JPH09243516A - Apparatus for measuring wavelength dispersion of optical fiber - Google Patents

Apparatus for measuring wavelength dispersion of optical fiber

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Publication number
JPH09243516A
JPH09243516A JP5170396A JP5170396A JPH09243516A JP H09243516 A JPH09243516 A JP H09243516A JP 5170396 A JP5170396 A JP 5170396A JP 5170396 A JP5170396 A JP 5170396A JP H09243516 A JPH09243516 A JP H09243516A
Authority
JP
Japan
Prior art keywords
wavelength
dispersion
modulation
signal light
local
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.)
Granted
Application number
JP5170396A
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Japanese (ja)
Other versions
JP3278129B2 (en
Inventor
Masahito Tomizawa
将人 富沢
Tomoyoshi Kataoka
智由 片岡
Nobuyuki Kawase
伸行 川瀬
Shinji Matsuoka
伸治 松岡
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Nippon Telegraph and Telephone Corp
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Nippon Telegraph and Telephone Corp
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Abstract

PROBLEM TO BE SOLVED: To realize a simple and economic measuring system by superposing a known intensity modulation before inputting light to a measuring fiber so as to make a local dispersion and a nonlinear interactive effect conspicuous. SOLUTION: In a transmission system 1, a single mode fiber 6 is inserted before an EDFA post amplifier 7 so as to generate an intensity modulation when the light enters. In a receiving system 9, a wavelength variable BPF 10 is installed so as to eliminate naturally emitted light. In order to measure a local wavelength dispersion, two parameters, i.e., a light power and a wavelength are changed and moreover, a known intensity modulation is superposed before the light is input to a measuring fiber so as to make a local dispersion and a nonlinear interaction conspicuous. An approximate theoretical formula is induced for a shift by the light power of a wavelength when the intensity modulation is minimum (minimum IM wavelength). A value of a local zero dispersion wavelength is obtained by fitting the minimum IM wavelength shift to the theoretical formula.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【発明の属する技術分野】本発明は、光ファイバの基本
特性の1つである波長分散の測定装置に関するものであ
る。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring chromatic dispersion, which is one of the basic characteristics of optical fibers.

【0002】[0002]

【従来の技術】Erドープファイバアンプ(以下、ED
FAという)の出現により、超高速・長スパン光伝送シ
ステムの経済的な実現が可能となった。高入射パワーを
必要とするこのような超高速・長スパンシステムでは、
非線形光学効果による波形劣化やスペクトル広がりを抑
圧するために伝送路の入射側に正常分散ファイバが配置
されている。しかし一旦ケーブル化され、融着されてし
まったファイバの入射側だけの波長分散を測定すること
は難しく、OTDR(光パルス試験器)の手段を借りて
時分割的にデータを解析するよりなかった。このOTD
Rに基づいた長手方向の波長分散分布測定法は数件発表
されている。一つの方法は、いくつもの波長の光パルス
をファイバ両端から別々に入射し、各波長について得ら
れる2つのOTDRデータからモードフィールド径の長
手分布を求めて波長分散分布を計算する[M.Ohashi and
M.Tateda,“Noval Technique for Measuring Longitud
inalChromatic Dispersion Distribution in Single-m
ode Fibres ”, Electron.Lett., Vol.29, No.5, pp.42
6-428, 1993 ]。もう一つの方法は高出力の励起光の波
長をシフトさせ、プローブパルスのパラメトリックゲイ
ンが生じる励起波長とファイバ位置の関係より零分散波
長の分布を直接求める[S.Nishi and M.Saruwatari,
“A Technique to Measure Distributed Zero Dispersi
on Wavelengthof Optical Fibers using Pulse Amplifi
cation due to Modulation Instability ”, Proc. in
IEEE OAA(Optical Amplifiers and their Application
s)'94, ThC4-1, PP.100-102, 1994 ]。また縮退4光波
混合の効率から分散分布を求める方法も提案されている
[H.Onaka, K.Otsuka, H.Miyata, and T.Chikama, “Me
asuring the Longitudinal Distribution of Four-Wave
Mixing Efficiency in Dispersion Shifted Fibers
”, IEEE Photon. Technol. Lett., Aug. 1994]。こ
れらの方法は短尺ファイバ内の微細な分散分布測定が主
な目的である。一方、一旦ケーブル化されたファイバに
ついては非線形効果の起きる有効距離の平均分散とトー
タルなファイバの平均分散の同時測定が必要である[M.
Nakazawa and H.Kubota,“Optical Soliton Communicat
ion in a Positively and Negatively Dispersion Allo
cated Oprical Fibre Transmission Line ”, Electro
n. Lett., Vol.31, pp.217-217, 1995 ]。
2. Description of the Related Art Er-doped fiber amplifier (hereinafter referred to as ED
With the advent of FA, it has become possible to economically realize ultra-high-speed, long-span optical transmission systems. In such an ultra-high-speed, long-span system that requires high incident power,
A normal dispersion fiber is placed on the incident side of the transmission line in order to suppress waveform deterioration and spectrum spread due to nonlinear optical effects. However, it was difficult to measure the chromatic dispersion only on the incident side of the fiber that was once made into a cable and fused, and there was no way to analyze the data in a time-sharing manner by borrowing the means of OTDR (optical pulse tester). . This OTD
Several methods of measuring wavelength dispersion distribution in the longitudinal direction based on R have been published. One method is to separately inject optical pulses of several wavelengths from both ends of the fiber, calculate the longitudinal distribution of the mode field diameter from two OTDR data obtained for each wavelength, and calculate the chromatic dispersion distribution [M. Ohashi and
M. Tateda, “Noval Technique for Measuring Longitud
inalChromatic Dispersion Distribution in Single-m
ode Fibers ”, Electron.Lett., Vol.29, No.5, pp.42
6-428, 1993]. Another method is to shift the wavelength of high-power pumping light and directly obtain the zero-dispersion wavelength distribution from the relationship between the pumping wavelength and the fiber position where the parametric gain of the probe pulse occurs [S. Nishi and M. Saruwatari,
“A Technique to Measure Distributed Zero Dispersi
on Wavelengthof Optical Fibers using Pulse Amplifi
cation due to Modulation Instability ”, Proc. in
IEEE OAA (Optical Amplifiers and their Application
s) '94, ThC4-1, PP.100-102, 1994]. A method for obtaining the dispersion distribution from the efficiency of degenerate four-wave mixing has also been proposed [H. Onaka, K. Otsuka, H. Miyata, and T. Chikama, “Me.
asuring the Longitudinal Distribution of Four-Wave
Mixing Efficiency in Dispersion Shifted Fibers
”, IEEE Photon. Technol. Lett., Aug. 1994]. These methods mainly aim to measure fine dispersion distribution in a short fiber. Simultaneous measurement of distance average dispersion and total fiber average dispersion is required [M.
Nakazawa and H. Kubota, “Optical Soliton Communicat
ion in a Positively and Negatively Dispersion Allo
cated Oprical Fiber Transmission Line ”, Electro
n. Lett., Vol.31, pp.217-217, 1995].

【0003】[0003]

【発明が解決しようとする課題】大橋らの測定法は全く
別の測定する、すなわち入口と出口から別々にOTDR
トレースを測定しなければならないので、遠端測定は不
可能である。また長尺のファイバを測定する際(分散マ
ネージメントは長スパンシステムに用いられている)、
ファイバ出口付近のOTDRデータには大きい誤差が含
まれる。したがって入口と出口を取り替えて2つのデー
タを使って得られるモードフィールド径の長手分布には
両端に大きな誤差が含まれていることになる。また西ら
の測定法では高出力の励起光の波長を可変にするが、光
アンプの波長帯域外に局所的零分散波長がある場合は測
定ができない。分散マネージドファイバの入り口付近の
零分散波長規格は1560nm程度から1575nm程
度であり、EDFAの帯域(1535nm〜1560n
m)を考慮すると測定できるファイバに限りがある。ま
たパラメトリックゲインの生じる波長から零分散波長の
値に換算するアルゴリズムを確立するのが難しく、した
がって今のところ自動測定には不向きである。
The measurement method of Ohashi et al. Measures completely differently, that is, the OTDR is separately provided from the entrance and the exit.
Far end measurements are not possible because the traces must be measured. Also, when measuring long fibers (dispersion management is used in long span systems),
The OTDR data near the fiber exit contains large errors. Therefore, the longitudinal distribution of the mode field diameter obtained by exchanging the inlet and the outlet and using the two data contains a large error at both ends. In the measurement method of Nishi et al., The wavelength of high-power pumping light is made variable, but measurement is not possible if the local zero-dispersion wavelength is outside the wavelength band of the optical amplifier. The zero dispersion wavelength standard near the entrance of the dispersion managed fiber is about 1560 nm to 1575 nm, and the band of the EDFA (1535 nm to 1560 n).
Considering m), there are limits to the fibers that can be measured. Moreover, it is difficult to establish an algorithm for converting the wavelength at which parametric gain occurs to the value of the zero-dispersion wavelength, and thus it is not suitable for automatic measurement at the present time.

【0004】尾中らの測定法でも同様に光アンプの波長
帯域内に零分散波長がなければ測定できない。また光ア
ンプに可変波長帯域でフラットなゲインシェイプを持つ
ものが要求される。また縮退4光波混合の効率は偏波に
対して敏感であり、入射側で偏波を合わせても偏波分散
のあるファイバでは誤差を生じる。
Similarly, the measurement method of Onaka et al. Cannot be performed unless there is a zero dispersion wavelength in the wavelength band of the optical amplifier. Moreover, an optical amplifier having a flat gain shape in the variable wavelength band is required. Further, the efficiency of degenerate four-wave mixing is sensitive to polarized waves, and even if the polarized waves are matched on the incident side, an error occurs in a fiber having polarization dispersion.

【0005】本発明は上記の事情に鑑みてなされたもの
で、シンプルで経済的な測定系を実現し得、且つ測定に
要する入射光パワーを抑え得、大きなダイナミックレン
ジをとり得る光ファイバの波長分散測定装置を提供する
ことを目的とする。
The present invention has been made in view of the above circumstances, and a wavelength of an optical fiber that can realize a simple and economical measurement system, can suppress the incident light power required for measurement, and can have a large dynamic range. An object is to provide a dispersion measuring device.

【0006】[0006]

【課題を解決するための手段】上記目的を達成するため
に本発明では、波長分散によるPM−AM(位相変調−
振幅変調)変換効果と非線形効果の重畳効果を利用し、
分散マネージドファイバの非線形有効距離の局所的零分
散波長を測定する。局所的波長分散を測定するに当た
り、光パワーと波長という2つのパラメータを変化さ
せ、さらに局所的分散と非線形の相互作用を顕著にする
ために測定ファイバに入力する前に既知の強度変調を重
畳させる。この局所的分散−非線形相互作用の結果生じ
る強度変調が最小となる波長(以下、最小IM波長と呼
ぶ)の光パワーによるシフトの近似的な理論式を導出す
る。低パワー光入射によるPM−AM変換で平均零分散
波長が、最小IM波長シフトの理論式へのフィッティン
グにより局所的零分散波長の値が得られる。
In order to achieve the above object, the present invention provides a PM-AM (phase modulation
Amplitude modulation) conversion effect and non-linear effect superposition effect are used,
We measure the local zero-dispersion wavelength of the nonlinear effective distance of a dispersion-managed fiber. In measuring the local chromatic dispersion, two parameters, optical power and wavelength, are changed, and a known intensity modulation is superposed before being input to the measurement fiber in order to make the local dispersion and the nonlinear interaction noticeable. . An approximate theoretical formula of the shift due to the optical power of the wavelength at which the intensity modulation resulting from this local dispersion-nonlinear interaction is minimized (hereinafter referred to as the minimum IM wavelength) is derived. The average zero-dispersion wavelength can be obtained by PM-AM conversion by incidence of low-power light, and the value of the local zero-dispersion wavelength can be obtained by fitting to the theoretical formula of the minimum IM wavelength shift.

【0007】[0007]

【発明の実施の形態】以下図面を参照して本発明の実施
の形態例を詳細に説明する。 実施形態例[1] 測定系及び測定方法 PM−AM変換はファイバの波長分散の効果によりCW
(連続波)位相変調光が強度変調に変換される効果であ
る[A.R.Chraplyvy, R.W.Tkach, L.L.Buhl, and R.C.Al
ferness,“Phase Modulation to Amplitude Modulation
Conversion ofCW Laser Light in Optical Fibres ”,
Electron. Lett., Vol.22, No.8, pp.409-410, 1986
]。この効果を利用した線形中継器多中継系の長尺の
平均分散の測定が提案されている[[Yamabayashi] : Y.
Yamabayashi, M.Tomizawa, and Y.Sato, “Direct Dis
persion Measurement for Multiple Fiber Section Con
catenated with Linear Amplifier Repeaters ”, Pro
c. in IEEE IMTC'94(Instrumentation and Measurement
Technology Conference)Vol.2, THAM9-5, pp.1040-104
3, 1994 [Murakami] : M.Murakami and M.Amemiya,“Simple and
Accurate Zero Dispersion Wavelength Measurement f
or Long Haul Optical Amplifier Systems using Induc
ed Phase to Amplitude Modulation Conversion ”, El
ectron. Lett.,Vol.31, No.8, pp.666-668, 1995 ]。
またすでにPM−AM変換と非線形効果を利用して、均
一性の保たれているファイバの極性を含む分散値を測定
する方法を提案した[[Tomizawa1] : M.Tomizawa, Y.Ya
mabayashi, Y.Sato, and T.Kataoka, “Nonlinear Infl
uence on PM-AM Conversion Measurement of Group Vel
ocity Dispersion in Optical Fibres”, Electron. Le
tt., Vol.30, No.17, pp.1434-1435, 1994 [Tomizawa2] : M.Tomizawa and Y.Yamabayashi, “Effe
ct of Modulation Instability on Phase Modulation-A
mplitude Modulation Conversion in OpticalFibers”,
Opt. Lett., Vol.20, No.10, pp.1128-1130, 1995
]。この方法を基礎に波長分散分布を測定するに当た
り、2つのパラメータを可変とする。すなわち光パワー
と波長である。さらに局所的な分散による効果を顕著に
するために、測定ファイバに入力する前に既知の強度変
調を重畳させる。
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. Embodiment example [1] Measurement system and measurement method PM-AM conversion is CW due to the effect of chromatic dispersion of the fiber.
(Continuous wave) Phase-modulated light is an effect that is converted into intensity modulation [ARChraplyvy, RWTkach, LLBuhl, and RCAl
ferness, “Phase Modulation to Amplitude Modulation
Conversion of CW Laser Light in Optical Fibers ”,
Electron. Lett., Vol.22, No.8, pp.409-410, 1986
]. It has been proposed to use this effect to measure long-term average dispersion of a linear repeater multi-repeater system [[Yamabayashi]: Y.
Yamabayashi, M.Tomizawa, and Y.Sato, “Direct Dis
persion Measurement for Multiple Fiber Section Con
catenated with Linear Amplifier Repeaters ”, Pro
c. in IEEE IMTC'94 (Instrumentation and Measurement
Technology Conference) Vol.2, THAM9-5, pp.1040-104
3, 1994 [Murakami]: M.Murakami and M.Amemiya, “Simple and
Accurate Zero Dispersion Wavelength Measurement f
or Long Haul Optical Amplifier Systems using Induc
ed Phase to Amplitude Modulation Conversion ”, El
ectron. Lett., Vol.31, No.8, pp.666-668, 1995].
In addition, we have already proposed a method to measure the dispersion value including the polarization of the fiber that maintains the homogeneity by using PM-AM conversion and nonlinear effects [[Tomizawa1]: M.Tomizawa, Y.Ya.
mabayashi, Y.Sato, and T.Kataoka, “Nonlinear Infl
uence on PM-AM Conversion Measurement of Group Vel
ocity Dispersion in Optical Fibers ”, Electron. Le
tt., Vol.30, No.17, pp.1434-1435, 1994 [Tomizawa2]: M.Tomizawa and Y.Yamabayashi, “Effe
ct of Modulation Instability on Phase Modulation-A
mplitude Modulation Conversion in OpticalFibers ”,
Opt. Lett., Vol.20, No.10, pp.1128-1130, 1995
]. In measuring the chromatic dispersion distribution based on this method, two parameters are made variable. That is, optical power and wavelength. In order to make the effect of local dispersion even more pronounced, a known intensity modulation is superposed before entering the measuring fiber.

【0008】図1に実験系を示す。本発明はデバイス・
部品としては新しいものを要求せず、いたってシンプル
で経済的な測定系を実現する。図1において、1の四角
で囲まれた部分は送信系で、波長可変光源2、7.4G
Hzの発振器4、広帯域のRF(高周波)アンプ5、L
iNbO3 の外部位相変調器3、EDFAポストアンプ
7、可変光減衰器8からなる。またEDFAの前段に
1.3μm零分散のシングルモードファイバ6が2km
挿入されている。これは入射時の強度変調を起こさせる
ためであるが既知の強度変調であればよく、分散媒質や
光源の直接変調でもよい。図1において、9は受信系で
あり、ASE(自然放出光)除去のための波長可変の半
値幅3nmのバンドパスフィルタ10、フィルタ10の
中心波長をアジャストするためのパワーモニタ11、フ
ォトディテクター12、サイドバンド(7.4GHz)
測定用のRFスペクトルアナライザ14と光強度を規格
化するためのDC(直流)電圧計13とから構成され
る。なおASEのパワーが無視できるのであれば、バン
ドパスフィルタとモニタ用パワーメータは必要ない。ま
たスペクトルアナライザ14は固定の電気フィルタと交
流電圧計でもよい。局所的分散測定の前に、図1の測定
系からSMF(シングルモードファイバ)を除き低パワ
ーを用いて通常のPM−AM変換により平均零分散波長
を測定する。あらかじめ平均零分散波長がわかっていれ
ば必要ない。次にSMFを挿入し、パワーを変化させて
それぞれのパワーにおける最小IM波長のシフトを求め
る。光パワーや波長を変化させるタイミングは受信側の
コマンドによって制御線を用いて制御される。この制御
インターフェース(コントロールIF)はGPIBでも
RS−232cでもよく、これらに限らない。各波長に
おいてそれぞれのパワー値におけるIM(強度変調)成
分を測定してもよいし、各パワーにおいてそれぞれの波
長値におけるIM成分を測定してもよい。
FIG. 1 shows an experimental system. The present invention is a device
Realizes a simple and economical measurement system without requiring new parts. In FIG. 1, a portion surrounded by a square 1 is a transmission system, and the wavelength tunable light source 2, 7.4G
Hz oscillator 4, broadband RF (high frequency) amplifier 5, L
It is composed of an external phase modulator 3 of iNbO 3 , an EDFA postamplifier 7, and a variable optical attenuator 8. In addition, a 1.3 μm zero-dispersion single mode fiber 6 is 2 km in front of the EDFA.
Has been inserted. This is to cause intensity modulation at the time of incidence, but any known intensity modulation may be used, and direct modulation of a dispersion medium or a light source may be used. In FIG. 1, reference numeral 9 denotes a receiving system, which has a wavelength-tunable bandpass filter 10 with a half-value width of 3 nm for removing ASE (spontaneous emission light), a power monitor 11 for adjusting the central wavelength of the filter 10, and a photodetector 12. , Sideband (7.4 GHz)
It is composed of an RF spectrum analyzer 14 for measurement and a DC (direct current) voltmeter 13 for normalizing the light intensity. If the ASE power can be ignored, the bandpass filter and the monitor power meter are not necessary. The spectrum analyzer 14 may be a fixed electric filter and an AC voltmeter. Prior to the local dispersion measurement, the mean zero dispersion wavelength is measured by ordinary PM-AM conversion using low power except for SMF (single mode fiber) from the measurement system of FIG. It is not necessary if the mean zero dispersion wavelength is known in advance. Next, SMF is inserted and the power is changed to find the minimum IM wavelength shift at each power. The timing of changing the optical power or wavelength is controlled by a command on the receiving side using a control line. The control interface (control IF) may be GPIB or RS-232c, and is not limited to these. The IM (intensity modulation) component at each power value at each wavelength may be measured, or the IM component at each wavelength value at each power may be measured.

【0009】実施形態例[2] データ解析方法 次に得られた結果から局所的零分散波長を求める解析方
法を示す。最初に、2つの位置LとL+dLに囲まれた
ファイバ微少部分に着目する。Lにおける強度変調の振
幅をh(L)とし、位相をφ(L)とする。ここで位相
は異常分散のPM−AM変換によって誘起される強度変
調の位相を基準とする。充分高い光パワーでは変調不安
定性(MI)を考慮しなければならない。MIの項を断
熱近似で取り扱うと[[Tomizawa2] : M.Tomizawa and
Y.Yamabayashi, “Effect of Modulation Instability
on Phase Modulation-Amplitude Modulation Conversio
n in Optical Fibers”, Opt. Lett., Vol.20, No.10,
pp.1128-1130, 1995 ]、 h(L)exp{jφ(L)}=V(L)exp{gL} (1) ここでV(L)は分散及び自己位相変調(SPM)によ
る項と位相項の積であり、これに関する微分方程式が立
てられる。gはMIゲインで近似的に
Embodiment [2] Data Analysis Method Next, an analysis method for obtaining a local zero-dispersion wavelength from the obtained results will be shown. At first, attention is paid to a minute portion of the fiber surrounded by two positions L and L + dL. The amplitude of intensity modulation in L is h (L), and the phase is φ (L). Here, the phase is based on the phase of intensity modulation induced by PM-AM conversion of anomalous dispersion. With sufficiently high optical power, modulation instability (MI) must be considered. Treating the MI term with adiabatic approximation [[Tomizawa2]: M.Tomizawa and
Y.Yamabayashi, “Effect of Modulation Instability
on Phase Modulation-Amplitude Modulation Conversio
n in Optical Fibers ”, Opt. Lett., Vol.20, No.10,
pp.1128-1130, 1995], h (L) exp {jφ (L)} = V (L) exp {gL} (1) where V (L) is a term due to dispersion and self-phase modulation (SPM). It is the product of the phase terms for which a differential equation is established. g is MI gain approximately

【0010】[0010]

【数3】 と表される[[Agrawal] : G.P.Agrawal,“Nonlinear Fi
ber Optics”, AcademicPress(San Diego), 1989 ;[To
mizawa2] : M.Tomizawa and Y.Yamabayashi, “Effect
of Modulation Instability on Phase Modulation-Ampl
itude Modulation Conversion in Optical Fibers”, O
pt. Lett., Vol.20, No.10, pp.1128-1130, 1995 ]。
ここでωm は変調周波数、P0 は光パワー、β″は波長
分散に相当する伝搬常数の角振動数による2階微分であ
る。γは非線形常数である。また(1)においてqはM
Iゲインの大きさを決定するパラメータで、異常分散で
はq=4であり、正常分散では、
(Equation 3) [[Agrawal]: GPAgrawal, “Nonlinear Fi
ber Optics ”, AcademicPress (San Diego), 1989; [To
mizawa2]: M.Tomizawa and Y.Yamabayashi, “Effect
of Modulation Instability on Phase Modulation-Ampl
itude Modulation Conversion in Optical Fibers ”, O
pt. Lett., Vol.20, No.10, pp.1128-1130, 1995].
Here, ω m is the modulation frequency, P 0 is the optical power, β ″ is the second derivative of the propagation constant corresponding to the chromatic dispersion due to the angular frequency. Γ is a nonlinear constant, and q is M in (1).
It is a parameter that determines the magnitude of the I gain, q = 4 for abnormal variance, and for normal variance,

【0011】[0011]

【数4】 と表される[[Agrawal2] : G.P.Agrawal, “Modulation
Instability Induced by Cross-Phase Modulation”,
Phys. Rev. Lett., Vol.59, No.8, pp.880-883,1987;
[Tomizawa2] : M.Tomizawa and Y.Yamabayashi, “Effe
ct of ModulationInstability on Phase Modulation-Am
plitude Modulation Conversion in Optical Fibers”,
Opt. Lett., Vol.20, No.10, pp.1128-1130, 1995
]。ここでS0 、S1 はそれぞれ0次の1次サイドバ
ンドの規格化パワーである。
(Equation 4) [[Agrawal2]: GPAgrawal, “Modulation
Instability Induced by Cross-Phase Modulation ”,
Phys. Rev. Lett., Vol.59, No.8, pp.880-883,1987;
[Tomizawa2]: M.Tomizawa and Y.Yamabayashi, “Effe
ct of ModulationInstability on Phase Modulation-Am
plitude Modulation Conversion in Optical Fibers ”,
Opt. Lett., Vol.20, No.10, pp.1128-1130, 1995
]. Here, S 0 and S 1 are the normalized powers of the 0th-order primary sideband, respectively.

【0012】位相変調光強度の振動項はビート波:Jn
k exp{j(n−k)wm t}と表せられる。ここ
でn,kは整数、Ji はi次のベッセル関数である。強
度変調を外部から重畳させると光強度の振動項には、本
質的な(intrinsic)ビート波の他に非本質的
な(extrinsic)ビート波:exp{j(n−
k±1)wm tとexp{±jwm t}とのカップリン
グの影響が現れる。光強度の1次のサイドバンドに寄与
する整数の組み合わせはn−k=±1の他にn−k=
0,±2が存在する。ここでは非本質的な(extri
nsic)項の寄与をV(L)<<1として無視する。
後で見るように、この近似による誤差を最小にするよう
に入射IM位相を選ぶことができる。L+dLにおける
強度変調成分V(L+dL)は
The oscillation term of the phase-modulated light intensity is a beat wave: J n
It can be expressed as J k exp {j (n−k) w m t}. Here, n and k are integers, and J i is an i-th order Bessel function. When intensity modulation is superposed from the outside, the oscillation term of the light intensity has an intrinsic beat wave and an extrinsic beat wave: exp {j (n-
k ± 1) The influence of the coupling between w m t and exp {± jw m t} appears. The combination of integers contributing to the first-order sideband of the light intensity is n−k = ± 1 as well as n−k =
There are 0 and ± 2. Here, the extrinsic
nsic) contribution is ignored as V (L) << 1.
As will be seen later, the incident IM phase can be chosen to minimize the error due to this approximation. The intensity modulation component V (L + dL) at L + dL is

【0013】[0013]

【数5】 となる。bm (L)とはLにおける位相変調指数であ
る。ここでdL<<1、β″dLnωm <<1とし、V
(L)の実数部分だけに着目した。(2)式におけるb
m (L+dL)と微少領域dLの入射側のbm (L)
は、SPMによる位相変調の分だけ異なっている[[Tom
izawa1] : M.Tomizawa, Y.Yamabayashi, Y.Sato, and
T.Kataoka, “Nonlinear Influence on PM-AM Conversi
on Measurementof Group Velocity Dispersion in Opti
cal Fibres”, Electron. Lett., Vol.30, No.17, pp.1
434-1435, 1994]。よって、V(L)の和を用いて次の
ような式を得る。
(Equation 5) Becomes b m (L) is the phase modulation index at L. Here, dL << 1, β ″ dLnω m << 1, and V
Focusing only on the real part of (L). B in equation (2)
m (L + dL) and b m (L) on the incident side of the minute area dL
Differ by the amount of phase modulation by SPM [[Tom
izawa1]: M.Tomizawa, Y.Yamabayashi, Y.Sato, and
T. Kataoka, “Nonlinear Influence on PM-AM Conversi
on Measurementof Group Velocity Dispersion in Opti
cal Fibers ”, Electron. Lett., Vol.30, No.17, pp.1
434-1435, 1994]. Therefore, the following equation is obtained using the sum of V (L).

【0014】[0014]

【数6】 ここでNdL=Lとした。(3)式を(2)式に代入
し、dL−>0、N無限大とし、もう一度Lで微分する
と簡単な2階の微分方程式が得られる。
(Equation 6) Here, NdL = L. By substituting equation (3) into equation (2), setting dL-> 0, N infinity, and differentiating again with L, a simple second-order differential equation is obtained.

【0015】[0015]

【数7】 式(4)の解は次の2つの初期条件により決定される。 V(0)=Aexp{jφ0 } (5)(Equation 7) The solution of equation (4) is determined by the following two initial conditions. V (0) = Aexp {jφ 0 } (5)

【0016】[0016]

【数8】 ここで、Aは入射光の振幅、φ0 は位相である。したが
って、解はつぎのように表される。
(Equation 8) Here, A is the amplitude of the incident light, and φ 0 is the phase. Therefore, the solution is expressed as

【0017】 h(L)=bm (0)β″ωm 2 Lexp{−jφ(L)}exp{gL}Ω(L) +Aexp{j(φ0 −φ(L))}exp{gL}[Ω(L)+Θ(L)] (7) ここで[0017] h (L) = b m ( 0) β "ω m 2 Lexp {-jφ (L)} exp {gL} Ω (L) + Aexp {j (φ 0 -φ (L))} exp {gL } [Ω (L) + Θ (L)] (7) where

【0018】[0018]

【数9】 である。(10)式でφ(L)は位相の異なる振動の和
の位相として求めた。上で求めた強度変調成分にはファ
イバロスの効果が入っていない。ここで最も簡単にロス
を見積る。すなわち有効距離内で非線形効果が一定のパ
ワーによって起き、それ以上では起きない。有効距離L
eff はファイバロスαを用いると、Leff=1/α[1
−exp{−αL}]と表される。任意の距離L(>L
eff )での強度変調は、(7)にLeff を代入した式と
残りの距離分の通常PM−AM変換の式の和で表され
る。さらにいくぶん粗い近似が導入される。すなわち局
所的な波長分散スロープが、平均の波長分散スロープと
等しいと仮定する。局所的な波長分散と平均の波長分散
の違いは零分散波長の違いに繰り込まれる。局所的な波
長分散項は、局所的な零分散波長λ0 と分散スロープs
(<0)を用いてβ″=s(λ−λ0 )と表される。形
式的にh(L)を次のように表す。 h(L)=bm (0)s(λ−λ0 (P0 ))ωm 2 L (11) 光入射パワーによる平均零分散波長のシフトΔλ0 (P
0 )は
[Equation 9] It is. In equation (10), φ (L) was obtained as the phase of the sum of vibrations having different phases. The intensity modulation component obtained above does not include the effect of fiber loss. The easiest way to estimate your losses here. That is, a non-linear effect occurs within the effective distance with a constant power, and no more than that. Effective distance L
If the fiber loss α is used for eff , L eff = 1 / α [1
-Exp {-αL}]. Arbitrary distance L (> L
The intensity modulation in ( eff ) is represented by the sum of the equation in which L eff is substituted in (7) and the equation for normal PM-AM conversion for the remaining distance. A more coarse approximation is introduced. That is, it is assumed that the local chromatic dispersion slope is equal to the average chromatic dispersion slope. The difference between local chromatic dispersion and average chromatic dispersion is incorporated into the difference in zero-dispersion wavelength. The local chromatic dispersion term is the local zero dispersion wavelength λ 0 and the dispersion slope s.
It is expressed as β ″ = s (λ−λ 0 ) using (<0). Formally expressing h (L) as follows: h (L) = b m (0) s (λ− λ 0 (P 0 )) ω m 2 L (11) Shift of average zero dispersion wavelength due to light incident power Δλ 0 (P
0 ) is

【0019】[0019]

【数10】 (12)式の零分散波長のシフトは局所的な零分散波長
と光パワーの関数となる。図2に最小IM波長のシフト
の光パワー依存性を局所的零分散波長をパラメータとし
て示す。この計算で平均零分散波長を1550nmとし
た。MIゲインのパラメータqの値は異常分散では4で
あり正常分散では0〜0.4ほどの値なので、両分散で
の平均値q=2とした。また非線形常数はγ=2.8と
した。図2に示されるように最小分散波長シフトのパワ
ー依存性は局所的零分散波長により特異な挙動を見せ
る。平均零分散波長よりも局所的零分散波長が小さい場
合(異常分散)、パワーとともに最小分散波長はいった
ん正の方向に1nmほどシフトしてから、急激に負の方
向にシフトする。一方、平均零分散波長よりも局所的零
分散波長が大きい場合(正常分散)、だいたいにおいて
なだらかな減少関数となる。強度変調が最小となる波長
を光パワーとともに求め(12)式にフィッティングす
れば、局所的零分散波長の値が得られる。従来の非線形
効果を用いた波長分散分布の測定は+20dBmの入射
パワーを使用していたのに対し、本方法では+16dB
m程度で充分である。
(Equation 10) The shift of the zero-dispersion wavelength in the equation (12) is a function of the local zero-dispersion wavelength and the optical power. FIG. 2 shows the optical power dependency of the shift of the minimum IM wavelength with the local zero-dispersion wavelength as a parameter. In this calculation, the average zero dispersion wavelength was set to 1550 nm. The value of the MI gain parameter q is 4 in the case of abnormal dispersion and is 0 to 0.4 in the case of normal dispersion, so the average value q = 2 in both dispersions was set. The non-linear constant is γ = 2.8. As shown in FIG. 2, the power dependence of the minimum dispersion wavelength shift shows a peculiar behavior depending on the local zero dispersion wavelength. When the local zero-dispersion wavelength is smaller than the average zero-dispersion wavelength (anomalous dispersion), the minimum-dispersion wavelength shifts positively in the positive direction by about 1 nm and then abruptly shifts in the negative direction. On the other hand, when the local zero-dispersion wavelength is larger than the average zero-dispersion wavelength (normal dispersion), the function generally becomes a gradual decreasing function. The value of the local zero-dispersion wavelength can be obtained by finding the wavelength at which the intensity modulation becomes the minimum together with the optical power and fitting it to the equation (12). While the measurement of the chromatic dispersion distribution using the conventional nonlinear effect used the incident power of +20 dBm, this method uses +16 dB.
m is sufficient.

【0020】実施形態例[3] 実験 前で述べられている局所的波長分散の測定を実験室にお
いて行った。図1の測定系でEDFAの前段に1.3μ
m零分散のシングルモードファイバ6が2km挿入され
ている。したがって(5)式のA=0.045、φ0
πが得られる。(10)式は常に0になる系を用いた。
上で述べた非本質的な(extrinsic)項の効果
はsinφ=0である限り、零分散波長近傍でかつその
波長に関して対称に現れる強度変調成分誤差である。し
たがって最小IM波長は前のセクションのように本質的
な(intrinsic)項(n−k=±1)のみを考
慮したものと等しい。テストに用いられたファイバは2
つの分散シフトファイバを結合させたものであり、片方
は零分散波長が1574.70nmの正常分散ファイバ
50km、もう一方が零分散波長1527.60nmの
異常分散ファイバ50kmの計100kmのファイバで
あり、平均の零分散波長は1549.0nmであった。
これらの値は従来の位相差法によって接続前に個別(破
壊測定)に測定した値である。局所的分散測定の前に、
図1の測定系からSMFを除き低パワーを用いて通常の
PM−AM変換により平均零分散波長を測定した。結果
は1549.50nmであった。局所的分散測定実験で
は比較のために正常分散側からの光入射による測定と異
常分散側から高出力光入射の測定をそれぞれ行い、最小
分散波長のシフトを別々に求めた。この実験系で、受信
レベルが−30dBm以下でも測定が可能である。した
がって0dBmでは非線形効果の影響がないと仮定する
と、ダイナミックレンジで30dB以上とれる。
Embodiment Example [3] Experiment The measurement of the local chromatic dispersion described before was performed in a laboratory. In the measurement system of Fig. 1, 1.3μ in front of the EDFA
A single mode fiber 6 having m zero dispersion is inserted for 2 km. Therefore, in the equation (5), A = 0.045, φ 0 =
π is obtained. The formula (10) used a system that always becomes 0.
The effect of the above-mentioned extrinsic term is an intensity modulation component error that appears near the zero-dispersion wavelength and symmetrically with respect to that wavelength, as long as sin φ = 0. Therefore, the minimum IM wavelength is equal to that considering only the intrinsic term (n−k = ± 1) as in the previous section. 2 fibers were used for testing
This is a combination of two dispersion-shifted fibers. One is a normal dispersion fiber with a zero-dispersion wavelength of 1574.70 nm, 50 km, and the other is an anomalous dispersion fiber with a zero-dispersion wavelength of 1527.60 nm, which is 100 km in total. Has a zero-dispersion wavelength of 1549.0 nm.
These values are the values measured individually (destruction measurement) before connection by the conventional phase difference method. Before the local variance measurement,
The average zero-dispersion wavelength was measured by ordinary PM-AM conversion using low power except SMF from the measurement system of FIG. The result was 1549.50 nm. For comparison, in the local dispersion measurement experiment, the measurement of light incident from the normal dispersion side and the measurement of high output light incidence from the abnormal dispersion side were performed, and the shift of the minimum dispersion wavelength was obtained separately. With this experimental system, measurement is possible even when the reception level is -30 dBm or less. Therefore, assuming that there is no influence of the nonlinear effect at 0 dBm, the dynamic range can be 30 dB or more.

【0021】図3、図4に測定で得られた測定波長分散
値の波長依存性を光パワーをパラメータとして示す。図
3は正常分散側から入射した場合の観測される波長分散
値の波長依存性である。黒丸プロットは0dBm入射の
場合、白丸プロットは+13dBm入射、+プロットは
+16dBm入射、xプロットは+19dBm入射の場
合である。0dBm入射の測定で零分散波長が154
5.5nmであったが、これは送信系1内の2km−S
MF6の分散の分だけ1549.5nmより短波長側に
線形にシフトした結果である。図3の高出力入射では、
どのパワーの測定でも最小IM波長が非線形効果によっ
て0dBm測定時よりも短波長側にシフトしている。例
えば+19dBm入射の場合では4nmほど短波長にシ
フトしている。また最小分散波長近傍で、測定分散値が
20ps/nmほどで飽和しているが、これが非本質的
な(extrinsic)項の効果である。重要なのは
強度変調の最小値を与える波長を求める際には誤差とは
ならず、これは波長を掃引した理由である。一方、図4
では異常分散側から各送信パワーで入射した際の波長依
存性が示されている。異常分散側からの入射の測定で特
徴的なのは、+13dBmと+16dBm入射の最小I
M波長が0dBm入射のものよりも長波長側にシフトし
ていることである。+19dBm入射では短波長側にシ
フトして、ちょうど0dBmの最小IM波長と一致す
る。図3と図4の両測定において、長波長領域で若干の
分散スロープの変化が見られる以外は分散スロープはほ
ぼ一定であった。図5は最小分散波長シフトの光パワー
依存性である。白丸プロットは正常分散側からの入射、
黒丸プロットは異常分散側からの入射である。また実線
は(12)式の理論曲線である。パラメータとしての局
所的零分散波長は最小二乗フィッティングを用いて15
70.87nmと1528.43nmと決定された。図
5に示すとおり理論と実験は一致している。ただし実験
値は理論値よりも高次の項を含んだ振る舞いを見せてい
る。以上の結果よりテストファイバの局所的零分散値は
0〜23kmの領域では1570.87nm、23〜7
7kmにおいては1549.37nm、77〜100k
mでは1528.43nmと測定された。表1に平均零
分散波長、局所的零分散波長、分散スロープを示す。
FIGS. 3 and 4 show the wavelength dependence of the measured chromatic dispersion value obtained by the measurement, using the optical power as a parameter. FIG. 3 shows the wavelength dependence of the chromatic dispersion value observed when the light is incident from the normal dispersion side. The black circle plot is for 0 dBm incidence, the white circle plot is for +13 dBm incidence, the + plot is for +16 dBm incidence, and the x plot is for +19 dBm incidence. The zero dispersion wavelength is 154 in the measurement of 0 dBm incidence.
It was 5.5 nm, which is 2 km-S in the transmission system 1.
This is the result of linearly shifting to the shorter wavelength side than 1549.5 nm by the amount of the dispersion of MF6. At high power injection in Figure 3,
In any power measurement, the minimum IM wavelength is shifted to the shorter wavelength side than that in 0 dBm measurement due to the nonlinear effect. For example, in the case of +19 dBm incidence, the wavelength is shifted to a shorter wavelength by about 4 nm. In addition, the measured dispersion value is saturated at about 20 ps / nm near the minimum dispersion wavelength, which is the effect of the extrinsic term. What is important is that there is no error in finding the wavelength that gives the minimum value of the intensity modulation, which is the reason why the wavelength is swept. On the other hand, FIG.
Shows the wavelength dependence when incident with each transmission power from the anomalous dispersion side. The characteristic of the incident measurement from the anomalous dispersion side is that the minimum I of +13 dBm and +16 dBm incidence is
That is, the M wavelength is shifted to the longer wavelength side than that of 0 dBm incident. When +19 dBm is incident, the wavelength shifts to the short wavelength side and coincides with the minimum IM wavelength of exactly 0 dBm. In both the measurements of FIG. 3 and FIG. 4, the dispersion slope was almost constant except that a slight change in the dispersion slope was observed in the long wavelength region. FIG. 5 shows the optical power dependence of the minimum dispersion wavelength shift. The white circle plot is the incident from the normal dispersion side,
The black circle plot is the incident from the anomalous dispersion side. The solid line is the theoretical curve of equation (12). The local zero-dispersion wavelength as a parameter is 15 using the least-squares fitting.
It was determined to be 70.87 nm and 1528.43 nm. As shown in FIG. 5, the theory and the experiment are in agreement. However, the experimental values show the behavior including terms higher than the theoretical values. From the above results, the local zero dispersion value of the test fiber is 1570.87 nm, 23 to 7 in the range of 0 to 23 km.
1549.37 nm at 77 km, 77 to 100 k
m was measured as 1528.43 nm. Table 1 shows the mean zero dispersion wavelength, the local zero dispersion wavelength, and the dispersion slope.

【0022】[0022]

【表1】 [Table 1]

【0023】表1において平均零分散波長と分散スロー
プは本発明と位相差法(従来法)で略一致しているが、
局所的零分散波長は1nmから4nmの違いがある。こ
の誤差の原因として、局所的零分散波長の測定距離が異
なることがまず挙げられる。さらに用いた近似の破れ
(主に局所的分散スロープに関する近似)が考えられる
が、従来の位相差法の誤差も無視できないことも注意さ
れるべきである。従来法の装置(アンリツ社製)で用い
られる波長としては1504nm,1534nm,15
54nm,1589nmである。したがって、従来の位
相差法が用いているセルマイヤー多項式のフィッティン
グは遅延の最小値が1534nmと1554nmの間に
ある場合には正確であるが、極端に短波長あるいは長波
長に零分散波長がある場合には最小値、スロープに誤差
を出しやすい。
In Table 1, the average zero-dispersion wavelength and the dispersion slope are almost the same in the present invention and the phase difference method (conventional method).
The local zero dispersion wavelength has a difference of 1 nm to 4 nm. The cause of this error is that the measurement distance of the local zero-dispersion wavelength is different. Further, it is possible to think of the approximation violation (mainly the approximation regarding the local dispersion slope), but it should be noted that the error of the conventional phase difference method cannot be ignored. The wavelengths used in the conventional apparatus (manufactured by Anritsu) are 1504 nm, 1534 nm, 15
54 nm and 1589 nm. Therefore, the fitting of the Sellmeier polynomial used in the conventional phase difference method is accurate when the minimum delay value is between 1534 nm and 1554 nm, but there is a zero dispersion wavelength in an extremely short wavelength or a long wavelength. In this case, it is easy to make an error in the minimum value and slope.

【0024】[0024]

【発明の効果】以上述べたように本発明では、波長分散
によるPM−AM変換効果と非線形効果の重畳効果を利
用し、分散マネージドファイバの非線形有効距離におけ
る局所的零分散波長の測定法を提案した。光パワーと波
長という2つのパラメータを変化させ、さらに局所的分
散と非線形の相互作用効果を顕著にするために測定ファ
イバに入力する前に既知の強度変調を重畳させる。最小
IM波長シフトのパワー依存性は平均零分散波長と局所
的零分散波長により特異な挙動を見せる。平均零分散波
長測定と、最小IM波長シフトの理論フィッティングに
より、局所的零分散波長の値が得られる。本発明はいた
ってシンプルで経済的な測定系を実現し、測定に要する
入射光パワーを+16dBm程度に抑える。またこの測
定法では30dB以上のダイナミックレンジがとれるの
で長尺ファイバの局所的分散測定に向いている。また局
所的零分散波長と平均のそれが大きく離れていればいる
ほど感度がよく、実際に敷設されている分散マネージド
ファイバの測定に向いている。
As described above, the present invention proposes a method for measuring the local zero-dispersion wavelength at the nonlinear effective distance of a dispersion-managed fiber by utilizing the PM-AM conversion effect due to wavelength dispersion and the superposition effect of the nonlinear effect. did. Two parameters, optical power and wavelength, are varied, and a known intensity modulation is superposed before entering the measurement fiber to accentuate local dispersion and nonlinear interaction effects. The power dependence of the minimum IM wavelength shift shows a peculiar behavior depending on the mean zero dispersion wavelength and the local zero dispersion wavelength. The value of the local zero-dispersion wavelength is obtained by the mean zero-dispersion wavelength measurement and the theoretical fitting of the minimum IM wavelength shift. The present invention realizes a simple and economical measurement system, and suppresses the incident light power required for measurement to about +16 dBm. Further, since this measurement method can provide a dynamic range of 30 dB or more, it is suitable for local dispersion measurement of a long fiber. Further, the greater the distance between the local zero-dispersion wavelength and the average is, the better the sensitivity is, and it is suitable for the measurement of the dispersion-managed fiber actually laid.

【図面の簡単な説明】[Brief description of drawings]

【図1】本発明の一実施形態例を示す構成説明図であ
る。
FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention.

【図2】本発明に係る最小IM波長のシフトの光パワー
依存性の一例を局所的零分散波長をパラメータとして示
す特性図である。
FIG. 2 is a characteristic diagram showing an example of the optical power dependence of the shift of the minimum IM wavelength according to the present invention, using the local zero-dispersion wavelength as a parameter.

【図3】本発明に係る正常分散側から入射した場合の観
測される波長分散値の波長依存性の一例を示す特性図で
ある。
FIG. 3 is a characteristic diagram showing an example of wavelength dependence of a chromatic dispersion value observed when light enters from a normal dispersion side according to the present invention.

【図4】本発明に係る異常分散側から各送信パワーで入
射した際の波長依存性の一例を示す特性図である。
FIG. 4 is a characteristic diagram showing an example of wavelength dependence when incident with each transmission power from the anomalous dispersion side according to the present invention.

【図5】本発明に係る最小分散波長シフトの光パワー依
存性の一例を示す特性図である。
FIG. 5 is a characteristic diagram showing an example of optical power dependence of the minimum dispersion wavelength shift according to the present invention.

【符号の説明】[Explanation of symbols]

1 送信系 2 波長可変光源 3 LiNbO3 の外部位相変調器 4 7.4GHzの発振器 5 広帯域のRFアンプ 6 1.3μm零分散のシングルモードファイバ 7 EDFAポストアンプ 8 可変光減衰器 9 受信系 10 波長可変の半値幅3nmのバンドパスフィルタ 11 パワーモニタ 12 フォトディテクター 13 DC電圧計 14 RFスペクトルアナライザ1 Transmitting System 2 Wavelength Variable Light Source 3 LiNbO 3 External Phase Modulator 4 7.4 GHz Oscillator 5 Broadband RF Amplifier 6 1.3 μm Zero-dispersion Single Mode Fiber 7 EDFA Post-Amplifier 8 Variable Optical Attenuator 9 Receiving System 10 Wavelength Variable band-pass filter with a half width of 3 nm 11 Power monitor 12 Photodetector 13 DC voltmeter 14 RF spectrum analyzer

───────────────────────────────────────────────────── フロントページの続き (72)発明者 松岡 伸治 東京都新宿区西新宿三丁目19番2号 日本 電信電話株式会社内 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shinji Matsuoka 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (3)

【特許請求の範囲】[Claims] 【請求項1】 位相変調もしくは周波数変調された光源
を信号光とし、光パワー可変手段を送信側に配置し、被
測定光ファイバより出射する出力信号のビートから生じ
る信号光強度の変調周波数成分と信号光強度の直流成分
の比を測定することにより符号を含めた平均波長分散値
を求めることを特徴とする光ファイバの波長分散測定装
置において、 送信装置には、前記信号光源に波長可変手段を具備し、
前記光パワー可変手段の前段に既知の強度変調を信号光
に重畳させる強度変調手段を具備し、 受信装置には、前記信号光強度の変調成分と直流成分の
比が最小となる波長の観測手段を具備し、 前記送受信装置の間を結ぶ制御線を具備することを特徴
とする光ファイバの波長分散測定装置。
1. A modulation frequency component of signal light intensity generated from a beat of an output signal emitted from an optical fiber to be measured, using a phase-modulated or frequency-modulated light source as signal light, and an optical power varying means arranged on the transmission side. In an optical fiber chromatic dispersion measuring apparatus characterized by obtaining an average chromatic dispersion value including a sign by measuring a ratio of a direct current component of signal light intensity, a transmitter includes wavelength tunable means in the signal light source. Be equipped with
An intensity modulation means for superimposing a known intensity modulation on the signal light is provided in front of the optical power varying means, and the receiving device has a wavelength observing means for minimizing the ratio of the modulation component of the signal light intensity to the DC component. A chromatic dispersion measuring device for an optical fiber, comprising: a control line connecting the transmitting and receiving devices.
【請求項2】 請求項1に記載の光ファイバの波長分散
測定装置において、 受信側に波長可変フィルタと、該フィルタを信号光に正
確にアジャストするためのモニタを具備することを特徴
とする光ファイバの波長分散測定装置。
2. The optical fiber chromatic dispersion measuring apparatus according to claim 1, wherein a tunable filter on the receiving side and a monitor for accurately adjusting the filter to signal light are provided. Fiber chromatic dispersion measuring device.
【請求項3】 請求項1又は2に記載の光ファイバの波
長分散測定装置であって、前記受信装置の観測した前記
信号光強度の変調成分と直流成分の比が最小となる波長
の、光パワーによる変動量Δλ0 (P0 )を次式にフィ
ッティングさせ局所零分散波長を求める計算手段を具備
することを特徴とする光ファイバの波長分散測定装置。 【数1】 【数2】
3. The chromatic dispersion measuring apparatus for an optical fiber according to claim 1, wherein the wavelength of the wavelength of which the ratio of the modulation component and the DC component of the signal light intensity observed by the receiving device is minimum. A chromatic dispersion measuring device for an optical fiber, comprising a calculating means for fitting a variation amount Δλ 0 (P 0 ) due to power to the following equation to obtain a local zero dispersion wavelength. [Equation 1] [Equation 2]
JP05170396A 1996-03-08 1996-03-08 Optical fiber chromatic dispersion measuring device Expired - Fee Related JP3278129B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP05170396A JP3278129B2 (en) 1996-03-08 1996-03-08 Optical fiber chromatic dispersion measuring device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP05170396A JP3278129B2 (en) 1996-03-08 1996-03-08 Optical fiber chromatic dispersion measuring device

Publications (2)

Publication Number Publication Date
JPH09243516A true JPH09243516A (en) 1997-09-19
JP3278129B2 JP3278129B2 (en) 2002-04-30

Family

ID=12894264

Family Applications (1)

Application Number Title Priority Date Filing Date
JP05170396A Expired - Fee Related JP3278129B2 (en) 1996-03-08 1996-03-08 Optical fiber chromatic dispersion measuring device

Country Status (1)

Country Link
JP (1) JP3278129B2 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002022612A (en) * 2000-07-10 2002-01-23 Advantest Corp Equipment and method for measuring optical characteristics, and recording medium
WO2002046715A1 (en) * 2000-11-22 2002-06-13 Center For Advanced Science And Technology Incubation, Ltd. Method and equipment for measuring wavelength dispersion
KR100358113B1 (en) * 2000-12-27 2002-10-25 한국전자통신연구원 The Apparatus and Method for Measuring the Zero-Dispersion Wavelength in Dispersion-Shifted Fiber using Spectrum-Siced Light Source

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002022612A (en) * 2000-07-10 2002-01-23 Advantest Corp Equipment and method for measuring optical characteristics, and recording medium
WO2002046715A1 (en) * 2000-11-22 2002-06-13 Center For Advanced Science And Technology Incubation, Ltd. Method and equipment for measuring wavelength dispersion
KR100358113B1 (en) * 2000-12-27 2002-10-25 한국전자통신연구원 The Apparatus and Method for Measuring the Zero-Dispersion Wavelength in Dispersion-Shifted Fiber using Spectrum-Siced Light Source

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