Although the output light from the optical amplifier 1 is stopped, the light from the LD 7 is always input. Therefore, reflection occurs at this time, and as long as there is a cause of reflection, the PD5-1 continues to receive the reflected light. ing. When the output connector 3 is normally connected and the cause of reflection is removed, the light from the LD 7 does not reflect, so the power of the reflected light received by the PD 5-1 also decreases. When the power falls below a certain threshold, the output stop signal 8 is not output from the detector 6-1 to the optical amplifier 1, and the output of the optical amplifier 1 is automatically restarted.
In this embodiment, by superimposing a specific modulation signal on the monitoring light, it is possible to remove the influence of the electromagnetic interference noise received by the analog circuit of the PD 5-1 or the detector 6-1, and stable monitoring light detection can be achieved. It becomes possible.
The same effect can be obtained by electrically superimposing the modulation signal on the LD drive current without using the optical modulator.

［実施例４］
次に、図４に第４の実施例を示す。ＬＤ７の出力光に光変調器１０で変調をかけた出力光と、光増幅器１からの出力光を合波／分波フィルタ２で合波する。出力コネクタ３が外れるなどして、反射が起きたとする。この時、反射光は合波／分波フィルタ２でＬＤ７の出力波長の光だけが分波されて、カプラ４−２に入射される。ＬＤ入射光とコネクタ端面反射光をそれぞれＰＤ５−２、５−３で受け、電気変換後の信号から帯域通過の電気的フィルタ９−２、９−３によって変調周波数成分を抽出し、それぞれの振幅レベルをモニタし、反射レベルを検出する。その比較値がある閾値を超えると、比較検出器６−２から光増幅器１へ出力停止信号８が入力され、光増幅器１は出力を停止する。
光増幅器１からの出力光は停止しているが、ＬＤ７からの光は常に出力されているので、この時も反射は起きていて、反射原因がある限り、ＰＤ５−３は反射光を受け続けている。
出力コネクタ３を正常に接続して、反射原因を除去すると、ＬＤ７からの光は反射しないので、ＰＤ５−３で受けていた反射光のパワーも落ちてくる。そのパワー比較値がある閾値を下回ると、比較検出器６−２から光増幅器１へ出力停止信号８が出力されなくなり、光増幅器１の出力が自動的に再開される。 [Example 4]
Next, FIG. 4 shows a fourth embodiment. The output light obtained by modulating the output light of the LD 7 by the optical modulator 10 and the output light from the optical amplifier 1 are combined by the multiplexing / demultiplexing filter 2. It is assumed that reflection occurs because the output connector 3 is disconnected. At this time, only the light having the output wavelength of the LD 7 is demultiplexed by the multiplexing / demultiplexing filter 2 and is incident on the coupler 4-2. The LD incident light and the connector end face reflected light are received by the PDs 5-2 and 5-3, respectively, and the modulation frequency components are extracted from the signals after the electrical conversion by the bandpass electrical filters 9-2 and 9-3, and the respective amplitudes Monitor the level and detect the reflection level. When the comparison value exceeds a certain threshold value, the output stop signal 8 is input from the comparison detector 6-2 to the optical amplifier 1, and the optical amplifier 1 stops the output.
Although the output light from the optical amplifier 1 is stopped, the light from the LD 7 is always output. Therefore, reflection occurs at this time, and as long as there is a cause of reflection, the PD 5-3 continues to receive the reflected light. ing.
When the output connector 3 is normally connected and the cause of reflection is removed, the light from the LD 7 does not reflect, so the power of the reflected light received by the PD 5-3 also decreases. When the power comparison value falls below a certain threshold, the output stop signal 8 is not output from the comparison detector 6-2 to the optical amplifier 1, and the output of the optical amplifier 1 is automatically restarted.

本実施例の構成を採ることによって、入射光と反射光の比較値を見ることで、反射状態を正確に検出することができる。また、反射光の検知精度が高まるため、コネクタ外れのように比較的反射レベルが高い障害だけではなく、光ファイバの折損のように折点における反射光の反射レベルが小さいような伝送路障害も監視できる可能性がある。
また、監視光に特定の信号を変調または重畳することによって、ＰＤ５−２、５−３や比較検出器６−２のアナログ回路が受ける電磁干渉雑音の影響を除去することができ、安定した監視光検出が可能となる。
変調は、光の強度変調、周波数変調、位相変調のいずれでのよい。強度変調であれば、光変調器を用いずに、ＬＤ駆動電流を電気的に変調またはＬＤ駆動電流に高周波信号を重畳しても同じ効果が得られる。 By adopting the configuration of the present embodiment, the reflected state can be accurately detected by looking at the comparison value between the incident light and the reflected light. In addition, since the accuracy of detection of reflected light is increased, not only a failure with a relatively high reflection level such as disconnection of a connector, but also a transmission path failure with a low reflection level of reflected light at a break point such as optical fiber breakage. There is a possibility of monitoring.
Further, by modulating or superimposing a specific signal on the monitoring light, it is possible to remove the influence of the electromagnetic interference noise received by the analog circuits of the PDs 5-2, 5-3 and the comparison detector 6-2, and stable monitoring. Light detection is possible.
The modulation may be any of light intensity modulation, frequency modulation, and phase modulation. In the case of intensity modulation, the same effect can be obtained by electrically modulating the LD drive current or superimposing a high frequency signal on the LD drive current without using an optical modulator.

［実施例５］
さらに、図５に本発明の第５の実施例を示す。これは波長多重伝送システムの光増幅器１において、システム監視信号光１１を用いて反射光を検出する方法である。これは反射モニタ用ＬＤの代わりにシステム監視信号光１１を用いているため、コストを削減できる。
図６は双方向波長多重伝送システムの構成ブロックを示す。端局装置Ａ１３と端局装置Ｂ１４の間に複数の中継装置１５を介して波長多重信号が双方向に伝送される。端局装置及び中継装置は、装置間の管理情報や監視情報を主信号１００とは異なる波長でシステム監視信号光として波長多重された主信号に多重して送出している。ＯＳＣ１６は、前段の装置からの光信号から受信システム監視信号光１２を分波して受信し、自装置の管理情報や監視情報を加えて新たな送信システム監視信号光１１を光増幅器の出力に合波して送出する。 [Example 5]
FIG. 5 shows a fifth embodiment of the present invention. This is a method of detecting reflected light using the system monitoring signal light 11 in the optical amplifier 1 of the wavelength division multiplexing transmission system. Since the system monitor signal light 11 is used instead of the reflection monitor LD, the cost can be reduced.
FIG. 6 shows a block diagram of the bidirectional wavelength division multiplexing transmission system. Wavelength multiplexed signals are transmitted bi-directionally between the terminal device A13 and the terminal device B14 via the plurality of relay devices 15. The terminal station device and the relay device multiplex and transmit management information and monitoring information between devices to a main signal wavelength-multiplexed as system monitoring signal light at a wavelength different from that of the main signal 100. The OSC 16 demultiplexes and receives the reception system monitoring signal light 12 from the optical signal from the preceding apparatus, adds the management information and monitoring information of the own apparatus, and uses the new transmission system monitoring signal light 11 as the output of the optical amplifier. Combine and send.

図５の第４の実施例に戻る。光増幅器１からの出力光とシステム監視信号光１１を合波／分波フィルタ２で合波する。出力コネクタ３が外れるなどして、反射が起きたとする。この時、反射光は合波／分波フィルタ２でシステム監視信号光１１の出力波長の光だけが分岐されて、カプラ４−１に入射される。このカプラ４−１を経て、ＰＤ５−１で反射光を受け、そのパワーをモニタする。そのパワーがある閾値を超えると、検出器６−１から光増幅器１へ出力停止信号８が出力され、光増幅器１は出力を停止する。光増幅器１からの出力光は停止しているが、システム監視信号光１１からの光は常に入力されているので、この時も反射は起きていて、反射原因がある限り、ＰＤ５−１は反射光を受け続けている。
出力コネクタ３を正常に接続して、反射原因を除去すると、システム監視信号光１１からの光は反射しないので、ＰＤ５−１で受けていた反射光のパワーも落ちてくる。そのパワーがある閾値を下回ると、検出器６−１から光増幅器１へ出力停止信号８が出力されなくなり、光増幅器１の出力が自動的に再開される。 Returning to the fourth embodiment of FIG. The output light from the optical amplifier 1 and the system monitoring signal light 11 are multiplexed by the multiplexing / demultiplexing filter 2. It is assumed that reflection occurs because the output connector 3 is disconnected. At this time, only the light of the output wavelength of the system monitoring signal light 11 is branched by the multiplexing / demultiplexing filter 2 and the reflected light is incident on the coupler 4-1. The reflected light is received by PD5-1 through this coupler 4-1, and its power is monitored. When the power exceeds a certain threshold value, the output stop signal 8 is output from the detector 6-1 to the optical amplifier 1, and the optical amplifier 1 stops the output. Although the output light from the optical amplifier 1 is stopped, the light from the system monitoring signal light 11 is always input. Therefore, reflection occurs at this time, and the PD5-1 reflects as long as there is a cause of reflection. I continue to receive light.
When the output connector 3 is normally connected and the cause of reflection is removed, the light from the system monitoring signal light 11 is not reflected, and the power of the reflected light received by the PD 5-1 is also reduced. When the power falls below a certain threshold, the output stop signal 8 is not output from the detector 6-1 to the optical amplifier 1, and the output of the optical amplifier 1 is automatically restarted.

上記の説明では、実施例１のＬＤ７をシステム監視信号光１１で置き換えた場合について説明したが、実施例２〜４のＬＤを置き換えた場合であっても有効に動作する。 In the above description, the case where the LD 7 of the first embodiment is replaced with the system monitoring signal light 11 has been described. However, even when the LD of the second to fourth embodiments is replaced, the operation is effective.

本発明の第１の実施例の構成を示す図である。It is a figure which shows the structure of the 1st Example of this invention. 本発明の第２の実施例の構成を示す図である。It is a figure which shows the structure of the 2nd Example of this invention. 本発明の第３の実施例の構成を示す図である。It is a figure which shows the structure of the 3rd Example of this invention. 本発明の第４の実施例の構成を示す図である。It is a figure which shows the structure of the 4th Example of this invention. 本発明の第５の実施例の構成を示す図である。It is a figure which shows the structure of the 5th Example of this invention. 本発明の第５の実施例が適用される波長多重伝送システムの構成を示す図である。It is a figure which shows the structure of the wavelength division multiplexing transmission system with which the 5th Example of this invention is applied. 従来の光増幅器の構成を示す図である。It is a figure which shows the structure of the conventional optical amplifier.

Explanation of symbols

１光増幅器
２合波／分波フィルタ
３出力コネクタ
４カプラ
５ＰＤ
６検出器
７ＬＤ
８出力停止信号
９フィルタ
１０変調器
１１システム監視信号光
１２システム監視信号光
１３端局装置Ａ
１４端局装置Ｂ
１５中継装置
１６ＯＳＣ
１００主信号
１０１光増幅器
１０２カプラ
１０３出力コネクタ
１０４ＰＤ
１０５検出器
１０６出力停止信号
1 optical amplifier 2 multiplexing / demultiplexing filter 3 output connector 4 coupler 5 PD
6 Detector 7 LD
8 Output Stop Signal 9 Filter 10 Modulator 11 System Monitor Signal Light 12 System Monitor Signal Light 13 Terminal Station A
14 Terminal equipment B
15 Relay device 16 OSC
100 Main signal 101 Optical amplifier 102 Coupler 103 Output connector 104 PD
105 Detector 106 Output stop signal

Claims

Means for multiplexing the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output waveguide in order to detect Fresnel reflected light from the output optical waveguide;
An optical amplifier comprising:

Means for multiplexing the monitoring light having a wavelength outside the signal wavelength band to be amplified in the light output direction of the output optical waveguide, and demultiplexing the Fresnel reflected light of the monitoring light from the output optical waveguide;
An optical amplifier comprising:

Means for multiplexing the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide, and demultiplexing the Fresnel reflected light of the monitoring light from the output optical waveguide;
Means for detecting the demultiplexed Fresnel reflected light and controlling the function of the signal amplification;
An optical amplifier comprising:

Means for multiplexing the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide, and demultiplexing the Fresnel reflected light of the monitoring light from the output optical waveguide;
Means for detecting the level of the demultiplexed Fresnel reflected light;
Means for controlling the function of the signal amplification according to the detected level;
An optical amplifier comprising:

Means for multiplexing the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide, and demultiplexing the Fresnel reflected light of the monitoring light from the output optical waveguide;
Means for detecting a ratio obtained by dividing the level of the demultiplexed Fresnel reflected light by the output level of the monitoring light;
Means for controlling the function of the signal amplification in accordance with the level ratio;
An optical amplifier comprising:

The signal light amplification function to be controlled is
Stop and restart the light amplification,
The optical amplifier according to claim 3, wherein the optical amplifier is an optical amplifier.

When the detected level or the level ratio exceeds a first predetermined value, the amplification is stopped;
Restarting the amplification when the detected level or the level ratio falls below a second predetermined value;
The optical amplifier according to claim 3, wherein the optical amplifier is an optical amplifier.

The monitoring light is
Is modulated,
Means for detecting the level of the Fresnel reflected light;
An electrical filter that filters and transmits the photoelectric conversion signal of the Fresnel reflected light in the modulation frequency band;
The optical amplifier according to claim 3, wherein the optical amplifier is an optical amplifier.

The light source of the monitoring light is
A semiconductor laser,
The optical amplifier according to claim 3, wherein the optical amplifier is an optical amplifier.

The light source of the monitoring light is
An optical signal having a wavelength outside the wavelength band occupied by the optical signal demultiplexed and extracted from the input optical signal to the optical amplifier,
The optical amplifier according to claim 3, wherein the optical amplifier is an optical amplifier.

The monitoring light having a wavelength outside the band of the signal wavelength to be amplified is multiplexed in the light output direction of the output optical waveguide,
Demultiplexing the Fresnel reflected light of the monitoring light from the output optical waveguide;
Detecting the level of the split Fresnel reflected light to control the function of the signal amplification;
A method for automatically controlling an amplification function of an optical amplifier.

The monitoring light having a wavelength outside the band of the signal wavelength to be amplified is multiplexed in the light output direction of the output optical waveguide,
Demultiplexing the Fresnel reflected light of the monitoring light from the output optical waveguide;
Detecting the level of the Fresnel reflected light that has been demultiplexed,
Controlling the function of the signal amplification according to the detected level;
A method for automatically controlling an amplification function of an optical amplifier.

The monitoring light having a wavelength outside the band of the signal wavelength to be amplified is multiplexed in the light output direction of the output optical waveguide,
Demultiplexing the Fresnel reflected light of the monitoring light from the output optical waveguide;
Detecting a ratio obtained by dividing the level of the demultiplexed Fresnel reflected light by the output level of the monitoring light,
Controlling the function of the signal amplification according to the level ratio;
A method for automatically controlling an amplification function of an optical amplifier.

The signal light amplification function to be controlled is
Stop and restart the light amplification,
14. The method for automatically controlling an amplification function of an optical amplifier according to claim 11 or 13.

When the detected level or the level ratio exceeds a first predetermined value, the amplification is stopped;
Restarting the amplification when the detected level or the level ratio falls below a second predetermined value;
14. The method for automatically controlling an amplification function of an optical amplifier according to claim 11 or 13.

The monitoring light is
Is modulated,
The level of the Fresnel reflected light or the level ratio is:
Detected through an electrical filter that filters and transmits a photoelectric conversion signal of the Fresnel reflected light in the frequency band of the modulation,
The method for automatically controlling an amplification function of an optical amplifier according to any one of claims 11 to 15.

The light source of the monitoring light is
A semiconductor laser,
The method for automatically controlling an amplification function of an optical amplifier according to any one of claims 11 to 16.

The light source of the monitoring light is
An optical signal having a wavelength outside the wavelength band occupied by the optical signal demultiplexed and extracted from the input optical signal to the optical amplifier,
The method for automatically controlling an amplification function of an optical amplifier according to any one of claims 11 to 16.

An optical amplifier control device comprising:
Means for multiplexing the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide, and demultiplexing the Fresnel reflected light of the monitoring light from the output optical waveguide;
Means for detecting the demultiplexed Fresnel reflected light and controlling the function of the signal amplification;
An optical amplifier control device comprising:

An optical amplifier control device comprising:
Means for multiplexing the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide, and demultiplexing the Fresnel reflected light of the monitoring light from the output optical waveguide;
Means for detecting the level of the demultiplexed Fresnel reflected light;
Means for controlling the function of the signal amplification according to the detected level;
An optical amplifier control device comprising:

An optical amplifier control device comprising:
Means for multiplexing the monitoring light having a wavelength outside the band of the signal wavelength to be amplified in the light output direction of the output optical waveguide, and demultiplexing the Fresnel reflected light of the monitoring light from the output optical waveguide;
Means for detecting a ratio obtained by dividing the level of the demultiplexed Fresnel reflected light by the output level of the monitoring light;
Means for controlling the function of the signal amplification in accordance with the level ratio;
An optical amplifier control device comprising:

The signal light amplification function to be controlled is
Stop and restart the light amplification,
The optical amplifier control device according to any one of claims 19 to 21.

When the detected level or the level ratio exceeds a first predetermined value, the amplification is stopped;
Restarting the amplification when the detected level or the level ratio falls below a second predetermined value;
The optical amplifier control device according to any one of claims 19 to 21.

The monitoring light is
Is modulated,
Means for detecting the level of the Fresnel reflected light;
An electrical filter that filters and transmits the photoelectric conversion signal of the Fresnel reflected light in the modulation frequency band;
24. The control device for an optical amplifier according to claim 19, wherein the control device is an optical amplifier.

The light source of the monitoring light is
A semiconductor laser,
25. The control device for an optical amplifier according to claim 19, wherein the control device is an optical amplifier.

The light source of the monitoring light is
An optical signal having a wavelength outside the wavelength band occupied by the optical signal demultiplexed and extracted from the input optical signal to the optical amplifier,
25. The control device for an optical amplifier according to claim 19, wherein the control device is an optical amplifier.

An optical communication apparatus comprising the optical amplifier according to claim 1.

An optical transmission system comprising the optical amplifier according to claim 1.