JPH05313025A - Transmission distortion compensating device, transmission distortion compensating light receiving device and transmission system - Google Patents
Transmission distortion compensating device, transmission distortion compensating light receiving device and transmission systemInfo
- Publication number
- JPH05313025A JPH05313025A JP4114649A JP11464992A JPH05313025A JP H05313025 A JPH05313025 A JP H05313025A JP 4114649 A JP4114649 A JP 4114649A JP 11464992 A JP11464992 A JP 11464992A JP H05313025 A JPH05313025 A JP H05313025A
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- Japan
- Prior art keywords
- optical fiber
- wavelength
- transmission
- light receiving
- receiving device
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Links
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- Light Guides In General And Applications Therefor (AREA)
- Optical Couplings Of Light Guides (AREA)
- Optical Communication System (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、ＣＡＴＶ等のアナロ
グ信号を伝送する光通信分野に使用する伝送歪補償装置
と伝送歪補償受光装置と伝送システムに関するものであ
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission distortion compensating device, a transmission distortion compensating light receiving device and a transmission system used in the optical communication field for transmitting analog signals such as CATV.
【０００２】[0002]
【従来の技術】図８に、従来の波長１３００nm帯アナロ
グ光伝送システムの構成図を示す。光送信部は、映像信
号入力端子１、増幅器２、及び信号用半導体レーザ３か
らなっている。光伝送路は、零分散波長が１３００nmの
単一モード光ファイバ４である。光受信部は、受光装置
５、増幅器６、及び、映像信号出力端子７からなってい
る。このようなシステムによれば、４０チャンネルのア
ナログAM映像信号を１０km程度の距離にわたって無中継
で伝送することができる。2. Description of the Related Art FIG. 8 is a block diagram of a conventional 1300 nm band analog optical transmission system. The optical transmitter includes a video signal input terminal 1, an amplifier 2, and a signal semiconductor laser 3. The optical transmission line is a single mode optical fiber 4 having a zero dispersion wavelength of 1300 nm. The light receiving unit includes a light receiving device 5, an amplifier 6, and a video signal output terminal 7. According to such a system, analog AM video signals of 40 channels can be transmitted without a relay over a distance of about 10 km.
【０００３】また、最近、１５５０nm帯の光を光のまま
直接増幅することができるエルビウムドープ光ファイバ
増幅器の出現により、これを用いたアナログ光伝送シス
テムの開発も行われている。図９に、従来のエルビウム
ドープ光ファイバ増幅器を用いた波長１５５０nm帯アナ
ログ光伝送システムの構成図を示す。８は波長１５５０
nm帯のＤＦＢレーザ、９は波長１４８０nm帯の半導体レ
ーザ励起のエルビウムドープ光ファイバ増幅器、１０は
１＊１６の光ファイバ分岐器、１１は零分散波長が１３
００nmの光ファイバ、１２は受光装置でありＩｎＧａＡ
ｓのフォトダイオードあるいはアバランシェフォトダイ
オードである。Further, recently, with the advent of an erbium-doped optical fiber amplifier capable of directly amplifying light in the 1550 nm band as light, an analog optical transmission system using the same has been developed. FIG. 9 shows a configuration diagram of a wavelength 1550 nm band analog optical transmission system using a conventional erbium-doped optical fiber amplifier. 8 is the wavelength 1550
DFB laser in the nm band, 9 is an erbium-doped optical fiber amplifier pumped by a semiconductor laser in the wavelength of 1480 nm, 10 is a 1 * 16 optical fiber branching device, 11 is a zero dispersion wavelength of 13
00 nm optical fiber, 12 is a light receiving device, InGaA
s photodiode or avalanche photodiode.
【０００４】ＤＦＢレーザ８は、ＡＭ−ＦＤＭあるいは
ＦＭ−ＦＤＭのアナログ信号で強度変調され、ＤＦＢレ
ーザ８から出射された信号光は、光ファイバ増幅器９で
増幅された後光ファイバ分岐器１０で分岐され、分岐さ
れた信号光は１０kmの光ファイバ１１を伝送した後、受
光装置１２で受光される。エルビウムドープ光ファイバ
増幅器９は、波長１５５０nm帯で高利得を有するため、
ブースターアンプとして用いればヘッドエンドからユー
ザ宅までをすべて光化した全光分配システムが構築で
き、１００チャンネル以上の映像分配サービスや高品位
ＴＶ映像分配サービス等の提供も可能となる。The DFB laser 8 is intensity-modulated with an analog signal of AM-FDM or FM-FDM, and the signal light emitted from the DFB laser 8 is amplified by an optical fiber amplifier 9 and then branched by an optical fiber branching device 10. The branched and branched signal light is transmitted through the optical fiber 11 of 10 km and then received by the light receiving device 12. Since the erbium-doped optical fiber amplifier 9 has a high gain in the wavelength 1550 nm band,
If it is used as a booster amplifier, it is possible to construct an all-optical distribution system in which everything from the head end to the user's home is made light, and it is possible to provide a video distribution service of 100 channels or more and a high-definition TV video distribution service.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら上記のよ
うなエルビウムドープ光ファイバ増幅器を用いたアナロ
グ光伝送システムでは、システム設計の許容度が大幅に
広がるが、信号用半導体レーザとしては波長１５５０nm
帯のものを用いなければならない。一方、光ファイバは
零分散波長１３００nmの１３００nm帯用の光ファイバが
広く普及し敷設が進んでいるため、波長１５５０nm帯の
光伝送においてもこの光ファイバ網が利用される。とこ
ろが、半導体レーザをアナログ信号で強度変調を行う
と、同時に周波数も変調されてしまい、このような周波
数変調された波長１５５０nmの光が前記光ファイバを伝
送すると、光信号の周波数変動が同ファイバが１５５０
nm帯で持つ大きな波長分散によって光の強度変動に変換
されて、強度変調された光信号を大きく歪ませてしま
う。However, in the analog optical transmission system using the erbium-doped optical fiber amplifier as described above, the tolerance of the system design greatly expands, but the wavelength of the signal semiconductor laser is 1550 nm.
You must use a belt. On the other hand, as an optical fiber, an optical fiber for the 1300 nm band having a zero dispersion wavelength of 1300 nm has been widely spread and is being installed. Therefore, this optical fiber network is also used for optical transmission in the wavelength of 1550 nm band. However, when the semiconductor laser is intensity-modulated with an analog signal, the frequency is also modulated at the same time, and when such frequency-modulated light having a wavelength of 1550 nm is transmitted through the optical fiber, the frequency fluctuation of the optical signal may occur in the fiber. 1550
Due to the large chromatic dispersion in the nm band, it is converted into intensity variation of light, and the intensity-modulated optical signal is greatly distorted.
【０００６】この発明の目的は、波長１５５０nm帯の信
号光が零分散波長１３００nmの光ファイバを伝送される
ことによって生じる伝送歪を低減し、低歪のアナログ光
伝送を実現する伝送歪補償装置と伝送歪補償受光装置と
伝送システムを提供することである。An object of the present invention is to provide a transmission distortion compensator for reducing transmission distortion caused by transmission of signal light in the wavelength band of 1550 nm through an optical fiber having a zero-dispersion wavelength of 1300 nm and realizing low distortion analog optical transmission. To provide a transmission distortion compensation light receiving device and a transmission system.
【０００７】[0007]
【課題を解決するための手段】請求項１記載の伝送歪補
償装置は、透過率が波長依存性を有する波長フィルタを
介して第１および第２の光ファイバを光学的に結合して
いる。請求項２記載の伝送歪補償装置は、請求項１記載
の伝送歪補償装置において、波長フィルタが両面に反射
膜を有するエタロン板からなり、第１の光ファイバから
の入射光に対して波長フィルタの入射面を傾斜させる制
御装置を設けたことを特徴とする。In the transmission distortion compensator according to the first aspect of the present invention, the first and second optical fibers are optically coupled via a wavelength filter whose transmittance has wavelength dependency. A transmission distortion compensator according to a second aspect is the transmission distortion compensator according to the first aspect, wherein the wavelength filter is an etalon plate having reflective films on both surfaces, and the wavelength filter is provided for the incident light from the first optical fiber. It is characterized in that a control device for inclining the incident surface of is provided.
【０００８】請求項３記載の伝送歪補償受光装置は、光
ファイバと、透過率が波長依存性を有する波長フィルタ
と、受光素子とを備え、光ファイバから出射した光が波
長フィルタを通過した後、受光素子に入射するようにし
ている。請求項４記載の伝送歪補償受光装置は、請求項
３記載の伝送歪補償受光装置において、波長フィルタが
両面に反射膜を有するエタロン板からなり、光ファイバ
からの入射光に対して波長フィルタの入射面を傾斜させ
る制御装置を設けたことを特徴とする。A transmission distortion compensating light receiving device according to a third aspect of the present invention comprises an optical fiber, a wavelength filter having a transmittance having wavelength dependency, and a light receiving element, and the light emitted from the optical fiber passes through the wavelength filter. The light is incident on the light receiving element. The transmission distortion compensating light receiving device according to claim 4 is the transmission distortion compensating light receiving device according to claim 3, wherein the wavelength filter is an etalon plate having reflective films on both surfaces, and the wavelength filter is provided for the incident light from the optical fiber. It is characterized in that a control device for inclining the incident surface is provided.
【０００９】請求項５記載のアナログ光伝送システム
は、波長１５５０nm帯の半導体レーザと、エルビウムド
ープの光ファイバ増幅器と、請求項１記載の伝送歪補償
装置と、零分散波長が１３００nmである光ファイバと、
受光装置とを備え、アナログ変調された半導体レーザか
ら出射した信号光が、光ファイバ増幅器と伝送歪補償装
置と光ファイバを通過した後、受光装置に入射するよう
にしている。An analog optical transmission system according to claim 5 is a semiconductor laser having a wavelength of 1550 nm, an erbium-doped optical fiber amplifier, a transmission distortion compensator according to claim 1, and an optical fiber having a zero dispersion wavelength of 1300 nm. When,
A light receiving device is provided, and the signal light emitted from the analog-modulated semiconductor laser passes through the optical fiber amplifier, the transmission distortion compensating device, and the optical fiber, and then enters the light receiving device.
【００１０】請求項６記載のアナログ光伝送システム
は、波長１５５０nm帯の半導体レーザと、エルビウムド
ープの光ファイバ増幅器と、零分散波長が１３００nmで
ある光ファイバと、請求項３記載の伝送歪補償受光装置
とを備え、アナログ変調された半導体レーザから出射し
た信号光が、光ファイバ増幅器と光ファイバを通過した
後、伝送歪補償受光装置に入射するようにしている。According to a sixth aspect of the present invention, there is provided an analog optical transmission system in which a semiconductor laser having a wavelength of 1550 nm band, an erbium-doped optical fiber amplifier, an optical fiber having a zero dispersion wavelength of 1300 nm, and a transmission distortion compensation light receiving element according to the third aspect. And a signal light emitted from an analog-modulated semiconductor laser passes through an optical fiber amplifier and an optical fiber and then enters a transmission distortion compensation light receiving device.
【００１１】[0011]
【作用】請求項１および請求項３記載の構成によれば、
光信号の周波数変動が光ファイバの波長分散によって強
度変動に変換されて生じる伝送歪成分は、光信号の周波
数変動が波長フィルタの透過率の波長依存性によって強
度変動に変換される成分によって補償されて歪が低減す
る。According to the constitutions of claims 1 and 3,
The transmission distortion component that occurs when the frequency fluctuation of the optical signal is converted into the strength fluctuation by the wavelength dispersion of the optical fiber is compensated by the component where the frequency fluctuation of the optical signal is converted into the strength fluctuation by the wavelength dependence of the transmittance of the wavelength filter. Distortion is reduced.
【００１２】また、請求項２および請求項４記載の構成
によれば、波長フィルタが両面に反射膜を有するエタロ
ン板からなり、エタロン内の多重反射光の干渉により透
過率が波長依存性を有するので伝送歪を補償することが
できる。さらに、制御装置により入射光に対して波長フ
ィルタの入射面の傾斜を変えることにより、多重反射光
の干渉度合いが変化するため、透過率の波長依存性を制
御することができる。したがって、伝送距離（伝送歪
量）に応じて伝送歪補償量を制御することができる。According to the second and fourth aspects of the invention, the wavelength filter is composed of an etalon plate having reflecting films on both surfaces, and the transmittance has wavelength dependence due to the interference of multiple reflected lights in the etalon. Therefore, transmission distortion can be compensated. Further, by changing the inclination of the incident surface of the wavelength filter with respect to the incident light by the control device, the degree of interference of the multiple reflected light changes, so that the wavelength dependence of the transmittance can be controlled. Therefore, the transmission distortion compensation amount can be controlled according to the transmission distance (transmission distortion amount).
【００１３】請求項５および請求項６記載の構成によれ
ば、半導体レーザをアナログ信号で強度変調することに
より同時に周波数変調された波長１５５０nmの光が、零
波長分散１３００nmの光ファイバを伝送されると、光信
号の周波数変動が光ファイバの波長分散によって強度変
動に変換されて伝送歪を生じるが、この伝送歪成分は、
光信号の周波数変動が波長フィルタの透過率の波長依存
性によって強度変動に変換される成分によって補償され
て歪が低減する。According to the fifth and sixth aspects, the light having the wavelength of 1550 nm, which is frequency-modulated at the same time by intensity-modulating the semiconductor laser with the analog signal, is transmitted through the optical fiber having the zero wavelength dispersion of 1300 nm. And, the frequency fluctuation of the optical signal is converted into the strength fluctuation by the wavelength dispersion of the optical fiber, and the transmission distortion occurs.
The frequency fluctuation of the optical signal is compensated by the component converted into the strength fluctuation by the wavelength dependence of the transmittance of the wavelength filter, and the distortion is reduced.
【００１４】[0014]
【実施例】以下、この発明の実施例を図面に基づいて説
明する。 〔第１の実施例；請求項１に対応〕この発明の第１の実
施例の伝送歪補償装置の構成を図１に示す。この伝送歪
補償装置は、図１に示すように、零分散波長１３００nm
の第１および第２の光ファイバ１３および１４を、透過
率が波長依存性を有する波長フィルタ１５を介して光学
的に結合して形成したものである。波長フィルタ１５は
誘電体多層膜フィルタである。第１の光ファイバ１３を
出射した信号光はロッドレンズ１６で平行光となり、波
長フィルタ１５を透過した後、ロッドレンズ１７で第２
の光ファイバ１４に結合される。波長フィルタ１５の透
過率の波長依存性を図６に示す。信号波長の変化に対し
て透過率が線形に変化するように設計されている。Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment; Corresponding to Claim 1] FIG. 1 shows the configuration of a transmission distortion compensator according to a first embodiment of the present invention. This transmission distortion compensator has a zero dispersion wavelength of 1300 nm as shown in FIG.
The first and second optical fibers 13 and 14 are optically coupled to each other via a wavelength filter 15 whose transmittance has wavelength dependency. The wavelength filter 15 is a dielectric multilayer filter. The signal light emitted from the first optical fiber 13 becomes parallel light at the rod lens 16, passes through the wavelength filter 15, and then becomes second light at the rod lens 17.
Is coupled to the optical fiber 14. FIG. 6 shows the wavelength dependence of the transmittance of the wavelength filter 15. It is designed so that the transmittance changes linearly with changes in the signal wavelength.
【００１５】変調周波数ωm で周波数変調された光の波
長フィルタの透過率T は、数１で示される。The transmittance T of the wavelength filter for light frequency-modulated at the modulation frequency ω m is given by the following equation 1.
【００１６】[0016]
【数１】T=To｛１-Xcos(ωmt) ｝ ここで、X は波長変動が強度変動に変換される割合であ
る。一方、変調度m 、変調周波数ωm で強度変調された
光が波長分散を持った光ファイバを伝送したときの光出
力P は、数２で示され、高調波歪が発生する。## EQU00001 ## T = To {1-Xcos (.omega.mt)} where X is the rate at which wavelength fluctuations are converted into intensity fluctuations. On the other hand, the optical output P when the light intensity-modulated at the modulation degree m and the modulation frequency ωm is transmitted through the optical fiber having the wavelength dispersion is shown by the equation 2, and harmonic distortion occurs.
【００１７】[0017]
【数２】 P=Po｛１+mcos(ωmt)+Acos(2ωmt)+Bcos(3ωmt)+・・・｝ したがって、波長フィルタを透過し、且つ波長分散を持
った光ファイバを伝送したときの光出力Ptは、つぎの数
３で示される。[Equation 2] P = Po {1 + mcos (ωmt) + Acos (2ωmt) + Bcos (3ωmt) + ...} Therefore, when transmitting an optical fiber that passes through the wavelength filter and has wavelength dispersion The optical output Pt is shown by the following Expression 3.
【００１８】[0018]
【数３】 Pt＝PoTo｛１+(m-X)cos(ωmt)+(A-mX/2)cos(２ωmt) ｝ 上式より、波長フィルタのパラメータX を変化すること
により２次歪を補償できることがわかる。すなわち、光
信号の周波数変動が光ファイバの波長分散によって強度
変動に変換されて生じる伝送歪成分は、光信号の周波数
変動が波長フィルタの透過率の波長依存性によって強度
変動に変換される成分によって補償されて歪が低減す
る。## EQU00003 ## Pt = PoTo {1+ (mX) cos (ωmt) + (A-mX / 2) cos (2ωmt)} From the above equation, it is possible to compensate the second-order distortion by changing the parameter X of the wavelength filter. I understand. That is, the transmission distortion component generated by converting the frequency fluctuation of the optical signal into the strength fluctuation by the wavelength dispersion of the optical fiber is due to the component in which the frequency fluctuation of the optical signal is converted into the strength fluctuation by the wavelength dependence of the transmittance of the wavelength filter. Compensation reduces distortion.
【００１９】この実施例によれば、波長フィルタ１５で
ある誘電体多層膜フィルタ内の光の干渉により透過率が
波長依存性を有するので伝送歪を補償することができ、
波長１５５０nmの信号光を零分散波長１３００nmの光フ
ァイバ１０km伝送したときの歪を補償することができ
る。 〔第２の実施例；請求項３に対応〕この発明の第２の実
施例の伝送歪補償受光装置の構成を図２に示す。According to this embodiment, the transmission distortion can be compensated because the transmittance has wavelength dependence due to the interference of light in the dielectric multilayer filter which is the wavelength filter 15.
It is possible to compensate for distortion when a signal light having a wavelength of 1550 nm is transmitted over an optical fiber of 10 km having a zero dispersion wavelength of 1300 nm. [Second Embodiment: Corresponding to Claim 3] FIG. 2 shows the configuration of a transmission distortion compensating light receiving device according to a second embodiment of the present invention.
【００２０】この伝送歪補償受光装置は、図２に示すよ
うに、零分散波長１３００nmの光ファイバ１８と透過率
が波長依存性を有する波長フィルタ１９と受光素子２０
を備え、光ファイバ１８から出射した光が、波長フィル
タ１９を通過した後、受光素子２０に入射するものであ
る。波長フィルタ１９は誘電体多層膜フィルタである。
光ファイバ１８を出射した信号光はロッドレンズ３０で
集光され、波長フィルタ１９を透過した後、受光素子２
０で受光される。As shown in FIG. 2, this transmission distortion compensating light receiving device comprises an optical fiber 18 having a zero dispersion wavelength of 1300 nm, a wavelength filter 19 having a transmittance dependent on wavelength, and a light receiving element 20.
The light emitted from the optical fiber 18 enters the light receiving element 20 after passing through the wavelength filter 19. The wavelength filter 19 is a dielectric multilayer filter.
The signal light emitted from the optical fiber 18 is condensed by the rod lens 30, passes through the wavelength filter 19, and then is received by the light receiving element 2.
Light is received at 0.
【００２１】この実施例によれば、第１の実施例同様、
波長フィルタ１９である誘電体多層膜フィルタ内の光の
干渉により透過率が波長依存性を有するので伝送歪を補
償することができ、波長１５５０nmの信号光を零分散波
長１３００nmの光ファイバ１０km伝送したときの歪を補
償することができる。なお、第１および第２の実施例に
おいて、ファイバ融着型カプラまたは両面に反射膜を有
するエタロン板を波長フィルタ（１５，１９）として用
いてもよい。波長フィルタとしてファイバ融着型カプラ
を用いた場合は、ファイバ融着型カプラの分岐比が結合
長の違いによって波長依存性を有するので伝送歪を補償
することができ、また、伝送路である光ファイバと融着
接続できるため、挿入損失を低減することができる。波
長フィルタとして両面に反射膜を有するエタロン板を用
いた場合は、エタロン内の多重反射光の干渉により透過
率が波長依存性を有するので伝送歪を補償することがで
きる。According to this embodiment, like the first embodiment,
Since the transmittance has wavelength dependency due to the interference of light in the dielectric multilayer film filter which is the wavelength filter 19, transmission distortion can be compensated, and the signal light of wavelength 1550 nm is transmitted over the optical fiber 10 km of zero dispersion wavelength 1300 nm. The distortion at the time can be compensated. In addition, in the first and second embodiments, a fiber fusion type coupler or an etalon plate having reflective films on both sides may be used as the wavelength filter (15, 19). When a fiber fusion type coupler is used as the wavelength filter, the branching ratio of the fiber fusion type coupler has wavelength dependence due to the difference in the coupling length, so that transmission distortion can be compensated for, and the optical fiber that is the transmission line is also used. Since the fiber can be fusion-spliced, the insertion loss can be reduced. When an etalon plate having reflective films on both sides is used as the wavelength filter, the transmission distortion can be compensated because the transmittance has wavelength dependency due to the interference of multiple reflected light in the etalon.
【００２２】〔第３の実施例；請求項４に対応〕この発
明の第３の実施例の伝送歪補償受光装置の構成を図３に
示す。この伝送歪補償受光装置は、第２の実施例（図
２）における波長フィルタ１９の代わりに、両面に反射
膜を有するエタロン板によって形成した波長フィルタ２
１を用いるとともに、さらに入射光に対して波長フィル
タ２１の入射面を傾斜させる制御装置２２を設けてい
る。光ファイバ１８を出射した信号光はロッドレンズ３
０で集光され波長フィルタ２１を透過した後、受光素子
２０で受光される。波長フィルタ２１の透過率の波長依
存性は図７のようになるが、信号光の波長域で波長変化
に対して透過率が線形に変化するように設計されてい
る。図７(a) および(b) は、波長フィルタ２１を傾斜さ
せたときの透過率の波長依存性を示す図である。同図よ
り、波長フィルタ２１の傾斜を変えることにより波長変
動が強度変動に変換される割合を制御できることがわか
る。[Third Embodiment; Corresponding to Claim 4] FIG. 3 shows a configuration of a transmission distortion compensating light receiving device according to a third embodiment of the present invention. This transmission distortion compensating light receiving device has a wavelength filter 2 formed by an etalon plate having reflective films on both sides instead of the wavelength filter 19 in the second embodiment (FIG. 2).
1 is used, and a control device 22 for inclining the incident surface of the wavelength filter 21 with respect to the incident light is provided. The signal light emitted from the optical fiber 18 is the rod lens 3
After being collected at 0 and transmitted through the wavelength filter 21, it is received by the light receiving element 20. The wavelength dependence of the transmittance of the wavelength filter 21 is as shown in FIG. 7, but the transmittance is designed to change linearly with respect to the wavelength change in the signal light wavelength range. FIGS. 7A and 7B are diagrams showing the wavelength dependence of the transmittance when the wavelength filter 21 is tilted. From the figure, it can be seen that the rate at which the wavelength fluctuation is converted into the intensity fluctuation can be controlled by changing the inclination of the wavelength filter 21.
【００２３】この実施例によれば、両面に反射膜を有す
るエタロン板からなる波長フィルタ２１の入射面の傾斜
を変えることにより多重反射光の干渉度合いが変化する
ため、透過率の波長依存性を制御することができる。し
たがって、伝送距離（伝送歪量）に応じて伝送歪補償量
を制御することができ、波長１５５０nmの信号光を零分
散波長１３００nmの光ファイバ５kmから２０kmまで伝送
したときの歪を波長フィルタ２１の傾斜を変えることに
より補償することができる。According to this embodiment, the degree of interference of the multiple reflected light is changed by changing the inclination of the incident surface of the wavelength filter 21 made of an etalon plate having reflecting films on both sides, so that the wavelength dependence of the transmittance is changed. Can be controlled. Therefore, the transmission distortion compensation amount can be controlled according to the transmission distance (transmission distortion amount), and the distortion when the signal light with the wavelength of 1550 nm is transmitted from 5 km to 20 km of the optical fiber with the zero dispersion wavelength of 1300 nm is measured by the wavelength filter 21. It can be compensated by changing the slope.
【００２４】なお、第１の実施例（図１）の伝送歪補償
装置において、波長フィルタ１５の代わりにエタロン板
の波長フィルタ２１を用い、入射光に対して波長フィル
タ２１の入射面を傾斜させる制御装置２２を設けても、
この第３の実施例と同様の効果が得られる（請求項２に
対応）。上記第１〜第３の実施例では、各光学部品間で
の多重反射によって歪が発生しないように光軸とレンズ
の軸をずらせた構成としている。In the transmission distortion compensator of the first embodiment (FIG. 1), the wavelength filter 21 of the etalon plate is used instead of the wavelength filter 15, and the incident surface of the wavelength filter 21 is inclined with respect to the incident light. Even if the control device 22 is provided,
The same effect as the third embodiment can be obtained (corresponding to claim 2). In the above-mentioned first to third embodiments, the optical axis and the lens axis are offset so that distortion does not occur due to multiple reflection between the optical components.
【００２５】〔第４の実施例；請求項５に対応〕この発
明の第４の実施例のアナログ光伝送システムの構成を図
４に示す。図４において、１は映像信号入力端子、２，
６は増幅器、７は映像信号出力端子、２３は波長１５５
０nm帯のＤＦＢレーザ（半導体レーザ）、２４は波長１
４８０nm帯の半導体レーザ励起のエルビウムドープの光
ファイバ増幅器、２５は上記実施例の伝送歪補償装置、
２６は零分散波長１３００nmの長さ１０kmの光ファイ
バ、２７はＩｎＧａＡｓのアバランシェフォトダイオー
ドを受光素子とする受光装置、２９は１＊１６の光ファ
イバ分岐器である。[Fourth Embodiment; Corresponding to Claim 5] FIG. 4 shows the configuration of an analog optical transmission system according to a fourth embodiment of the present invention. In FIG. 4, 1 is a video signal input terminal, 2,
6 is an amplifier, 7 is a video signal output terminal, and 23 is a wavelength 155.
0nm band DFB laser (semiconductor laser), 24 wavelength 1
An erbium-doped optical fiber amplifier pumped by a semiconductor laser in the 480 nm band, 25 is the transmission distortion compensator of the above embodiment,
26 is an optical fiber having a zero dispersion wavelength of 1300 nm and a length of 10 km, 27 is a light receiving device using an InGaAs avalanche photodiode as a light receiving element, and 29 is a 1 * 16 optical fiber branching device.
【００２６】このアナログ光伝送システムは、図４に示
すように、波長１５５０nm帯のＤＦＢレーザ２３と、エ
ルビウムドープの光ファイバ増幅器２４と、伝送歪補償
装置２５と、零分散波長が１３００nmである光ファイバ
２６と、受光装置２７と、光ファイバ分岐器２９とを備
えている。ＤＦＢレーザ２３は４２チャンネルのＡＭ−
ＦＤＭのアナログ信号で強度変調され、ＤＦＢレーザ２
３から出射された信号光は、伝送歪補償装置２５を通過
した後、光ファイバ増幅器２４で増幅されて光ファイバ
分岐器２９で分岐され、分岐された信号光は光ファイバ
２６を伝送した後、受光装置２７で受光される。As shown in FIG. 4, this analog optical transmission system includes a DFB laser 23 having a wavelength of 1550 nm, an erbium-doped optical fiber amplifier 24, a transmission distortion compensator 25, and an optical signal having a zero dispersion wavelength of 1300 nm. A fiber 26, a light receiving device 27, and an optical fiber branching device 29 are provided. The DFB laser 23 is a 42-channel AM-
The intensity is modulated by the FDM analog signal, and the DFB laser 2
After passing through the transmission distortion compensator 25, the signal light emitted from 3 is amplified by the optical fiber amplifier 24 and branched by the optical fiber branching device 29, and the branched signal light is transmitted through the optical fiber 26. The light is received by the light receiving device 27.
【００２７】この実施例は、光ファイバ分岐器２９で分
岐された１６個の受光装置２７までの伝送距離がほぼ等
しいシステムである。このようなシステムでは、この実
施例のように送信側に一つの伝送歪補償装置２５を用い
るだけで１６個の受光装置２７で歪が低減された光信号
を受光することができる。このようにこの実施例によれ
ば、ＤＦＢレーザ２３をアナログ信号で強度変調するこ
とにより同時に周波数変調された波長１５５０nmの光
が、零波長分散１３００nmの光ファイバ２６を伝送する
と、光信号の周波数変動が光ファイバの波長分散によっ
て強度変動に変換されて伝送歪が生じるが、この伝送歪
成分は、光信号の周波数変動が伝送歪補償装置２５内の
波長フィルタの透過率の波長依存性によって強度変動に
変換される成分によって補償されて歪が低減する。This embodiment is a system in which the transmission distances to the 16 light receiving devices 27 branched by the optical fiber branching device 29 are substantially equal. In such a system, it is possible to receive optical signals with reduced distortion by the 16 light receiving devices 27 by using only one transmission distortion compensating device 25 on the transmitting side as in this embodiment. As described above, according to this embodiment, when the light having the wavelength of 1550 nm, which is frequency-modulated at the same time by intensity-modulating the DFB laser 23 with the analog signal, is transmitted through the optical fiber 26 having the zero wavelength dispersion of 1300 nm, the frequency fluctuation of the optical signal is generated. Is converted into intensity fluctuation due to wavelength dispersion of the optical fiber, and transmission distortion occurs. This transmission distortion component is intensity fluctuation due to wavelength dependence of transmittance of a wavelength filter in the transmission distortion compensator 25. The distortion is reduced by being compensated by the component converted to.
【００２８】〔第５の実施例；請求項６に対応〕この発
明の第５の実施例のアナログ光伝送システムの構成を図
５に示す。図５において、２８は図３に示す伝送歪補償
受光装置であり、図４に対応するものには同一符号を付
している。このアナログ光伝送システムは、図５に示す
ように、波長１５５０nm帯のＤＦＢレーザ２３と、エル
ビウムドープの光ファイバ増幅器２４と、零分散波長が
１３００nmである光ファイバ２６と伝送歪補償受光装置
２８とを備えている。アナログ変調されたＤＦＢレーザ
２３から出射した信号光は、光ファイバ増幅器２４で増
幅されて光ファイバ分岐器２９で分岐され、分岐された
信号光は光ファイバ２６を伝送した後、伝送歪補償受光
装置２８で受光される。[Fifth Embodiment: Corresponding to Claim 6] FIG. 5 shows the configuration of an analog optical transmission system according to a fifth embodiment of the present invention. In FIG. 5, 28 is the transmission distortion compensating light receiving device shown in FIG. 3, and those corresponding to FIG. 4 are designated by the same reference numerals. As shown in FIG. 5, this analog optical transmission system includes a DFB laser 23 having a wavelength of 1550 nm, an erbium-doped optical fiber amplifier 24, an optical fiber 26 having a zero dispersion wavelength of 1300 nm, and a transmission distortion compensating light receiving device 28. Is equipped with. The signal light emitted from the analog-modulated DFB laser 23 is amplified by the optical fiber amplifier 24 and branched by the optical fiber branching device 29, and the branched signal light is transmitted through the optical fiber 26, and then the transmission distortion compensation light receiving device. The light is received at 28.
【００２９】この実施例において、図４に示す第４の実
施例と異なるのは、光ファイバ分岐器２９で分岐された
１６個の受光素子までの伝送距離がそれぞれ違うこと
と、伝送歪補償装置２５の代わりに図３に示す伝送歪補
償受光装置２８を用いていることである。伝送距離が違
うと伝送後の波長分散による歪量が異なるが、伝送歪補
償受光装置２８の波長フィルタ２１（図３）のエタロン
板を傾斜させて歪補償量を制御することにより、１６個
の受光素子２０（図３）で歪が低減された光信号を受光
することができる。This embodiment is different from the fourth embodiment shown in FIG. 4 in that the transmission distances to the 16 light-receiving elements branched by the optical fiber branching device 29 are different from each other and the transmission distortion compensator. Instead of 25, the transmission distortion compensation light receiving device 28 shown in FIG. 3 is used. When the transmission distance is different, the amount of distortion due to chromatic dispersion after transmission is different. However, by tilting the etalon plate of the wavelength filter 21 (FIG. 3) of the transmission distortion compensating light receiving device 28 to control the amount of distortion compensation, The light receiving element 20 (FIG. 3) can receive an optical signal with reduced distortion.
【００３０】なお、上記第４および第５の実施例では、
１６分岐の例を示したが、光ファイバ増幅器と光ファイ
バ分岐器を多段接続すれば、低歪でさらに多分配が可能
となる。In the fourth and fifth embodiments described above,
Although an example of 16 branches is shown, if an optical fiber amplifier and an optical fiber branching device are connected in multiple stages, it is possible to further distribute with low distortion.
【００３１】[0031]
【発明の効果】請求項１記載の伝送歪補償装置および請
求項３記載の伝送歪補償受光装置は、光信号の周波数変
動が光ファイバの波長分散によって強度変動に変換され
て生じる伝送歪成分を、光信号の周波数変動が波長フィ
ルタの透過率の波長依存性によって強度変動に変換され
る成分によって補償することにより歪を低減することが
できる。According to the transmission distortion compensating apparatus of the first aspect and the transmission distortion compensating light receiving apparatus of the third aspect, the transmission distortion component generated when the frequency variation of the optical signal is converted into the intensity variation by the wavelength dispersion of the optical fiber is provided. The distortion can be reduced by compensating the frequency fluctuation of the optical signal with the component converted into the strength fluctuation by the wavelength dependence of the transmittance of the wavelength filter.
【００３２】また、請求項２記載の伝送歪補償装置およ
び請求項４記載の伝送歪補償受光装置は、波長フィルタ
が両面に反射膜を有するエタロン板からなり、エタロン
内の多重反射光の干渉により透過率が波長依存性を有す
るので伝送歪を補償することができる。さらに、制御装
置により入射光に対して波長フィルタの入射面の傾斜を
変えることにより、多重反射光の干渉度合いが変化する
ため、透過率の波長依存性を制御することができる。し
たがって、伝送距離（伝送歪量）に応じて伝送歪補償量
を制御することができる。Further, in the transmission distortion compensating device according to the second aspect and the transmission distortion compensating light receiving device according to the fourth aspect, the wavelength filter is composed of an etalon plate having reflective films on both sides, and the multiple reflection light in the etalon interferes with each other. Since the transmittance has wavelength dependency, transmission distortion can be compensated. Further, by changing the inclination of the incident surface of the wavelength filter with respect to the incident light by the control device, the degree of interference of the multiple reflected light changes, so that the wavelength dependence of the transmittance can be controlled. Therefore, the transmission distortion compensation amount can be controlled according to the transmission distance (transmission distortion amount).
【００３３】請求項５および請求項６記載のアナログ光
伝送システムは、半導体レーザをアナログ信号で強度変
調することにより同時に周波数変調された波長１５５０
nmの光が、零波長分散１３００nmの光ファイバを伝送さ
れると、光信号の周波数変動が光ファイバの波長分散に
よって強度変動に変換されて伝送歪を生じるが、この伝
送歪成分は、伝送歪補償装置（請求項５）あるいは伝送
歪補償受光装置（請求項６）を用いることにより、光信
号の周波数変動が波長フィルタの透過率の波長依存性に
よって強度変動に変換される成分によって補償すること
ができ、低歪のアナログ光伝送を実現することができ
る。また、エルビウムドープの光ファイバ増幅器で波長
１５５０nmの信号光を増幅できるため多分配することが
できる。According to the fifth and sixth aspects of the analog optical transmission system, the wavelength 1550 is simultaneously frequency-modulated by intensity-modulating the semiconductor laser with an analog signal.
When the light of wavelength nm is transmitted through the optical fiber with zero wavelength dispersion of 1300 nm, the frequency fluctuation of the optical signal is converted into the strength fluctuation due to the wavelength dispersion of the optical fiber to cause the transmission distortion. By using a compensating device (Claim 5) or a transmission distortion compensating light receiving device (Claim 6), the frequency fluctuation of the optical signal is compensated by the component converted into the intensity fluctuation by the wavelength dependence of the transmittance of the wavelength filter. Therefore, analog optical transmission with low distortion can be realized. Further, since the signal light having the wavelength of 1550 nm can be amplified by the erbium-doped optical fiber amplifier, it can be multi-distributed.
【図１】この発明の第１の実施例の伝送歪補償装置の構
成図である。FIG. 1 is a configuration diagram of a transmission distortion compensating apparatus according to a first embodiment of the present invention.
【図２】この発明の第２の実施例の伝送歪補償受光装置
の構成図である。FIG. 2 is a configuration diagram of a transmission distortion compensation light receiving device according to a second embodiment of the present invention.
【図３】この発明の第３の実施例の伝送歪補償受光装置
の構成図である。FIG. 3 is a configuration diagram of a transmission distortion compensation light receiving device of a third embodiment of the present invention.
【図４】この発明の第４の実施例のアナログ光伝送シス
テムの構成図である。FIG. 4 is a configuration diagram of an analog optical transmission system according to a fourth embodiment of the present invention.
【図５】この発明の第５の実施例のアナログ光伝送シス
テムの構成図である。FIG. 5 is a configuration diagram of an analog optical transmission system according to a fifth embodiment of the present invention.
【図６】この発明の第１の実施例の伝送歪補償装置に用
いた波長フィルタの透過率の波長依存性を示す図であ
る。FIG. 6 is a diagram showing the wavelength dependence of the transmittance of the wavelength filter used in the transmission distortion compensating apparatus of the first embodiment of the present invention.
【図７】この発明の第３の実施例の伝送歪補償受光装置
に用いた波長フィルタの透過率の波長依存性を示す図で
ある。FIG. 7 is a diagram showing the wavelength dependence of the transmittance of the wavelength filter used in the transmission distortion compensation light receiving device of the third embodiment of the present invention.
【図８】従来の波長１３００nm帯アナログ光伝送システ
ムの構成図である。FIG. 8 is a block diagram of a conventional 1300 nm band analog optical transmission system.
【図９】従来の波長１５５０nm帯アナログ光伝送システ
ムの構成図である。FIG. 9 is a block diagram of a conventional 1550 nm band analog optical transmission system.
１３ 第１の光ファイバ １４ 第２の光ファイバ １８，２６ 光ファイバ １５，１９，２１ 波長フィルタ ２０ 受光素子 ２２ 制御装置 ２３ ＤＦＢレーザ（半導体レーザ） ２４ エルビウムドープの光ファイバ増幅器 ２５ 伝送歪補償装置 ２７ 受光装置 ２８ 伝送歪補償受光装置 13 1st optical fiber 14 2nd optical fiber 18,26 Optical fiber 15,19,21 Wavelength filter 20 Photodetector 22 Control device 23 DFB laser (semiconductor laser) 24 Erbium-doped optical fiber amplifier 25 Transmission distortion compensator 27 Light receiving device 28 Transmission distortion compensation light receiving device
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.5 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｈ０４Ｂ 10/18 ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 5 Identification code Office reference number FI technical display location H04B 10/18
Claims (6)
タを介して第１および第２の光ファイバを光学的に結合
した伝送歪補償装置。1. A transmission distortion compensator in which a first optical fiber and a second optical fiber are optically coupled via a wavelength filter whose transmittance has wavelength dependency.
タロン板からなり、第１の光ファイバからの入射光に対
して前記波長フィルタの入射面を傾斜させる制御装置を
設けたことを特徴とする請求項１記載の伝送歪補償装
置。2. The wavelength filter is formed of an etalon plate having reflective films on both sides, and a control device for tilting the incident surface of the wavelength filter with respect to the incident light from the first optical fiber is provided. The transmission distortion compensator according to claim 1.
する波長フィルタと、受光素子とを備え、前記光ファイ
バから出射した光が前記波長フィルタを通過した後、前
記受光素子に入射するようにした伝送歪補償受光装置。3. An optical fiber, a wavelength filter having a transmittance having wavelength dependency, and a light receiving element, wherein light emitted from the optical fiber is incident on the light receiving element after passing through the wavelength filter. Distortion compensating light receiving device.
タロン板からなり、光ファイバからの入射光に対して前
記波長フィルタの入射面を傾斜させる制御装置を設けた
ことを特徴とする請求項３記載の伝送歪補償受光装置。4. The wavelength filter is formed of an etalon plate having reflective films on both sides, and a control device for tilting the incident surface of the wavelength filter with respect to incident light from an optical fiber is provided. The transmission distortion compensation light receiving device described.
ルビウムドープの光ファイバ増幅器と、請求項１記載の
伝送歪補償装置と、零分散波長が１３００nmである光フ
ァイバと、受光装置とを備え、アナログ変調された前記
半導体レーザから出射した信号光が、前記光ファイバ増
幅器と前記伝送歪補償装置と前記光ファイバを通過した
後、前記受光装置に入射するようにしたアナログ光伝送
システム。5. A semiconductor laser having a wavelength of 1550 nm, an erbium-doped optical fiber amplifier, the transmission distortion compensator according to claim 1, an optical fiber having a zero dispersion wavelength of 1300 nm, and a light receiving device, and an analog device. An analog optical transmission system in which the modulated signal light emitted from the semiconductor laser passes through the optical fiber amplifier, the transmission distortion compensator, and the optical fiber, and then enters the light receiving device.
ルビウムドープの光ファイバ増幅器と、零分散波長が１
３００nmである光ファイバと、請求項３記載の伝送歪補
償受光装置とを備え、アナログ変調された前記半導体レ
ーザから出射した信号光が、前記光ファイバ増幅器と前
記光ファイバを通過した後、前記伝送歪補償受光装置に
入射するようにしたアナログ光伝送システム。6. A semiconductor laser having a wavelength of 1550 nm, an erbium-doped optical fiber amplifier, and a zero dispersion wavelength of 1
An optical fiber having a wavelength of 300 nm and a transmission distortion compensating light receiving device according to claim 3, wherein the signal light emitted from the semiconductor laser that has been analog-modulated passes through the optical fiber amplifier and the optical fiber, and then the transmission is performed. An analog optical transmission system that is made to enter a distortion compensation light receiving device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4114649A JPH05313025A (en) | 1992-05-07 | 1992-05-07 | Transmission distortion compensating device, transmission distortion compensating light receiving device and transmission system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4114649A JPH05313025A (en) | 1992-05-07 | 1992-05-07 | Transmission distortion compensating device, transmission distortion compensating light receiving device and transmission system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05313025A true JPH05313025A (en) | 1993-11-26 |
Family
ID=14643097
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4114649A Pending JPH05313025A (en) | 1992-05-07 | 1992-05-07 | Transmission distortion compensating device, transmission distortion compensating light receiving device and transmission system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05313025A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5539563A (en) * | 1994-05-31 | 1996-07-23 | At&T Corp. | System and method for simultaneously compensating for chromatic dispersion and self phase modulation in optical fibers |
-
1992
- 1992-05-07 JP JP4114649A patent/JPH05313025A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5539563A (en) * | 1994-05-31 | 1996-07-23 | At&T Corp. | System and method for simultaneously compensating for chromatic dispersion and self phase modulation in optical fibers |
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