JP4839954B2 - Wavelength multiplexed signal optical receiver and optical amplification method thereof - Google Patents

Wavelength multiplexed signal optical receiver and optical amplification method thereof Download PDF

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JP4839954B2
JP4839954B2 JP2006130925A JP2006130925A JP4839954B2 JP 4839954 B2 JP4839954 B2 JP 4839954B2 JP 2006130925 A JP2006130925 A JP 2006130925A JP 2006130925 A JP2006130925 A JP 2006130925A JP 4839954 B2 JP4839954 B2 JP 4839954B2
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隆 横山
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本発明は波長多重信号光受信装置及びその光増幅方法に関し、特に波長多重光信号を受信してこれを増幅する光増幅装置の改良に関するものである。 The present invention relates to a wavelength division multiplexed signal light receiving apparatus and an optical amplification method therefor , and more particularly to an improvement in an optical amplification apparatus that receives a wavelength multiplexed optical signal and amplifies it.

複数の光増幅器を多段接続して、光波長多重信号を伝送するようにした光通信ネットワークシステムにおいて、光増幅器からの出力レベルを安定に保つことが、信号光の品質を高く維持するために重要である。特に、要求される信号容量に応じて波長多重数を変更するシステムでは、波長多重数が変化しても、一波長あたりの信号光レベルを変化させないようにする制御が必須である。   In an optical communication network system in which multiple optical amplifiers are connected in multiple stages to transmit optical wavelength division multiplexed signals, keeping the output level from the optical amplifier stable is important for maintaining high signal light quality. It is. In particular, in a system that changes the number of wavelength multiplexing according to the required signal capacity, it is essential to control the signal light level per wavelength so as not to change even if the wavelength multiplexing number changes.

従来、一波長あたりの信号光レベルを一定に維持するための光増幅器の出力制御としては、波長多重数（Ｎ）と一波長あたりの信号光レベル（Ｓｐ）とを、単純に掛け合わせたレベル（Ｎ・Ｓｐ）に制御する方法が一般的である。   Conventionally, as output control of an optical amplifier for maintaining the signal light level per wavelength constant, a level obtained by simply multiplying the wavelength multiplexing number (N) and the signal light level (Sp) per wavelength. A method of controlling to (N · Sp) is common.

図４は、この様な光増幅器の出力制御を採用した従来例を示す図であり、波長多重信号光受信装置１の光増幅部１１は波長多重信号光入力部からの信号光を増幅して、光波長分離部１２へ供給するものである。この光波長分離部１２により分離された各波長信号光は、対応する信号光受信部１３〜１５へそれぞれ入力され、受信処理される。一方、光増幅部１１の出力は分岐されて演算部２１へ入力されて演算処理され、出力制御部２２を介して光増幅部１１の増幅制御がなされるようになっている。   FIG. 4 is a diagram showing a conventional example employing such output control of an optical amplifier. The optical amplifying unit 11 of the wavelength multiplexed signal light receiving apparatus 1 amplifies the signal light from the wavelength multiplexed signal light input unit. The light is supplied to the optical wavelength separator 12. Each wavelength signal light separated by the optical wavelength separation unit 12 is input to the corresponding signal light reception units 13 to 15 and subjected to reception processing. On the other hand, the output of the optical amplifying unit 11 is branched and input to the arithmetic unit 21 for arithmetic processing, and amplification control of the optical amplifying unit 11 is performed via the output control unit 22.

なお、この様な構成の光受信装置の例は、特許文献１に開示されている。また、特許文献２には、光増幅器の出力を光波長分離部で分離した後、各波長信号光を可変減衰器を用いてそれぞれにレベル制御する技術が開示されている。   An example of the optical receiver having such a configuration is disclosed in Patent Document 1. Patent Document 2 discloses a technique in which the output of an optical amplifier is separated by an optical wavelength separation unit, and then each wavelength signal light is level-controlled using a variable attenuator.

特開平１１−２２５１１５号公報Japanese Patent Laid-Open No. 11-225115 特開２０００−２１６７３１号公報JP 2000-216731 A

図４に示した波長多重信号光受信装置１では、波長多重数（Ｎ）と一波長あたりの信号光レベル（Ｓｐ）とを、単純に掛け合わせたレベル（Ｎ・Ｓｐ）に制御するものであるから、次のような問題がある。波長多重数が少なく、光増幅器が多段接続された状態においては、累積する雑音光、すなわち自然放出光（ＡＳＥ光）のレベルが大きくなり、信号光レベルが相対的に小さくなってしまうことにより、波長分離後の信号光レベルが低下してしまい、よって受信器の入力レンジを広く確保することが必要になるという問題がある。   In the wavelength multiplexing signal light receiving apparatus 1 shown in FIG. 4, the wavelength multiplexing number (N) and the signal light level per wavelength (Sp) are controlled to a level (N · Sp) which is simply multiplied. There are the following problems. In a state where the number of wavelength multiplexing is small and optical amplifiers are connected in multiple stages, the level of accumulated noise light, that is, spontaneous emission light (ASE light) becomes large, and the signal light level becomes relatively small. There is a problem that the signal light level after wavelength separation is lowered, and therefore it is necessary to ensure a wide input range of the receiver.

また、特許文献２に開示のように、多重信号光を分離した後に、個々の信号光毎にレベル制御を行う構成では、多重数が多ければ、それだけ可変減衰器も増大し、また全ての信号光のレベルを均一に制御することも困難になってくるという問題がある。   Also, as disclosed in Patent Document 2, in the configuration in which the level control is performed for each signal light after separating the multiplexed signal light, the greater the number of multiplexing, the larger the number of variable attenuators, and all the signals. There is a problem that it becomes difficult to control the light level uniformly.

本発明の目的は、光増幅器を多段接続した場合に生ずるＡＳＥ光の累積によって、受信端で光波長多重信号の各信号光レベルが相対的に小さくなることを防止して、ＡＳＥ光によらず一波長あたりの信号光レベルを一定に制御することが可能な波長多重信号光受信装置及びその光増幅方法を提供することである。 An object of the present invention is to prevent the signal light level of an optical wavelength multiplexed signal from becoming relatively small at the receiving end due to accumulation of ASE light that occurs when optical amplifiers are connected in multiple stages. It is an object of the present invention to provide a wavelength multiplexed signal light receiving apparatus capable of controlling the signal light level per wavelength to be constant and an optical amplification method thereof .

本発明の他の目的は、波長多重数によらず一波長あたりの信号光レベルを一定に制御して高品質でかつ安定的に信号を供給することが可能な波長多重信号光受信装置及びその光増幅方法を提供することである。 Another object of the present invention is to provide a wavelength-multiplexed signal light receiving apparatus capable of stably supplying a signal with high quality by controlling the signal light level per wavelength to be constant regardless of the number of wavelength multiplexing, and its An optical amplification method is provided.

本発明による波長多重信号光受信装置は、
波長多重信号光を増幅する増幅手段と、この増幅出力を個々の波長信号光に分離する分離手段と、この分離後の各信号光を受信処理する信号光受信手段とを含む波長多重信号光受信装置であって、
前記分離後の各信号光を分岐してこれら分岐信号光のレベルの平均値を算出してこの平均値が一定になるよう前記増幅手段を制御する制御手段を含むことを特徴とする。 The wavelength division multiplexing optical signal receiver according to the present invention is:
Wavelength multiplexed signal light reception including amplification means for amplifying wavelength multiplexed signal light, separation means for separating the amplified output into individual wavelength signal lights, and signal light receiving means for receiving and processing each separated signal light A device,
Characterized in that it comprises a control means for the mean value by calculating the average of the levels of these branched signal light branches each signal light after the separation to control the amplification means so as to be constant.

本発明による増幅方法は、
波長多重信号光を増幅する増幅手段と、この増幅出力を個々の波長信号光に分離する分離手段と、この分離後の各信号光を受信処理する信号光受信手段とを含む波長多重信号光受信装置における光増幅方法であって、
前記分離後の各信号光を分岐してこれら分岐信号光のレベルの平均値を算出してこの平均値が一定になるよう前記増幅手段を制御する制御ステップを含むことを特徴とする。 The amplification method according to the present invention comprises:
Wavelength multiplexed signal light reception including amplification means for amplifying wavelength multiplexed signal light, separation means for separating the amplified output into individual wavelength signal lights, and signal light receiving means for receiving and processing each separated signal light An optical amplification method in an apparatus, comprising:
Characterized in that it comprises a control step of this average value by calculating the average of the levels of these branched signal light branches each signal light after the separation to control the amplification means so as to be constant.

本発明によれば、光増幅装置において、波長多重数によらず一波長あたりの信号光レベルを一定に制御することができるという効果がある。また、ＡＳＥ光レベルによらず一波長あたりの信号光レベルを一定に制御することができるという効果もあり、更に、信号光レベルを一定に維持することにより、高品質でかつ安定的に信号を供給できるという効果もある。   According to the present invention, in the optical amplifying device, there is an effect that the signal light level per wavelength can be controlled to be constant regardless of the number of wavelength multiplexing. In addition, there is an effect that the signal light level per wavelength can be controlled to be constant regardless of the ASE light level. Furthermore, by maintaining the signal light level constant, the signal can be stably output with high quality. There is also an effect that it can be supplied.

以下に、本発明の実施の形態について図面を参照して説明する。図１を参照すると、本発明の実施の形態による光増幅装置を含む波長多重信号光受信装置１の機能ブロック図であり、図４と同等部分は同一符号により示している。図１において、図示せぬ光伝送路から入力された波長多重信号光は、光増幅部１１において増幅され、この増幅出力は光波長分離部１２によって個別の信号光に分離される。分離された各信号光の一部は、図示せぬ光分岐器によって分岐されて光／電気変換部１６〜１８へそれぞれ入力され、残りは信号光受信部１３〜１５へそれぞれ入力される。信号光受信部１３〜１５においては、各信号光の受信処理が行われる。 Embodiments of the present invention will be described below with reference to the drawings. Referring to FIG. 1, there is shown a functional block diagram of a wavelength multiplexed signal light receiving apparatus 1 including an optical amplifying apparatus according to an embodiment of the present invention. The same parts as those in FIG. In FIG. 1, wavelength multiplexed signal light input from an optical transmission line (not shown) is amplified by an optical amplifying unit 11, and this amplified output is separated into individual signal lights by an optical wavelength demultiplexing unit 12. A part of each separated signal light is branched by an optical branching unit (not shown) and inputted to the optical / electrical converters 16 to 18 respectively, and the rest is inputted to the signal light receiving parts 13 to 15 respectively. In the signal light receiving units 13 to 15, reception processing of each signal light is performed.

各光／電気変換部１６〜１８では、各信号光のレベルに応じた電気信号に変換されて演算部１９へ入力される。演算部１９は、入力された各信号光レベルに応じた電気信号から、平均値を算出してこの値が一定になるように、出力制御部２０を介して、光増幅部１１に対してフィードバック制御（利得制御）をかけるようになっている。なお、入力されている波長多重信号光の波長数を示す情報は、波長多重信号光の一部に重畳されている監視信号光によって、波長多重信号光受信装置１へ転送されているものとする。   In each of the optical / electrical converters 16 to 18, it is converted into an electrical signal corresponding to the level of each signal light and input to the arithmetic unit 19. The arithmetic unit 19 calculates an average value from electric signals corresponding to the input signal light levels and feeds back to the optical amplifying unit 11 via the output control unit 20 so that this value becomes constant. Control (gain control) is applied. Note that the information indicating the number of wavelengths of the input wavelength multiplexed signal light is transferred to the wavelength multiplexed signal light receiving apparatus 1 by the monitoring signal light superimposed on a part of the wavelength multiplexed signal light. .

なお、図１において、本発明の光増幅装置は、光増幅部１１と、光波長分離部１２と、光／電気変換部１６〜１８と、演算部１９と、出力制御部２０とからなるものとし、波長多重信号光受信装置１はこの光増幅装置により増幅された信号光を、信号光受信部１３〜１５にてそれぞれ受信処理するものである。   In FIG. 1, the optical amplifying device of the present invention includes an optical amplifying unit 11, an optical wavelength separating unit 12, optical / electrical converters 16 to 18, an arithmetic unit 19, and an output control unit 20. The wavelength-multiplexed signal light receiving apparatus 1 receives the signal light amplified by the optical amplifying apparatus at the signal light receiving units 13 to 15 respectively.

図２は信号光の波長多重数と光増幅装置（波長多重信号光受信装置１の光増幅部１１に対応）から出力される一波長あたりの信号光レベルとの関係を示す図である。図２（ａ）は光増幅装置から出力される波長多重信号光のトータルレベルを一波長あたりの信号光レベルに波長多重数を乗じたレベルに出力制御した場合（従来例の場合）であって、（ａ−１）はＡＳＥ光レベルが小さい場合、（ａ−２）はＡＳＥ光レベルが大きい場合である。   FIG. 2 is a diagram showing the relationship between the number of multiplexed signal lights and the level of signal light per wavelength output from the optical amplifying apparatus (corresponding to the optical amplifying unit 11 of the wavelength multiplexed signal light receiving apparatus 1). FIG. 2A shows a case where the total level of the wavelength multiplexed signal light output from the optical amplifying device is output controlled to a level obtained by multiplying the signal light level per wavelength by the number of wavelength multiplexing (in the case of the conventional example). , (A-1) shows a case where the ASE light level is low, and (a-2) shows a case where the ASE light level is high.

この場合の算出条件は以下のとおりである。光ＳＮＲは、（ａ−１）において３０ｄＢ／０．１ｎｍ、（ａ−２）において２０ｄＢ／０．１ｎｍであり、光増幅装置出力は１ｍＷ×波長数であり、ＡＳＥ算出波長帯域は３０ｎｍ（帯域内レベルは一定、帯域外レベルは考慮せず）である。   The calculation conditions in this case are as follows. The optical SNR is 30 dB / 0.1 nm in (a-1), 20 dB / 0.1 nm in (a-2), the output of the optical amplifier is 1 mW × number of wavelengths, and the ASE calculation wavelength band is 30 nm (bandwidth). The inner level is constant and the out-of-band level is not considered).

図２（ａ）に示す如く、ＡＳＥ光のレベルが小さい場合は、波長多重数が減少しても一波長あたりの信号光レベルの低下が小さいが（ａ−１）、ＡＳＥ光のレベルが大きくなると、波長数が少ない場合に一波長あたりの信号光レベルの低下が大きくなっていることが判る（ａ−２）。   As shown in FIG. 2A, when the level of the ASE light is small, the decrease in the signal light level per wavelength is small even if the number of wavelength multiplexing decreases (a-1), but the level of the ASE light is large. Thus, it can be seen that when the number of wavelengths is small, the decrease in the signal light level per wavelength is large (a-2).

この様な減少を定量的に説明すると以下のようになる。光増幅装置から出力される光のトータルレベル（Ｐout ）を一波長あたりの信号光レベル（Ｐs 、設定目標値）に波長多重数（Ｎ）を乗じたレベルに出力制御した場合、光増幅装置の出力レベルＰout は、
Ｐout ＝Ｐs ×Ｎ
で表わされる。 This decrease can be explained quantitatively as follows. When the output level of the total level (Pout) of light output from the optical amplifying device is controlled to a level obtained by multiplying the signal light level per wavelength (Ps, set target value) by the number of multiplexed wavelengths (N), The output level Pout is
Pout = Ps × N
It is represented by

このとき、光増幅装置からの出力がＡＳＥ光を含まず信号光のみであれば、一波長あたりの信号光レベルはＰs となる（Ｐs ＝Ｐout ／Ｎ）。しかしながら、実際の光増幅装置からの出力には、ＡＳＥ光（Ｐase ）が含まれているので、実際に得られる信号光のレベルＰs ’は、
Ｐs ’＝（Ｐs ×Ｎ−Ｐase ）／Ｎ
＝Ｐs −Ｐase ／Ｎ
となる。 At this time, if the output from the optical amplifying device does not include ASE light but only signal light, the signal light level per wavelength is Ps (Ps = Pout / N). However, since the ASE light (Pase) is included in the output from the actual optical amplifying device, the level Ps ′ of the signal light actually obtained is
Ps' = (Ps × N-Pase) / N
= Ps -Pase / N
It becomes.

このとき光増幅装置から出力されるＡＳＥ光は、波長多重数によらず一定となるために、波長多重数が少ないほどＡＳＥ光の影響を受けることが判る。   At this time, since the ASE light output from the optical amplifying device is constant regardless of the number of wavelength multiplexing, it can be seen that the smaller the number of wavelength multiplexing, the more affected by the ASE light.

これに対して、本発明では、光増幅装置から出力された波長多重信号光を光波長分離部１２により個別の信号光波長に分離して各信号光レベルの平均値が一定になるように制御しているので、図２（ｂ）に示すようになり、ＡＳＥ光レベル、波長多重数によらず一波長あたりの信号光レベルは一定になる。これは、光波長分離部１２が、信号光以外の波長（ＡＳＥ光も含む）をブロックするので、ＡＳＥ光を含まない信号光レベルによって出力制御が実施され、ＡＳＥ光のレベルに影響を受けないことによる。   On the other hand, in the present invention, the wavelength multiplexed signal light output from the optical amplifying device is separated into individual signal light wavelengths by the optical wavelength separation unit 12 and controlled so that the average value of each signal light level becomes constant. Therefore, as shown in FIG. 2B, the signal light level per wavelength is constant regardless of the ASE light level and the number of wavelength multiplexing. This is because the optical wavelength separation unit 12 blocks wavelengths other than the signal light (including ASE light), so output control is performed according to the signal light level not including the ASE light, and is not affected by the level of the ASE light. It depends.

図３は図１に示した波長多重信号光受信装置１を、ネットワークに適用した場合のブロック図であり、図１と同等部分は同一符号により示している。図３において、波長多重信号光送信装置２からの送信信号光は、光ファイバ伝送路３、光増幅部４、光ファイバ伝送路５、光増幅部６により、多段増幅されて、本発明による光増幅装置を有する波長多重信号光受信装置１へ入力される。   FIG. 3 is a block diagram when the wavelength division multiplexing optical signal receiver 1 shown in FIG. 1 is applied to a network, and the same parts as those in FIG. 1 are denoted by the same reference numerals. In FIG. 3, the transmission signal light from the wavelength multiplexing signal light transmission apparatus 2 is amplified in multiple stages by the optical fiber transmission path 3, the optical amplification section 4, the optical fiber transmission path 5, and the optical amplification section 6, and the light according to the present invention. The signal is input to the wavelength-multiplexed signal light receiving device 1 having an amplifying device.

本発明の実施の形態を示すブロック図である。It is a block diagram which shows embodiment of this invention. （ａ）は従来技術における波長多重数と一波長あたりの信号光レベルとの関係を示すもので、（ａ−１）はＡＳＥ光レベルが小さい場合、（ａ−２）はＡＳＥ光レベルが大きい場合である。（ｂ）は本発明における波長多重数と一波長あたりの信号レベルとの関係を示す図である。(A) shows the relationship between the number of multiplexed wavelengths and the signal light level per wavelength in the prior art. (A-1) shows a low ASE light level and (a-2) shows a high ASE light level. Is the case. (B) is a figure which shows the relationship between the wavelength multiplexing number in this invention, and the signal level per wavelength. 本発明を適用したネットワークのブロック図である。It is a block diagram of a network to which the present invention is applied. 波長多重信号光受信装置の従来例を示す図である。It is a figure which shows the prior art example of a wavelength multiplexing signal optical receiver.

符号の説明Explanation of symbols

１ 波長多重信号光受信装置
２ 波長多重信号光送信装置
３，５ 光ファイバ伝送路
４，６，１１ 光増幅部
１２ 光波長分離部
１３〜１５ 信号光受信部
１６〜１８ 光／電気変換部
１９ 演算部
２０ 出力制御部 1 Wavelength multiplexed signal optical receiver
2 Wavelength division multiplexed signal transmitter 3, 5 Optical fiber transmission line 4, 6, 11 Optical amplifier
12 Optical wavelength demultiplexing unit 13-15 Signal light receiving unit 16-18 Optical / electrical conversion unit
19 Calculation unit
20 Output controller

Claims (4)

波長多重信号光を増幅する増幅手段と、この増幅出力を個々の波長信号光に分離する分離手段と、この分離後の各信号光を受信処理する信号光受信手段とを含む波長多重信号光受信装置であって、
前記分離後の各信号光を分岐してこれら分岐信号光の各レベルの平均値を算出してこの平均値が一定になるよう前記増幅手段を制御する制御手段を含むことを特徴とする波長多重信号光受信装置。 Wavelength multiplexed signal light reception including amplification means for amplifying wavelength multiplexed signal light, separation means for separating the amplified output into individual wavelength signal lights, and signal light receiving means for receiving and processing each separated signal light A device,
Wavelength multiplexing, characterized in that it comprises a control means for the mean value by calculating an average value of each level of branching signal light is branched signal lights after the separation to control the amplification means so as to be constant Signal light receiver . 前記制御手段は、前記分岐信号光の各信号光レベルに応じた電気信号に基づいて前記平均値を算出する手段と、前記平均値が一定になるよう前記増幅手段の利得制御をなす手段とを有することを特徴とする請求項１記載の波長多重信号光受信装置。 The control means includes means for calculating the average value based on an electric signal corresponding to each signal light level of the branched signal light, and means for performing gain control of the amplification means so that the average value becomes constant. The wavelength-multiplexed signal light receiving apparatus according to claim 1, comprising: 波長多重信号光を増幅する増幅手段と、この増幅出力を個々の波長信号光に分離する分離手段と、この分離後の各信号光を受信処理する信号光受信手段とを含む波長多重信号光受信装置における光増幅方法であって、
前記分離後の各信号光を分岐してこれら分岐信号光の各レベルの平均値を算出してこの平均値が一定になるよう前記増幅手段を制御する制御ステップを含むことを特徴とする光増幅方法。 Wavelength multiplexed signal light reception including amplification means for amplifying wavelength multiplexed signal light, separation means for separating the amplified output into individual wavelength signal lights, and signal light receiving means for receiving and processing each separated signal light An optical amplification method in an apparatus, comprising:
Optical amplification, characterized in that it comprises a control step of this average value by calculating an average value of each level of branching signal light is branched signal lights after the separation to control the amplification means so as to be constant Method. 前記制御ステップは、前記分岐信号光の各信号光レベルに応じた電気信号に基づいて前記平均値を算出するステップと、前記平均値が一定になるよう前記増幅手段の利得制御をなすステップとを有することを特徴とする請求項３記載の光増幅方法。 The control step includes a step of calculating the average value based on an electric signal corresponding to each signal light level of the branched signal light, and a step of performing gain control of the amplifying means so that the average value becomes constant. 4. The optical amplification method according to claim 3, further comprising:
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