JP2002204210A - Device and method for optical reception - Google Patents
Device and method for optical receptionInfo
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- JP2002204210A JP2002204210A JP2000400988A JP2000400988A JP2002204210A JP 2002204210 A JP2002204210 A JP 2002204210A JP 2000400988 A JP2000400988 A JP 2000400988A JP 2000400988 A JP2000400988 A JP 2000400988A JP 2002204210 A JP2002204210 A JP 2002204210A
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- Prior art keywords
- optical
- signal
- coupler
- receiver
- optical receiver
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Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は光受信器、特に光フ
ァイバーを使用する光通信システムにおける閾値を自動
的に調整する自動閾値調整回路を備える光受信器及び光
受信方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical receiver, and more particularly to an optical receiver having an automatic threshold adjusting circuit for automatically adjusting a threshold in an optical communication system using an optical fiber and an optical receiving method.
【0002】[0002]
【従来の技術】光ファイバを使用する光通信は、大通信
容量、優れた対ノイズ特性等により従来の電気通信に代
わり加入者電話、データ通信およびLAN(ローカルエ
リアネットワーク)等の分野で急速に普及しつつある。2. Description of the Related Art Optical communication using optical fibers is rapidly replacing conventional telecommunications in fields such as subscriber telephones, data communication, and LANs (local area networks) due to their large communication capacity and excellent noise immunity. Spreading.
【0003】斯かる技術分野における従来技術は、例え
ば特開2000−236298号公報の「自動分散補償
回路およびそれを用いた光伝送システム」、特開平11
−68657号公報の「波長分散制御のための方法と装
置および分散量検出方法」特開昭62−134535号
公報の「ファイバオプチック分散方法および装置」およ
び特開平10−163962号公報の「自動分散補償式
光伝送システム」等に開示されている。The prior art in such a technical field is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2000-236298, "Automatic dispersion compensation circuit and optical transmission system using the same,"
"Method and Apparatus for Controlling Chromatic Dispersion and Method of Detecting Dispersion Amount" in JP-A-68657, "Fiberoptic Dispersion Method and Apparatus" in JP-A-62-134535, and "Automatic Method and Apparatus" in JP-A-10-163962. And the like.
【0004】D−WDM(Dense Wavelength Divisio
n Multiplexing)システムにおいては、30〜100
程度の異なる波長の光信号が、それぞれ異なった劣化
(又は受信エラー等)を持って光受信器に入力される。
これに対して、受信器では、基本的に全て同一構成およ
び調整で実現するのが好ましい。しかし、従来技術で
は、特定(又は基本)波長の信号で調整されるため、そ
の他の波長の信号を受信する場合には、基本波長の信号
に比較して劣化が大きい場合があった。[0004] D-WDM (Dense Wavelength Divisio)
n Multiplexing) system, 30 to 100
Optical signals of different wavelengths are input to the optical receiver with different degradations (or reception errors or the like).
On the other hand, it is preferable that all receivers are basically realized by the same configuration and adjustment. However, in the related art, since adjustment is performed using a signal of a specific (or fundamental) wavelength, when a signal of another wavelength is received, there is a case where deterioration is greater than that of a signal of the fundamental wavelength.
【0005】[0005]
【発明が解決しようとする課題】例えば基幹系光通信に
おいて、伝送路に1.3μm零分散ファイバを使用し、
1.5μm帯の光信号を伝送する場合に、約18ps/nm/km
の分散を持つことが知られている。この分散の影響によ
る光信号の劣化のため、長距離伝送において光信号を正
しく送受信できない場合がある。特に、D−WDMの場
合には、1nm以下の間隔で30〜100以上の光信号を
一括して送信するので、送信する光信号の波長が多岐に
わたる。そのため、伝送距離又は波長により、それぞれ
の光信号が分散の影響で受ける劣化の程度が異なってし
まう。伝送路の分散をある波長を基準に0になるように
補償を行ったとしても、その他の波長では基準とした光
信号との波長差の分だけ分散が残ってしまう。これによ
り引き起こされる光波形の劣化の程度によって、受信器
の識別再生部での劣化が生じ、正しく信号を伝送できな
いといった問題があった。For example, in backbone optical communication, a 1.3 μm zero-dispersion fiber is used for a transmission line.
Approximately 18 ps / nm / km when transmitting optical signals in the 1.5 μm band
Is known to have a variance of Due to the deterioration of the optical signal due to the influence of the dispersion, the optical signal may not be transmitted and received correctly in long-distance transmission. In particular, in the case of D-WDM, 30 to 100 or more optical signals are transmitted collectively at intervals of 1 nm or less, so that the wavelengths of the transmitted optical signals are diversified. Therefore, the degree of deterioration of each optical signal affected by dispersion differs depending on the transmission distance or the wavelength. Even if the dispersion of the transmission line is compensated so as to be 0 with reference to a certain wavelength, the dispersion remains at other wavelengths by the wavelength difference from the reference optical signal. Depending on the degree of deterioration of the optical waveform caused by this, there is a problem that deterioration occurs in the discriminating / reproducing unit of the receiver and a signal cannot be transmitted correctly.
【0006】[0006]
【発明の目的】従って、本発明の目的は、上述した課題
を解決又は軽減し、波長分散による劣化の程度に合わせ
て識別再生部の閾値を制御することにより受信劣化を防
ぐ光受信器及び光受信方法を提供することである。SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to solve or mitigate the above-mentioned problems, and to control the threshold value of the discrimination / reproduction unit in accordance with the degree of deterioration due to chromatic dispersion, thereby preventing the reception deterioration from occurring. The purpose is to provide a receiving method.
【0007】[0007]
【課題を解決するための手段】本発明の光受信器は、そ
れぞれ異なる波長の光を使用する複数の光送信器および
監視用光送信器を含む光送信部と、光ファイバ伝送路の
両端にWDMカプラを含む伝送部と、複数の光受信部お
よび監視用光受信器を含む光受信部とを有するWDMシ
ステムの光受信器であって、WDMカプラを介して受信
する光信号を分岐する光カプラと、この光カプラにより
分岐された一方の光を増幅する光アンプと、この光アン
プの出力側に接続される識別再生部と、光アンプにより
分岐された他方の光を電気信号に変換する光―電気変換
回路と、この光―電気変換回路の出力側に接続されたロ
ーパスフィルタと、このローパスフィルタの出力信号お
よび上述した監視用光受信器の出力信号の位相差を検出
する位相差検出回路と、この位相差検出回路の出力を入
力とし識別再生部の閾値を制御する閾値調整回路を備え
る。SUMMARY OF THE INVENTION An optical receiver according to the present invention comprises: an optical transmission section including a plurality of optical transmitters each using light of a different wavelength and a monitoring optical transmitter; What is claimed is: 1. An optical receiver for a WDM system, comprising: a transmission unit including a WDM coupler; and an optical reception unit including a plurality of optical receivers and a monitoring optical receiver, wherein the optical receiver splits an optical signal received via the WDM coupler. A coupler, an optical amplifier that amplifies one of the lights split by the optical coupler, an identification reproducing unit connected to an output side of the optical amplifier, and converts the other light split by the optical amplifier into an electric signal. An optical-to-electrical conversion circuit, a low-pass filter connected to the output side of the optical-to-electrical conversion circuit, and a phase difference detector for detecting a phase difference between an output signal of the low-pass filter and an output signal of the above-mentioned monitoring optical receiver. Times When provided with a threshold adjustment circuit that controls the threshold of the reproducing unit receives the output of the phase difference detecting circuit.
【0008】また、本発明の光受信器の好適実施形態に
よると、WDMシステムに使用される複数の光受信器を
同一構成とする。光アンプと識別再生部間に受光部およ
び等化増幅器を備える。識別再生部として、PLLを使
用する識別再生回路を用いる。伝送する光信号を1.5
μm帯とし、伝送路に1.3μm帯零分散ファイバを使
用する。According to a preferred embodiment of the optical receiver of the present invention, a plurality of optical receivers used in the WDM system have the same configuration. A light receiving unit and an equalizing amplifier are provided between the optical amplifier and the identification reproducing unit. An identification reproduction circuit using a PLL is used as the identification reproduction unit. The optical signal to be transmitted is 1.5
The transmission line is a 1.3 μm band zero dispersion fiber.
【0009】更に、本発明の光受信方法は、それぞれ異
なる波長の光を使用する複数の光送信器および監視制御
用光送信器を含む光送信部と、光ファイバ伝送路の両端
に配置されたWDMカプラを含む伝送部と、複数の光受
信器および監視用光受信器を含む光受信部とを有するW
DMシステムの光受信方法において、WDMカプラを介
して受信する光信号を光カプラにより分岐し、分岐され
た一方の光を増幅した後、識別再生し、前記光カプラに
よる分岐された他方の光を電気信号に変換してローパス
フィルタに通し、該ローパスフィルタの出力信号および
監視用光受信器の出力信号の位相差に基づいて前記識別
再生の閾値を制御する。Further, in the optical receiving method of the present invention, an optical transmitting unit including a plurality of optical transmitters using different wavelengths of light and a supervisory control optical transmitter, and the optical transmitting unit are disposed at both ends of an optical fiber transmission line. W having a transmission unit including a WDM coupler and an optical reception unit including a plurality of optical receivers and a monitoring optical receiver
In an optical receiving method of a DM system, an optical signal received via a WDM coupler is branched by an optical coupler, one of the branched lights is amplified, and then discriminated and reproduced, and the other light branched by the optical coupler is separated. The signal is converted into an electric signal and passed through a low-pass filter, and the threshold value of the identification reproduction is controlled based on the phase difference between the output signal of the low-pass filter and the output signal of the monitoring optical receiver.
【0010】[0010]
【発明の実施の形態】以下、本発明による光受信器及び
光受信方法の好適実施形態の構成および動作を、添付図
面を参照して詳細に説明する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration and operation of a preferred embodiment of an optical receiver and an optical receiving method according to the present invention will be described below in detail with reference to the accompanying drawings.
【0011】先ず、図1は、本発明による光受信器及び
光受信方法が適用可能な光伝送システムのシステム構成
図である。この光伝送システムは、光送信部、光伝送部
および光受信部により構成される。光送信部は、複数の
光送信器1、2、監視制御用光送信器3および低周波重
畳回路4を含んでいる。光伝送部は、WDMカプラ5、
伝送路(光ファイバー)6およびWDMカプラ7を含ん
でいる。また、光受信部は、複数の光受信器10、20
および監視用光受信器30を含んでいる。FIG. 1 is a system configuration diagram of an optical transmission system to which an optical receiver and an optical receiving method according to the present invention can be applied. This optical transmission system includes an optical transmission unit, an optical transmission unit, and an optical reception unit. The optical transmitter includes a plurality of optical transmitters 1 and 2, a supervisory control optical transmitter 3, and a low-frequency superimposing circuit 4. The optical transmission unit is a WDM coupler 5,
The transmission path (optical fiber) 6 and the WDM coupler 7 are included. Further, the optical receiving unit includes a plurality of optical receivers 10 and 20.
And a monitoring optical receiver 30.
【0012】図1の光伝送システムは、監視制御用の第
1光信号波と、光主信号用の第2信号波を持つWDMシ
ステムの場合について説明する。尚、これは本発明の単
なる例示であり、本発明は波長数に制限はない。光送信
部の光送信器1は、例えば1.552μmの光主信号を
送信する。光送信器2は、例えば1.600μmの光主
信号を送信する。また、監視制御用光送信器3は、例え
ば1.520μmの光信号を送信する。低周波重畳回路
4は、光送信器1および2の光主信号に、それぞれ監視
制御用の低周波のパルス信号を重畳する。また、図1に
示す如く、光送信器1、2は、光アンプ(増幅器)1
a、2aを含み、それぞれの光主信号と監視制御用の光信
号を増幅する。そして、光伝送部のWDMカプラ5は、
これら光送信器1、2および監視制御用光送信器3から
の光波長を合成する。The optical transmission system shown in FIG. 1 will be described as a WDM system having a first optical signal wave for monitoring and control and a second signal wave for an optical main signal. Note that this is merely an example of the present invention, and the present invention has no limitation on the number of wavelengths. The optical transmitter 1 of the optical transmitter transmits an optical main signal of, for example, 1.552 μm. The optical transmitter 2 transmits an optical main signal of, for example, 1.600 μm. The supervisory control optical transmitter 3 transmits an optical signal of, for example, 1.520 μm. The low-frequency superimposing circuit 4 superimposes a low-frequency pulse signal for monitoring and control on the optical main signals of the optical transmitters 1 and 2, respectively. Further, as shown in FIG. 1, optical transmitters 1 and 2 include an optical amplifier (amplifier) 1.
a, 2a, and amplifies each optical main signal and the optical signal for monitoring and control. And the WDM coupler 5 of the optical transmission unit is
The optical wavelengths from the optical transmitters 1 and 2 and the supervisory control optical transmitter 3 are combined.
【0013】送信された光信号は、光ファイバを使用す
る伝送路6(この例では80km)を伝搬される。そし
て、WDMカプラ7にて分岐され、それぞれ光受信器1
0、20、30に入力される。The transmitted optical signal is propagated on a transmission line 6 (80 km in this example) using an optical fiber. Then, the light is branched by the WDM coupler 7 and the optical receiver 1
0, 20, and 30 are input.
【0014】次に、図2は、図1中に示される本発明に
よる光受信器(例えば光受信器10)の第1実施形態の
構成を示すブロック図である。尚、光受信器10および
20は同一構成である。また、監視用光受信器30は、
監視制御信号用であり、光カプラ101、光−電気変換
する光−電気変換回路103およびそこから低周波信号
を抽出するローパスフィルタ104については同様であ
る。光波長数を増やした場合には、光受信器10、20
等の数も増加する。FIG. 2 is a block diagram showing the configuration of the first embodiment of the optical receiver (eg, optical receiver 10) according to the present invention shown in FIG. The optical receivers 10 and 20 have the same configuration. Further, the monitoring optical receiver 30 includes:
The same applies to the optical coupler 101, the optical-to-electrical conversion circuit 103 for performing optical-to-electrical conversion, and the low-pass filter 104 for extracting a low-frequency signal therefrom, for monitoring control signals. When the number of optical wavelengths is increased, the optical receivers 10, 20
Etc. also increase.
【0015】光受信器10は、光カプラ101、光アン
プ102、光―電気変換回路103、ローパスフィルタ
104、位相差検出回路105、受光部106、等化増
幅部107、CLK(クロック)用フィルタ108、識
別再生部109および閾値調整回路110により構成さ
れている。ここで、光カプラ101は、入力された光信
号を分岐する。光―電気変換回路103は、光カプラ1
01により分岐された光信号を光−電気変換する。ロー
パスフィルタ104、光−電気変換回路103により電
気信号に変換された信号から重畳した低周波信号を抽出
する。位相差検出回路105は、ローパスフィルタ10
4によって検出された位相と、受信器30にて検出され
た位相とを比較する。The optical receiver 10 includes an optical coupler 101, an optical amplifier 102, an optical-electrical conversion circuit 103, a low-pass filter 104, a phase difference detection circuit 105, a light receiving section 106, an equalizing amplification section 107, and a CLK (clock) filter. 108, an identification reproducing unit 109 and a threshold adjustment circuit 110. Here, the optical coupler 101 splits the input optical signal. The optical-electrical conversion circuit 103 includes the optical coupler 1
01 is subjected to optical-electrical conversion of the optical signal split by 01. The low-pass filter 104 extracts a superposed low-frequency signal from the signal converted into an electric signal by the optical-electrical conversion circuit 103. The phase difference detection circuit 105 includes the low-pass filter 10
4 is compared with the phase detected by the receiver 30.
【0016】次に、本発明による光受信器の動作を、図
1乃至図3を参照して説明する。ここでは、監視制御用
の光信号、第1光信号波および第2光信号波のWDMシ
ステムの構成について説明する。1.550μmの光主
信号を送信する光送信器1と、1.600μmの光主信
号を送信する光送信器2と、監視制御用の1.520μ
mの光信号を送信する監視制御用光送信器3には、それ
ぞれ同期のとれた低周波のパルス信号を重畳する低周波
重畳回路4にて低周波の信号を重畳する。これらの光主
信号は光アンプ1a、2aを経て、また監視制御用の光信
号はそのままWDMカプラ5に入力される。低周波信号
の重畳された、それぞれの光信号の位相関係は、図1中
のAに示す。送信された光信号は、光ファイバーを使用
する伝送路6の80kmを伝搬される。そして、WDM
カプラ7にて分岐された後の位相関係は、それぞれ伝送
路の分散の影響を受けてA’のようになる。Next, the operation of the optical receiver according to the present invention will be described with reference to FIGS. Here, the configuration of the WDM system of the monitoring control optical signal, the first optical signal wave, and the second optical signal wave will be described. An optical transmitter 1 for transmitting an optical main signal of 1.550 μm, an optical transmitter 2 for transmitting an optical main signal of 1.600 μm, and 1.520 μ for monitoring and control
The low-frequency superimposing circuit 4 superimposing the synchronized low-frequency pulse signal is superimposed on the supervisory control optical transmitter 3 transmitting the m optical signal. These optical main signals pass through the optical amplifiers 1a and 2a, and the optical signals for monitoring and control are directly input to the WDM coupler 5. The phase relationship between the respective optical signals on which the low-frequency signal is superimposed is shown in FIG. The transmitted optical signal propagates through 80 km of the transmission line 6 using an optical fiber. And WDM
The phase relationship after being branched by the coupler 7 is as shown by A 'under the influence of the dispersion of the transmission path.
【0017】光受信器10、20に入力される光信号
は、それぞれ基準にとった1.520μmと比較して11
8nsec(ナノ秒)および46nsecの位相差を生じる。こ
の位相差は、通常の位相差検出回路で検出するには十分
な値である。受信器10では、入力された光を光カプラ
101にて分岐する。光カプラ101により分岐された
一方は、主信号として光アンプ102にて増幅され、受
光部106へ入力される。ここから等化増幅部107で
等化増幅およびCLK用フィルタ108でCLK抽出を
行い、識別再生部109へ入力される。光カプラ101
で分岐された他方の光信号は、光−電気変換する光−電
気変換回路103により電気信号に変換され、ローパス
フィルタ104にて重畳した低周波信号を抽出する。こ
こで、検出された位相は、同様に検出された光受信器3
0の信号の位相と位相差検出回路105にて比較され
る。The optical signals input to the optical receivers 10 and 20 are compared with 1.520 μm, which is a reference, respectively.
This produces a phase difference of 8 nsec (nanoseconds) and 46 nsec. This phase difference is a value sufficient to be detected by a normal phase difference detection circuit. In the receiver 10, the input light is split by the optical coupler 101. One branched by the optical coupler 101 is amplified by the optical amplifier 102 as a main signal and input to the light receiving unit 106. From here, the equalization amplification section 107 performs equalization amplification and CLK extraction with the CLK filter 108, and inputs the same to the identification reproduction section 109. Optical coupler 101
The other optical signal branched by is converted into an electric signal by an optical-electrical conversion circuit 103 that performs optical-electrical conversion, and a low-frequency signal superimposed by a low-pass filter 104 is extracted. Here, the detected phase is the same as the detected optical receiver 3.
The phase of the 0 signal is compared with the phase difference detection circuit 105.
【0018】図3は、分散と最適な識別レベルの関係を
簡単に示す説明図である。図3(a)は分散0の場合を
示し、(b)は分散が小さい場合を示し、(c)は分散
が大きい場合を示す。一般に、分散による波形劣化で
は、図3(a)〜(c)から明らかな如く、識別の最適
値は「0」側近づく傾向がある。従って、位相差検出回
路105で示された値に基づき、閾値調整回路110に
て識別再生部109の電圧を調整する。これにより、如
何なる波長の光信号を使用する場合でも常に、最適な識
別レベルを維持することが可能である。FIG. 3 is an explanatory diagram simply showing the relationship between the variance and the optimum identification level. 3A shows a case where the variance is 0, FIG. 3B shows a case where the variance is small, and FIG. 3C shows a case where the variance is large. Generally, in waveform deterioration due to dispersion, as is apparent from FIGS. 3A to 3C, the optimum value of identification tends to approach the “0” side. Therefore, based on the value indicated by the phase difference detection circuit 105, the threshold adjustment circuit 110 adjusts the voltage of the identification reproduction unit 109. Thereby, it is possible to always maintain the optimum discrimination level even when an optical signal of any wavelength is used.
【0019】次に、図4は、本発明による光受信器の第
2実施形態の構成図を示す。尚、この光受信器10’に
おいて、図3に示す光受信器10の構成要素に対応する
構成要素には、便宜上、同様の参照符号を使用する。光
受信器10’は、光カプラ101、光アンプ102、光
―電気変換回路103、ローパスフィルタ104、位相
差検出回路105、受光部106およびPLL(Phase
Locked Loop)を使用する識別再生回路120により
構成される。この他の実施形態では、 主信号部分が、
フィルタを使用するクロック抽出による等化増幅と識別
再生回路ではなく、これに代わりPLLを使用する識別
再生回路120としている。Next, FIG. 4 shows a configuration diagram of a second embodiment of the optical receiver according to the present invention. In the optical receiver 10 ', the same reference numerals are used for the components corresponding to the components of the optical receiver 10 shown in FIG. 3 for convenience. The optical receiver 10 'includes an optical coupler 101, an optical amplifier 102, an optical-electrical conversion circuit 103, a low-pass filter 104, a phase difference detection circuit 105, a light receiving unit 106, and a PLL (Phase
It is composed of an identification reproduction circuit 120 using a locked loop. In another embodiment, the main signal portion is
Instead of the equalization amplification and identification reproduction circuit using clock extraction using a filter, the identification reproduction circuit 120 uses a PLL instead.
【0020】以上、本発明による光受信器及び光受信方
法の好適実施形態の構成および動作を詳述した。しか
し、斯かる実施形態は、本発明の単なる例示に過ぎず、
何ら本発明を限定するものではないことに留意された
い。本発明の要旨を逸脱することなく、特定用途に応じ
て種々の変形変更が可能であること、当業者には容易に
理解できよう。The configuration and operation of the preferred embodiment of the optical receiver and the optical receiving method according to the present invention have been described above in detail. However, such embodiments are merely exemplary of the present invention,
It should be noted that the present invention is not limited in any way. It will be readily apparent to those skilled in the art that various modifications can be made in accordance with the particular application without departing from the spirit of the invention.
【0021】[0021]
【発明の効果】以上の説明から理解される如く、本発明
の光受信器及び光受信方法によると、次の如き実用上の
顕著な効果が得られる。即ち、伝送路が切り替わり分散
量が変化した場合でも、最適値に合わせて識別再生部の
閾値を自動的に調整することが可能である。従って、受
信波長によって個別に閾値を調整する必要がなくなる。As will be understood from the above description, according to the optical receiver and the optical receiving method of the present invention, the following remarkable practical effects can be obtained. That is, even when the transmission path is switched and the amount of dispersion changes, the threshold value of the identification reproducing unit can be automatically adjusted to the optimum value. Therefore, it is not necessary to individually adjust the threshold according to the reception wavelength.
【図1】本発明による光受信器及び光受信方法を適用し
得るWDMシステムのシステム構成図である。FIG. 1 is a system configuration diagram of a WDM system to which an optical receiver and an optical receiving method according to the present invention can be applied.
【図2】図1中に示される本発明による光受信器の第1
実施形態の構成を示すブロック図である。FIG. 2 shows a first embodiment of the optical receiver according to the invention shown in FIG.
FIG. 2 is a block diagram illustrating a configuration of the embodiment.
【図3】図2に示す光受信器の動作説明図である。FIG. 3 is an operation explanatory diagram of the optical receiver shown in FIG. 2;
【図4】本発明による光受信器の第2実施形態の構成を
示すブロック図である。FIG. 4 is a block diagram showing a configuration of a second embodiment of the optical receiver according to the present invention.
1、2 光送信器 3 監視制御用光送信器 4 低周波重畳回路 5、7 WDMカプラ 6 伝送路(光ファイバ) 10、20 光受信器 30 監視用光受信器 101 光カプラ 102 光アンプ 103 光―電気変換回路 104 ローパスフィルタ 105 位相差検出回路 106 受光部 107 等化増幅部 109 識別再生部 110 閾値調整回路 120 PLLを使用する識別再生回路 1, 2 optical transmitter 3 supervisory control optical transmitter 4 low frequency superposition circuit 5, 7 WDM coupler 6 transmission line (optical fiber) 10, 20 optical receiver 30 supervisory optical receiver 101 optical coupler 102 optical amplifier 103 light -Electric conversion circuit 104 Low-pass filter 105 Phase difference detection circuit 106 Light receiving unit 107 Equalization amplification unit 109 Identification reproduction unit 110 Threshold adjustment circuit 120 Identification reproduction circuit using PLL
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 FI テーマコート゛(参考) H04J 14/00 14/02 ──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat ゛ (Reference) H04J 14/00 14/02
Claims (6)
光送信器および監視制御用光送信器を含む光送信部と、
光ファイバ伝送路の両端に配置されたWDMカプラを含
む伝送部と、複数の光受信器および監視用光受信器を含
む光受信部とを有するWDMシステムの光受信器におい
て、 前記WDMカプラを介して受信する光信号を分岐する光
カプラと、該カプラにより分岐された一方の光を増幅す
る光アンプと、該光アンプの出力側に接続される識別再
生部と、前記光カプラによる分岐された他方の光を電気
信号に変換する光―電気変換回路と、該光―電気変換回
路の出力側に接続されたローパスフィルタと、該ローパ
スフィルタの出力信号および前記監視用光受信器の出力
信号の位相差を検出する位相差検出回路と、該位相差検
出回路の出力を入力とし前記識別再生部の閾値を制御す
る閾値調整回路とを備えることを特徴とする光受信器。An optical transmitter including a plurality of optical transmitters each using light of a different wavelength and an optical transmitter for supervisory control;
An optical receiver of a WDM system including a transmission unit including a WDM coupler disposed at both ends of an optical fiber transmission line and an optical reception unit including a plurality of optical receivers and a monitoring optical receiver. An optical coupler that splits an optical signal to be received by the optical amplifier, an optical amplifier that amplifies one of the lights split by the coupler, an identification reproducing unit connected to an output side of the optical amplifier, and an optical coupler that is split by the optical coupler. An optical-electrical conversion circuit for converting the other light into an electric signal, a low-pass filter connected to the output side of the optical-electrical conversion circuit, and an output signal of the low-pass filter and an output signal of the monitoring optical receiver. An optical receiver, comprising: a phase difference detection circuit that detects a phase difference; and a threshold adjustment circuit that receives an output of the phase difference detection circuit as an input and controls a threshold of the identification reproducing unit.
の光受信器を同一構成とすることを特徴とする請求項1
に記載の光受信器。2. The apparatus according to claim 1, wherein the plurality of optical receivers used in the WDM system have the same configuration.
An optical receiver according to claim 1.
および等化増幅部を備えることを特徴とする請求項1又
は2に記載の光受信器。3. The optical receiver according to claim 1, further comprising a light receiving unit and an equalizing amplifier between said optical amplifier and said reproducing unit.
ocked Loop)を使用する識別再生回路を用いることを
特徴とする請求項1又は2に記載の光受信器。4. A phase-locked loop (PLL) as said discrimination reproducing section.
3. The optical receiver according to claim 1, wherein an identification reproduction circuit using an ocked loop is used.
前記伝送路に1.3μm帯零分散ファイバを使用するこ
とを特徴とする請求項1乃至4の何れかに記載の光受信
器。5. An optical signal to be transmitted having a band of 1.5 μm,
5. The optical receiver according to claim 1, wherein a 1.3 μm band zero dispersion fiber is used for the transmission line.
光送信器および監視制御用光送信器を含む光送信部と、
光ファイバ伝送路の両端に配置されたWDMカプラを含
む伝送部と、複数の光受信器および監視用光受信器を含
む光受信部とを有するWDMシステムの光受信方法にお
いて、 WDMカプラを介して受信する光信号を光カプラにより
分岐し、分岐された一方の光を増幅した後、識別再生
し、前記光カプラによる分岐された他方の光を電気信号
に変換してローパスフィルタに通し、該ローパスフィル
タの出力信号および監視用光受信器の出力信号の位相差
に基づいて前記識別再生の閾値を制御することを特徴と
する光受信方法。6. An optical transmission unit including a plurality of optical transmitters each using light of a different wavelength and an optical transmitter for supervisory control,
In an optical receiving method of a WDM system having a transmitting unit including a WDM coupler disposed at both ends of an optical fiber transmission line and an optical receiving unit including a plurality of optical receivers and a monitoring optical receiver, The optical signal to be received is split by an optical coupler, one of the split lights is amplified, and then discriminated and reproduced. The other light split by the optical coupler is converted into an electric signal and passed through a low-pass filter. An optical receiving method, comprising: controlling a threshold value of the identification and reproduction based on a phase difference between an output signal of a filter and an output signal of a monitoring optical receiver.
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2007021161A1 (en) * | 2005-08-19 | 2007-02-22 | Korea Advanced Institute Of Science And Technology | A receiver having an apparatus for varying decision threshold level and an optical transmission system having the same |
US7253943B2 (en) | 2003-09-05 | 2007-08-07 | Samsung Electronics Co., Ltd. | Phase optimization apparatus and method for obtaining maximum extinction ratio in mach-zehnder interferometer wavelength converter using cross phase modulation of semiconductor optical amplifier |
JP2008042493A (en) * | 2006-08-04 | 2008-02-21 | Fujitsu Ltd | Optical receiving circuit and its identification level control method |
-
2000
- 2000-12-28 JP JP2000400988A patent/JP3582488B2/en not_active Expired - Fee Related
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7253943B2 (en) | 2003-09-05 | 2007-08-07 | Samsung Electronics Co., Ltd. | Phase optimization apparatus and method for obtaining maximum extinction ratio in mach-zehnder interferometer wavelength converter using cross phase modulation of semiconductor optical amplifier |
WO2007021161A1 (en) * | 2005-08-19 | 2007-02-22 | Korea Advanced Institute Of Science And Technology | A receiver having an apparatus for varying decision threshold level and an optical transmission system having the same |
KR100706874B1 (en) * | 2005-08-19 | 2007-04-12 | 한국과학기술원 | The apparatus for varying decision threshold level in the receiver of light communication system |
JP2008517552A (en) * | 2005-08-19 | 2008-05-22 | コリア アドバンスト インスティチュート オブ サイエンス アンド テクノロジー | Receiver having apparatus for changing judgment threshold level and optical transmission system having the receiver |
US7920797B2 (en) | 2005-08-19 | 2011-04-05 | Korea Advanced Institute Of Science And Technology | Receiver having an apparatus for varying decision threshold level and an optical transmission system having the same |
JP2008042493A (en) * | 2006-08-04 | 2008-02-21 | Fujitsu Ltd | Optical receiving circuit and its identification level control method |
JP4729454B2 (en) * | 2006-08-04 | 2011-07-20 | 富士通株式会社 | Optical receiving circuit and identification level control method thereof |
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