JP2000275143A - Wavelength-dispersion measuring apparatus - Google Patents
Wavelength-dispersion measuring apparatusInfo
- Publication number
- JP2000275143A JP2000275143A JP11080149A JP8014999A JP2000275143A JP 2000275143 A JP2000275143 A JP 2000275143A JP 11080149 A JP11080149 A JP 11080149A JP 8014999 A JP8014999 A JP 8014999A JP 2000275143 A JP2000275143 A JP 2000275143A
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- Prior art keywords
- light
- chromatic dispersion
- optical
- light receiving
- wavelength
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、光ファイバ等の光
伝送路の波長分散値を測定する装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the chromatic dispersion of an optical transmission line such as an optical fiber.
【０００２】[0002]
【従来の技術】光通信伝送路として利用されている光フ
ァイバには、光信号の群速度が波長によって異なる波長
分散特性がある。このため、光信号の搬送波に含まれる
波長成分の間で伝播遅延差が生じ、受信部では光信号波
形の歪み、劣化が生じる。2. Description of the Related Art An optical fiber used as an optical communication transmission line has a chromatic dispersion characteristic in which the group velocity of an optical signal varies depending on the wavelength. For this reason, a propagation delay difference occurs between the wavelength components included in the carrier of the optical signal, and the optical signal waveform is distorted and deteriorated in the receiving unit.
【０００３】このような波長分散による光信号の劣化を
最小限に抑えるためには、光信号の搬送波を光ファイバ
の波長分散が零になる波長に一致させる等の、なんらか
の方法で波長分散を精密に補償する対策が必要となる。
そのため、光通信システムを設計する上では、光ファイ
バの波長分散を正確に測定する技術が重要となってい
る。In order to minimize the deterioration of an optical signal due to such chromatic dispersion, the chromatic dispersion is precisely adjusted by some method such as making the carrier of the optical signal coincide with the wavelength at which the chromatic dispersion of the optical fiber becomes zero. It is necessary to take measures to compensate.
Therefore, in designing an optical communication system, a technique for accurately measuring the chromatic dispersion of an optical fiber is important.
【０００４】さらに、海底光通信システムのように、長
距離の光ファイバ通信を行うためには、光信号の強度を
強めるための中継器を光ファイバケーブルの途中に設置
する必要があるが、中継器として光ファイバ増幅器を用
いた多中継伝送路においては、補償を行わずに線形に再
生中継が行われている場合が多く、長い伝送路にわたっ
て波長分散の効果が累積されるという問題がある。この
ようなシステムにおいては、全伝送路の総波長分散が重
要な設計パラメータとなる。Further, in order to perform long-distance optical fiber communication as in a submarine optical communication system, it is necessary to install a repeater for increasing the intensity of an optical signal in the middle of the optical fiber cable. In a multi-relay transmission line using an optical fiber amplifier as a device, the regenerative relay is often performed linearly without compensation, and there is a problem that the effect of chromatic dispersion is accumulated over a long transmission line. In such a system, the total chromatic dispersion of all transmission paths is an important design parameter.
【０００５】また、光ファイバ増幅器を用いたシステム
で超高速、長距離伝送を実用化するためには、光ファイ
バ増幅器によって発生される自然放出光間のビート雑音
による受信感度の劣化を低減しなければならない問題も
ある。この対策としては、各中継器に波長幅で１ｎｍ程
度の光帯域フィルタを挿入し、この帯域外の自然放出光
の雑音を除去する方法が取られている。しかし、このよ
うなシステムの総波長分散を測定するためには、波長分
散測定に使用できる波長範囲が光フィルタの帯域内に限
定されるといった問題が生じる。[0005] Further, in order to put ultra-high speed and long distance transmission to practical use in a system using an optical fiber amplifier, it is necessary to reduce the deterioration of reception sensitivity due to beat noise between spontaneous emission light generated by the optical fiber amplifier. There are also issues that must be addressed. As a countermeasure, a method of inserting an optical bandpass filter having a wavelength width of about 1 nm into each repeater to remove noise of spontaneous emission light outside the band is adopted. However, in order to measure the total chromatic dispersion of such a system, there arises a problem that the wavelength range that can be used for chromatic dispersion measurement is limited to within the band of the optical filter.
【０００６】これらの問題を解決あるいは回避するため
に、単一波長の位相変調光を測定光とし、測定光の波長
分散に依存する強度変調振幅から総波長分散値を求める
方法が提案されている(A.R.CHRAPLYVY etc.(AT&T Bell
Laboratories), ELECTRONICSLETTERS, Vol.22, No.8, 4
09, 1986)。In order to solve or avoid these problems, a method has been proposed in which phase-modulated light of a single wavelength is used as measurement light, and a total chromatic dispersion value is obtained from an intensity modulation amplitude dependent on the chromatic dispersion of the measurement light. (ARCHRAPLYVY etc. (AT & T Bell
Laboratories), ELECTRONICSLETTERS, Vol.22, No.8, 4
09, 1986).
【０００７】以下、この方法を簡単に説明する。ある単
一光周波数のＣＷ（連続）光を位相変調して被測定物で
ある光ファイバに入射すると、元の光周波数から変調周
波数の整数倍ずれた複数の光を入射することとなり、光
ファイバの波長分散特性によって各周波数の光に速度差
が生じる。その結果、被測定物である光ファイバを伝播
した出射光は、この速度差によって強度変調を受ける。
すなわち、入射光の位相変調成分が光ファイバの波長分
散のために強度変調成分に変換されるため、この強度変
調成分を測定することによって、総波長分散値を求める
ことができる。Hereinafter, this method will be briefly described. When CW (continuous) light of a certain single optical frequency is phase-modulated and is incident on an optical fiber as an object to be measured, a plurality of lights which are shifted from the original optical frequency by an integral multiple of the modulation frequency are incident on the optical fiber. The wavelength dispersion characteristic causes a speed difference in the light of each frequency. As a result, the outgoing light propagating through the optical fiber, which is the device under test, is subjected to intensity modulation due to this speed difference.
That is, since the phase modulation component of the incident light is converted into the intensity modulation component due to the wavelength dispersion of the optical fiber, the total chromatic dispersion value can be obtained by measuring the intensity modulation component.
【０００８】この波長分散量に依存する強度変調成分を
測定することによって、総波長分散値を求める方法は、
光帯域フィルタを通過する単一波長の測定光のみを測定
することによって実現できるため、上述の海底光通信シ
ステムのような多中継伝送路の評価においても適用が可
能である。A method for obtaining a total chromatic dispersion value by measuring an intensity modulation component depending on the amount of chromatic dispersion is as follows.
Since it can be realized by measuring only the measurement light of a single wavelength that passes through the optical bandpass filter, it can be applied to the evaluation of a multi-repeater transmission line such as the above-mentioned submarine optical communication system.
【０００９】図４は、この報告で使用された波長分散測
定装置１００の構成を示すブロック図である。FIG. 4 is a block diagram showing the configuration of the chromatic dispersion measuring apparatus 100 used in this report.
【００１０】図４において、波長分散測定装置１００
は、光源２と、信号発生器３と、位相変調器４と、被測
定物（以下ＤＵＴと呼ぶ。）５と、受光器６と、信号処
理演算部７とから構成されており、波長 1.5μｍのＤＦ
Ｂ（Distributed Feed Back）レーザで光源２から出射
される出射光は、位相変調器４に入射され、信号発生器
３の信号に応じた位相変調を受ける。そして、位相変調
を受けた光は、長さ約５０ｋｍの1.3μｍ零分散単一モ
ード光ファイバであるＤＵＴ５に入射され、ＤＵＴ５か
らの出射光が受光器６で光強度に応じた電気信号に変換
された後、その電気信号が信号処理演算部７に入力され
る。信号処理演算部７では、測定光強度の変調周波数成
分と直流成分との比が取られる。この比は変調条件と総
波長分散値の関数であり、上記報告書中では、変調指数
π／２（ｒａｄ）、変調周波数４ＧHz付近で、従来の測
定法による実験値との一致が確認された旨、記載されて
いる。In FIG. 4, a chromatic dispersion measuring device 100
Is composed of a light source 2, a signal generator 3, a phase modulator 4, a device under test (hereinafter referred to as a DUT) 5, a light receiver 6, and a signal processing operation unit 7, and has a wavelength of 1.5. μm DF
Light emitted from the light source 2 by a B (Distributed Feed Back) laser is incident on the phase modulator 4 and undergoes phase modulation according to the signal of the signal generator 3. The light subjected to the phase modulation is incident on a DUT 5 which is a 1.3 μm zero-dispersion single mode optical fiber having a length of about 50 km, and the light emitted from the DUT 5 is converted into an electric signal corresponding to the light intensity by a light receiver 6. After that, the electric signal is input to the signal processing operation unit 7. In the signal processing operation unit 7, the ratio between the modulation frequency component of the measurement light intensity and the DC component is obtained. This ratio is a function of the modulation condition and the total chromatic dispersion value, and in the above report, agreement with experimental values obtained by a conventional measurement method was confirmed around a modulation index of π / 2 (rad) and a modulation frequency of 4 GHz. To the effect.
【００１１】ここで、単一光角周波数をωcとおき、位
相変調をＡsin(Ωｔ)とすれば、測定光の位相ψ(ｔ)は
（１）式で表せる。ただし、Ａは変調指数、Ωは変調角
周波数、ｔは時間である。 ψ(ｔ)＝ωcｔ＋Ａsin(Ωｔ) ・・・（１）Here, if the single light angular frequency is ωc and the phase modulation is Asin (Ωt), the phase 測定 (t) of the measurement light can be expressed by the following equation (1). Here, A is a modulation index, Ω is a modulation angular frequency, and t is time. ψ (t) = ωct + Asin (Ωt) (1)
【００１２】また、mを整数とすると、この式は、
（２）式で表せる位相ψｍ(ｔ)の光に展開できる。 ψｍ(ｔ)＝(ωc＋mΩ)ｔ ・・・（２） すなわち、搬送波の角周波数ωcを中心として、角周波
数間隔Ωで配置された光に展開される。また、変調指数
Ａによって、各周波数の光の振幅が決定される。Further, if m is an integer, this equation becomes:
It can be expanded to light having a phase Δm (t) expressed by the equation (2). ψm (t) = (ωc + mΩ) t (2) That is, the light is developed into light arranged at angular frequency intervals Ω around the angular frequency ωc of the carrier. Further, the amplitude of light at each frequency is determined by the modulation index A.
【００１３】これらの光が光ファイバ中を伝播すると、
波長分散によって各周波数に応じた遅延が生じる。伝播
した後の位相ψｍ(ｔ)の光は、例えば（３）式のように
表せる。 ψｍ(ｔ)＝(ωc＋mΩ)ｔ＋φｍ ・・・（３）When these lights propagate through the optical fiber,
The chromatic dispersion causes a delay corresponding to each frequency. The light having the phase ψm (t) after propagating can be expressed, for example, by Expression (3). ψm (t) = (ωc + mΩ) t + φm (3)
【００１４】位相遅れφｍは、波長分散に依存している
ため、各周波数ごとに異なる。また、受光部の出力光
（測定光）に観測される各周波数どうしのビート周波数
からビート角周波数Ωの成分をフィルタによって取り出
すと、その振幅は波長分散量Ｄに依存していることが分
かる。Since the phase delay φm depends on chromatic dispersion, it differs for each frequency. In addition, when a component of the beat angular frequency Ω is extracted from the beat frequency of each frequency observed in the output light (measurement light) of the light receiving unit by a filter, it is understood that the amplitude depends on the chromatic dispersion amount D.
【００１５】定性的であるが、このビート角周波数Ωの
振幅をδｉとおき、ＤＣレベルをｉ 0とすれば、概ね
（４）式のような関係となる。 δｉ/ｉ0＝ｇ(Ａ)sin(ｈ(Ω)Ｄ) ・・・（４） ここで、ｇ(Ａ)とｈ(Ω)は、それぞれ変調指数Ａとビー
ト角周波数Ωの関数である。[0015] Qualitatively, this beat angular frequency Ω
Let the amplitude be δi and the DC level be i 0If so, generally
The relationship is as shown in equation (4). δi / i0= G (A) sin (h (Ω) D) (4) where g (A) and h (Ω) are the modulation index A and the
It is a function of the angular frequency Ω.
【００１６】図５（ａ）〜（ｃ）は、受光部において、
フィルタを通過した測定光の受光強度を示す図であり、
図５（ａ）は、強度変調された測定光強度の時間変化を
示し、図５（ｂ）、（ｃ）は、波長分散値に対する強度
変調振幅の変化、すなわち（４）式を示す図である。図
５（ｂ）に示すように、変調指数Ａによって振幅の大き
さが変化し、図５（ｃ）に示すように、変調周波数（ビ
ート角周波数）Ωによって振幅の変動周期が変化する。
したがって、変調指数や変調周波数を大きくすることは
測定感度を上げることとなる。ただし、周期性を考慮す
ると、（５）式の条件内で、適当な変調周波数Ωの値を
選び、波長分散量を測定する必要がある。 ｜ｈ(Ω)Ｄ｜≦π／２ ・・・（５）FIGS. 5 (a) to 5 (c) show that the light receiving section
It is a diagram showing the received light intensity of the measurement light passed through the filter,
FIG. 5A shows a time change of the intensity-modulated measurement light intensity, and FIGS. 5B and 5C show a change of the intensity modulation amplitude with respect to the chromatic dispersion value, that is, the equation (4). is there. As shown in FIG. 5B, the amplitude changes according to the modulation index A, and as shown in FIG. 5C, the fluctuation period of the amplitude changes according to the modulation frequency (beat angle frequency) Ω.
Therefore, increasing the modulation index or the modulation frequency increases the measurement sensitivity. However, in consideration of the periodicity, it is necessary to select an appropriate value of the modulation frequency Ω and measure the amount of chromatic dispersion within the condition of Expression (5). | H (Ω) D | ≦ π / 2 (5)
【００１７】以上のように、従来の波長分散測定装置１
００では、単一波長光を用いることにより、遠端での波
長分散量を測定することが可能である。このため、利得
帯域の狭い光増幅器を用いた線形中継器を含む多中継伝
送路の波長分散値を一括して測定できる利点がある。As described above, the conventional chromatic dispersion measuring apparatus 1
In the case of 00, it is possible to measure the amount of chromatic dispersion at the far end by using single-wavelength light. Therefore, there is an advantage that the chromatic dispersion value of a multi-repeater transmission line including a linear repeater using an optical amplifier having a narrow gain band can be collectively measured.
【００１８】[0018]
【発明が解決しようとする課題】しかしながら、このよ
うな単一波長光を用いた従来の波長分散測定装置１００
では、変調周波数の振幅を測定しているために、波長分
散の絶対値を測定していることとなり、符号はわからな
いという問題点がある。However, such a conventional chromatic dispersion measuring apparatus 100 using such a single wavelength light.
In this case, since the amplitude of the modulation frequency is measured, the absolute value of the chromatic dispersion is measured, and the sign is not known.
【００１９】波長分散値の符号を知るための手段として
は、日本電信電話株式会社の富沢将人らによって発明さ
れた波長分散測定装置（特開平7-113722）がある。この
波長分散測定装置は、測定光強度を上げた時に光ファイ
バ中で発生する自己位相変調と、測定光に加えた位相変
調とが強め合うかどうかで波長分散の符号を求める装置
である。As a means for knowing the sign of the chromatic dispersion value, there is a chromatic dispersion measuring device (JP-A-7-113722) invented by Masato Tomizawa et al. Of Nippon Telegraph and Telephone Corporation. This chromatic dispersion measuring device is a device that obtains the sign of chromatic dispersion based on whether the self-phase modulation generated in the optical fiber when the intensity of the measuring light is increased and the phase modulation applied to the measuring light are strengthened.
【００２０】この波長分散測定装置は、上記従来例の図
４と同じ構成であり、光源が測定光強度を変えて出射で
きるように構成されている。この波長分散測定装置の動
作原理を簡単に説明する。まず、通常の測定光強度で
（４）式の振幅δｉ/ｉ0を測定し、この時に、波長分散
の絶対値も測定する。次に、測定光強度を光ファイバ伝
播に際して自己位相変調が生じる程度に十分強くして、
（４）式の振幅δｉ/ｉ0を測定し、通常測定の場合と比
較して波長分散の符号を求める。This chromatic dispersion measuring apparatus has the same configuration as that of the conventional example shown in FIG. 4, and is configured so that the light source can emit the light while changing the intensity of the measuring light. The operation principle of this chromatic dispersion measuring device will be briefly described. First, the amplitude δi / i 0 of the equation (4) is measured at a normal measurement light intensity, and at this time, the absolute value of the chromatic dispersion is also measured. Next, the intensity of the measurement light is made strong enough to cause self-phase modulation during optical fiber propagation,
The amplitude δi / i 0 in the equation (4) is measured, and the sign of the chromatic dispersion is obtained in comparison with the case of normal measurement.
【００２１】ここで、自己位相変調とは、光ファイバ中
の光強度が十分強いと光ファイバの屈折率が変化するた
めに、自分自身の光強度によって屈折率変化を介して位
相変調が生じる現象であり、強い短パルス光を伝送する
場合などに問題となる非線形現象の１つである。Here, the self-phase modulation is a phenomenon in which, when the light intensity in an optical fiber is sufficiently strong, the refractive index of the optical fiber changes. This is one of the nonlinear phenomena that becomes a problem when transmitting strong short-pulse light.
【００２２】さて、波長分散により位相変調が強度変調
に変換された測定光は、光強度変化に応じて自己位相変
調を生じるが、測定光の位相変調と自己位相変調が同位
相か逆位相かによって、みかけの変調指数Ａが変化する
ことにより、図５（ｂ）の点線のように、振幅δｉ/ｉ0
が変化する。これは、単に変調指数Ａを変えた場合の変
化と異なり、波長分散の符号に依存して変わっているた
め、２つの測定の振幅δｉ/ｉ0を比較すれば、波長分散
の符号が求められる。The measuring light whose phase modulation has been converted to intensity modulation by chromatic dispersion causes self-phase modulation in accordance with the change in light intensity. Whether the phase modulation of the measuring light and the self-phase modulation are in phase or opposite phase, respectively. As a result, as the apparent modulation index A changes, the amplitude δi / i 0 as shown by the dotted line in FIG.
Changes. This is different from the change when the modulation index A is simply changed, and changes depending on the sign of the chromatic dispersion. Therefore, the sign of the chromatic dispersion can be obtained by comparing the amplitudes δi / i 0 of the two measurements. .
【００２３】しかし、この波長分散測定装置では、自己
位相変調という非線形現象を取り扱うために、単一波長
の高出力の光源を、例えばＬＤ（Laser Diode）と光ア
ンプと光可変減衰器で構成する必要があるため、構成が
複雑で、かつ高価な装置となってしまう。However, in this chromatic dispersion measuring apparatus, a single-wavelength high-output light source is composed of, for example, an LD (Laser Diode), an optical amplifier, and an optical variable attenuator in order to handle a nonlinear phenomenon called self-phase modulation. This necessitates a complicated configuration and an expensive device.
【００２４】また、他の手段として、日本電信電話株式
会社の吉田誠史によって発明された波長分散測定装置
（特開平8-5516）がある。この波長分散測定装置は、測
定光にあらかじめ位相変調に同期した強度変調も加えて
おき、この強度変調と、波長分散により位相変調が変換
された結果の強度変調との位相関係から波長分散の符号
を求める装置である。As another means, there is a chromatic dispersion measuring apparatus (JP-A-8-5516) invented by Seiji Yoshida of Nippon Telegraph and Telephone Corporation. This chromatic dispersion measuring apparatus adds an intensity modulation synchronized with the phase modulation to the measurement light in advance, and determines the code of the chromatic dispersion based on the phase relationship between the intensity modulation and the intensity modulation obtained by converting the phase modulation by the chromatic dispersion. Is a device for obtaining
【００２５】図６は、この波長分散測定装置２００の構
成を示すブロック図である。波長分散測定装置２００
は、上記図４の波長分散装置１００の位相変調器４とＤ
ＵＴ５の間に強度変調器８を備え、信号発生器３が位相
変調器４と強度変調器８の変調同期を取るように構成さ
れており、他の波長分散装置１００と同一の部分には同
一符号を付している。FIG. 6 is a block diagram showing the configuration of the chromatic dispersion measuring apparatus 200. Chromatic dispersion measurement device 200
Are the phase modulators 4 and D of the wavelength dispersion device 100 of FIG.
An intensity modulator 8 is provided between the UTs 5 and the signal generator 3 is configured to synchronize the modulation of the phase modulator 4 and the intensity modulator 8. Signs are attached.
【００２６】波長分散測定装置２００は、上記の自己位
相変調を利用した波長分散測定装置（特開平7-113722）
と同様に、測定される強度変調光の位相が波長分散の符
号によって、π（ｒａｄ）ずれていることを利用して、
位相変調に同期して加えた強度変調により、振幅δｉ/
ｉ0が強められるかどうかに基づいて、波長分散の符号
を判定する装置である。The chromatic dispersion measuring device 200 is a chromatic dispersion measuring device utilizing the above-described self-phase modulation (Japanese Patent Laid-Open No. Hei 7-113722).
Similarly to the above, utilizing the fact that the phase of the measured intensity modulated light is shifted by π (rad) by the sign of the chromatic dispersion,
By the intensity modulation applied in synchronization with the phase modulation, the amplitude δi /
This is a device that determines the sign of chromatic dispersion based on whether i 0 is strengthened.
【００２７】しかし、波長分散測定装置２００は、光変
調器を２つ使用し、この２つの光変調器の同期を適切に
制御しなければならず、装置構成及び制御が複雑となる
ために、高価な装置となってしまっていた。However, the chromatic dispersion measuring apparatus 200 uses two optical modulators, and it is necessary to appropriately control the synchronization between the two optical modulators, and the configuration and control of the apparatus become complicated. It was an expensive device.
【００２８】また、先の波長分散測定装置（特開平7-11
3722）は、測定光の入射側で測定光の強度を変更する必
要があり、後の波長分散測定装置２００は、測定光の入
射側で測定光の制御を行うことが必要である。このた
め、両装置とも、従来の測定光のままでは波長分散の符
号を求めることができず、測定光を制御するための入射
側の装置構成によって、装置全体が複雑かつ高価なもの
となっている。Further, the chromatic dispersion measuring device described above (Japanese Unexamined Patent Publication No.
3722), it is necessary to change the intensity of the measurement light on the incident side of the measurement light, and the chromatic dispersion measuring apparatus 200 needs to control the measurement light on the incident side of the measurement light. Therefore, in both devices, the sign of the chromatic dispersion cannot be obtained with the conventional measurement light as it is, and the entire device becomes complicated and expensive due to the configuration of the incident side device for controlling the measurement light. I have.
【００２９】本発明の課題は、単一波長の従来の測定光
を用いて、光ファイバ等の光学素子の波長分散値及び符
号を受光側で容易に測定することのできる波長分散測定
装置を提供することである。An object of the present invention is to provide a chromatic dispersion measuring apparatus capable of easily measuring a chromatic dispersion value and a sign of an optical element such as an optical fiber on a light receiving side using a conventional measuring light having a single wavelength. It is to be.
【００３０】[0030]
【課題を解決するための手段】請求項１記載の発明の波
長分散測定装置は、光伝送路を伝播した測定光を直接受
光し、受光強度に応じた信号を出力する第１の受光手段
と、前記測定光を波長分散値が既知の分散素子を介して
受光し、受光強度に応じた信号を出力する第２の受光手
段と、前記第１の受光手段から出力される信号と、前記
第２の受光手段から出力される信号と、前記分散素子の
既知の波長分散値とに基づいて、前記光伝送路の波長分
散値を演算する演算手段と、を備えることを特徴として
いる。According to a first aspect of the present invention, there is provided a chromatic dispersion measuring apparatus comprising: a first light receiving means for directly receiving measurement light propagated through an optical transmission line and outputting a signal corresponding to a received light intensity; A second light receiving unit that receives the measurement light through a dispersion element having a known wavelength dispersion value and outputs a signal corresponding to a received light intensity, a signal output from the first light receiving unit, And a calculating means for calculating a chromatic dispersion value of the optical transmission line based on a signal output from the second light receiving means and a known chromatic dispersion value of the dispersion element.
【００３１】この請求項１記載の発明の波長分散測定装
置によれば、第１の受光手段は、光伝送路を伝播した測
定光を直接受光して、受光強度に応じた信号を出力し、
第２の受光手段は、前記測定光を波長分散値が既知の分
散素子を介して受光して、受光強度に応じた信号を出力
し、演算手段は、前記第１の受光手段から出力される信
号と、前記第２の受光手段から出力される信号と、前記
分散素子の既知の波長分散値とに基づいて、前記光伝送
路の波長分散値を演算する。According to the chromatic dispersion measuring apparatus of the present invention, the first light receiving means directly receives the measuring light propagating through the optical transmission line and outputs a signal corresponding to the received light intensity.
The second light receiving means receives the measurement light via a dispersion element having a known chromatic dispersion value, and outputs a signal corresponding to the received light intensity. The arithmetic means is output from the first light receiving means. A chromatic dispersion value of the optical transmission line is calculated based on a signal, a signal output from the second light receiving unit, and a known chromatic dispersion value of the dispersion element.
【００３２】また、請求項２記載の発明の波長分散測定
装置は、光伝送路を伝播した測定光を入射し、出射先を
切り替える光スイッチと、前記光スイッチから出射され
る測定光を直接受光し、受光強度に応じた信号を出力す
る第１の受光手段と、前記光スイッチから出射される測
定光を波長分散値が既知の分散素子を介して受光し、受
光強度に応じた信号を出力する第２の受光手段と、前記
光スイッチに出射先を切り替える信号を出力して、前記
第１の受光手段から出力される信号と、前記第２の受光
手段から出力される信号と、前記分散素子の既知の波長
分散値とに基づいて、前記光伝送路の波長分散値を演算
する演算手段と、を備えることを特徴としている。According to a second aspect of the present invention, there is provided a chromatic dispersion measuring apparatus, comprising: an optical switch for inputting measurement light propagated through an optical transmission line and switching an output destination; and directly receiving measurement light emitted from the optical switch. First light receiving means for outputting a signal corresponding to the received light intensity, and receiving the measurement light emitted from the optical switch via a dispersion element having a known chromatic dispersion value, and outputting a signal corresponding to the received light intensity. A second light receiving means for outputting a signal for switching an emission destination to the optical switch, a signal output from the first light receiving means, a signal output from the second light receiving means, Calculating means for calculating a chromatic dispersion value of the optical transmission line based on a known chromatic dispersion value of the element.
【００３３】この請求項２記載の発明の波長分散測定装
置によれば、光スイッチは、光伝送路を伝播した測定光
を入射して、出射先を切り替え、第１の受光手段は、前
記光スイッチから出射される測定光を直接受光して、受
光強度に応じた信号を出力し、第２の受光手段は、前記
光スイッチから出射される測定光を波長分散値が既知の
分散素子を介して受光して、受光強度に応じた信号を出
力し、演算手段は、前記光スイッチに出射先を切り替え
る信号を出力して、前記第１の受光手段から出力される
信号と、前記第２の受光手段から出力される信号と、前
記分散素子の既知の波長分散値とに基づいて、前記光伝
送路の波長分散値を演算する。According to the chromatic dispersion measuring apparatus of the present invention, the optical switch receives the measurement light propagating through the optical transmission line and switches the output destination, and the first light receiving means includes the light receiving means. The measuring light emitted from the switch is directly received, and a signal corresponding to the intensity of the received light is output. The second light receiving unit transmits the measuring light emitted from the optical switch via a dispersion element having a known chromatic dispersion value. The arithmetic means outputs a signal for switching the emission destination to the optical switch, and outputs a signal output from the first light receiving means, A chromatic dispersion value of the optical transmission line is calculated based on a signal output from a light receiving unit and a known chromatic dispersion value of the dispersion element.
【００３４】したがって、請求項１及び請求項２記載の
発明によって、単一波長の従来の測定光を用いて、総波
長分散値の絶対値及び符号を受光側で容易に測定するこ
とができる。また、光伝送路に入射される測定光は、従
来の単一波長の測定光と同一であるため、測定光を光伝
送路に入射する入射側に新たな機器を構成したり、入射
する測定光を制御するといった必要がない。このため、
構成が単純であり、かつ安価な波長分散測定装置を提供
することができる。Therefore, according to the first and second aspects of the present invention, it is possible to easily measure the absolute value and the sign of the total chromatic dispersion value on the light receiving side using the conventional measurement light having a single wavelength. In addition, since the measurement light incident on the optical transmission line is the same as the conventional single-wavelength measurement light, a new device may be configured on the incident side where the measurement light is incident on the optical transmission line, or the measurement light may be incident on the optical transmission line. There is no need to control light. For this reason,
It is possible to provide an inexpensive chromatic dispersion measuring apparatus having a simple configuration.
【００３５】また、請求項３記載の発明は、請求項２記
載の波長分散測定装置において、分散素子の波長分散値
が異なる前記第２の受光手段を複数備え、前記演算手段
は、前記第１の受光手段を選択させる信号と、前記光伝
送路に応じて択一的に前記第２の受光手段を選択させる
信号を前記光スイッチに出力し、前記第１の受光手段か
ら出力される信号と、前記択一選択した第２の受光手段
から出力される信号と、前記択一選択した第２の受光手
段における分散素子の既知の波長分散値とに基づいて、
前記光伝送路の波長分散値を演算することを特徴として
いる。According to a third aspect of the present invention, in the chromatic dispersion measuring apparatus according to the second aspect, a plurality of the second light receiving means having different chromatic dispersion values of the dispersive elements are provided, and the arithmetic means is provided with the first light receiving means. A signal for selecting the light receiving means, and a signal for selectively selecting the second light receiving means according to the optical transmission path, to the optical switch, and a signal output from the first light receiving means. Based on a signal output from the alternatively selected second light receiving unit and a known chromatic dispersion value of a dispersion element in the alternatively selected second light receiving unit,
The chromatic dispersion value of the optical transmission line is calculated.
【００３６】この請求項３記載の発明によれば、請求項
２記載の発明の効果に加えて、光スイッチによって、受
光した光の光路を切り替えることができるため、光伝送
路の波長分散値に応じた受光光路を選択することによ
り、光伝送路の適用範囲を広げたり、光伝送路の波長分
散値に応じた細かな光路選択を行うことが可能となるた
め、より実用的な波長分散測定装置を提供することがで
きる。According to the third aspect of the present invention, in addition to the effect of the second aspect, the optical path of the received light can be switched by the optical switch. By selecting an appropriate light receiving optical path, it becomes possible to expand the applicable range of the optical transmission path or to select a fine optical path according to the chromatic dispersion value of the optical transmission path. An apparatus can be provided.
【００３７】また、請求項４記載の発明は、請求項１〜
３のいずれか記載の波長分散測定装置において、測定光
を前記光伝送路に入射する可変波長光源を更に備えるこ
とを特徴としている。Further, the invention described in claim 4 is the same as that in claim 1.
3. The chromatic dispersion measuring apparatus according to any one of 3), further comprising a variable wavelength light source for inputting measurement light to the optical transmission line.
【００３８】この請求項４記載の発明によれば、可変波
長光源が測定光の波長を任意に設定できるため、例えば
光伝送路に光帯域フィルタが含まれる時のような、伝送
できる波長に制限がある場合であっても、波長分散測定
が可能となる。According to the fourth aspect of the present invention, the variable wavelength light source can arbitrarily set the wavelength of the measurement light, so that it is limited to the wavelength that can be transmitted, for example, when the optical transmission line includes an optical bandpass filter. Even when there is, chromatic dispersion measurement can be performed.
【００３９】請求項５記載の発明は、請求項１〜４のい
ずれか記載の波長分散測定装置において、前記光伝送路
を伝播した測定光を増幅する光増幅手段を更に備えるこ
とを特徴としている。According to a fifth aspect of the present invention, in the chromatic dispersion measuring apparatus according to any one of the first to fourth aspects, the apparatus further comprises an optical amplifying means for amplifying the measurement light propagated through the optical transmission line. .
【００４０】この請求項５記載の発明によれば、光増幅
手段が測定光を増幅することができるため、測定光に対
するノイズの影響を低減することが可能となる。According to the fifth aspect of the present invention, since the optical amplification means can amplify the measurement light, it is possible to reduce the influence of noise on the measurement light.
【００４１】請求項６記載の発明は、請求項１〜５のい
ずれか記載の波長分散測定装置において、前記測定光
は、位相変調された単一波長ＣＷ光であることを特徴と
している。According to a sixth aspect of the present invention, in the chromatic dispersion measuring apparatus according to any one of the first to fifth aspects, the measurement light is phase-modulated single-wavelength CW light.
【００４２】この請求項６記載の発明によれば、従来利
用されている測定光である、位相変調された単一波長Ｃ
Ｗ光を用いて、総波長分散値の絶対値及び符号を受光側
で容易に測定することができる。According to the sixth aspect of the invention, the phase-modulated single wavelength C, which is conventionally used measurement light, is used.
Using the W light, the absolute value and the sign of the total chromatic dispersion value can be easily measured on the light receiving side.
【００４３】[0043]
【発明の実施の形態】以下、図を参照して本発明の実施
の形態を詳細に説明する。 （第１の実施の形態）図１〜図２は、本発明を適用した
第１の実施の形態における波長分散測定装置１を示す図
である。Embodiments of the present invention will be described below in detail with reference to the drawings. (First Embodiment) FIGS. 1 and 2 show a chromatic dispersion measuring apparatus 1 according to a first embodiment of the present invention.
【００４４】まず構成を説明する。図１は、本実施の形
態における波長分散測定装置１の構成を示すブロック図
である。本実施の形態の波長分散測定装置１では、上記
従来の波長分散測定装置１００の構成と同一の部分には
同一符号を付している。First, the configuration will be described. FIG. 1 is a block diagram illustrating a configuration of a chromatic dispersion measuring apparatus 1 according to the present embodiment. In the chromatic dispersion measuring apparatus 1 of the present embodiment, the same parts as those of the configuration of the conventional chromatic dispersion measuring apparatus 100 are denoted by the same reference numerals.
【００４５】図１において、波長分散測定装置１（請求
項１記載の波長分散測定装置に対応する。）は、光源２
と、信号発生器３と、位相変調器４と、ＤＵＴ５と、受
光器６（請求項１記載の第１の受光手段に対応する。）
と、信号処理演算部７（請求項１記載の演算手段に対応
する。）と、分散素子９と、受光器１０（請求項１記載
の第２の受光手段に対応する。）とから構成されてい
る。In FIG. 1, a chromatic dispersion measuring device 1 (corresponding to the chromatic dispersion measuring device according to the first aspect) includes a light source 2.
, A signal generator 3, a phase modulator 4, a DUT 5, and a light receiver 6 (corresponding to the first light receiving means in claim 1).
, A signal processing operation unit 7 (corresponding to the operation means described in claim 1), a dispersion element 9, and a light receiver 10 (corresponding to the second light reception means in claim 1). ing.
【００４６】まずＤＵＴ５へ測定光を入射する入射側の
構成は、上記従来の波長分散測定装置１００と同様に、
光源２と、信号発生器３と、位相変調器４とにより構成
されており、波長 1.5μｍのＤＦＢレーザ等により構成
される光源２から出射される単一光周波数のＣＷ光は、
位相変調器４に入射される。位相変調器４は、例えば光
周波数コム発生器のような変調指数の高い変調器から構
成されており、信号発生器３から入力する変調信号によ
り入射ＣＷ光を位相変調し、測定光としてＤＵＴ５へ出
力する。ＤＵＴ５は、例えば、長さ約５０ｋｍの1.3μ
ｍ零分散単一モード光ファイバ等により構成されてい
る。First, the configuration of the incident side where the measurement light is incident on the DUT 5 is the same as that of the conventional chromatic dispersion measuring apparatus 100 described above.
The CW light of a single optical frequency, which is composed of a light source 2, a signal generator 3, and a phase modulator 4, and is emitted from the light source 2 composed of a 1.5 μm wavelength DFB laser or the like,
The light enters the phase modulator 4. The phase modulator 4 is composed of a modulator having a high modulation index, such as an optical frequency comb generator. The phase modulator 4 phase-modulates the incident CW light by a modulation signal input from the signal generator 3 and sends it to the DUT 5 as measurement light. Output. The DUT 5 is, for example, 1.3 μm having a length of about 50 km.
It is composed of an m-zero dispersion single mode optical fiber or the like.
【００４７】そして、ＤＵＴ５から出力される測定光の
受光側では、ＤＵＴ５を伝播した測定光が光分岐結合器
（不図示）等によって分岐され、直接受光器６と、分散
素子９を介した受光器１０へ入射される。分散素子９
は、測定波長にも依るが1.3μｍ零分散光ファイバや各
種光ファイバ、あるいはファイバーグレーティングのよ
うな特定波長帯で大きな分散値を有する素子によって構
成されており、この素子の波長分散値の大きさと符号は
既知である。また、受光器６及び受光器１０に入射され
た光は、光強度に応じた電気信号に変換されて信号処理
演算部７に入力される。そして、信号処理演算部７で
は、受光器６及び受光器１０から入力される電気信号の
信号処理を行って、波長分散の絶対値と符号を演算す
る。On the light receiving side of the measurement light output from the DUT 5, the measurement light propagated through the DUT 5 is branched by an optical branching coupler (not shown) or the like, and is directly received by the light receiver 6 and the dispersion element 9 Incident on the vessel 10. Dispersion element 9
Although it depends on the measurement wavelength, it is composed of an element having a large dispersion value in a specific wavelength band, such as a 1.3 μm zero-dispersion optical fiber or various optical fibers, or a fiber grating. The sign is known. The light incident on the light receiver 6 and the light receiver 10 is converted into an electric signal corresponding to the light intensity and input to the signal processing operation unit 7. Then, the signal processing operation unit 7 performs signal processing of the electric signals input from the light receiver 6 and the light receiver 10 to calculate the absolute value and the sign of the chromatic dispersion.
【００４８】以下、本実施例における信号処理演算部７
等によって波長分散値の絶対値及び符号が測定・演算さ
れる動作原理について説明する。Hereinafter, the signal processing operation unit 7 in this embodiment will be described.
The operation principle in which the absolute value and the sign of the chromatic dispersion value are measured and calculated by, for example, will be described.
【００４９】まず、ＤＵＴ５から出力される測定光を直
接受光した受光器６の出力信号から求められるのは、上
記従来例で説明したように、波長分散値の絶対値｜Ｄ｜
である。続いて、分散素子９を介した受光器１０の出力
信号から測定できるのは、ＤＵＴ５の波長分散値Ｄと分
散素子９の波長分散値Ｄaの和の絶対値｜Ｄ＋Ｄa｜であ
る。ただし、分散素子９の波長分散値Ｄaは、上記の通
り、値の大きさと符号が既知である。First, the absolute value of the chromatic dispersion value | D | is obtained from the output signal of the light receiver 6 which directly receives the measurement light output from the DUT 5, as described in the above conventional example.
It is. Subsequently, the absolute value | D + Da | of the sum of the wavelength dispersion value D of the DUT 5 and the wavelength dispersion value Da of the dispersion element 9 can be measured from the output signal of the light receiver 10 via the dispersion element 9. However, as described above, the magnitude and sign of the wavelength dispersion value Da of the dispersion element 9 are known.
【００５０】ここで、測定された絶対値を以下のように
おく。 Ｄ1＝｜Ｄ｜ ・・・（６） Ｄ2＝｜Ｄ＋Ｄa｜ ・・・（７） 両辺２乗すると以下の式となる。 Ｄ1 2＝Ｄ2 ・・・（８） Ｄ2 2＝(Ｄ＋Ｄa)2＝Ｄ2＋２ＤＤa＋Ｄa2 ・・・（９）Here, the measured absolute value is set as follows. D 1 = | D | (6) D 2 = | D + Da | (7) When both sides are squared, the following equation is obtained. D 1 2 = D 2 ··· ( 8) D 2 2 = (D + Da) 2 = D 2 + 2DDa + Da 2 ··· (9)
【００５１】また、（８）、（９）式より、 Ｄ＝(Ｄ2 2−Ｄ1 2−Ｄa2)／(２Ｄa) ・・・（１０） となり、波長分散値Ｄを符号つきで求めることができ
る。[0051] Further, (8), obtained by (9) than, D = (D 2 2 -D 1 2 -Da 2) / (2Da) ··· (10) , and the signed wavelength dispersion value D be able to.
【００５２】また、測定する振幅δｉ／ｉ0は、（５）
式あるいは図５に示したように、波長分散値によって正
弦波として変化するため、波長分散値Ｄaの値には条件
が必要である。以下、図２を用いて具体的に説明する。The amplitude δi / i 0 to be measured is given by (5)
As shown in the equation or FIG. 5, the chromatic dispersion changes as a sine wave depending on the chromatic dispersion. Therefore, a condition is required for the value of the chromatic dispersion Da. Hereinafter, a specific description will be given with reference to FIG.
【００５３】図２は縦軸を振幅、波長分散値Ｄを角度と
して測定光を複素平面に表した図である。この図２にお
いて、今、測定光の波長分散値Ｄの符号がプラス、振幅
がδであるとする。まず、波長分散値Ｄaがプラスの時
を考える。この時、振幅はδより大きい必要があるた
め、図から明らかなように、 ０＜Ｄa＜π−２Ｄ ・・・（１１） が条件となる。FIG. 2 is a diagram showing the measurement light on a complex plane with the vertical axis representing the amplitude and the wavelength dispersion value D representing the angle. In FIG. 2, it is assumed that the sign of the wavelength dispersion value D of the measurement light is plus and the amplitude is δ. First, consider the case where the wavelength dispersion value Da is positive. At this time, since the amplitude needs to be larger than δ, as is clear from the figure, the condition is 0 <Da <π−2D (11).
【００５４】また、波長分散値Ｄaがマイナスの場合に
は、振幅が−δ以下にならない、 −２Ｄ＜Ｄa＜０ ・・・（１２） が条件となる。勿論、（１１）式、（１２）式共に、角
度表現であるため、２πを加える等の条件設定が可能で
ある。If the chromatic dispersion value Da is negative, the condition is that the amplitude does not fall below -δ, -2D <Da <0 (12). Of course, since both Expressions (11) and (12) are angle expressions, it is possible to set conditions such as adding 2π.
【００５５】以上のように、本発明を適用した第１の実
施の形態における波長分散測定装置１によれば、上記
（１０）〜（１２）式に基づいて、演算・測定を行うこ
とにより、波長分散値Ｄを符号つきで求めることができ
るため、単一波長の従来の測定光を用いて、総波長分散
値の絶対値及び符号を受光側で容易に測定することがで
きる。また、測定光の入射側は従来の波長分散測定装置
１００と同一構成であるため、入射側に新たな機器を構
成したり、入射する測定光を制御するといった必要がな
くなり、構成が単純であり、かつ安価な波長分散測定装
置を提供することができる。As described above, according to the chromatic dispersion measuring apparatus 1 of the first embodiment to which the present invention is applied, calculation and measurement are performed based on the above equations (10) to (12). Since the chromatic dispersion value D can be obtained with a sign, the absolute value and the sign of the total chromatic dispersion value can be easily measured on the light receiving side using the conventional measurement light having a single wavelength. In addition, since the incident side of the measurement light has the same configuration as that of the conventional chromatic dispersion measuring apparatus 100, there is no need to configure a new device on the incident side or control the incident measurement light, and the configuration is simple. And an inexpensive chromatic dispersion measuring apparatus can be provided.
【００５６】なお、本発明は、上記実施の形態の内容に
限定されるものではなく、本発明の趣旨を逸脱しない範
囲で適宜変更可能であり、例えば、光源２を可変波長光
源（請求項４記載の可変波長光源に対応する。）として
構成することとしてもよい。その場合には、可変波長光
源により、測定光の波長は任意に設定できるので、ＤＵ
Ｔ５に光帯域フィルタが含まれる時のような伝送できる
波長に制限がある場合であっても、波長分散測定が可能
となる。It should be noted that the present invention is not limited to the contents of the above-described embodiment, but can be appropriately changed without departing from the spirit of the present invention. For example, the light source 2 may be a variable wavelength light source (claim 4). Corresponding to the variable wavelength light source described above). In that case, the wavelength of the measurement light can be set arbitrarily by the variable wavelength light source.
Even when the wavelength that can be transmitted is limited, such as when an optical bandpass filter is included in T5, chromatic dispersion measurement can be performed.
【００５７】また、ＤＵＴ５と受光器６の間に少なくと
も１つの光アンプ（請求項５記載の光増幅手段に対応す
る。）を備えるように波長分散測定装置を構成すること
としてもよい。その場合には、微小信号時に光アンプを
用いることで、ノイズの影響を低減することができる。Further, the chromatic dispersion measuring apparatus may be configured to include at least one optical amplifier (corresponding to the optical amplifying means according to claim 5) between the DUT 5 and the light receiver 6. In that case, the influence of noise can be reduced by using an optical amplifier for a small signal.
【００５８】（第２の実施の形態）次に、本発明を適用
した第２の実施の形態における波長分散測定装置（請求
項２記載の波長分散測定装置に対応する。）について、
図３を参照して説明する。図３は、本第２の実施の形態
における波長分散測定装置２０の構成を示すブロック図
である。(Second Embodiment) Next, a chromatic dispersion measuring apparatus according to a second embodiment of the present invention (corresponding to the chromatic dispersion measuring apparatus according to claim 2) will be described.
This will be described with reference to FIG. FIG. 3 is a block diagram showing the configuration of the chromatic dispersion measuring device 20 according to the second embodiment.
【００５９】波長分散測定装置２０は、光源２、信号発
生器３、位相変調器４、ＤＵＴ５、光スイッチ１１（請
求項２記載の光スイッチに対応する。）、分散素子１
２、分散素子１３、受光器６、信号処理演算部７（請求
項２及び請求項３記載の演算手段に対応する。）によっ
て構成されており、測定光をＤＵＴ５へ入射する入射側
は、上記従来の波長分散測定装置１００における入射
側、及び第１の実施の形態の波長分散装置１における入
射側と同様の構成であるため、同一の部分には同一符号
を付し、重複する説明を省略する。The chromatic dispersion measuring device 20 includes a light source 2, a signal generator 3, a phase modulator 4, a DUT 5, an optical switch 11 (corresponding to the optical switch described in claim 2), and a dispersion element 1.
2, a dispersive element 13, a light receiver 6, and a signal processing operation unit 7 (corresponding to the operation means according to claims 2 and 3). Since the configuration is the same as that of the incident side of the conventional chromatic dispersion measuring apparatus 100 and the incident side of the chromatic dispersion apparatus 1 of the first embodiment, the same portions are denoted by the same reference numerals, and redundant description will be omitted. I do.
【００６０】図３において、波長分散測定装置２０は、
第１の実施の形態の波長分散測定装置１と同様に、位相
変調された測定光がＤＵＴ５に入射される。そして、Ｄ
ＵＴ５を伝播した測定光は、光スイッチ１１に入射され
る。そして、光スイッチ１１は、受光器６へ直接出射す
る光路を選択して、直接受光器６へ入射光を出射する
（請求項２記載の第１の受光手段に対応する。）ととも
に、分散素子１１を介して受光器６へ出射する光路と、
分散素子１２を介して受光器６へ出射する光路との何れ
か一方（この２つの光路が請求項２記載の第２の受光手
段及び請求項３記載の複数の第２の受光手段に対応す
る。）を、信号処理演算部７から入力される指示信号に
応じて、適宜切り替えて出射する。分散素子１１と分散
素子１２は、波長分散値が異なる素子であり、これら２
つの分散素子それぞれに光路を設けた理由は、分散素子
の波長分散値には（１１）式、（１２）式に示したよう
な制約があるため、ＤＵＴ５に応じた適当な分散素子を
選べるようにするためである。In FIG. 3, the chromatic dispersion measuring device 20
As in the case of the chromatic dispersion measuring apparatus 1 according to the first embodiment, the phase-modulated measurement light is incident on the DUT 5. And D
The measurement light that has propagated through the UT 5 enters the optical switch 11. Then, the optical switch 11 selects an optical path to be directly emitted to the light receiver 6, and directly emits the incident light to the light receiver 6 (corresponding to the first light receiving means according to claim 2), and also has a dispersion element. An optical path exiting to the light receiver 6 through the optical path 11;
Either one of the optical paths to the light receiver 6 via the dispersion element 12 (the two optical paths correspond to the second light receiving means according to claim 2 and the plurality of second light receiving means according to claim 3). ) Is appropriately switched and output in accordance with an instruction signal input from the signal processing operation unit 7. The dispersion element 11 and the dispersion element 12 are elements having different chromatic dispersion values.
The reason that the optical path is provided for each of the two dispersion elements is that the wavelength dispersion value of the dispersion element has the constraint as shown in the equations (11) and (12), so that an appropriate dispersion element according to the DUT 5 can be selected. In order to
【００６１】受光器６は、入射された光を光強度に応じ
た電気信号に変換して信号処理演算部７に出力する。信
号処理演算部７は、この電気信号を入力し、光スイッチ
１１によって切り替えられた各光路に対応した波長分散
値の絶対値を求める。また、信号処理演算部７は、光ス
イッチ１１から直接受光器６に入射した時の測定値以外
に、最低もう１経路の測定値が入力されるため、これら
の測定値を用いて、（６）〜（１０）式のように波長分
散値の符号を求める。The light receiver 6 converts the incident light into an electric signal corresponding to the light intensity and outputs the electric signal to the signal processing operation unit 7. The signal processing operation unit 7 receives the electric signal and obtains the absolute value of the chromatic dispersion value corresponding to each optical path switched by the optical switch 11. In addition, since the signal processing operation unit 7 receives the measured values of at least one other path in addition to the measured values when the light is directly incident on the optical receiver 6 from the optical switch 11, the signal processing operation unit 7 uses these measured values to obtain (6 ) To (10), the sign of the chromatic dispersion value is obtained.
【００６２】以上のように、本発明を適用した第２の実
施の形態における波長分散測定装置２０によれば、ＤＵ
Ｔ５の波長分散値に応じた受光光路を選択することがで
きるため、ＤＵＴ５の波長分散値によって装置構成を変
える必要がなく、容易に単一波長の従来の測定光を用い
た総波長分散値の絶対値と符号を求めることができるた
め、実用的な波長分散測定装置を提供することができ
る。As described above, according to the chromatic dispersion measuring apparatus 20 of the second embodiment to which the present invention is applied, the DU
Since the light receiving optical path can be selected according to the chromatic dispersion value of T5, there is no need to change the device configuration according to the chromatic dispersion value of the DUT 5, and the total chromatic dispersion value using the conventional measurement light of a single wavelength can be easily determined. Since the absolute value and the sign can be obtained, a practical chromatic dispersion measuring device can be provided.
【００６３】なお、本発明は、上記説明内容に限定され
るものではなく、本発明の趣旨を逸脱しない範囲で適宜
変更可能であり、例えば、波長分散値の異なる分散素子
を３以上備えて、３以上の光路の中から光路を選択する
ように構成することとしてもよい。その場合には、ＤＵ
Ｔ５の適用範囲をさらに広げたり、ＤＵＴ５の波長分散
値に応じた細かな光路選択を行うことが可能となるた
め、より実用的な波長分散測定装置を提供することがで
きる。また、光路を１とすることにより第１の実施の形
態の波長分散測定装置と同様の構成とすることも可能で
ある。It should be noted that the present invention is not limited to the above description, and can be appropriately changed without departing from the spirit of the present invention. For example, three or more dispersion elements having different chromatic dispersion values are provided. It may be configured to select an optical path from three or more optical paths. In that case, DU
Since the applicable range of T5 can be further expanded and a fine optical path can be selected according to the chromatic dispersion value of the DUT 5, a more practical chromatic dispersion measuring device can be provided. Further, by setting the number of optical paths to 1, it is also possible to make the configuration similar to that of the chromatic dispersion measuring apparatus of the first embodiment.
【００６４】また、上記第１の実施の形態において説明
した通り、光源２を可変波長光源とした構成を本第２の
実施の形態の波長分散測定装置に適用することとしても
よい。同様に、その場合には、可変波長光源により、測
定光の波長は任意に設定できるため、ＤＵＴ５に光帯域
フィルタが含まれる時のような伝送できる波長に制限が
ある場合であっても、波長分散測定が可能となる。As described in the first embodiment, the configuration in which the light source 2 is a variable wavelength light source may be applied to the chromatic dispersion measuring apparatus of the second embodiment. Similarly, in this case, the wavelength of the measurement light can be arbitrarily set by the variable wavelength light source. Therefore, even if the wavelength that can be transmitted is limited, such as when the DUT 5 includes an optical bandpass filter, Dispersion measurement becomes possible.
【００６５】また、ＤＵＴ５と受光器６の間に光アンプ
を備えるように構成することとしてもよく、その場合に
は、微小信号時に光アンプを用いることで、ノイズの影
響を低減することが可能となる。Further, an optical amplifier may be provided between the DUT 5 and the light receiver 6, and in this case, the effect of noise can be reduced by using the optical amplifier for a small signal. Becomes
【００６６】[0066]
【発明の効果】請求項１及び請求項２記載の発明によれ
ば、単一波長の従来の測定光を用いて、総波長分散値の
絶対値及び符号を受光側で容易に測定することができ
る。また、光伝送路に入射される測定光は、従来の単一
波長の測定光と同一であるため、測定光を光伝送路に入
射する入射側に新たな機器を構成したり、入射する測定
光を制御するといった必要がない。このため、構成が単
純であり、かつ安価な波長分散測定装置を提供すること
ができる。According to the first and second aspects of the present invention, it is possible to easily measure the absolute value and the sign of the total chromatic dispersion value on the light receiving side using the conventional measuring light having a single wavelength. it can. In addition, since the measurement light incident on the optical transmission line is the same as the conventional single-wavelength measurement light, a new device may be configured on the incident side where the measurement light is incident on the optical transmission line, or the measurement light may be incident on the optical transmission line. There is no need to control light. Therefore, it is possible to provide an inexpensive chromatic dispersion measuring apparatus having a simple configuration.
【００６７】請求項３記載の発明によれば、請求項２記
載の発明の効果に加えて、光スイッチによって、受光し
た光の光路を切り替えることができるため、光伝送路の
波長分散値に応じた受光光路を選択することにより、光
伝送路の適用範囲を広げたり、光伝送路の波長分散値に
応じた細かな光路選択を行うことが可能となるため、よ
り実用的な波長分散測定装置を提供することができる。According to the third aspect of the invention, in addition to the effect of the second aspect of the invention, the optical path of the received light can be switched by the optical switch. By selecting a light receiving optical path, it is possible to expand the applicable range of the optical transmission path or to select a fine optical path according to the chromatic dispersion value of the optical transmission path, so that a more practical chromatic dispersion measuring device is used. Can be provided.
【００６８】請求項４記載の発明によれば、請求項１〜
３記載の発明の効果に加えて、可変波長光源が測定光の
波長を任意に設定できるため、例えば光伝送路に光帯域
フィルタが含まれる時のような、伝送できる波長に制限
がある場合であっても、波長分散測定が可能となる。According to the invention described in claim 4, claims 1 to 1 are provided.
In addition to the effects of the invention described in 3, the variable wavelength light source can arbitrarily set the wavelength of the measurement light, so that there is a limit to the wavelength that can be transmitted, for example, when an optical bandpass filter is included in an optical transmission line. Even if there is, chromatic dispersion measurement becomes possible.
【００６９】請求項５記載の発明によれば、請求項１〜
４記載の発明の効果に加えて、光増幅手段が測定光を増
幅することができるため、測定光に対するノイズの影響
を低減することが可能となる。According to the fifth aspect of the present invention, the first to fifth aspects are provided.
In addition to the effects of the invention described in Item 4, since the optical amplification means can amplify the measurement light, it is possible to reduce the influence of noise on the measurement light.
【００７０】請求項６記載の発明によれば、請求項１〜
５記載の発明の効果に加えて、従来利用されている測定
光である、位相変調された単一波長ＣＷ光を用いて、総
波長分散値の絶対値及び符号を受光側で容易に測定する
ことができる。According to the invention of claim 6, according to claims 1 to
In addition to the effects of the invention described in 5, the absolute value and the sign of the total chromatic dispersion value are easily measured on the light receiving side using the phase-modulated single-wavelength CW light, which is the measuring light conventionally used. be able to.
【図１】第１の実施の形態における波長分散測定装置１
の構成を示すブロック図。FIG. 1 is a chromatic dispersion measuring apparatus 1 according to a first embodiment.
FIG. 2 is a block diagram showing the configuration of FIG.
【図２】第１の実施の形態における測定光を、縦軸を振
幅、波長分散値Ｄを角度として複素平面に表した図。FIG. 2 is a diagram illustrating measurement light according to the first embodiment on a complex plane with the vertical axis representing amplitude and the wavelength dispersion value D as an angle.
【図３】第２の実施の形態における波長分散測定装置２
０の構成を示すブロック図。FIG. 3 is a chromatic dispersion measuring device 2 according to a second embodiment.
FIG. 2 is a block diagram showing a configuration of a zero.
【図４】従来の波長分散測定装置１００の構成を示すブ
ロック図。FIG. 4 is a block diagram showing a configuration of a conventional chromatic dispersion measuring apparatus 100.
【図５】従来の波長分散測定装置１００の受光部におい
て、フィルタを通過した測定光の受光強度を示す図。FIG. 5 is a diagram showing the received light intensity of measurement light that has passed through a filter in a light receiving unit of a conventional chromatic dispersion measuring apparatus 100.
【図６】従来の波長分散測定装置２００の構成を示すブ
ロック図。FIG. 6 is a block diagram showing a configuration of a conventional chromatic dispersion measuring apparatus 200.
１、２０ 波長分散測定装置 ２ 光源 ３ 信号発生器 ４ 位相変調器 ５ ＤＵＴ ６、１０ 受光器 ７ 信号処理演算部 ９、１２、１３ 分散素子 １１ 光スイッチ DESCRIPTION OF SYMBOLS 1, 20 Chromatic dispersion measuring device 2 Light source 3 Signal generator 4 Phase modulator 5 DUT 6, 10 Light receiver 7 Signal processing operation part 9, 12, 13 Dispersion element 11 Optical switch
Claims (6)
受光強度に応じた信号を出力する第１の受光手段と、 前記測定光を波長分散値が既知の分散素子を介して受光
し、受光強度に応じた信号を出力する第２の受光手段
と、 前記第１の受光手段から出力される信号と、前記第２の
受光手段から出力される信号と、前記分散素子の既知の
波長分散値とに基づいて、前記光伝送路の波長分散値を
演算する演算手段と、 を備えることを特徴とする波長分散測定装置。1. A method for directly receiving measurement light propagating through an optical transmission line,
A first light receiving unit that outputs a signal corresponding to the received light intensity, a second light receiving unit that receives the measurement light through a dispersion element having a known chromatic dispersion value, and outputs a signal corresponding to the received light intensity, A chromatic dispersion value of the optical transmission line is calculated based on a signal output from the first light receiving unit, a signal output from the second light receiving unit, and a known chromatic dispersion value of the dispersion element. A chromatic dispersion measuring apparatus comprising:
先を切り替える光スイッチと、 前記光スイッチから出射される測定光を直接受光し、受
光強度に応じた信号を出力する第１の受光手段と、 前記光スイッチから出射される測定光を波長分散値が既
知の分散素子を介して受光し、受光強度に応じた信号を
出力する第２の受光手段と、 前記光スイッチに出射先を切り替える信号を出力して、
前記第１の受光手段から出力される信号と、前記第２の
受光手段から出力される信号と、前記分散素子の既知の
波長分散値とに基づいて、前記光伝送路の波長分散値を
演算する演算手段と、 を備えることを特徴とする波長分散測定装置。2. An optical switch for inputting measurement light propagating through an optical transmission line and switching an output destination, and a first switch for directly receiving the measurement light emitted from the optical switch and outputting a signal corresponding to the received light intensity. A second light receiving means for receiving the measurement light emitted from the optical switch through a dispersion element having a known chromatic dispersion value and outputting a signal corresponding to the intensity of the received light, and emitting the light to the optical switch. Output a signal to switch the destination,
A chromatic dispersion value of the optical transmission line is calculated based on a signal output from the first light receiving unit, a signal output from the second light receiving unit, and a known chromatic dispersion value of the dispersion element. A chromatic dispersion measuring apparatus comprising:
受光手段を複数備え、 前記演算手段は、前記第１の受光手段を選択させる信号
と、前記光伝送路に応じて択一的に前記第２の受光手段
を選択させる信号を前記光スイッチに出力し、前記第１
の受光手段から出力される信号と、前記択一選択した第
２の受光手段から出力される信号と、前記択一選択した
第２の受光手段における分散素子の既知の波長分散値と
に基づいて、前記光伝送路の波長分散値を演算すること
を特徴とする請求項２記載の波長分散測定装置。3. The apparatus according to claim 2, further comprising a plurality of said second light receiving means having different chromatic dispersion values of the dispersion element, wherein said calculating means selects one of the first light receiving means and a signal according to the optical transmission path. Outputs a signal for selecting the second light receiving means to the optical switch,
Based on the signal output from the light receiving means, the signal output from the selected second light receiving means, and the known chromatic dispersion value of the dispersion element in the selected second light receiving means. 3. The chromatic dispersion measuring apparatus according to claim 2, wherein a chromatic dispersion value of the optical transmission line is calculated.
光源を更に備えることを特徴とする請求項１〜３のいず
れか記載の波長分散測定装置。4. The chromatic dispersion measuring apparatus according to claim 1, further comprising a variable wavelength light source for inputting measurement light to said optical transmission line.
光増幅手段を更に備えることを特徴とする請求項１〜４
のいずれか記載の波長分散測定装置。5. The apparatus according to claim 1, further comprising an optical amplifier for amplifying the measurement light propagated through said optical transmission line.
The chromatic dispersion measuring device according to any one of the above.
Ｗ光であることを特徴とする請求項１〜５のいずれか記
載の波長分散測定装置。6. The measurement light has a phase-modulated single wavelength C.
6. The chromatic dispersion measuring apparatus according to claim 1, wherein the chromatic dispersion is W light.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11080149A JP2000275143A (en) | 1999-03-24 | 1999-03-24 | Wavelength-dispersion measuring apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11080149A JP2000275143A (en) | 1999-03-24 | 1999-03-24 | Wavelength-dispersion measuring apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2000275143A true JP2000275143A (en) | 2000-10-06 |
Family
ID=13710241
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11080149A Pending JP2000275143A (en) | 1999-03-24 | 1999-03-24 | Wavelength-dispersion measuring apparatus |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2000275143A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6614511B1 (en) | 1999-10-29 | 2003-09-02 | Ando Electric Co., Ltd. | Light wavelength dispersion measuring apparatus and light wavelength dispersion measuring method |
-
1999
- 1999-03-24 JP JP11080149A patent/JP2000275143A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6614511B1 (en) | 1999-10-29 | 2003-09-02 | Ando Electric Co., Ltd. | Light wavelength dispersion measuring apparatus and light wavelength dispersion measuring method |
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