JP2000031901A - Optical limiter circuit - Google Patents
Optical limiter circuitInfo
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- JP2000031901A JP2000031901A JP10192930A JP19293098A JP2000031901A JP 2000031901 A JP2000031901 A JP 2000031901A JP 10192930 A JP10192930 A JP 10192930A JP 19293098 A JP19293098 A JP 19293098A JP 2000031901 A JP2000031901 A JP 2000031901A
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- optical
- signal light
- input signal
- wavelength
- light
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- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
- Optical Communication System (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、超高速（テラビッ
トクラス）の光信号の波形歪みや雑音を抑圧する光リミ
ッタ回路に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical limiter circuit for suppressing waveform distortion and noise of an ultra-high-speed (terabit class) optical signal.
【０００２】[0002]
【従来の技術】光伝送システムでは、その伝送媒体であ
る光ファイバのもつ波長分散や、伝送路中に設置された
光増幅器から発生する自然放出光（ＡＳＥ）による干渉
雑音等により、光信号の波形および信号対雑音比が劣化
し、最大伝送距離や伝送容量を制限する要因になってい
る。従来は、このような光信号の波形歪みや雑音を抑圧
するために光再生中継回路が用いられていた。2. Description of the Related Art In an optical transmission system, an optical signal is transmitted due to chromatic dispersion of an optical fiber as a transmission medium or interference noise due to spontaneous emission (ASE) generated from an optical amplifier installed in a transmission line. The waveform and the signal-to-noise ratio are degraded, which limits the maximum transmission distance and transmission capacity. Conventionally, an optical regenerative repeater circuit has been used to suppress such waveform distortion and noise of an optical signal.
【０００３】図８は、光再生中継回路の構成例を示す。
入力信号光は、光増幅器８１でその光パワーが増幅さ
れ、受光器８２に入力されて電気信号に変換される。こ
の電気信号は増幅器８３で所定のレベルまで増幅され、
分岐してタイミング抽出回路８４および識別回路８５に
入力される。タイミング抽出回路８４では、狭帯域フィ
ルタ等を用いてクロック成分を抽出する。識別回路８５
では、タイミング抽出回路８４で抽出されたクロックに
より与えられるタイミングに基づいてディジタル信号の
識別を行うことにより、波形歪みや雑音を抑圧する。こ
のようにして波形整形された電気信号は、駆動回路８６
で所定のレベルまで増幅され、光変調器８７に変調信号
として与えられる。光変調器８７は、この電気信号によ
り光源８８から出力される無変調光を変調し、光信号の
再生を行う。この再生信号光は、光増幅器８９で次の伝
送に必要な光パワーまで増幅され、伝送用光ファイバに
送出される。FIG. 8 shows an example of the configuration of an optical regenerative repeater circuit.
The optical power of the input signal light is amplified by the optical amplifier 81 and input to the light receiver 82 to be converted into an electric signal. This electric signal is amplified to a predetermined level by the amplifier 83,
The signal is branched and input to the timing extraction circuit 84 and the identification circuit 85. The timing extraction circuit 84 extracts a clock component using a narrow band filter or the like. Identification circuit 85
Then, the waveform distortion and the noise are suppressed by identifying the digital signal based on the timing given by the clock extracted by the timing extraction circuit 84. The electric signal whose waveform has been shaped in this manner is supplied to the drive circuit 86.
, And is given to the optical modulator 87 as a modulation signal. The optical modulator 87 modulates the unmodulated light output from the light source 88 with the electric signal and reproduces the optical signal. The reproduced signal light is amplified by the optical amplifier 89 to the optical power required for the next transmission, and sent out to the transmission optical fiber.
【０００４】[0004]
【発明が解決しようとする課題】従来の光再生中継回路
は、電気回路の応答速度限界により動作速度が制限され
るので、テラビットクラスの超高速信号光の識別再生に
用いることができなかった。また、タイミング抽出回路
８４は、ある一定のクロック周波数成分しか抽出できな
いためにビットレートが固定され、異なるビットレート
の信号を扱う場合には再構成する必要があった。また、
従来の再生中継回路は部品点数も多く、高価であった。Since the operation speed of the conventional optical regenerative repeater circuit is limited by the response speed limit of the electric circuit, it cannot be used for discriminating and reproducing a terabit-class ultra-high-speed signal light. Further, since the timing extraction circuit 84 can extract only a certain fixed clock frequency component, the bit rate is fixed, and it is necessary to reconfigure when handling signals of different bit rates. Also,
The conventional regenerative repeater circuit has many components and is expensive.
【０００５】ところで、光増幅器を介して中継伝送する
超高速の光伝送システムにおいて、その伝送距離は主に
光増幅器の雑音による信号対雑音比の劣化により制限さ
れ、タイミングジッタの増加による伝送特性の劣化はわ
ずかである。したがって、光信号の波形歪みや雑音の抑
圧（波形整形）のためにタイミング抽出回路８４を用い
たリタイミング処理は必ずしも必要ではない。In an ultra-high-speed optical transmission system for relay transmission via an optical amplifier, the transmission distance is limited mainly by the deterioration of the signal-to-noise ratio due to the noise of the optical amplifier, and the transmission characteristic is increased by the increase in timing jitter. Degradation is slight. Therefore, retiming processing using the timing extraction circuit 84 for suppressing waveform distortion and noise of an optical signal (waveform shaping) is not always necessary.
【０００６】本発明は、リタイミング手段を含まない簡
単な構成で、超高速信号光の波形歪みや雑音を抑圧し、
伝送距離および伝送容量の拡大を可能にする光リミッタ
回路を提供することを目的とする。The present invention suppresses waveform distortion and noise of ultra-high-speed signal light with a simple configuration that does not include retiming means.
An object of the present invention is to provide an optical limiter circuit capable of increasing a transmission distance and a transmission capacity.
【０００７】[0007]
【課題を解決するための手段】本発明の光リミッタ回路
は、零分散波長が入力信号光波長に等しいか、またはや
や短波長側にずれた値を有する光ファイバに、入力信号
光および補助光を入力して四光波混合過程を誘起する。
このような光ファイバでは、入力信号光パワーがある閾
値以上になったときに四光波混合光パワーが急激に大き
くなり、その反動で光ファイバ内の入力信号光パワーが
低下し、出力信号光パワーが一定値にクランプされる。
この光リミッタ動作により、入力光信号の「１」レベル
の雑音が抑圧される。SUMMARY OF THE INVENTION An optical limiter circuit according to the present invention comprises an optical fiber having a zero-dispersion wavelength equal to the input signal light wavelength or having a value slightly shifted to a shorter wavelength side. To induce the four-wave mixing process.
In such an optical fiber, when the input signal light power exceeds a certain threshold, the four-wave mixing light power rapidly increases, and the reaction causes the input signal light power in the optical fiber to decrease, and the output signal light power to decrease. Is clamped to a constant value.
By this optical limiter operation, the “1” level noise of the input optical signal is suppressed.
【０００８】[0008]
【発明の実施の形態】（第１の実施形態）図１は、本発
明の光リミッタ回路の第１の実施形態を示す。(First Embodiment) FIG. 1 shows a first embodiment of an optical limiter circuit according to the present invention.
【０００９】入力信号光は、光増幅器１１、偏波制御器
１２−１を介して光合波器１３に入力される。一方、補
助光源１４から出力される補助光（連続光）は、偏波制
御器１２−２を介して光合波器１３に入力される。光合
波器１３で合波された入力信号光および補助光は、偏光
子１５を介して光ファイバ１６に入力される。光ファイ
バ１６の出力光は光フィルタ１７に入力され、入力信号
光成分のみが出力される。The input signal light is input to the optical multiplexer 13 via the optical amplifier 11 and the polarization controller 12-1. On the other hand, the auxiliary light (continuous light) output from the auxiliary light source 14 is input to the optical multiplexer 13 via the polarization controller 12-2. The input signal light and auxiliary light multiplexed by the optical multiplexer 13 are input to the optical fiber 16 via the polarizer 15. The output light of the optical fiber 16 is input to the optical filter 17, and only the input signal light component is output.
【００１０】光増幅器１１は、エルビウム添加光ファイ
バ型増幅器または半導体光増幅器を用い、入力信号光パ
ワーを光ファイバ１６で四光波混合が十分に起こる程度
まで増幅する。この増幅する光パワーは、四光波混合を
担う光ファイバ１６の有効断面積、零分散波長、波長分
散スロープ、長さにより決定される。偏波制御器１２−
１は、増幅された入力信号光の光パワーが偏光子１５の
出力端で最大になるように、その偏波状態を調整する。
偏波制御器１２−２は、補助光源１４から出力された補
助光の光パワーが偏光子１５の出力端で所定のレベルに
なるように、その偏波状態を調整する。偏波状態が調整
された入力信号光および補助光を合波する光合波器１３
は、ファイバ融着型光カプラ、またはレンズおよびプリ
ズムにより構成される空間結合系を用いる。The optical amplifier 11 uses an erbium-doped optical fiber type amplifier or a semiconductor optical amplifier, and amplifies the input signal light power to the extent that four-wave mixing sufficiently occurs in the optical fiber 16. The optical power to be amplified is determined by the effective area, the zero dispersion wavelength, the chromatic dispersion slope, and the length of the optical fiber 16 that performs four-wave mixing. Polarization controller 12-
1 adjusts the polarization state of the amplified input signal light so that the optical power of the input signal light becomes maximum at the output end of the polarizer 15.
The polarization controller 12-2 adjusts the polarization state of the auxiliary light output from the auxiliary light source 14 so that the optical power of the auxiliary light is at a predetermined level at the output end of the polarizer 15. Optical multiplexer 13 for multiplexing input signal light and auxiliary light whose polarization state has been adjusted
Uses a fiber fusion type optical coupler or a spatial coupling system constituted by a lens and a prism.
【００１１】光ファイバ１６の零分散波長は、入力信号
光の波長よりもやや短波長側にずれたものを用いる。光
フィルタ１７は、光ファイバ１６を通過してきた入力信
号光成分および補助光成分、光ファイバ１６で四光波混
合過程により発生した四光波混合光成分のうち、入力信
号光成分のみを通過させるものであり、誘電体多層膜フ
ィルタ、グレーティングを用いた反射型の光フィルタ、
帯域反射（透過）型のファイバグレーティング等を用い
る。As the zero dispersion wavelength of the optical fiber 16, a wavelength slightly shifted from the wavelength of the input signal light to the shorter wavelength side is used. The optical filter 17 passes only the input signal light component of the input signal light component and the auxiliary light component that have passed through the optical fiber 16 and the four-wave mixing light component generated by the four-wave mixing process in the optical fiber 16. Yes, dielectric multilayer filter, reflection type optical filter using grating,
A band reflection (transmission) type fiber grating or the like is used.
【００１２】以下、本実施形態において、入力信号光の
波形歪みおよび雑音が抑圧される動作について、図２〜
５を参照して説明する。光ファイバ１６の零分散波長
は、図２に示すように入力信号光の波長よりもやや短波
長側に設定され、入力信号光波長と補助光波長との間に
も所定の波長差が設定される。なお、図２では補助光波
長を入力信号光波長の長波長側に設定しているが、入力
信号光波長の短波長側であってもよい。Hereinafter, the operation of the present embodiment for suppressing the waveform distortion and noise of the input signal light will be described with reference to FIGS.
This will be described with reference to FIG. The zero dispersion wavelength of the optical fiber 16 is set slightly shorter than the wavelength of the input signal light as shown in FIG. 2, and a predetermined wavelength difference is set between the input signal light wavelength and the auxiliary light wavelength. You. In FIG. 2, the auxiliary light wavelength is set on the long wavelength side of the input signal light wavelength, but may be on the short wavelength side of the input signal light wavelength.
【００１３】このような波長配置では、入力信号光の光
パワーに応じた光カー効果により、高い光パワーを入力
したときの四光波混合の位相整合条件が変化し、光ファ
イバ１６の零分散波長が信号光波長に一致しているとき
よりも四光波混合が起こりやすくなる。すなわち、図３
に示すように、入力信号光パワーがある閾値を越えると
急激に四光波混合におけるパラメトリック利得が増大
し、四光波混合光パワーが急激に成長する。一方、入力
信号光の光パワーは、パラメトリック利得により四光波
混合光成分が得た光パワーにほぼ等しい分だけ減少し、
出力信号光パワーが飽和状態となる。In such a wavelength arrangement, the phase matching condition of four-wave mixing when high optical power is input changes due to the optical Kerr effect according to the optical power of the input signal light, and the zero dispersion wavelength of the optical fiber 16 is changed. Is more likely to occur than when the signal wavelength matches the signal light wavelength. That is, FIG.
As shown in (1), when the input signal light power exceeds a certain threshold, the parametric gain in four-wave mixing rapidly increases, and the four-wave mixing light power grows rapidly. On the other hand, the optical power of the input signal light decreases by an amount substantially equal to the optical power obtained by the four-wave mixing optical component due to parametric gain,
The output signal light power becomes saturated.
【００１４】このように、光ファイバ１６の零分散波長
を入力信号光波長よりも短波長側に設定すると、入力信
号光パワーに応じた光カー効果の影響が大きく現れ、入
力信号光パワーに対する出力信号光パワーは、図４の
ようにある入力信号光パワーを閾値として飽和特性を示
す。これにより、入力信号光に対する光リミッタ回路と
して動作することになる。この効果を実験により確認し
た結果を図５に示す。入力信号光パワーに対して出力信
号光パワーをプロットすると、入力信号光パワーが40ｍ
Ｗを越えた時点で明瞭に光リミッタ動作を確認できた。As described above, when the zero dispersion wavelength of the optical fiber 16 is set to be shorter than the wavelength of the input signal light, the influence of the optical Kerr effect according to the input signal light power appears greatly, and the output with respect to the input signal light power is increased. The signal light power shows a saturation characteristic using a certain input signal light power as a threshold as shown in FIG. Thereby, it operates as an optical limiter circuit for the input signal light. The result of confirming this effect by an experiment is shown in FIG. When the output signal light power is plotted against the input signal light power, the input signal light power is 40 m.
The optical limiter operation could be clearly confirmed at the time when W exceeded W.
【００１５】なお、入力信号光パワーに対する出力信号
光パワーは、四光波混合が起こらない場合には、図４
に示すようにほぼ線形の依存性を示す。また、四光波混
合光を発生させるために通常用いられる光ファイバの零
分散波長と入力信号光波長を一致させた場合には、入力
信号光パワーに応じた光カー効果の影響は小さく、図４
に示すように逆２乗の依存性を示す。In the case where four-wave mixing does not occur, the output signal light power with respect to the input signal light power is shown in FIG.
Shows a substantially linear dependence as shown in FIG. When the zero-dispersion wavelength of an optical fiber generally used to generate four-wave mixing light is made to coincide with the input signal light wavelength, the effect of the optical Kerr effect according to the input signal light power is small, and FIG.
Shows the inverse squared dependence as shown in FIG.
【００１６】本発明の光リミッタ回路は、光伝送路を伝
搬し、光増幅器で増幅された光信号の「１」レベルの雑
音について、図４および図５に示す光リミッタ動作に
より抑圧するものである。この光リミッタ動作のもとに
なる四光波混合過程は、非共鳴過程のために非常に高速
であり、テラビットクラスの光信号の波形整形にも十分
に適用可能である。図６は、実際に増幅された自然放出
光雑音を重畳した光信号に対して、本発明の光リミッタ
回路を用いて波形整形したときの効果を確認する実験結
果である。図６(a) は光リミッタ処理前の信号光波形、
図６(b) は光リミッタ処理後の信号光波形、図６(c) は
光リミッタ処理前の信号光ヒストグラム、図６(d) は光
リミッタ処理後の信号光ヒストグラムを示す。光リミッ
タ処理することにより雑音が抑圧され、「１」レベルの
分散値が小さくなっていることがわかる。The optical limiter circuit of the present invention suppresses "1" level noise of an optical signal propagated through an optical transmission line and amplified by an optical amplifier by an optical limiter operation shown in FIGS. is there. The four-wave mixing process, which is the basis of the optical limiter operation, is very fast because of the non-resonant process, and is sufficiently applicable to the shaping of a terabit-class optical signal. FIG. 6 shows an experimental result for confirming the effect of waveform shaping using the optical limiter circuit of the present invention on an optical signal on which spontaneous emission optical noise actually amplified is superimposed. FIG. 6A shows the signal light waveform before the optical limiter processing,
6B shows a signal light waveform after the optical limiter processing, FIG. 6C shows a signal light histogram before the optical limiter processing, and FIG. 6D shows a signal light histogram after the optical limiter processing. It can be seen that the noise is suppressed by the optical limiter processing, and the variance at the “1” level is reduced.
【００１７】（第２の実施形態）図７は、本発明の光リ
ミッタ回路の第２の実施形態を示す。入力信号光は、光
増幅器１１、自動偏波制御器２１を介して偏波保持型光
合波器２２に入力される。一方、偏波保持出力型補助光
源２３から出力される補助光（連続光）は、偏波保持型
光ファイバ２４を介して偏波保持型光合波器２２に入力
される。偏波保持型光合波器２２で合波された入力信号
光および補助光は光ファイバ１６に入力され、さらに光
フィルタ１７を介して入力信号光成分のみが出力され
る。(Second Embodiment) FIG. 7 shows a second embodiment of the optical limiter circuit of the present invention. The input signal light is input to the polarization-maintaining optical multiplexer 22 via the optical amplifier 11 and the automatic polarization controller 21. On the other hand, auxiliary light (continuous light) output from the polarization-maintaining output auxiliary light source 23 is input to the polarization-maintaining optical multiplexer 22 via the polarization-maintaining optical fiber 24. The input signal light and auxiliary light multiplexed by the polarization-maintaining optical multiplexer 22 are input to the optical fiber 16, and only the input signal light component is output via the optical filter 17.
【００１８】光増幅器１１、光ファイバ１６および光フ
ィルタ１７は、第１の実施形態と同様である。自動偏波
制御器２１は、増幅された入力信号光がその出力端で常
に直線偏波になるように偏波状態を調整する。したがっ
て、偏波保持型光合波器２２に入力される入力信号光お
よび補助光の偏波状態が常に同一になるように調整する
ことができるので、入力信号光の偏波状態が変動して
も、光ファイバ１６に入力される合波光の偏波状態は常
に一定となる。これにより、入力信号光の偏波状態に依
存しない常に安定した光リミッタ動作を実現することが
できる。The optical amplifier 11, the optical fiber 16, and the optical filter 17 are the same as in the first embodiment. The automatic polarization controller 21 adjusts the polarization state so that the amplified input signal light always becomes linearly polarized at its output end. Therefore, since the polarization states of the input signal light and the auxiliary light input to the polarization maintaining optical multiplexer 22 can be adjusted to be always the same, even if the polarization state of the input signal light fluctuates. The polarization state of the multiplexed light input to the optical fiber 16 is always constant. This makes it possible to realize an always stable optical limiter operation that does not depend on the polarization state of the input signal light.
【００１９】以上説明した第１の実施形態および第２の
実施形態の光リミッタ回路において、光ファイバ１６の
零分散波長と入力信号光波長の波長差を変化させること
により、信号光成分が飽和する入力信号光パワーの閾
値、および入出力特性の形を変化させることができる。In the optical limiter circuits of the first and second embodiments described above, the signal light component is saturated by changing the wavelength difference between the zero dispersion wavelength of the optical fiber 16 and the input signal light wavelength. The threshold of the input signal light power and the shape of the input / output characteristics can be changed.
【００２０】なお、光ファイバ１６の零分散波長と入力
信号光との波長差を調整するには、零分散波長の異なる
光ファイバを用いるか、光ファイバ１６の温度を制御し
て零分散波長を変化させればよい。例えば、温度制御に
より光ファイバ１６の零分散波長を短波長側にずらして
零分散波長と入力信号光波長の波長差を大きくすると、
信号光成分が飽和する入力信号光パワーの閾値が高めに
設定され、信号光成分が飽和する形が急峻になる。逆
に、零分散波長を長波長側にずらして零分散波長と入力
信号光波長の波長差を小さくすると、信号光成分が飽和
する入力信号光パワーの閾値が低めに設定され、信号光
成分が飽和する形がなだらかになる。このように、光フ
ァイバ１６の温度制御により、連続的にリミッタ特性を
微調整することができる。In order to adjust the wavelength difference between the zero dispersion wavelength of the optical fiber 16 and the input signal light, an optical fiber having a different zero dispersion wavelength is used, or the temperature of the optical fiber 16 is controlled to reduce the zero dispersion wavelength. You only need to change it. For example, when the zero dispersion wavelength of the optical fiber 16 is shifted to the short wavelength side by temperature control to increase the wavelength difference between the zero dispersion wavelength and the input signal light wavelength,
The threshold value of the input signal light power at which the signal light component is saturated is set higher, and the shape at which the signal light component is saturated becomes steep. Conversely, when the zero-dispersion wavelength is shifted to the longer wavelength side to reduce the wavelength difference between the zero-dispersion wavelength and the input signal light wavelength, the threshold of the input signal light power at which the signal light component is saturated is set lower, and the signal light component is reduced. The saturated shape becomes gentle. In this way, by controlling the temperature of the optical fiber 16, the limiter characteristics can be continuously finely adjusted.
【００２１】また、補助光パワーを変化させることによ
り、信号光成分が飽和する形を微調整することができ
る。例えば、補助光パワーを大きくすると、信号光成分
が飽和する入力信号光パワーの閾値が低めに設定され
る。なお、補助光パワーを調整するには、第１の実施形
態では偏波制御器１２−２で偏波状態を調整するか、出
力光パワーを制御できる補助光源１４または偏波保持出
力型補助光源２３を用いればよい。Further, by changing the auxiliary light power, the form in which the signal light component is saturated can be finely adjusted. For example, when the auxiliary light power is increased, the threshold value of the input signal light power at which the signal light component is saturated is set lower. To adjust the auxiliary light power, in the first embodiment, the polarization state is adjusted by the polarization controller 12-2, or the auxiliary light source 14 or the polarization-maintaining output auxiliary light source that can control the output light power is used. 23 may be used.
【００２２】また、入力信号光と補助光の波長差は、接
近させるほど信号光成分が飽和する入力信号光パワーの
閾値を低くすることができる。ただし、光ファイバ１６
の後段に配置される光フィルタ１７で分離できる波長差
が限界となるが、光フィルタ１７として、例えばアレイ
導波路回折格子型光フィルタを用いることにより入力信
号光と補助光の波長差をかなり小さく設定することがで
きる。なお、入力信号光と補助光の波長差を可変調整す
る際には、補助光源１４または偏波保持出力型補助光源
２３として、ＤＦＢレーザまたは外部共振器型の波長可
変レーザを用いて補助光波長を可変させればよい。Further, as the wavelength difference between the input signal light and the auxiliary light becomes closer, the threshold value of the input signal light power at which the signal light component is saturated can be lowered. However, the optical fiber 16
The wavelength difference that can be separated by the optical filter 17 disposed at the subsequent stage is limited, but by using, for example, an arrayed waveguide diffraction grating type optical filter as the optical filter 17, the wavelength difference between the input signal light and the auxiliary light can be considerably reduced. Can be set. When the wavelength difference between the input signal light and the auxiliary light is variably adjusted, a DFB laser or an external resonator type wavelength-variable laser is used as the auxiliary light source 14 or the polarization-maintaining output auxiliary light source 23. Can be varied.
【００２３】[0023]
【発明の効果】以上説明したように、本発明の光リミッ
タ回路は、光リミッタ動作のもとになる四光波混合過程
が非常に高速であるために、テラビットクラスの光信号
の波形歪みおよび雑音の抑圧にも十分に適用可能であ
る。As described above, in the optical limiter circuit of the present invention, since the four-wave mixing process that is the basis of the optical limiter operation is very fast, the waveform distortion and noise of the terabit class optical signal are reduced. Is sufficiently applicable to the suppression of
【００２４】また、本発明の光リミッタ回路は、光再生
中継回路のようにリタイミング処理を行う構成ではない
ので、様々のビットレートの光信号に対して適用するこ
とが可能であり、汎用性が高い。Further, since the optical limiter circuit of the present invention does not have a configuration for performing retiming processing unlike an optical regenerative repeater circuit, it can be applied to optical signals of various bit rates, and is versatile. Is high.
【００２５】さらに、本発明の光リミッタ回路は部品点
数が少なく、非常に簡単かつ安価に構成することができ
る。Further, the optical limiter circuit of the present invention has a small number of components and can be configured very simply and at low cost.
【図１】本発明の光リミッタ回路の第１の実施形態を示
す図。FIG. 1 is a diagram showing a first embodiment of an optical limiter circuit according to the present invention.
【図２】光ファイバの零分散波長、入力信号光波長、補
助光波長の関係を示す図。FIG. 2 is a diagram illustrating a relationship among a zero dispersion wavelength, an input signal light wavelength, and an auxiliary light wavelength of an optical fiber.
【図３】入力信号光パワーと四光波混合光パワーの関係
を示す図。FIG. 3 is a diagram showing a relationship between input signal light power and four-wave mixing light power.
【図４】入力信号光パワーと出力信号光パワーの関係を
示す図。FIG. 4 is a diagram illustrating a relationship between input signal light power and output signal light power.
【図５】入力信号光パワーに対する出力信号光パワーの
実験結果を示す図。FIG. 5 is a diagram showing experimental results of output signal light power with respect to input signal light power.
【図６】本発明の光リミッタ回路の効果を確認する実験
結果を示す図。FIG. 6 is a view showing experimental results for confirming the effect of the optical limiter circuit of the present invention.
【図７】本発明の光リミッタ回路の第２の実施形態を示
す図。FIG. 7 is a diagram showing a second embodiment of the optical limiter circuit of the present invention.
【図８】光再生中継回路の構成例を示す図。FIG. 8 is a diagram showing a configuration example of an optical regenerative repeater circuit.
１１ 光増幅器 １２ 偏波制御器 １３ 光合波器 １４ 補助光源 １５ 偏光子 １６ 光ファイバ １７ 光フィルタ ２１ 自動偏波制御器 ２２ 偏波保持型光合波器 ２３ 偏波保持出力型補助光源 ２４ 偏波保持型光ファイバ Reference Signs List 11 optical amplifier 12 polarization controller 13 optical multiplexer 14 auxiliary light source 15 polarizer 16 optical fiber 17 optical filter 21 automatic polarization controller 22 polarization-maintaining optical multiplexer 23 polarization-maintaining output-type auxiliary light source 24 polarization maintaining Type optical fiber
───────────────────────────────────────────────────── フロントページの続き (72)発明者 遊部 雅生 東京都新宿区西新宿三丁目19番２号 日本 電信電話株式会社内 (72)発明者 山林 由明 東京都新宿区西新宿三丁目19番２号 日本 電信電話株式会社内 (72)発明者 片岡 智由 東京都新宿区西新宿三丁目19番２号 日本 電信電話株式会社内 Ｆターム(参考） 2K002 AA02 AB40 BA03 CA15 DA10 GA10 HA31 5K002 AA06 BA02 BA05 CA00 CA01 CA02 CA13 FA01 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Masao Yube, Inventor 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Yoshiaki Yamabayashi 3-19, Nishishinjuku, Shinjuku-ku, Tokyo No. 2 Nippon Telegraph and Telephone Corporation (72) Inventor Tomoyoshi Kataoka 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo F-Term within Nippon Telegraph and Telephone Corporation 2K002 AA02 AB40 BA03 CA15 DA10 GA10 HA31 5K002 AA06 BA02 BA05 CA00 CA01 CA02 CA13 FA01
Claims (6)
を発生する補助光源と、 入力信号光および前記補助光を合波する光合波器と、 零分散波長が前記入力信号光波長に等しいかまたはやや
短波長側にずれた値を有し、前記光合波器で合波された
入力信号光および補助光を入力して四光波混合過程を誘
起する光ファイバと、 前記光ファイバから出力される前記入力信号光、前記補
助光、前記四光波混合過程により発生する四光波混合光
を入力し、信号光成分のみを波形整形された出力信号光
として出力する光フィルタとを備えたことを特徴とする
光リミッタ回路。An auxiliary light source for generating auxiliary light having a wavelength close to the wavelength of the input signal light; an optical multiplexer for multiplexing the input signal light and the auxiliary light; and a zero dispersion wavelength equal to the input signal light wavelength. An optical fiber having a value slightly shifted to the short wavelength side, and an input fiber and an auxiliary light that are input by the optical multiplexer to induce a four-wave mixing process, and output from the optical fiber. And an optical filter that inputs the input signal light, the auxiliary light, and the four-wave mixing light generated by the four-wave mixing process, and outputs only the signal light component as output signal light whose waveform is shaped. And an optical limiter circuit.
光成分の飽和が起こる光パワーまで入力信号光を増幅し
て光合波器に入力する光増幅器を備えたことを特徴とす
る請求項１に記載の光リミッタ回路。2. An optical amplifier according to claim 1, further comprising an optical amplifier for amplifying the input signal light to an optical power at which the signal light component is saturated by the four-wave mixing process in the optical fiber and inputting the amplified signal light to the optical multiplexer. An optical limiter circuit as described.
致するように制御する偏波制御手段を備えたことを特徴
とする請求項１に記載の光リミッタ回路。3. The optical limiter circuit according to claim 1, further comprising a polarization control means for controlling the polarization states of the input signal light and the auxiliary light so that they match.
する偏波制御器を備え、 補助光源は、前記偏波制御器で制御される直線偏波と同
じ偏波状態の補助光を出力する偏波保持出力型とし、 光合波器は、同じ直線偏波の入力信号光と補助光を合波
する偏波保持型とすることを特徴とする請求項１に記載
の光リミッタ回路。4. A polarization controller for controlling the polarization state of the input signal light to linear polarization, wherein the auxiliary light source has an auxiliary light having the same polarization state as the linear polarization controlled by the polarization controller. The optical limiter circuit according to claim 1, wherein the optical multiplexer is a polarization maintaining type that combines the input signal light and the auxiliary light having the same linear polarization. .
を可変させる手段を備えたことを特徴とする請求項１〜
４のいずれかに記載の光リミッタ回路。5. The apparatus according to claim 1, further comprising means for controlling the temperature of the optical fiber to vary the zero dispersion wavelength.
5. The optical limiter circuit according to any one of 4.
は光パワーの少なくとも一方を可変させる手段を備えた
ことを特徴とする請求項１〜４のいずれかに記載の光リ
ミッタ回路。6. The optical limiter circuit according to claim 1, wherein the auxiliary light source includes means for changing at least one of a wavelength of the auxiliary light to be output and an optical power.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19293098A JP3461121B2 (en) | 1998-07-08 | 1998-07-08 | Optical limiter circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19293098A JP3461121B2 (en) | 1998-07-08 | 1998-07-08 | Optical limiter circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000031901A true JP2000031901A (en) | 2000-01-28 |
| JP3461121B2 JP3461121B2 (en) | 2003-10-27 |
Family
ID=16299369
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19293098A Expired - Fee Related JP3461121B2 (en) | 1998-07-08 | 1998-07-08 | Optical limiter circuit |
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| Country | Link |
|---|---|
| JP (1) | JP3461121B2 (en) |
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