JP2003198467A - Waveform distortion detector, system and method - Google Patents
Waveform distortion detector, system and methodInfo
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- JP2003198467A JP2003198467A JP2001394746A JP2001394746A JP2003198467A JP 2003198467 A JP2003198467 A JP 2003198467A JP 2001394746 A JP2001394746 A JP 2001394746A JP 2001394746 A JP2001394746 A JP 2001394746A JP 2003198467 A JP2003198467 A JP 2003198467A
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】光伝送における光パルスの歪
みの状態を検出する波形歪み検出装置、システム、及び
方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveform distortion detecting apparatus, system, and method for detecting a distortion state of an optical pulse in optical transmission.
【０００２】[0002]
【従来の技術】一般に、光ファイバー通信システムの光
伝送路として用いられる光ファイバーは波長分散特性を
有する。波長分散特性は、光信号の伝搬時間が波長によ
って異なる特性である。波長分散特性を有する光ファイ
バー中を伝搬するディジタル光信号は、その伝送速度が
増加するに従い、または光ファイバーの伝送距離が長く
なるに従い、伝送後の光波形が劣化する。そのため、伝
送速度の高速化および伝送距離の長距離化に伴い、分散
補償技術はより重要になってくる。典型的なシングルモ
ード光ファイバーの波長分散特性は、波長分散値＝１７
ｐｓ／ｎｍ／ｋｍ＠波長１．５５μｍの程度である。こ
の光ファイバー８０ｋｍを、例えば伝送速度１０Ｇｂｉ
ｔ／ｓのディジタル信号を伝搬させた場合、伝送特性は
多大な影響を受け、伝送後の光波形は波長分散のため大
きく歪む。その結果、受信されるディジタル波形は、マ
ークとスペースの判別がつかなくなるため、誤り率の十
分小さい良好な品質での光伝送が不可能となる。この波
長分散による波形歪みを補正する手段として、光ファイ
バーの分散を補償する方法、すなわち、光ファイバーの
分散量と絶対値が等しく符号が逆の分散値を有する光デ
バイスを光ファイバーに挿入方法が検討されている。2. Description of the Related Art Generally, an optical fiber used as an optical transmission line of an optical fiber communication system has chromatic dispersion characteristics. The wavelength dispersion characteristic is a characteristic in which the propagation time of an optical signal varies depending on the wavelength. A digital optical signal propagating in an optical fiber having a wavelength dispersion characteristic has a post-transmission optical waveform that deteriorates as the transmission speed increases or the transmission distance of the optical fiber increases. Therefore, the dispersion compensation technique becomes more important as the transmission speed increases and the transmission distance increases. The wavelength dispersion characteristic of a typical single-mode optical fiber is as follows:
It is about ps / nm / km @ wavelength of 1.55 μm. This optical fiber 80km, for example, transmission speed 10Gbi
When a t / s digital signal is propagated, the transmission characteristics are greatly affected, and the optical waveform after transmission is greatly distorted due to wavelength dispersion. As a result, the received digital waveform is indistinguishable between a mark and a space, and optical transmission with good quality with a sufficiently small error rate is impossible. As a method of correcting the waveform distortion due to the wavelength dispersion, a method of compensating for the dispersion of the optical fiber, that is, a method of inserting an optical device having a dispersion value whose absolute value is equal to the dispersion value of the optical fiber and whose sign is opposite to the optical fiber into the optical fiber has been studied. There is.
【０００３】[0003]
【発明が解決しようとする課題】一般に、分散補償デバ
イスには、分散値が伝送路と逆符号となる分散補償ファ
イバーやバーチャリイメージドフェイズドアレイ型補償
器やチャープト・グレーティング型補償器が用いられて
いる。これらのデバイスを用いて分散補償を行う場合に
は、伝送路の総分散量と分散補償デバイスの補償量を一
致させる必要がある。Generally, a dispersion compensating device uses a dispersion compensating fiber whose dispersion value has an opposite sign to that of a transmission line, a virtual imaged phased array compensator, or a chirp grating compensator. ing. When dispersion compensation is performed using these devices, it is necessary to match the total dispersion amount of the transmission line with the compensation amount of the dispersion compensation device.
【０００４】ところで、伝送路分散量と送信器の変調器
が有するチャープ特性との相関関係により、波形歪みの
状態は異なる。図１４に変調器のチャープ特性と伝送路
分散量との相関関係による波形歪みの様子を示す。一例
として、変調器のチャープ特性が正で、伝送路分散量が
正であるとき、図１４（ａ）に示すように波形は拡がる
傾向に歪む。このように、伝送路分散により波形は歪
み、これにより受信感度の劣化が生じる。By the way, the state of waveform distortion differs depending on the correlation between the amount of channel dispersion and the chirp characteristic of the modulator of the transmitter. FIG. 14 shows the waveform distortion caused by the correlation between the chirp characteristic of the modulator and the dispersion amount of the transmission path. As an example, when the chirp characteristic of the modulator is positive and the transmission path dispersion amount is positive, the waveform is distorted in a tendency to spread as shown in FIG. In this way, the waveform is distorted due to the dispersion of the transmission path, which causes deterioration of the reception sensitivity.
【０００５】一方、伝送路の総分散量と分散補償量とが
一致した場合、（図１４（ｂ）の場合）受信波形は光送
信部波形と同等の波形となり、光受信部で感度劣化のな
い良好な光伝送が実現される。On the other hand, when the total dispersion amount of the transmission line and the dispersion compensation amount match (in the case of FIG. 14B), the received waveform becomes the same waveform as the optical transmission unit waveform, and the sensitivity deterioration occurs in the optical reception unit. Not good optical transmission is realized.
【０００６】図１４はチャープ特性（正）に対する分散
によるパルス歪みの状態（パルス圧縮かパルス拡がり
か）の関係を示す。一般的に用いられている外部変調器
のチャープ特性は正のものが多いためここではチャープ
特性が正の場合について述べる。チャープ特性が正の場
合において、伝送路分散量が正であれば波形歪みは拡が
る傾向（図１４（ａ））にあり、伝送路分散量が負であ
れば波形歪みは圧縮する傾向（図１４（ｃ））にある。FIG. 14 shows the relationship between the state of pulse distortion (pulse compression or pulse expansion) due to dispersion with respect to the chirp characteristic (positive). Since most of the commonly used external modulators have a positive chirp characteristic, the case where the chirp characteristic is positive will be described here. When the chirp characteristic is positive, the waveform distortion tends to spread if the transmission line dispersion amount is positive (FIG. 14A), and the waveform distortion tends to compress if the transmission line dispersion amount is negative (FIG. 14A). (C)).
【０００７】光伝送システムでは、非線形光学効果によ
る影響もパルス歪みを生じさせ、これにより伝送距離が
制限される。このパルス歪みを補正するにあたって、光
線路を伝搬した光信号の歪み検出方法は非常に重要であ
る。In an optical transmission system, the influence of nonlinear optical effects also causes pulse distortion, which limits the transmission distance. In correcting this pulse distortion, it is very important to detect the distortion of the optical signal propagated through the optical line.
【０００８】従来、分散による波形変化の検出方法は特
開平１１−１２２１７３号公報に開示されたものがよく
知られている。以下、この従来技術について図１９を参
照して説明する。コンパレータ１００は入力信号を基準
信号と比較し、コンパレータ１００の出力、すなわちハ
イレベル信号若しくはローレベル信号を低域フィルタ２
００で検出する。例えばコンパレータ１００の出力がハ
イレベルだとして、その出力から低域フィルタ２００で
検出された直流成分は入力信号のデューティを示す。こ
のデューティ検出によって分散による波形変化を検出し
ている。Conventionally, as a method of detecting a waveform change due to dispersion, the method disclosed in Japanese Patent Application Laid-Open No. 11-122173 is well known. Hereinafter, this conventional technique will be described with reference to FIG. The comparator 100 compares the input signal with the reference signal and outputs the output of the comparator 100, that is, the high level signal or the low level signal, to the low pass filter 2.
00 is detected. For example, assuming that the output of the comparator 100 is at a high level, the DC component detected by the low pass filter 200 from the output indicates the duty of the input signal. A waveform change due to dispersion is detected by this duty detection.
【０００９】しかし、上記波形歪み検出に用いられるコ
ンパレータは理想的には“１”又は“０”を出力するモ
ジュールであるため、わずかな分散等の波形劣化の検出
が難しい。又、分散補償器への帰還に関し、波形変化検
出信号がパルス圧縮又はパルス拡がりのいずれかでどの
ように差異が生じたのか明確ではない。このためどのよ
うに自動分散補償を行っているのかが不明であり、実験
検証まで行なわれていないのが実情である。However, since the comparator used for detecting the waveform distortion is ideally a module which outputs "1" or "0", it is difficult to detect waveform deterioration such as slight dispersion. Further, regarding the feedback to the dispersion compensator, it is not clear how the waveform change detection signal is different in either pulse compression or pulse expansion. How they perform automatic dispersion compensation for this is unknown, not been performed until the experiment verification is reality.
【００１０】さらに、上記装置では、光入力パワ変動が
生ずると検出ができず、雑音成分に対してはそれを除去
すべく手段が講じられていないので検出精度が低い。Further, in the above-mentioned device, if the optical input power fluctuation occurs, it cannot be detected, and no measure is taken to remove the noise component, so that the detection accuracy is low.
【００１１】さらに、上記装置にはビットレートに対し
て十分に帯域のある高速なモジュールが必要であり、コ
ストがかかるという問題がある。Further, the above device requires a high-speed module having a sufficient band for the bit rate, which causes a problem of cost.
【００１２】本発明の目的は、歪みを受けた後の波形と
歪みを受ける前の波形の状態を差動増幅器を用いて比較
し、それらの波形の相違を検出することによって、精度
の良い波形歪み検出を行うことができる波形歪み検出装
置、システム、及び方法を提供することである。An object of the present invention is to compare a state of a waveform after being distorted with a state of the waveform before being distorted by using a differential amplifier, and detect a difference between these waveforms to obtain a highly accurate waveform. An object of the present invention is to provide a waveform distortion detection device, system, and method capable of performing distortion detection.
【００１３】[0013]
【課題を解決するための手段】本発明は、受信器端での
光入力パワを一定の状態にし、光入力信号を光電気変換
した後の電気パルス信号を所望の飽和レベル振幅まで増
幅し、その増幅された反転出力、非反転出力の平均値
（電流、電圧）を検出することで、分散等による波形歪
みの変化を検出することを特徴とする。According to the present invention, the optical input power at the receiver end is kept constant, and the electrical pulse signal after photoelectric conversion of the optical input signal is amplified to a desired saturation level amplitude. By detecting the average value (current, voltage) of the amplified inverted output and non-inverted output, a change in waveform distortion due to dispersion or the like is detected.
【００１４】[0014]
【発明の実施の形態】以下、本発明に係る波形歪み検出
装置の第１の実施の形態について図６を参照して説明す
る。図６に示すように、光ファイバー１を伝搬した光送
信波形２が波形歪みを生じ、伝送後光波形３となり、光
増幅器４へ入力され、出力パワ一定に増幅された後、光
電気変換器５にて光信号から電気信号へ変換され、その
信号を波形歪み検出器６にて平均値化することにより波
形歪み状態を検出する。BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of a waveform distortion detector according to the present invention will be described below with reference to FIG. As shown in FIG. 6, the optical transmission waveform 2 propagating through the optical fiber 1 causes waveform distortion, becomes an optical waveform 3 after transmission, is input to the optical amplifier 4, is amplified to a constant output power, and then is converted into a photoelectric converter 5. The optical signal is converted into an electrical signal in step S3, and the waveform distortion detector 6 averages the signal to detect the waveform distortion state.
【００１５】次に波形歪み検出器６にて検出される波形
歪み検出信号についての動作を説明する。光ファイバー
１を伝搬した光送信波形が図１に示すようなパルス拡が
りを生じた場合、伝送後光波形は、光増幅器４にて出力
パワが一定に増幅され、光電気変換器５にて電気信号に
変換された後、波形歪み検出器６にて所望の飽和レベル
まで増幅され、平均値化される。このとき、歪みがない
波形に比べ平均値は増加する。一方、図２に示すように
パルス圧縮を生じた場合には、歪みがない波形に比べ平
均値は減少する。この波形歪みの検出原理については後
述する。Next, the operation of the waveform distortion detection signal detected by the waveform distortion detector 6 will be described. When the optical transmission waveform propagating through the optical fiber 1 has a pulse spread as shown in FIG. 1, the output optical power of the optical waveform after transmission is constantly amplified by the optical amplifier 4, and the optical signal is converted by the photoelectric converter 5. After being converted into, the waveform distortion detector 6 amplifies it to a desired saturation level and averages it. At this time, the average value increases as compared with the waveform having no distortion. On the other hand, when pulse compression occurs as shown in FIG. 2, the average value decreases as compared with the waveform without distortion. The principle of detecting this waveform distortion will be described later.
【００１６】次に、本発明に係る波形歪み検出装置の第
２の実施の形態について図７を参照して説明する。光フ
ァイバー１を伝搬した光送信波形２が波形歪みを生じ、
伝送後光波形３となり、光増幅器４へ入力され、出力パ
ワが一定に増幅された後、光電気変換器５にて光パワ信
号から電気信号へ変換され、波形歪み検出器６に入力さ
れる場合を考える。波形歪み検出器６へ入力された信号
は、差動増幅器７へ入力される。このとき差動増幅器７
にはオフセット調整器８より、基準電圧値が入力され
る。差動増幅器７はこの基準電圧値と波形歪みを生じた
電気信号の差を比較して所望の飽和レベルまで増幅し、
増幅された非反転信号及び反転信号をそれぞれ出力す
る。Next, a second embodiment of the waveform distortion detecting device according to the present invention will be described with reference to FIG. The optical transmission waveform 2 propagated through the optical fiber 1 causes waveform distortion,
The optical waveform 3 after transmission is input to the optical amplifier 4, the output power is amplified to a constant level, the optical power signal is converted to an electrical signal by the optical-electrical converter 5, and the optical signal is input to the waveform distortion detector 6. Consider the case. The signal input to the waveform distortion detector 6 is input to the differential amplifier 7. At this time, the differential amplifier 7
A reference voltage value is input from the offset adjuster 8. The differential amplifier 7 compares the difference between the reference voltage value and the electric signal having the waveform distortion and amplifies it to a desired saturation level.
The amplified non-inverted signal and the inverted signal are output respectively.
【００１７】非反転信号及び反転信号はそれぞれ低域フ
ィルタ９，１０へ入力され、それぞれ低周波の信号へ変
換、すなわち平均値化される。そしてこれらの信号は電
圧比較器１１へ入力され、電圧比較器１１からはこれら
信号の差が出力され、この信号が波形歪み検出信号とな
る。波形歪み検出器６に歪みがない波形が入力されてい
る状態で、オフセット調整器８の基準電圧値を適当に調
整し、電圧比較器１１から出力される波形歪み検出信号
を”０”にすることで、入力波形にパルス拡がり、およ
びパルス圧縮のどちらの状態が生じているのかを波形歪
み検出信号の正負の違いで判別することが可能になる。The non-inverted signal and the inverted signal are input to the low-pass filters 9 and 10, respectively, and converted into low-frequency signals, that is, averaged. Then, these signals are input to the voltage comparator 11, the difference between these signals is output from the voltage comparator 11, and this signal becomes the waveform distortion detection signal. With a waveform having no distortion being input to the waveform distortion detector 6, the reference voltage value of the offset adjuster 8 is appropriately adjusted, and the waveform distortion detection signal output from the voltage comparator 11 is set to "0". As a result, it is possible to determine which state of pulse broadening or pulse compression occurs in the input waveform, based on the positive / negative difference of the waveform distortion detection signal.
【００１８】はじめに図８に示すように基準となる波形
が入力されている状態においてオフセット調整器８の基
準電圧値を入力波形の振幅の中心になるようように設定
し、電圧比較器１１からの出力される波形歪み検出信号
が”０”になるようにする。First, as shown in FIG. 8, when the reference waveform is input, the reference voltage value of the offset adjuster 8 is set to be the center of the amplitude of the input waveform, and the voltage comparator 11 outputs the reference voltage value. The output waveform distortion detection signal is set to "0".
【００１９】この状態の下、図９に示すようにパルス圧
縮された波形が入力された場合を考える。差動増幅器７
からは所望の飽和レベルにまで増幅されて反転、非反転
された波形が出力される。パルス圧縮が生じたことによ
り、非反転出力の平均電圧値は減少し、反転出力の平均
電圧値は増加する。尚、飽和レベルのラインを0ボルト
とし、絶対値をとらずにみた場合であり、以下のパルス
拡がりの場合も同様である。よって電圧比較器１１より
出力される非反転出力と反転出力の平均電圧値の差は”
負”になる。Under this condition, consider the case where a pulse-compressed waveform is input as shown in FIG. Differential amplifier 7
Output a waveform which is amplified to the desired saturation level and inverted / non-inverted. Due to the occurrence of pulse compression, the average voltage value of the non-inverted output decreases and the average voltage value of the inverted output increases. The saturation level line is set to 0 V and the absolute value is not taken, and the same applies to the following pulse expansion. Therefore, the difference between the average voltage values of the non-inverted output and the inverted output output from the voltage comparator 11 is "
Becomes negative.
【００２０】続いて、図１０に示すようにパルス拡がり
を生じた波形が入力された場合を考える。差動増幅器７
からは所望の飽和レベルにまで増幅されて反転、非反転
された波形が出力される。パルス拡がりが生じたことに
より、非反転出力の平均電圧値は増加し、反転出力の平
均電圧値は減少する。よって電圧比較器１１より出力さ
れる非反転出力と反転出力の平均電圧値の差は”正”に
なる。すなわち基準となる入力波形に対して適当な基準
電圧値を設定し、その設定状態のもと、電力が等しい歪
みを生じた波形が波形歪み検出器６に入力されること
で、差動増幅器７の出力平均電圧値は波形の歪みに応じ
て変化する。その変化分を検出することで、波形歪みを
検出している。Next, consider the case where a waveform having a pulse spread as shown in FIG. 10 is input. Differential amplifier 7
Output a waveform which is amplified to the desired saturation level and inverted / non-inverted. Due to the pulse broadening, the average voltage value of the non-inverting output increases and the average voltage value of the inverting output decreases. Therefore, the difference between the average voltage values of the non-inverted output and the inverted output output from the voltage comparator 11 becomes "positive". That is, an appropriate reference voltage value is set for the reference input waveform, and under the set state, the waveform having the same power distortion is input to the waveform distortion detector 6, whereby the differential amplifier 7 The output average voltage value of changes according to the distortion of the waveform. The waveform distortion is detected by detecting the change.
【００２１】このように波形歪み検出を差動増幅器７の
出力平均電圧値に基いて行っているが、以下その検出原
理について、図３〜図５を参照してより詳細に説明す
る。As described above, the waveform distortion is detected based on the output average voltage value of the differential amplifier 7. The detection principle will be described in more detail with reference to FIGS. 3 to 5.
【００２２】最初に、図３を参照して入力波形が理想的
な場合について説明する。差動増幅器に理想的な波形が
入力された場合において、差動増幅器の反転、非反転出
力の平均値が等しくなるように基準電圧をあらかじめ設
定する。このとき、差動増幅器は任意に決められた飽和
レベルまて入力信号を増幅し、出力する。非反転出力及
び反転出力の平均値が理想的な波形入力時の差動増幅器
出力の平均値に比して増加、減少、若しくは等しいのい
ずれかであるかは、それぞれ図３の真ん中の図における
領域Ａと領域Ｂの面積の差及び下の図における領域Ａ’
と領域Ｂ’の面積の差で考察すればよい。したがって、
入力波形が理想的な場合における非反転出力の平均値
は、領域Ａと領域Ｂの面積は等しいので理想的な波形入
力時の差動増幅器出力の平均値と等しい。従って、非反
転出力の平均値は上限と下限の飽和レベルの中間値とな
る。First, the case where the input waveform is ideal will be described with reference to FIG. When the ideal waveform is input to the differential amplifier, the reference voltage is set in advance so that the average values of the inverted and non-inverted outputs of the differential amplifier become equal. At this time, the differential amplifier amplifies and outputs the input signal to a saturation level arbitrarily determined. Whether the average values of the non-inverted output and the inverted output are increased, decreased, or equal to the average value of the differential amplifier output at the time of ideal waveform input is shown in the middle diagram of FIG. 3, respectively. Area difference between area A and area B and area A'in the figure below
And the area of the region B'can be considered. Therefore,
The average value of the non-inverted output when the input waveform is ideal is equal to the average value of the differential amplifier output when the ideal waveform is input because the areas of the regions A and B are equal. Therefore, the average value of the non-inverted output is an intermediate value between the upper and lower saturation levels.
【００２３】一方、反転出力の平均値は、領域Ａ’と領
域Ｂ’の面積は等しいので理想的な波形入力時の差動増
幅器出力の平均値と等しい。尚、差動増幅器にて増幅さ
れた波形は（図中の破線）は出力飽和レベルがあるた
め、飽和レベルで頭打ちになった波形が出力される。On the other hand, the average value of the inverted output is equal to the average value of the output of the differential amplifier at the time of ideal waveform input because the areas A'and B'are equal. Since the waveform amplified by the differential amplifier (broken line in the figure) has an output saturation level, a waveform that has reached a peak at the saturation level is output.
【００２４】次に図４を参照して入力波形がパルス圧縮
を受けた場合について説明する。パルス圧縮を受けた場
合、図１４（ｃ）に示すように波形は変化する。すなわ
ち、出力波形は差動増幅器の出力飽和レベルにより制限
を受け、本来の平均値を示すレベル（図中の破線）に対
して出力波形の上下の割合が変化する。このとき全体と
しての平均値は変化していないが、飽和レベルが決めら
れていることにより出力波形の平均値が変化する。図３
の場合と同様に考察すると、非反転出力の平均値は、領
域Ａより領域Ｂの面積の方が大きいので、理想的な波形
入力時の差動増幅器出力の平均値に比べて減少する。一
方、反転出力の平均値は、領域Ａ’の面積が領域Ｂ’の
面積より大きいので、理想的な波形入力時の差動増幅器
出力の平均値に比べて増加する。このため非反転出力の
平均値と反転出力の平均値の差は負となる。Next, a case where the input waveform is pulse-compressed will be described with reference to FIG. When subjected to pulse compression, the waveform changes as shown in FIG. That is, the output waveform is limited by the output saturation level of the differential amplifier, and the ratio of the upper and lower sides of the output waveform changes with respect to the level (broken line in the figure) indicating the original average value. At this time, the average value as a whole does not change, but the average value of the output waveform changes because the saturation level is determined. Figure 3
Considering in the same manner as in the above case, the average value of the non-inverted output is smaller than the average value of the differential amplifier output at the time of ideal waveform input because the area of the region B is larger than that of the region A. On the other hand, since the area of the region A'is larger than the area of the region B ', the average value of the inverted output increases as compared with the average value of the differential amplifier output at the time of ideal waveform input. Therefore, the difference between the average value of the non-inverted output and the average value of the inverted output is negative.
【００２５】次に図５を参照して入力波形がパルス拡が
りを受けた場合について説明する。パルス拡がりを受け
た場合、図１４（ａ）に示すように波形は変化する。こ
の場合もパルス圧縮の時と同様、出力波形は差動増幅器
の出力飽和レベルにより制限を受け、本来の平均値を示
すレベル（図中の破線）に対して出力波形の上下の割合
が変化する。このとき全体としての平均値は変化してい
ないが、飽和レベルが決められていることにより出力波
形の平均値が変化する。図３の場合と同様に考察する
と、非反転出力の平均値は、領域Ａの面積が領域Ｂの面
積より大きいので、理想的な波形入力時の差動増幅器出
力の平均値に比べて増加する。一方、反転出力の平均値
は、領域Ａより領域Ｂの面積の方が大きいので、理想的
な波形入力時の差動増幅器出力の平均値に比べて減少す
る。このため非反転出力の平均値と反転出力の平均値の
差は正となる。Next, the case where the input waveform is subjected to pulse broadening will be described with reference to FIG. When subjected to pulse broadening, the waveform changes as shown in FIG. In this case as well, as in the case of pulse compression, the output waveform is limited by the output saturation level of the differential amplifier, and the ratio of the upper and lower sides of the output waveform changes with respect to the level indicating the original average value (broken line in the figure). . At this time, the average value as a whole does not change, but the average value of the output waveform changes because the saturation level is determined. Considering as in the case of FIG. 3, the average value of the non-inverted output increases as compared with the average value of the differential amplifier output at the time of ideal waveform input because the area of the area A is larger than the area of the area B. . On the other hand, since the average value of the inverted output is larger in the area B than in the area A, it is smaller than the average value of the differential amplifier output when the ideal waveform is input. Therefore, the difference between the average value of the non-inverted output and the average value of the inverted output is positive.
【００２６】上述には分散によるパルス圧縮、パルス拡
がりの波形歪みを生じた波形が差動増幅器に入力された
場合を例に説明を行ったが、これ以外にも自己位相変調
や相互位相変調等の非線形光学効果による場合や、偏波
分散による影響など、さまざまな波形歪みについても同
様に（基準となる理想的な波形入力時の平均値に対して
変化することで）検出が可能である。In the above description, a case where a waveform having waveform distortion such as pulse compression and pulse expansion due to dispersion is input to the differential amplifier has been described as an example. However, other than this, self phase modulation, cross phase modulation, etc. Various waveform distortions such as due to the non-linear optical effect of (1) and the influence of polarization dispersion can be similarly detected (by changing with respect to the average value at the time of ideal reference waveform input).
【００２７】またここでは図９及び図１０に示すように
波形歪み検出器に入力される波形のパワは図８に示され
る基準となる波形のパワと等しくする必要がある。なお
ここで差動増幅器７は入力波形のビットレートまでの帯
域は必要としない。また光電気変換器５は飽和すること
なく動作することが望ましい。Further, here, as shown in FIGS. 9 and 10, the power of the waveform input to the waveform distortion detector needs to be equal to the power of the reference waveform shown in FIG. Here, the differential amplifier 7 does not require a band up to the bit rate of the input waveform. Further, it is desirable that the photoelectric converter 5 operates without being saturated.
【００２８】次に本発明の有効性を示すための実験を行
った。その実験系を図１１に示す。実験には光送波形２
は４０Ｇｂｉｔ／ｓのＮＲＺ光信号を用いたが、本シス
テムはビットレ−トによらず使用することが可能であ
る。また光ファイバ１にはシングルモ−ドファイバおよ
び分散補償ファイバを用いて波形歪みを生成させた。光
増幅器４で出力パワが一定になるように増幅された光波
形は光電気変換器５にて電気波形に変換され、差動増幅
器７へ入力される。尚、図１１に示すような検証実験で
は光ファイバの分散値が０ｐｓ／ｎｍのとき波形歪み検
出信号が”０”になるように基準電圧値を設定した。Next, an experiment was conducted to show the effectiveness of the present invention. The experimental system is shown in FIG. Waveform 2 for experiment
Used an NRZ optical signal of 40 Gbit / s, but this system can be used regardless of the bit rate. In addition, the optical fiber 1 uses a single mode fiber and a dispersion compensating fiber to generate waveform distortion. The optical waveform amplified by the optical amplifier 4 so that the output power is constant is converted into an electrical waveform by the photoelectric converter 5 and input to the differential amplifier 7. In the verification experiment as shown in FIG. 11, the reference voltage value was set so that the waveform distortion detection signal was “0” when the dispersion value of the optical fiber was 0 ps / nm.
【００２９】検証実験では、この状態のもと、光ファイ
バ１の分散値を変化させ波形歪み検出信号を測定し、そ
の結果を図１２に示す。この測定結果から光ファイバの
分散値の量に応じて、波形歪み検出信号が変化すること
が確認された。すなわち本システムにおいて分散による
波形歪みをモニタできることが確認できた。尚、本実験
ではＮＲＺ信号を用いて検証を行ったが、ＲＺ系の信号
を用いても波形歪みの傾向はＮＲＺ信号と同様であるこ
とから、波形歪み検出は可能である。In the verification experiment, under this condition, the dispersion value of the optical fiber 1 was changed and the waveform distortion detection signal was measured. The result is shown in FIG. From this measurement result, it was confirmed that the waveform distortion detection signal changed depending on the amount of dispersion value of the optical fiber. That is, it was confirmed that waveform distortion due to dispersion can be monitored in this system. In this experiment, verification was performed using the NRZ signal, but even if an RZ system signal is used, the tendency of waveform distortion is the same as that of the NRZ signal, and therefore waveform distortion can be detected.
【００３０】次に、本発明に係る波形歪み検出方法の第
３の実施形態について図１３を参照して説明する。波形
歪み検出器６にて検出された波形歪み検出信号を可変分
散補償器１２にフィ−ドバックすることにより、自動分
散補償が可能になる。上述したように、波形歪み検出器
に歪みがない波形が入力されている状態で、オフセット
調整器８の基準電圧値を任意に調整し、初期状態として
電圧比較器１１から出力される波形歪み検出信号を”
０”にすることで、入力波形にパルス拡がり、およびパ
ルス圧縮のどちらの状態が生じているのかを波形歪み検
出信号の正負の違いで判別することが可能になる。すな
わち正分散、負分散の判別も可能となる。そのため自動
分散補償器１２の制御も効率よく行うことが可能であ
る。Next, a third embodiment of the waveform distortion detecting method according to the present invention will be described with reference to FIG. By feeding back the waveform distortion detection signal detected by the waveform distortion detector 6 to the variable dispersion compensator 12, automatic dispersion compensation becomes possible. As described above, in the state where a waveform having no distortion is input to the waveform distortion detector, the reference voltage value of the offset adjuster 8 is arbitrarily adjusted to detect the waveform distortion output from the voltage comparator 11 as an initial state. Signal
By setting it to 0 ", it is possible to determine which state, pulse expansion or pulse compression, is occurring in the input waveform, based on the positive / negative difference of the waveform distortion detection signal. Therefore, the automatic dispersion compensator 12 can be efficiently controlled.
【００３１】但し、チャープが”０”の場合には、分散
量の正負によらず波形歪みはパルス拡がりを示すため、
上記方式では帰還制御をかけることができないため、上
記実施の形態では、入力波形はチャープが”０”でない
変調器にて生成された波形に限る。However, when the chirp is "0", the waveform distortion shows pulse broadening regardless of whether the amount of dispersion is positive or negative.
Since feedback control cannot be applied in the above method, in the above embodiment, the input waveform is limited to the waveform generated by the modulator whose chirp is not "0".
【００３２】次に本発明に係る波形歪み検出装置の第４
の実施の形態について図１５を参照して説明する。これ
まで、波形歪み検出器に入力される信号はパワが一定で
あるとしてきたが、本実施の形態では、光増幅器がな
く、光電気変換器への入力パワが一定でない場合を想定
した。このとき光電気変換器への入力パワの変動分をパ
ワ検出器１３で検出する。補正回路１４では、検出され
た入力パワの変動分に応じてオフセット調整器８より出
力される基準電圧信号を補正すると共にパワ変動を検出
したときに差勤増幅器の利得を調整する。すなわち、パ
ワ検出器から差動増幅器にパワ検出信号を入力し、差動
増幅器の利得を自動的に調整するものである。例えば任
意の初期設定状態に対して、パワ検出レベルが２分のｌ
及び３分の１になった場合、それぞれ差動増幅器の利得
を初期設定状態の２倍及び３倍に調整する自動利得制御
機能を差動増幅器に含ませている。波形歪み検出器に入
力されるパワに応じた基準電圧信号を生成し、自動的に
利得制御することで、入力パワ変動による問題を解決し
ている。尚、このとき差勤増幅器の飽和レベルは変化し
ない。Next, the fourth embodiment of the waveform distortion detecting apparatus according to the present invention
The embodiment will be described with reference to FIG. Up to now, the signal input to the waveform distortion detector has been assumed to have a constant power, but in the present embodiment, it is assumed that there is no optical amplifier and the input power to the photoelectric converter is not constant. At this time, the power detector 13 detects the fluctuation of the input power to the photoelectric converter. The correction circuit 14 corrects the reference voltage signal output from the offset adjuster 8 according to the detected variation in the input power, and adjusts the gain of the differential amplifier when the power variation is detected. That is, the power detection signal is input from the power detector to the differential amplifier, and the gain of the differential amplifier is automatically adjusted. For example, the power detection level is 1/2 of an arbitrary initial setting state.
And 1/3, the differential amplifier includes an automatic gain control function for adjusting the gain of the differential amplifier to double and triple the initial setting state, respectively. The problem due to input power fluctuation is solved by generating a reference voltage signal according to the power input to the waveform distortion detector and automatically controlling the gain. At this time, the saturation level of the differential amplifier does not change.
【００３３】次に本発明に係る波形歪み検出装置の第５
の実施形態について図１６を参照して説明する。差動増
幅器７は入力信号の非反転、反転出力の平均電圧値比較
しているため雑音成分の影響をうち消す効果も合わせ持
っている。図１６に示すように雑音が重畳された入力波
形が波形歪み検出器６に入力された場合、差動増幅器７
からはそれぞれ雑音が重畳された反転、非反転信号が出
力される。電圧比較器１１にてこれらの信号の差分を取
ることで、雑音成分は相殺される。すなわち電圧比較器
１１からは雑音成分が相殺された波形歪み検出信号が出
力され、検出精度の向上が可能となる。Next, the fifth embodiment of the waveform distortion detecting apparatus according to the present invention
The embodiment will be described with reference to FIG. Since the differential amplifier 7 compares the average voltage values of the non-inverted and inverted outputs of the input signal, it also has an effect of canceling out the influence of noise components. When an input waveform on which noise is superimposed is input to the waveform distortion detector 6 as shown in FIG.
Outputs an inverted signal and a non-inverted signal on which noise is superimposed respectively. By taking the difference between these signals in the voltage comparator 11, the noise component is canceled. In other words, the voltage comparator 11 outputs a waveform distortion detection signal in which the noise component is canceled, and the detection accuracy can be improved.
【００３４】次に本発明に係る波形歪み検出装置の第６
の実施の形態について図１７を参照して説明する。光受
信器２０は、等化増幅（ｒｅｓｈａｐｅ）、リタイミン
グ（ｒｅｔｉｍｉｎｇ）、及び識別再生（ｒｅｇｅｎｅ
ｒａｔｉｎｇ）の３Ｒ機能を有し、データ信号とクロッ
ク信号を生成する。後段の符号誤り率検出器２１は、符
号誤り訂正機能を有するＦＥＣ回路等である。符号誤り
率検出器２１にて誤り率検出を行うに際し、光受信器２
０にて光ファイバ１（光伝送路）における分散の影響が
非常に大きく、３Ｒ機能が有効に動作しない場合には、
波形歪み検出器６の検出信号のみを可変分散補償器１２
に帰還させる。３Ｒ機能が有効な動作を行った時点で、
可変分散補償器１２に帰還させる信号を符号誤り率検出
器２１のモニタ値とすることで、符号誤り率が最適とな
る可変分散補償量を自動制御することができる。尚、伝
送路残留分散量が０になる場合が符号誤り率の最適とは
必ずしもならない点留意する。波形歪み検出器６からの
検出信号、もしくは符号誤り率検出器２１からの符号誤
り率検出信号のどちらかを可変分散補償回路１２に帰還
するかは補正回路２２にて判断する。可変分散補償回路
１２は、光受信器２０が正常動作時には符号誤り率検出
回路２１のモニタ値を用いて分散補償し、光受信器２０
が正常に動作できていない場合は波形歪み検出器６の検
出信号を用いて分散補償する。Next, the sixth embodiment of the waveform distortion detecting apparatus according to the present invention
The embodiment will be described with reference to FIG. The optical receiver 20 includes equalization amplification (reshape), retiming (retiming), and identification reproduction (regene).
It has a 3R function of "rating" and generates a data signal and a clock signal. The code error rate detector 21 in the latter stage is an FEC circuit or the like having a code error correction function. When the error rate is detected by the code error rate detector 21, the optical receiver 2
When the influence of dispersion in the optical fiber 1 (optical transmission line) is very large at 0, and the 3R function does not operate effectively,
Only the detection signal of the waveform distortion detector 6 is applied to the variable dispersion compensator 12
To return to. When the 3R function is effective,
By using the signal fed back to the variable dispersion compensator 12 as the monitor value of the code error rate detector 21, it is possible to automatically control the variable dispersion compensation amount that optimizes the code error rate. It should be noted that the bit error rate is not necessarily optimal when the residual dispersion amount of the transmission path is 0. The correction circuit 22 determines whether the detection signal from the waveform distortion detector 6 or the code error rate detection signal from the code error rate detector 21 is fed back to the variable dispersion compensation circuit 12. The variable dispersion compensating circuit 12 performs dispersion compensation using the monitor value of the code error rate detecting circuit 21 when the optical receiver 20 operates normally, and the optical receiver 20
Is not operating normally, dispersion compensation is performed using the detection signal of the waveform distortion detector 6.
【００３５】以下、上記した第６の実施の形態の応用例
としてのＷＤＭ伝送システムについて図１８を参照して
述べる。図１８に示すように、光送信器３０よりλ１〜
λｎの光データを生成し、それぞれ送信側の可変分散補
償器３１により個別に分散補償を行い、光合波器３２に
よりλ１〜λｎの波長を合波し、光増幅器４０にて増幅
し、伝送路光ファイバ４１を介して光分波器５０に送信
する。A WDM transmission system as an application example of the above-described sixth embodiment will be described below with reference to FIG. As shown in FIG.
Optical data of λn is generated, dispersion compensation is individually performed by the variable dispersion compensator 31 on the transmission side, wavelengths of λ1 to λn are multiplexed by the optical multiplexer 32, and amplified by the optical amplifier 40 to be transmitted through the transmission line. It transmits to the optical demultiplexer 50 via the optical fiber 41.
【００３６】伝送路光ファイバ４１にて受ける分散の影
響は一括して光増幅器４０及び光中継器内に組み込んだ
分散補償ファイバ４２にて大まかに補償される。その
後、光受信側の光分波器５０にて、λ１〜λｎの波長ご
とに分波された光信号波形はそれぞれ受信側の可変分散
補償器５１にて個別に補償され、光受信器６０に入力さ
れる。上記した第６の実施の形態と同様に、波形歪み検
出器６及び符号誤り率検出器２１にて検出された信号を
送信側及び受信側の可変分散補償器３１，５１に帰還制
御することで、伝送路の分散の状態を自動的により最適
な状態に制御することができる。The influence of dispersion on the transmission line optical fiber 41 is roughly compensated for collectively by the dispersion compensating fiber 42 incorporated in the optical amplifier 40 and the optical repeater. After that, the optical signal waveforms demultiplexed by the optical demultiplexer 50 on the optical receiving side for each wavelength of λ1 to λn are individually compensated by the variable dispersion compensator 51 on the receiving side, and the optical receiver 60 receives them. Is entered. Similar to the above-described sixth embodiment, the signals detected by the waveform distortion detector 6 and the code error rate detector 21 are feedback-controlled to the variable dispersion compensators 31 and 51 on the transmission side and the reception side. , It is possible to automatically control the dispersion state of the transmission path to an optimum state.
【００３７】ここでも上記した実施の形態と同様に、３
Ｒ機能が正常な動作を行った時点で、送信側及び受信側
の可変分散補償器３１，５１に帰還させる信号を符号誤
り率検出器２１のモニタ値とすることで、符号誤り率が
最適となる可変分散補償量を自動的に制御することがで
きる。尚、３Ｒ機能が正常に動作するまでは波形歪みモ
ニタの値をもとに可変分散補償器３１，５１を制御す
る。Here, as in the above-described embodiment, 3
When the R function operates normally, the signal to be fed back to the variable dispersion compensators 31 and 51 on the transmitting side and the receiving side is used as the monitor value of the code error rate detector 21 to optimize the code error rate. It is possible to automatically control the variable dispersion compensation amount. The variable dispersion compensators 31 and 51 are controlled based on the value of the waveform distortion monitor until the 3R function operates normally.
【００３８】以下、なぜ自動的に分散補償が必要になる
理由を述べる。第１に、伝送路光ファイバの敷設場所に
おける温度変化による分散値が変化する。第２に、伝送
路光ファイバの条件（各波長における分散値やファイバ
の種類）や、光増幅器の出カパワの状態によって自己位
相変調や相互位相変調といった非線形光学効果による波
形歪みが生じる。このような影響を低減するため、送信
側にて任意に分散状態を付加することで、波形歪みの影
響を低減することができる。分散量は伝送路に用いられ
るファイバの種類や分散補償量、さらには光信号の入カ
パワといった様々な要因により変化するため、分散補償
量を明確に定義することは難しいが、本実施の形態はこ
の問題を解決する手段の―つである。The reason why the dispersion compensation is automatically required will be described below. First, the dispersion value changes due to temperature changes at the installation location of the transmission line optical fiber. Secondly, waveform distortion due to nonlinear optical effects such as self-phase modulation and cross-phase modulation occurs depending on the conditions of the transmission line optical fiber (dispersion value at each wavelength and fiber type) and the output power state of the optical amplifier. In order to reduce such an influence, the influence of waveform distortion can be reduced by arbitrarily adding a dispersion state on the transmitting side. Since the amount of dispersion changes due to various factors such as the type of fiber used in the transmission line, the amount of dispersion compensation, and the input power of the optical signal, it is difficult to clearly define the amount of dispersion compensation. It is one of the means to solve this problem.
【００３９】[0039]
【発明の効果】光伝送システムにおいて、伝送路の分散
補償を行うに際し、伝送路の総分散量を補償することが
必要であり、波形歪みの影響がパルス圧縮なのかそれと
もパルス拡がりなのかを判別することが重要となる。In the optical transmission system, when the dispersion compensation of the transmission line is performed, it is necessary to compensate the total dispersion amount of the transmission line, and it is determined whether the influence of the waveform distortion is the pulse compression or the pulse expansion. It becomes important to do.
【００４０】本発明はパルス歪みがない状態をもとに、
パルス圧縮またはパルス拡がりに関して、差動増幅器の
所望の飽和レベル振幅にまで増幅された反転信号及び非
反転信号の平均値の差を検出することで、波形歪み状態
を精度良く検出することを可能にした。またこの検出信
号を可変分散補償器に帰還制御することで、自動分散補
償を行うことを可能にする。The present invention is based on the condition that there is no pulse distortion.
With respect to pulse compression or pulse expansion, it is possible to detect the waveform distortion state with high accuracy by detecting the difference between the average values of the inverted signal and the non-inverted signal amplified to the desired saturation level amplitude of the differential amplifier. did. In addition, feedback control of this detection signal to the variable dispersion compensator enables automatic dispersion compensation.
【００４１】また、分散以外の非線形光学効果の影響
や、偏波モード分散による波形の歪みも検出することが
可能である。Further, it is possible to detect the influence of non-linear optical effects other than dispersion and the distortion of the waveform due to polarization mode dispersion.
【００４２】さらに本システムは構成が簡単なため、Ｌ
ＳＩ内部に機能を埋め込むことも可能であり、小型化の
可能性を十分に持ち合わせている。Furthermore, since this system has a simple structure, L
It is also possible to embed functions inside the SI, and there is ample potential for downsizing.
【図１】パルス拡がりの状態を示した図である。FIG. 1 is a diagram showing a pulse spread state.
【図２】パルス圧縮の状態を示した図である。FIG. 2 is a diagram showing a state of pulse compression.
【図３】本発明における波形歪み検出原理を説明するた
めの図である。FIG. 3 is a diagram for explaining the principle of waveform distortion detection in the present invention.
【図４】本発明における波形歪み検出原理を説明するた
めの図である。FIG. 4 is a diagram for explaining the principle of waveform distortion detection in the present invention.
【図５】本発明における波形歪み検出原理を説明するた
めの図である。FIG. 5 is a diagram for explaining the principle of waveform distortion detection in the present invention.
【図６】本発明の第１の実施の形態を示した図である。FIG. 6 is a diagram showing a first exemplary embodiment of the present invention.
【図７】本発明の第２の実施の形態を示した図である。FIG. 7 is a diagram showing a second exemplary embodiment of the present invention.
【図８】入力波形が理想的な場合における、第２の実施
の形態の動作説明図である。FIG. 8 is an operation explanatory diagram of the second embodiment when an input waveform is ideal.
【図９】入力波形がパルス圧縮を生じた場合における、
第２の実施の形態の動作説明図である。FIG. 9 shows a case where an input waveform causes pulse compression,
It is operation | movement explanatory drawing of 2nd Embodiment.
【図１０】入力波形がパルス拡がりを生じた場合におけ
る、図７に示した装置の動作説明図である。FIG. 10 is an operation explanatory diagram of the apparatus shown in FIG. 7 when the input waveform causes pulse broadening.
【図１１】本発明の有効性を示すための実験系を示した
図である。FIG. 11 is a diagram showing an experimental system for showing the effectiveness of the present invention.
【図１２】検証実験における光ファイバ分散値と波形歪
み検出信号の関係を示した図である。FIG. 12 is a diagram showing a relationship between an optical fiber dispersion value and a waveform distortion detection signal in a verification experiment.
【図１３】本発明の第３の実施の形態を示した図であ
る。FIG. 13 is a diagram showing a third exemplary embodiment of the present invention.
【図１４】変調器のチャープ特性（正の場合）と伝送路
分散量による波形歪みの状態を示した図である。FIG. 14 is a diagram showing a chirp characteristic of a modulator (when positive) and a state of waveform distortion due to a transmission line dispersion amount.
【図１５】本発明の第４の実施の形態を示した図であ
る。FIG. 15 is a diagram showing a fourth exemplary embodiment of the present invention.
【図１６】本発明の第５の実施の形態を示した図であ
る。FIG. 16 is a diagram showing a fifth exemplary embodiment of the present invention.
【図１７】本発明の第６の実施の形態を示した図であ
る。FIG. 17 is a diagram showing a sixth exemplary embodiment of the present invention.
【図１８】本発明に係る波形歪み検出システムの一実施
の形態を示した図である。FIG. 18 is a diagram showing an embodiment of a waveform distortion detection system according to the present invention.
【図１９】従来の波形歪み検出装置の構成を示した図で
ある。FIG. 19 is a diagram showing a configuration of a conventional waveform distortion detection device.
１ 光ファイバ ４ 光増幅器 ５ 光電気変換器 ６ 波形歪み検出器 ７ 差動増幅器 ８ オフセット調整器 ９，１０ 低域フィルタ １１ 電圧比較器 １２ 可変分散補償器 １３ パワ検出器 １４ 補正回路 ２０ 光受信器 ２１ 符号誤り率検出器 ２２ 補正回路 ３０ 光送信器 ３１，５１ 可変分散補償器 ３２ 光合波器 ４０ 光増幅器 ４１ 伝送路光ファイバ ４２ 分散補償ファイバ ５０ 光分波器 ６０ 光受信器 1 optical fiber 4 Optical amplifier 5 photoelectric converter 6 Waveform distortion detector 7 Differential amplifier 8 Offset adjuster 9,10 low-pass filter 11 Voltage comparator 12 Variable dispersion compensator 13 Power detector 14 Correction circuit 20 Optical receiver 21 Code error rate detector 22 Correction circuit 30 optical transmitter 31,51 Variable dispersion compensator 32 optical multiplexer 40 Optical amplifier 41 Transmission line optical fiber 42 Dispersion compensating fiber 50 Optical demultiplexer 60 optical receiver
Claims (15)
ルス信号に変換する光電気変換手段と、 前記電気パルス信号の歪み状態がパルス圧縮かパルス拡
がりかを検出する波形歪み検出手段を有し、 前記波形歪み検出手段は、所定の基準電圧値と波形歪み
を生じた前記電気パルス信号の電圧値との差を比較して
増幅し、それぞれ非反転信号及び反転信号として出力す
る差動増幅器と、 前記非反転信号及び前記反転信号をそれぞれ所定周波の
信号へ変換し、平均値化する第１及び第２の低域フィル
タと、 前記２つの平均値化された信号の差をとって波形歪み検
出信号として出力する電圧比較器を具備し、 前記光伝送路の波長分散による信号波形の変化を検出す
ることを特徴とする波形歪み検出装置。1. An optical-electrical converting means for converting an input optical signal propagating through an optical transmission line into an electric pulse signal, and a waveform distortion detecting means for detecting whether the distortion state of the electric pulse signal is pulse compression or pulse expansion. The waveform distortion detecting means compares and amplifies a difference between a predetermined reference voltage value and a voltage value of the electric pulse signal in which the waveform distortion has occurred, and amplifies the difference, and outputs the non-inverted signal and the inverted signal, respectively. A first and a second low-pass filter for converting the non-inverted signal and the inverted signal into a signal of a predetermined frequency and averaging, respectively, and a waveform taking a difference between the two averaged signals. A waveform distortion detecting device comprising a voltage comparator for outputting as a distortion detection signal, and detecting a change in a signal waveform due to wavelength dispersion of the optical transmission line.
光増幅器が前記光電気変換手段の前段に配置されている
ことを特徴とする請求項１記載の波形歪み検出装置。2. The waveform distortion detecting apparatus according to claim 1, wherein an optical amplifier that amplifies the output power of the optical waveform at a constant level is arranged in front of the opto-electric converting means.
形が入力されている状態で出力される波形歪み検出信号
が常に“０”になるように、前記基準電圧値を設定して
出力するオフセット調整器を有することを特徴とする請
求項１又は２記載の波形歪み検出装置。3. The waveform distortion detection means sets and outputs the reference voltage value so that the waveform distortion detection signal output in a state where a waveform having no distortion is input is always “0”. The waveform distortion detection device according to claim 1 or 2, further comprising an offset adjuster.
の変動分を検出するパワ検出器と、歪みがない波形が入
力されている状態で出力される波形歪み検出信号が常に
“０”になるように設定された基準電圧値をもつ基準電
圧信号を出力するオフセット調整器と、前記出力パワの
変動分に応じて前記基準電圧値を補正すると共に前記差
勤増幅器の利得を調整する補正回路を有することを特徴
とする請求項１又は２記載の波形歪み検出装置。4. The waveform distortion detecting means is a power detector for detecting a variation of the output power, and a waveform distortion detection signal output while a waveform having no distortion is input is always "0". And an offset adjuster for outputting a reference voltage signal having a reference voltage value set so that the reference voltage value is corrected according to the variation of the output power and the gain of the differential amplifier is adjusted. The waveform distortion detector according to claim 1 or 2, further comprising:
畳された入力光信号が前記波形歪み検出器に入力された
場合、前記電圧比較器は、前記雑音の成分を相殺するよ
うに、該雑音が重畳された反転信号及び非反転信号の差
分を取ることを特徴とする請求項１乃至４のいずれかに
記載の波形歪み検出装置。5. When a noise-superimposed input optical signal output from the differential amplifier is input to the waveform distortion detector, the voltage comparator cancels the noise component. 5. The waveform distortion detection device according to claim 1, wherein the difference between the inverted signal and the non-inverted signal on which noise is superimposed is calculated.
歪み変化に従って光伝送路の波長分散を制御し、波形歪
みの無い状態と比較して変化した分を補償する可変分散
補償器を有することを特徴とする請求項１乃至４のいず
れかに記載の波形歪み検出装置。6. A variable dispersion compensator for controlling the chromatic dispersion of an optical transmission line according to a change in waveform distortion based on whether the waveform distortion detection signal is positive or negative, and compensating for the changed amount as compared with a state without waveform distortion. The waveform distortion detection device according to any one of claims 1 to 4, characterized in that.
ス信号の等化増幅、リタイミング、及び識別再生の機能
が有効に動作した時点で該電気パルス信号を出力する光
受信器と、 該光受信器からの電気パルス信号の符号誤り率を検出し
て符号誤り率検出信号を出力する符号誤り率検出器と、 前記波形歪み検出信号及び前記符号誤り率検出信号のい
ずれを前記可変分散補償器に帰還するかを判断する補正
回路をさらに有し、 前記補正回路は、前記光受信器が電気パルス信号を出力
する時は前記符号誤り率検出信号を前記可変分散補償器
に帰還させ、前記光受信器が電気パルス信号を出力しな
い時は前記波形歪み検出信号を前記可変分散補償器に帰
還させることを特徴とする請求項６記載の波形歪み検出
装置。7. An optical receiver that outputs the electric pulse signal when the functions of equalizing amplification, retiming, and identification reproduction of the electric pulse signal from the opto-electric conversion means are effectively operated, and the optical receiver. A code error rate detector for detecting a code error rate of an electric pulse signal from a receiver and outputting a code error rate detection signal, and the variable dispersion compensator for either the waveform distortion detection signal or the code error rate detection signal. Further comprising a correction circuit for determining whether to return to the variable dispersion compensator, the correction circuit, when the optical receiver outputs an electrical pulse signal, returns the code error rate detection signal to the variable dispersion compensator, 7. The waveform distortion detecting device according to claim 6, wherein the waveform distortion detecting signal is fed back to the variable dispersion compensator when the receiver does not output the electric pulse signal.
れた入力光信号を電気パルス信号に変換する光電気変換
手段と、 所定の基準電圧値と波形歪みを生じた前記電気パルス信
号の電圧値との差を比較して増幅し、それぞれ非反転信
号及び反転信号として出力し、前記非反転信号及び前記
反転信号の平均値電圧の差をとって、前記電気パルス信
号の歪み状態がパルス圧縮かパルス拡がりかを示す波形
歪み検出信号として出力する波形歪み検出手段と、 前記電気パルス信号に対して前記光受信器の機能が有効
に動作した時点で入力される電気パルス信号の符号誤り
率を検出して符号誤り率検出信号を出力する符号誤り率
検出手段と、 前記光受信器が電気パルス信号を出力する時は前記符号
誤り率検出信号を受信側あるいは送信側の可変分散補償
器に帰還させ、前記光受信器が電気パルス信号を出力し
ない時は前記波形歪み検出信号を前記受信側あるいは前
記送信側の可変分散補償器に帰還させる補正手段を有
し、 前記光伝送路の波長分散による入力光信号波形の変化を
検出することを特徴とする波形歪み検出システム。8. An opto-electrical conversion means for converting an input optical signal propagating through an optical transmission line and received by an optical receiver into an electric pulse signal, and the electric pulse having a predetermined reference voltage value and a waveform distortion. The difference between the voltage value of the signal is compared and amplified, and output as a non-inverted signal and an inverted signal, respectively, and the difference in the average value voltage of the non-inverted signal and the inverted signal is taken to obtain the distortion state of the electric pulse signal. Waveform distortion detection means for outputting as a waveform distortion detection signal indicating whether the pulse compression or the pulse expansion, and the code of the electric pulse signal input when the function of the optical receiver effectively operates for the electric pulse signal A code error rate detecting means for detecting an error rate and outputting a code error rate detection signal, and a variable dispersion compensation for the code error rate detection signal on the receiving side or the transmitting side when the optical receiver outputs an electric pulse signal. And a correction means for returning the waveform distortion detection signal to the variable dispersion compensator on the receiving side or the transmitting side when the optical receiver does not output an electric pulse signal, A waveform distortion detection system characterized by detecting a change in an input optical signal waveform due to wavelength dispersion.
幅器と、 前記非反転及び前記反転信号をそれぞれ所定周波の信号
へ変換し、平均値化する第１及び第２の低域フィルタ
と、 前記２つの平均値化された信号の差をとって、前記電気
パルス信号の歪み状態がパルス圧縮かパルス拡がりかを
示す波形歪み検出信号として出力する電圧比較器とを有
することを特徴とする請求項８記載の波形歪み検出シス
テム。9. The waveform distortion detecting means comprises: a differential amplifier which outputs the non-inverted signal and the inverted signal; and a non-inverted signal and an inverted signal which are respectively converted into signals of a predetermined frequency and averaged. 1st and 2nd low pass filter, voltage comparison which outputs the difference between the two averaged signals and outputs as a waveform distortion detection signal indicating whether the distortion state of the electric pulse signal is pulse compression or pulse expansion 9. The waveform distortion detection system according to claim 8, further comprising:
気変換手段からの前記電気パルス信号に対して等化増
幅、リタイミング、及び識別再生の機能が有効に動作し
た時点で該電気パルス信号を出力する光受信器を有する
ことを特徴とする請求項９記載の波形歪み検出システ
ム。10. The electrical pulse signal is detected by the code error rate detection means when the functions of equalizing amplification, retiming, and identification reproduction are effectively operated on the electrical pulse signal from the photoelectric conversion means. The waveform distortion detection system according to claim 9, further comprising an optical receiver that outputs
パルス信号に変換するステップ（１）と、 前記電気パルス信号の歪み状態がパルス圧縮かパルス拡
がりかを検出するステップ（２）と、 所定の基準電圧値と波形歪みを生じた前記電気パルス信
号の電圧値との差を比較して増幅し、それぞれ非反転信
号及び反転信号として出力するステップ（３）と、 前記非反転信号及び前記反転信号をそれぞれ所定周波の
信号へ変換し、平均値化するステップ（４）と、 前記２つの平均値化された信号の差をとって波形歪み検
出信号として出力するステップ（５）を有し、 前記光伝送路の波長分散による信号波形の変化を検出す
ることを特徴とする波形歪み検出方法。11. A step (1) of converting an input optical signal propagating through an optical transmission line into an electric pulse signal, and a step (2) of detecting whether a distortion state of the electric pulse signal is pulse compression or pulse expansion. A step (3) of comparing and amplifying a difference between a predetermined reference voltage value and a voltage value of the electric pulse signal having the waveform distortion, and outputting the non-inverted signal and the inverted signal, respectively; The method further includes a step (4) of converting each of the inverted signals into a signal of a predetermined frequency and averaging, and a step (5) of taking a difference between the two averaged signals and outputting the difference as a waveform distortion detection signal. A waveform distortion detecting method, characterized in that a change in a signal waveform due to wavelength dispersion of the optical transmission line is detected.
ない波形が入力されている状態で出力される波形歪み検
出信号が常に“０”になるように、前記基準電圧値を設
定して出力するステップ（６）をさらに有することを特
徴とする請求項１１記載の波形歪み検出方法。12. In the step (3), the reference voltage value is set and output so that the waveform distortion detection signal output in the state where the waveform having no distortion is input is always “0”. The method for detecting waveform distortion according to claim 11, further comprising step (6).
換した後、前記電気パルス信号の出力パワの変動分を検
出するステップ（７）と、 歪みがない波形が入力されている状態で出力される波形
歪み検出信号が常に“０”になるように設定された基準
電圧値をもつ基準電圧信号を出力するステップ（８）
と、 前記出力パワの変動分に応じて前記基準電圧値の補正と
前記ステップ（３）の処理を行う差動増幅器の利得を調
整するステップ（９）をさらに有することを特徴とする
請求項１１又は１２記載の波形歪み検出方法。13. A step (7) of detecting a variation of the output power of the electric pulse signal after converting the input optical signal into an electric pulse signal, and outputting the waveform with no distortion. Outputting a reference voltage signal having a reference voltage value set so that the waveform distortion detection signal is always "0" (8)
And a step (9) of adjusting the reference voltage value and adjusting the gain of a differential amplifier that performs the process of step (3) according to the variation of the output power. Alternatively, the waveform distortion detection method according to item 12.
形歪み変化に従って光伝送路の波長分散を制御し、波形
歪みの無い状態と比較して変化した分を補償するステッ
プ（１０）を有することを特徴とする請求項１１乃至１
３のいずれかに記載の波形歪み検出方法。14. A step (10) of controlling chromatic dispersion of an optical transmission line according to a change in waveform distortion based on whether the waveform distortion detection signal is positive or negative, and compensating for the changed amount as compared with a state without waveform distortion. 11. The method according to claim 11, wherein
The waveform distortion detection method according to any one of 3 above.
ルス信号の等化増幅、リタイミング、及び識別再生の機
能が有効に動作した時点で該電気パルス信号を出力する
ステップ（１１）と、 該光受信器からの電気パルス信号の符号誤り率を検出し
て符号誤り率検出信号を出力するステップ（１２）と、 前記波形歪み検出信号及び前記符号誤り率検出信号のい
ずれを前記可変分散補償器に帰還するかを判断するステ
ップ（１３）をさらに有し、 前記光受信器が電気パルス信号を出力する時は前記符号
誤り率検出信号を前記可変分散補償器に帰還させ、前記
光受信器が電気パルス信号を出力しない時は前記波形歪
み検出信号を前記可変分散補償器に帰還させるステップ
（１４）を有することを特徴とする請求項１４記載の波
形歪み検出方法。15. A step (11) of outputting the electric pulse signal when the functions of equalizing amplification, retiming, and identification reproduction of the electric pulse signal from the photoelectric conversion means are effectively operated, A step (12) of detecting a code error rate of an electric pulse signal from an optical receiver and outputting a code error rate detection signal; and the variable dispersion compensator for determining either the waveform distortion detection signal or the code error rate detection signal. Further comprising a step (13) of determining whether to return to the variable dispersion compensator when the optical receiver outputs an electric pulse signal. 15. The waveform distortion detection method according to claim 14, further comprising a step (14) of feeding back the waveform distortion detection signal to the variable dispersion compensator when an electric pulse signal is not output.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001394746A JP4038656B2 (en) | 2001-12-26 | 2001-12-26 | Waveform distortion detection system |
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| JP2001394746A JP4038656B2 (en) | 2001-12-26 | 2001-12-26 | Waveform distortion detection system |
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| JP2003198467A true JP2003198467A (en) | 2003-07-11 |
| JP4038656B2 JP4038656B2 (en) | 2008-01-30 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7324758B2 (en) | 2002-11-21 | 2008-01-29 | Fujitsu Limited | Optical dispersion monitoring apparatus and optical dispersion monitoring method, and optical transmission system using same |
| JP2010141786A (en) * | 2008-12-15 | 2010-06-24 | Mitsubishi Electric Corp | Optical transmission system, and optical transmission apparatus |
| JP2012178858A (en) * | 2012-04-27 | 2012-09-13 | Nippon Telegr & Teleph Corp <Ntt> | Cross-point detection circuit of receiving optical signal and optical receiving apparatus using the same |
-
2001
- 2001-12-26 JP JP2001394746A patent/JP4038656B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7324758B2 (en) | 2002-11-21 | 2008-01-29 | Fujitsu Limited | Optical dispersion monitoring apparatus and optical dispersion monitoring method, and optical transmission system using same |
| JP2010141786A (en) * | 2008-12-15 | 2010-06-24 | Mitsubishi Electric Corp | Optical transmission system, and optical transmission apparatus |
| JP2012178858A (en) * | 2012-04-27 | 2012-09-13 | Nippon Telegr & Teleph Corp <Ntt> | Cross-point detection circuit of receiving optical signal and optical receiving apparatus using the same |
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| Publication number | Publication date |
|---|---|
| JP4038656B2 (en) | 2008-01-30 |
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