JPH07248276A - Method and device for measuring wavelength dispersion of optical device - Google Patents
Method and device for measuring wavelength dispersion of optical deviceInfo
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- JPH07248276A JPH07248276A JP6438594A JP6438594A JPH07248276A JP H07248276 A JPH07248276 A JP H07248276A JP 6438594 A JP6438594 A JP 6438594A JP 6438594 A JP6438594 A JP 6438594A JP H07248276 A JPH07248276 A JP H07248276A
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- wavelength
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、長尺の光ファイバにも
適用可能な光デバイスの波長分散測定方法及び装置に関
する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring chromatic dispersion of an optical device applicable to a long optical fiber.
【０００２】[0002]
【従来の技術】光ファイバ通信システムにおいて、光信
号は伝搬中に光ファイバが持つ波長分散によって波形ひ
ずみを生じ劣化する。また、超高速全光スイッチングに
おいて、スイッチング速度は使用される光デバイスの波
長分散によって制限される。従って、光ファイバを含む
光デバイスの波長分散は光通信システムや全光スイッチ
ング回路等を設計する際の最も重要なパラメータであ
る。光デバイスの波長分散測定法は大別して干渉法，パ
ルス法，位相シフト測定法の３つがある〔LEONARD G. C
OHEN: "Comparision of Single-Mode Fiber Dispersion
Measurement Techniques", JOURANL OF LIGHTWAVE TEC
HNOLOGY, VOL. LT-3, No.5, OCTOBER 1985, pp 958-966
参照〕。干渉法は、光源として可干渉長の十分短いハ
ロゲンランプ等のＣＷ白色光源を用いてマッハ・ツェン
ダあるいはマイケルソンの干渉計を構成し、参照光と被
測定光デバイスによる分散の影響を受けた測定光との干
渉のコントラストが最大になるときの２つの干渉腕の光
路差から相対遅延時間を求めて波長分散を算出する。パ
ルス法は、波長可変パルス光源や白色パルス光源を用い
て光パルスが被測定デバイス中で生じる群遅延時間を光
パルスの時間遅延量として測定し、波長分散を算出す
る。波長可変パルス光源としては、波長可変モード同期
レーザ等が利用され、白色パルス光源は超短パルス光で
単一モードファイバを励起したときに波長範囲数１００
ｎｍにわたって発生するスーパーコンティニューム光や
高次誘導ラマン散乱光を利用する。また、位相シフト法
は、ＬＥＤやＬＤの正弦波変調光を用いて相対遅延時間
を光包絡線の位相シフト量として測定し、波長分散を算
出する。この方法では、光源，受光系に電気の帯域の制
限を受けることなく、パルス法と同等以上の時間精度の
測定が可能となる。2. Description of the Related Art In an optical fiber communication system, an optical signal deteriorates due to waveform distortion due to chromatic dispersion of the optical fiber during propagation. Also, in ultrafast all-optical switching, the switching speed is limited by the chromatic dispersion of the optical device used. Therefore, the chromatic dispersion of an optical device including an optical fiber is the most important parameter when designing an optical communication system or an all-optical switching circuit. Wavelength dispersion measurement methods for optical devices are roughly classified into three methods: interferometry, pulse method, and phase shift measurement method [LEONARD G. C.
OHEN: "Comparision of Single-Mode Fiber Dispersion
Measurement Techniques ", JOURANL OF LIGHTWAVE TEC
HNOLOGY, VOL. LT-3, No.5, OCTOBER 1985, pp 958-966
reference〕. In the interferometry, a Mach-Zehnder or Michelson interferometer is constructed by using a CW white light source such as a halogen lamp having a sufficiently short coherence length as a light source, and the measurement is affected by the dispersion of the reference light and the measured optical device. The chromatic dispersion is calculated by calculating the relative delay time from the optical path difference between the two interference arms when the contrast of interference with light is maximized. The pulse method uses a variable wavelength pulse light source or a white pulse light source to measure the group delay time that an optical pulse occurs in a device under measurement as the time delay amount of the optical pulse, and calculates the chromatic dispersion. A wavelength tunable mode-locked laser or the like is used as the wavelength tunable pulse light source, and the white pulse light source has a wavelength range of 100 when a single mode fiber is excited by ultrashort pulsed light.
The supercontinuum light and the higher-order stimulated Raman scattering light generated over nm are used. In the phase shift method, the relative delay time is measured as the phase shift amount of the optical envelope by using the sine wave modulated light of LED or LD, and the chromatic dispersion is calculated. With this method, it is possible to perform measurement with time accuracy equal to or higher than that of the pulse method without being restricted by the electric band of the light source and the light receiving system.
【０００３】[0003]
【発明が解決しようとする課題】しかし、干渉法では上
記干渉光と上記測定光の光路長を一致させることが必要
で、ｋｍオーダー以上の条長をもつ光ファイバの測定に
対しては全く不向きであった。However, in the interferometry, it is necessary to match the optical path lengths of the interference light and the measurement light, and it is completely unsuitable for measurement of an optical fiber having a strip length of the order of km or more. Met.
【０００４】次に、パルス法は、広い波長域をカバーす
る光源の利用が可能であるという利点を有しているが、
直接測定される遅延時間の精度がＯ／Ｅ変換器の帯域で
制限され、サンプロスコープやストリークカメラ等の広
帯域の測定器が必要で、測定時間の精度は現状でたかだ
か１０ピコ秒程度であった。また、位相シフト法は、電
気系の帯域制限をうけないという利点を有しているが、
従来光源としてＬＥＤやＬＤが用いられたため、単一光
源で広い波長範囲をカバーすることが困難であるという
欠点を有している。このように、従来技術では、ｋｍオ
ーダー以上の条長を持つ光ファイバを含む光デバイスの
波長分散を広い波長範囲にわたって電気系の帯域制限を
受けることなく高精度に測定するのは困難であった。Next, the pulse method has the advantage that a light source covering a wide wavelength range can be used.
The accuracy of the delay time measured directly is limited by the bandwidth of the O / E converter, and a wideband measuring device such as a sunproscope or streak camera is required. The accuracy of the measuring time is currently about 10 picoseconds. . Further, the phase shift method has an advantage that it is not limited by the band of the electric system,
Since LEDs and LDs have been conventionally used as light sources, it has a drawback that it is difficult to cover a wide wavelength range with a single light source. As described above, according to the conventional technique, it is difficult to measure the chromatic dispersion of an optical device including an optical fiber having a strip length of the order of km or more with high accuracy without being subject to band limitation of an electric system over a wide wavelength range. .
【０００５】本発明は、上記課題を解決するため、パル
ス法と位相シフト法の利点を兼備した方法及び装置、す
なわち、電気系の帯域制限を受けない位相シフト法の利
点と、広い波長域をカバーする光源が利用できるパルス
法の利点を兼備した光デバイスの波長分散測定方法及び
装置を提供する。In order to solve the above-mentioned problems, the present invention provides a method and an apparatus having the advantages of the pulse method and the phase shift method, that is, the advantage of the phase shift method which is not subject to the band limitation of the electric system and the wide wavelength range. Provided is a method and apparatus for measuring chromatic dispersion of an optical device, which has the advantages of the pulse method in which a light source to be covered can be used.
【０００６】[0006]
【課題を解決するための手段】本発明は、繰り返し光パ
ルス列が被測定デバイスを通過することによって生じる
遅延時間を、光パルス包絡線の１フーリエ正弦波成分の
位相シフト量として測定し分散特性を求める。この原理
を周波数軸上で説明するためのスペクトラム図を図１に
示す。１−１はキャリア（光）角周波数ω0 で繰り返し
角周波数Ωの光パルス列のスペクトルを表し、その包絡
線は単一光パルスのスペクトルに対応する。１−２は１
−１を包絡線検波して得た電気信号で、１−３は１−２
からろ波されたフーリエ正弦波成分の１つ（ここでは基
本周波成分）を表す。パルス法の場合、測定時間精度の
向上のために広帯域Ｏ／Ｅ変換で多くの高調波成分を検
波する必要があるが、本装置では繰り返しの基本周波成
分もしくは１高調波成分のみをろ波して被測定デバイス
前後における位相差を測定する。According to the present invention, the dispersion characteristic is measured by measuring the delay time caused by the repeated optical pulse train passing through the device under test as the phase shift amount of one Fourier sine wave component of the optical pulse envelope. Ask. FIG. 1 shows a spectrum diagram for explaining this principle on the frequency axis. 1-1 represents the spectrum of an optical pulse train having a carrier (optical) angular frequency ω 0 and a repetitive angular frequency Ω, and its envelope corresponds to the spectrum of a single optical pulse. 1-2 is 1
-1 is an electric signal obtained by envelope detection, 1-3 is 1-2
It represents one of the Fourier sine wave components filtered here (fundamental frequency component here). In the case of the pulse method, it is necessary to detect many harmonic components by wideband O / E conversion in order to improve the accuracy of measurement time, but in this device, only the fundamental frequency component or one harmonic component that is repeated is filtered. To measure the phase difference before and after the device under test.
【０００７】本発明方法を時間軸上で説明する。繰り返
し周期Ｔの光パルス列（キャリア角周波数ω0 ）が伝搬
定数β（ω）をもつ被測定デバイス中を距離ｚだけ伝搬
したときの波形ｆ（ｔ，ｚ；ω0 ）は次のように表され
る。The method of the present invention will be described on the time axis. The waveform f (t, z; ω 0 ) when the optical pulse train (carrier angular frequency ω 0 ) with the repetition period T propagates through the device under test having the propagation constant β (ω) by the distance z is expressed as follows. To be done.
【数５】 但し、Ｆ0 （ω）は単一光パルス包絡線ｆ0 （ｔ) のフ
ーリエ変換を表し、Ω＝２π／Ｔである。従来の位相シ
フト法はｎ＝０、±１のみＦ0 （ｎΩ）≠０となる場合
に対応する。ｆ0 （ｔ）が実関数で、ｎΩがω0 に比べ
て十分小さいと仮定すると、ｆ（ｔ，ｚ；ω0 ）はさら
に正弦波cos ｎΩｔの重ね合わせとして[Equation 5] However, F 0 (ω) represents the Fourier transform of the single optical pulse envelope f 0 (t), and Ω = 2π / T. The conventional phase shift method corresponds to the case where F 0 (nΩ) ≠ 0 only for n = 0 and ± 1. Assuming that f 0 (t) is a real function and nΩ is sufficiently smaller than ω 0 , f (t, z; ω 0 ) is a superposition of sinusoidal cos nΩt.
【数６】 と書ける。但し、φ（ω）はＦ0 （ω）の偏角で実奇関
数である。β1(ω0)はβ（ω）のω＝ω0 における微分
係数を表し、これが被測定デバイスの群遅延量である。
波長分散Ｄ（λ）は、[Equation 6] Can be written. However, φ (ω) is an argument of F 0 (ω) and is a real-odd function. β 1 (ω 0 ) represents the differential coefficient of β (ω) at ω = ω 0 , and this is the group delay amount of the device under measurement.
The wavelength dispersion D (λ) is
【数７】 で算出される（ｃは真空中の光速度）。群遅延量β1(ω
0)はロックインアンプやベクトル電圧計等の狭帯域の測
定器を用いて上記光パルス列ｆ（ｔ，ｚ；ω0 ）の包絡
線に含まれるｎ次高調波成分（cos ｎΩｔ）の被測定デ
バイス（長さＬ）前後での位相遅延量θd ＝ｎΩβ1(ω
0)Ｌを測定することにより求まる。位相遅延量θd は高
調波の次数ｎに比例して大きくなる。このため、基本波
のみを用いた従来の位相シフト法と異なって、短光パル
スを検波して高調波成分の利用が可能な本発明方法で
は、Ｆ0 （ｎΩ）が十分大きいｎの範囲でより大きなｎ
次高調波成分を測定することにより、白色パルスの繰り
返し周波数や被測定デバイス長を大きくすることなく容
易に位相測定の高感度化が可能となる。[Equation 7] (C is the speed of light in a vacuum). Group delay β 1 (ω
0 ) is the measured n-th harmonic component (cos nΩt) contained in the envelope of the optical pulse train f (t, z; ω 0 ) using a narrow-band measuring instrument such as a lock-in amplifier or a vector voltmeter. Phase delay before and after device (length L) θ d = nΩβ 1 (ω
0 ) Obtained by measuring L. The amount of phase delay θ d increases in proportion to the harmonic order n. Therefore, unlike the conventional phase shift method using only the fundamental wave, in the method of the present invention in which a short optical pulse is detected and a higher harmonic component can be used, F 0 (nΩ) is sufficiently large in the range of n. Greater n
By measuring the second harmonic component, it is possible to easily increase the sensitivity of phase measurement without increasing the repetition frequency of the white pulse and the device length to be measured.
【０００８】[0008]
【作用】請求項１，３による作用を図２を用いて説明す
る。３−１，３−２は各々参照光、被測定デバイス出力
に対応する波長λの光パルスで、その時間差ｔd （λ）
＝ｔout （λ）−ｔin（λ）は被測定デバイスの群遅延
量β1 （２πｃ／λ）に対応する。３−３，３−４は各
々光パルス３−１，３−２の包絡線の１フーリエ正弦波
成分で、ここでは基本周波数成分（１／Ｔ）である。正
弦波３−３，３−４のその位相差θd （λ）はベクトル
電圧計等の位相差検出手段を用いて測定される。一般に
ｎ次高調波を検出する場合、θd （λ）とｔd （λ）は
θd （λ）／（２πｎ）＝ｔd （λ）／Ｔの関係で結ば
れる。従って、、The operation according to claims 1 and 3 will be described with reference to FIG. Reference numerals 3-1 and 3-2 respectively denote a reference light and an optical pulse having a wavelength λ corresponding to the output of the device under measurement, and their time difference t d (λ).
= T out (λ) -t in (λ) corresponds to the group delay amount β 1 (2πc / λ) of the device under measurement. Reference numerals 3-3 and 3-4 denote 1 Fourier sine wave components of the envelopes of the optical pulses 3-1 and 3-2, respectively, which are fundamental frequency components (1 / T) here. The phase difference θ d (λ) of the sine waves 3-3 and 3-4 is measured using a phase difference detecting means such as a vector voltmeter. Generally, when detecting the nth harmonic, θ d (λ) and t d (λ) are connected by the relationship of θ d (λ) / (2πn) = t d (λ) / T. Therefore,
【数８】ｔd ＝β1(２πｃ／λ）Ｌ＝Ｔθd (λ）／
（２πｎ） (4) これを式（３）に代入すると## EQU00008 ## t d = β 1 (2πc / λ) L = Tθ d (λ) /
(2πn) (4) Substituting this into equation (3)
【数９】 が得られる。[Equation 9] Is obtained.
【０００９】請求項２，４に相当する本願第２の発明を
図３を用いて説明する。４−１は被測定デバイスへの入
射白色パルスの時間分解分光像、４−２は被測定デバイ
スからの出射白色パルスの時間分解分光像で、これらは
白色パルスに含まれる各波長成分の相対時間関係を表
す。４−３，４−４は各々前記被測定デバイスの入射光
４−１からバンドパスフィルタ等でろ波された波長
λ1 ，λの光パルス、４−５，４−６は各々前記被測定
デバイスの出射光４−２からろ波された波長λ2 ，λの
光パルスである。第２の発明は第１の発明のように被測
定デバイス入射光パルス（参照光）に対する出射光パル
スの遅延時間を直接比較するのではなく、前記時間分解
分光像４−３，４−４，４−５，４−６から得られる白
色パルス光の波長成分の相対遅延時間Δｔin（λ）およ
びΔｔout （λ）を測定し、被測定デバイスによる遅延
時間A second invention of the present application corresponding to claims 2 and 4 will be described with reference to FIG. 4-1 is a time-resolved spectroscopic image of the white pulse incident on the device under test, 4-2 is a time-resolved spectroscopic image of the white pulse output from the device under test, and these are relative times of each wavelength component included in the white pulse. Represents a relationship. Reference numerals 4-3 and 4-4 denote optical pulses of wavelengths λ 1 and λ, which are filtered from the incident light 4-1 of the device under test with a bandpass filter or the like, and 4 5 and 4-6 are the device under test, respectively. Are optical pulses of wavelengths λ 2 and λ filtered from the outgoing light 4-2. The second invention does not directly compare the delay time of the emitted light pulse with respect to the incident light pulse (reference light) of the device under measurement as in the first invention, but rather the time-resolved spectroscopic images 4-3, 4-4. The relative delay times Δt in (λ) and Δt out (λ) of the wavelength components of the white pulsed light obtained from 4-5 and 4-6 are measured, and the delay time due to the device under measurement is measured.
【数１０】 ｔd （λ）＝Δｔout （λ）−Δｔin（λ） (6) を得る。これらの光パルスとその包絡線のフーリエ正弦
波成分の関係を図４に示す。５−１，５−２，５−３，
５−４は各々図３の光パルス４−３，４−４，４−５，
４−６にそれぞれ対応し、５−５，５−６，５−７，５
−８は光パルス５−１，５−２，５−３，５−４の包絡
線の基本フーリエ正弦波成分をそれぞれ表す。ここで正
弦波５−５，５−６の位相差Δθin（λ）からΔｔ
in（λ）が導かれ、正弦波５−７，５−８の位相差Δθ
out （λ）からΔｔout （λ）が導かれる。但し、ここ
ではΔθin（λ）／２π＝Δｔin（λ）／Ｔ、Δθout
（λ）／２π＝Δｔout （λ）／Ｔである。従って、## EQU10 ## t d (λ) = Δt out (λ) −Δt in (λ) (6) is obtained. The relationship between these light pulses and the Fourier sine wave component of their envelope is shown in FIG. 5-1, 5-2, 5-3
5-4 are optical pulses 4-3, 4-4, 4-5 of FIG.
4-5, 5-5, 5-6, 5-7, 5
-8 represents the fundamental Fourier sine wave component of the envelope of the optical pulses 5-1, 5-2, 5-3, 5-4. Here, from the phase difference Δθ in (λ) of the sine waves 5-5 and 5-6, Δt
in (λ) is introduced, and the phase difference Δθ between the sine waves 5-7 and 5-8
Δt out (λ) is derived from the out (λ). However, here, Δθ in (λ) / 2π = Δt in (λ) / T, Δθ out
(Λ) / 2π = Δt out (λ) / T. Therefore,
【数１１】 式（３），式（４），式（６）から[Equation 11] From equation (3), equation (4), and equation (6)
【数１２】 が得られる。[Equation 12] Is obtained.
【００１０】[0010]
【実施例】本発明で利用される白色パルス光源の１例を
図５に示す。６−１は励起短光パルス光源、６−２は励
起用光ファイバである。励起短光パルス光源６−１から
発せられた短光パルスは励起用光ファイバ６−２の伝搬
に伴い誘導ラマン散乱や４光波混合過程を原因とした白
色パルスを発生する。上記短光パルスから上記白色パル
スへのエネルギ変換が不完全な場合、白色パルス中に励
起短光パルス成分が点線で示すように残留する。図６は
励起用光ファイバの後段に残留励起パルス成分を減衰さ
せるための帯域除去光フィルタを設けた白色パルス光源
の他の例で、請求項５に対応する。７−１は励起短光パ
ルス光源、７−２は励起用光ファイバ、７−３は帯域除
去光フィルタである。残留励起パルス成分を減衰させる
ことにより被測定デバイス中で新たに生じる不要な非線
形効果を抑圧することができる。FIG. 5 shows an example of a white pulse light source used in the present invention. Reference numeral 6-1 is a pumping short optical pulse light source, and 6-2 is a pumping optical fiber. The short optical pulse emitted from the excitation short optical pulse light source 6-1 generates a white pulse due to the stimulated Raman scattering and the four-wave mixing process along with the propagation of the excitation optical fiber 6-2. When the energy conversion from the short light pulse to the white pulse is incomplete, the excitation short light pulse component remains in the white pulse as shown by the dotted line. FIG. 6 is another example of the white pulse light source in which a band elimination optical filter for attenuating the residual excitation pulse component is provided in the subsequent stage of the excitation optical fiber, and corresponds to claim 5. Reference numeral 7-1 is a pumping short optical pulse light source, 7-2 is a pumping optical fiber, and 7-3 is a band elimination optical filter. By attenuating the residual excitation pulse component, unnecessary non-linear effects newly generated in the device under test can be suppressed.
【００１１】本発明による光デバイスの波長分散測定法
の実施例を以下に述べる。請求項１，３（第１の発明）
に対応する実施例を図７に示す。８−１は白色パルス光
源、８−２は波長可変光バンドパスフィルタで、波長可
変パルス光源を構成する〔特願平４−３４４８７６号
「波長広帯域パルス光発生装置」参照〕。８−３は波長
可変バンドパスフィルタ８−２の出力を次の被測定デバ
イスへの入射光と参照光に分岐する光分岐器、８−４は
被測定デバイス、８−５，８−６はＯ／Ｅ変換器、８−
７，８−８はＲＦバンドパスフィルタで白色パルスの基
本周波数１／Ｔもしくはその高調波のみを通す。８−９
はベクトル電圧計等の位相差検出手段である。参照光と
被測定デバイス出力光は各々別のＯ／Ｅ変換器８−５，
８−６によってそれらの包絡線信号が検出される。これ
ら２つの包絡線信号は各々のＲＦバンドパスフィルタ８
−７，８−８によってその繰り返しの基本周波成分もし
くはその高調波成分が抽出されその位相差θd （λ）を
測定することによって被測定デバイスによる遅延時間ｔ
d （λ）を算出する。Ｏ／Ｅ変換器とＲＦバンドパスフ
ィルタの対８−５，８−７及び８−６，８−８は各々所
望の正弦波成分のみに感度を持つ狭帯域の受光器で代用
可能である。An embodiment of the wavelength dispersion measuring method for an optical device according to the present invention will be described below. Claims 1 and 3 (first invention)
FIG. 7 shows an embodiment corresponding to. Reference numeral 8-1 is a white pulse light source, and 8-2 is a wavelength tunable optical bandpass filter, which constitutes a wavelength tunable pulse light source [see Japanese Patent Application No. 4-344876 "Wavelength Broadband Pulse Light Generator"]. 8-3 is an optical branching device for branching the output of the wavelength tunable bandpass filter 8-2 into incident light to the next device under test and reference light, 8-4 is the device under test, 8-5, 8-6 are O / E converter, 8-
Reference numerals 7 and 8-8 are RF band pass filters which pass only the fundamental frequency 1 / T of the white pulse or its harmonics. 8-9
Is a phase difference detecting means such as a vector voltmeter. The reference light and the output light of the device under measurement are different O / E converters 8-5 and 5-5, respectively.
The envelope signals are detected by 8-6. These two envelope signals are applied to the respective RF bandpass filters 8
The repeated fundamental frequency component or its harmonic component is extracted by -7, 8-8, and the phase difference θ d (λ) is measured to determine the delay time t of the device under test.
Calculate d (λ). The O / E converter and RF bandpass filter pairs 8-5, 8-7 and 8-6, 8-8 can each be replaced by a narrow band photoreceiver sensitive only to the desired sine wave component.
【００１２】続いて請求項２，４（第２の発明）に基づ
く実施例を図８に示す。９−１は白色パルス光源、９−
２は被測定デバイス、９−３は光分岐器、９−４は通過
波長が固定された光バンドパスフィルタ、９−５は波長
可変光バンドパスフィルタである。９−６，９−７はＯ
／Ｅ変換器、９−８，９−９はＲＦバンドパスフィルタ
で白色パルスの基本周波数１／Ｔもしくはその高調波の
みを通す。９−１０は位相差検出手段である。Ｏ／Ｅ変
換器とＲＦバンドパスフィルタの対９−６，９−８及び
９−７，９−９は各々所望の正弦波成分のみに感度を持
つ狭帯域の受光器で代用可能である。被測定デバイスか
ら出力された白色パルス列は９−３で分岐され、図３に
示す３−２の波長−遅延時間特性Δｔout （λ）に対す
る波長−位相特性Δθout （λ）が測定される。このΔ
θout （λ）から予め測定した被測定デバイスなしの測
定結果Δθin（λ）を差し引いてθd （λ）を求め、遅
延時間ｔd （λ）を算出する。この実施例は第１の発明
のような参照光のための光路を特に設けず、被測定デバ
イス出力の一部を参照光パルスとして用いるため、温
度，振動等の外乱に対し安定な測定を可能とする。この
ため、この構成は敷設されたファイバの遠端測定に特に
適した実施例である。Next, an embodiment based on claims 2 and 4 (second invention) is shown in FIG. 9-1 is a white pulse light source, 9-
2 is a device to be measured, 9-3 is an optical branching device, 9-4 is an optical bandpass filter with a fixed passing wavelength, and 9-5 is a wavelength tunable optical bandpass filter. 9-6 and 9-7 are O
The / E converters 9-8 and 9-9 are RF band pass filters and pass only the fundamental frequency 1 / T of the white pulse or its harmonics. Reference numeral 9-10 is a phase difference detecting means. The O / E converter and RF bandpass filter pairs 9-6, 9-8 and 9-7, 9-9 can each be replaced by a narrow band photodetector sensitive to only the desired sine wave component. The white pulse train output from the device under test is branched at 9-3, and the wavelength-phase characteristic Δθ out (λ) with respect to the wavelength-delay time characteristic Δt out (λ) of 3-2 shown in FIG. 3 is measured. This Δ
The measurement result Δθ in (λ) without the device to be measured which has been measured in advance is subtracted from θ out (λ) to obtain θ d (λ), and the delay time t d (λ) is calculated. Since this embodiment does not particularly provide an optical path for the reference light as in the first invention and uses a part of the output of the device under test as the reference light pulse, it is possible to perform stable measurement against disturbances such as temperature and vibration. And As such, this configuration is an embodiment that is particularly suitable for far-end measurements of laid fibers.
【００１３】第１の発明，第２の発明とも、より高次の
高調波成分の位相を測定することにより、白色パルス光
の繰り返し周波数や被測定デバイス長を大きくすること
なくθd （λ）を大きくすることができ、高分解能の位
相測定が容易に可能となる。In both the first and second inventions, by measuring the phase of the higher harmonic component, θ d (λ) can be obtained without increasing the repetition frequency of the white pulsed light and the length of the device under test. Can be increased, and high-resolution phase measurement can be easily performed.
【００１４】測定される高調波成分の周波数が高くロッ
クインアンプ等で測定不可能な場合、ヘテロダイン法を
用いれば、測定可能な中間周波数に変換可能である。こ
れを第２の発明に適用した実施例を図９に示す。１０−
１は繰り返し周波数ｆの白色パルス光源、１０−２は被
測定デバイス、１０−３は光分岐器、１０−４は通過波
長が固定された光バンドパスフィルタ、１０−５は波長
可変光バンドパスフィルタである。１０−６，１０−７
はＯ／Ｅ変換器、１０−８，１０−９はＲＦバンドパス
フィルタ、１０−１０は周波数ｆL の局部発振器、１０
−１１，１０−１２は周波数ミキサ、９−１０は位相差
検出手段である。この場合、周波数ミキサ１０−１１，
１０−１２には白色パルス光の繰り返し周波数の高調波
（周波数ｎｆ）と局部発振器からの信号が入力され、出
力からは周波数ｎｆ−ｆL の信号が得られる。上記高調
波の位相情報は中間周波信号に変換されても保存され
る。When the frequency of the harmonic component to be measured is high and cannot be measured by a lock-in amplifier or the like, it can be converted to a measurable intermediate frequency by using the heterodyne method. An embodiment in which this is applied to the second invention is shown in FIG. 10-
1 is a white pulse light source having a repetition frequency f, 10-2 is a device to be measured, 10-3 is an optical branching device, 10-4 is an optical bandpass filter with a fixed passing wavelength, and 10-5 is a variable wavelength optical bandpass. It is a filter. 10-6, 10-7
Is an O / E converter, 10-8 and 10-9 are RF band pass filters, 10-10 is a local oscillator of frequency f L , and
-11 and 10-12 are frequency mixers, and 9-10 is a phase difference detecting means. In this case, the frequency mixer 10-11,
A harmonic of the repetition frequency of the white pulsed light (frequency nf) and a signal from the local oscillator are input to 10-12, and a signal of frequency nf-f L is obtained from the output. The phase information of the above harmonics is preserved even if it is converted into an intermediate frequency signal.
【００１５】[0015]
【発明の効果】以上説明したように、本発明は、パルス
法と位相シフト法の利点を兼ね備えた方法及び装置を提
供する。このためサンプロスコープやストリークカメラ
のような高価な測定器を用いる必要がなく、簡単な構成
で広い波長域をカバーする白色パルス光源を用いた光デ
バイスの波長分散測定が可能となる。検波された光パル
スのより高次の正弦波成分の測定により高感度の位相測
定が容易に可能となる。さらに第２の発明の方法を用い
れば外乱に強く、敷設されたファイバにも適用できる測
定手段を提供する。As described above, the present invention provides a method and an apparatus that combine the advantages of the pulse method and the phase shift method. Therefore, it is not necessary to use an expensive measuring instrument such as a sunproscope or a streak camera, and it becomes possible to measure the chromatic dispersion of an optical device using a white pulse light source that covers a wide wavelength range with a simple configuration. By measuring the higher-order sine wave component of the detected optical pulse, highly sensitive phase measurement can be easily performed. Further, by using the method of the second aspect of the present invention, there is provided a measuring means that is resistant to disturbance and can be applied to the laid fiber.
【図１】本発明の原理を説明するための周波数スペクト
ラム図である。FIG. 1 is a frequency spectrum diagram for explaining the principle of the present invention.
【図２】本願第１の発明の原理を説明するためのタイム
チャートである。FIG. 2 is a time chart for explaining the principle of the first invention of the present application.
【図３】本願第２の発明の原理を説明するための波長対
遅延時間特性図である。FIG. 3 is a wavelength vs. delay time characteristic diagram for explaining the principle of the second invention of the present application.
【図４】本願第２の発明の原理を説明するためのタイム
チャートである。FIG. 4 is a time chart for explaining the principle of the second invention of the present application.
【図５】本発明に用いる光源の１例を示す図である。FIG. 5 is a diagram showing an example of a light source used in the present invention.
【図６】本発明に用いる光源の他の例を示す図である。FIG. 6 is a diagram showing another example of a light source used in the present invention.
【図７】本願第１の発明の実施例を示すブロック図であ
る。FIG. 7 is a block diagram showing an embodiment of the first invention of the present application.
【図８】本願第２の発明の実施例を示すブロック図であ
る。FIG. 8 is a block diagram showing an embodiment of the second invention of the present application.
【図９】図８の実施例の変形例を示すブロック図であ
る。9 is a block diagram showing a modification of the embodiment of FIG.
１−１ 光パルス列のスペクトル １−２ 電気信号（基本波成分） １−３ フーリエ正弦波成分 ３−１ 被測定デバイスへの入力前の白色パルスの１波
長成分 ３−２ 被測定デバイスからの出力後の白色パルスの１
波長成分 ３−３ ３−１のフーリエ正弦波成分 ３−４ ３−２のフーリエ正弦波成分 ４−１ 被測定デバイス入射白色光の時間分解分光像 ４−２ 被測定デバイス出射白色光の時間分解分光像 ４−３ 波長λ1 の光パルス ４−４ 波長λの光パルス ４−５ 波長λ2 の光パルス ４−６ 波長λの光パルス ５−１，５−２，５−３，５−４ 光パルス ５−５，５−６，５−７，５−８ 包絡線の基本フーリ
エ正弦波成分 ６−１，７−１ 励起短光パルス光源 ６−２，７−２ 励起用光ファイバ ７−３ 帯域除去光フィルタ ８−１，９−１，１０−１ 白色パルス光源 ８−２ 波長可変光バンドパスフィルタ ８−３，９−３，１０−３ 光分岐器 ８−４，９−２，１０−２ 被測定デバイス ８−５，８−６，９−６，９−７，１０−６，１０−７
Ｏ／Ｅ変換器 ８−７，８−８，９−８，９−９，１０−８，１０−９
ＲＦバンドパスフィルタ ８−９，９−１０，１０−１３ 位相差測定手段 ９−４，９−５，１０−４，１０−５ 光バンドパスフ
ィルタ １０−１０，１０−１１ 周波数ミキサ １０−１２ 局部発振器1-1 Spectrum of optical pulse train 1-2 Electric signal (fundamental wave component) 1-3 Fourier sine wave component 3-1 1 wavelength component of white pulse before input to device under test 3-2 Output from device under test 1 of the later white pulse
Wavelength component 3-3 Fourier sine wave component of 3-1 3-4 Fourier sine wave component of 3-2 4-1 Time-resolved spectral image of incident white light of the device under measurement 4-2 Time-resolved of white light emitted from the device under measurement Spectral image 4-3 Optical pulse with wavelength λ 1 4-4 Optical pulse with wavelength λ 4-5 Optical pulse with wavelength λ 2 4-6 Optical pulse with wavelength λ 5-1, 5-2, 5-3, 5- 4 Optical pulse 5-5, 5-6, 5-7, 5-8 Basic Fourier sine wave component of envelope 6-1, 7-1 Excitation short optical pulse light source 6-2, 7-2 Excitation optical fiber 7 -3 Band elimination optical filter 8-1, 9-1, 10-1 White pulse light source 8-2 Variable wavelength optical bandpass filter 8-3, 9-3, 10-3 Optical branching device 8-4, 9-2 , 10-2 Device under test 8-5, 8-6, 9-6, 9-7, 10-6, 10-7
O / E converter 8-7, 8-8, 9-8, 9-9, 10-8, 10-9
RF band pass filter 8-9, 9-10, 10-13 Phase difference measuring means 9-4, 9-5, 10-4, 10-5 Optical band pass filter 10-10, 10-11 Frequency mixer 10-12 Local oscillator
Claims (5)
列を２分岐し、その一方を時間遅延の参照光とし、もう
一方を素子長Ｌの被測定光デバイスに入射し、前記参照
パルス列の包絡線のｎ次高調波成分に対する、前記被測
定デバイスの出力光パルス列の包絡線のｎ次高調波成分
の位相遅延量θd （λ） [ｒａｄ] を波長λの関数とし
て測定し、 【数１】 から波長分散Ｄを求めることを特徴とする光デバイスの
波長分散測定方法。1. An optical pulse train having a center wavelength λ and a repetition period T is branched into two, one of which is used as a reference light with a time delay, and the other is made incident on an optical device to be measured having an element length L, and an envelope of the reference pulse train. The phase delay amount θ d (λ) [rad] of the nth harmonic component of the envelope of the output optical pulse train of the device under measurement with respect to the nth harmonic component of the line is measured as a function of the wavelength λ, and ] A chromatic dispersion measuring method for an optical device, characterized in that the chromatic dispersion D is obtained from
る固定された中心波長λ1 の光パルス列の包絡線のｎ次
高調波成分に対する、任意の中心波長λの光パルス列の
包絡線のｎ次高調波成分の位相遅延量Δθin（λ） [ｒ
ａｄ] を波長λの関数として予め測定した上で、上記白
色パルス列を素子長Ｌの被測定光デバイスに入射し、そ
の出射光に含まれる固定された中心波長λ2 の光パルス
列の包絡線のｎ次高調波成分に対する、任意の中心波長
λの光パルス列の包絡線のｎ次高調波成分の位相遅延量
Δθout （λ） [ｒａｄ] を波長λの関数として測定
し、 【数２】 から波長分散Ｄを求めることを特徴とする光デバイスの
波長分散測定方法。2. An nth harmonic of an envelope of an optical pulse train having an arbitrary center wavelength λ with respect to an nth harmonic component of an envelope of an optical pulse train having a fixed center wavelength λ 1 included in a white pulse train having a repetition period T. Phase delay amount of wave component Δθ in (λ) [r
[ad] as a function of wavelength λ in advance, and then the white pulse train is incident on the optical device under test having the element length L, and the envelope of the optical pulse train of the fixed center wavelength λ 2 included in the emitted light The phase delay amount Δθ out (λ) [rad] of the n-th harmonic component of the envelope of the optical pulse train having an arbitrary center wavelength λ with respect to the n-th harmonic component is measured as a function of the wavelength λ, and A chromatic dispersion measuring method for an optical device, characterized in that the chromatic dispersion D is obtained from
と、 前記波長可変パルス光源の出力を分岐し、その一部を時
間遅延の参照光とし、他の一部を素子長Ｌの被測定光デ
バイスに入射する光分岐手段と、 前記参照光に含まれる中心波長λの光パルス列の包絡線
のｎ次高調波成分に対する、前記被測定デバイスの出力
光に含まれる中心波長λの光パルス列の包絡線のｎ次高
調波成分の位相遅延量θd （λ） [ｒａｄ] を波長λの
関数として測定し、 【数３】 から波長分散Ｄを求める測定手段を備えることを特徴と
する光デバイスの波長分散測定装置。3. A wavelength tunable pulse light source having a repetition period T, and an output of the wavelength tunable pulse light source is branched, part of which is used as time-delayed reference light, and another part of which is an optical device under test having an element length L. And an n-th harmonic component of the envelope of the optical pulse train of center wavelength λ contained in the reference light, the envelope of the optical pulse train of center wavelength λ contained in the output light of the device under test. The phase delay amount θ d (λ) [rad] of the nth harmonic component of is measured as a function of wavelength λ, and A chromatic dispersion measuring apparatus for an optical device, comprising: a measuring unit for obtaining the chromatic dispersion D from
る固定された中心波長λ1 の光パルス列の包絡線のｎ次
高調波成分に対する、任意の中心波長λの光パルス列の
包絡線のｎ次高調波成分の位相遅延量Δθin（λ） [ｒ
ａｄ] を波長λの関数として予め測定した上で、前記白
色パルス列を素子長Ｌの被測定光デバイスに入射し、そ
の出射光に含まれる固定された中心波長λ2 の光パルス
列の包絡線のｎ次高調波成分に対する、任意の中心波長
λの光パルス列の包絡線のｎ次高調波成分の位相遅延量
Δθout （λ） [ｒａｄ] を波長λの関数として測定
し、 【数４】 から波長分散Ｄを求める測定手段を備え、 前記白色パルス列は少なくとも１組の励起用短パルス光
源と励起用光ファイバとから構成される光源手段から発
生されるように構成されたことを特徴とする光デバイス
の波長分散測定装置。4. An n-th harmonic of an envelope of an optical pulse train having an arbitrary center wavelength λ with respect to an n-th harmonic component of an envelope of an optical pulse train having a fixed center wavelength λ 1 included in a white pulse train having a repetition period T. Phase delay amount of wave component Δθ in (λ) [r
[ad] as a function of wavelength λ, and then the white pulse train is incident on an optical device under test having an element length L, and the envelope of the optical pulse train of fixed center wavelength λ 2 included in the emitted light The phase delay amount Δθ out (λ) [rad] of the n-th harmonic component of the envelope of the optical pulse train having an arbitrary center wavelength λ with respect to the n-th harmonic component is measured as a function of the wavelength λ, and And a measuring means for obtaining the chromatic dispersion D from the white pulse train, wherein the white pulse train is generated from a light source means composed of at least one set of a short pulse light source for excitation and an optical fiber for excitation. Wavelength dispersion measuring device for optical devices.
ルス光の波長成分を前記被測定光デバイスへの入射前に
除去する手段と、前記被測定光デバイスへの入射前に前
記白色光パルス列の強度を減衰させる手段とのうち、少
なくとも一方の手段をさらに備えたことを特徴とする請
求項４に記載の光デバイスの波長分散測定装置。5. A means for removing a wavelength component of the excitation short pulse light from the white light pulse train before entering the measured optical device, and a means for removing the white light pulse train before entering the measured optical device. The chromatic dispersion measuring apparatus for an optical device according to claim 4, further comprising at least one of means for attenuating the intensity.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06438594A JP3237384B2 (en) | 1994-03-09 | 1994-03-09 | Method and apparatus for measuring chromatic dispersion of optical device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06438594A JP3237384B2 (en) | 1994-03-09 | 1994-03-09 | Method and apparatus for measuring chromatic dispersion of optical device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07248276A true JPH07248276A (en) | 1995-09-26 |
| JP3237384B2 JP3237384B2 (en) | 2001-12-10 |
Family
ID=13256804
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP06438594A Expired - Lifetime JP3237384B2 (en) | 1994-03-09 | 1994-03-09 | Method and apparatus for measuring chromatic dispersion of optical device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3237384B2 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0908710A2 (en) * | 1997-09-26 | 1999-04-14 | Japan Science and Technology Corporation | Apparatus and method for measuring characteristics of light |
| JP2002022612A (en) * | 2000-07-10 | 2002-01-23 | Advantest Corp | Equipment and method for measuring optical characteristics, and recording medium |
| JP2002250679A (en) * | 2001-02-23 | 2002-09-06 | Toshio Goto | Measurement instrument for wavelength dispersion |
| JP2002365165A (en) * | 2001-06-08 | 2002-12-18 | Sumitomo Electric Ind Ltd | Wavelength dispersion measuring device and method |
| JP2010513937A (en) * | 2006-12-18 | 2010-04-30 | ザイゴ コーポレーション | Sinusoidal phase shift interferometry |
-
1994
- 1994-03-09 JP JP06438594A patent/JP3237384B2/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0908710A2 (en) * | 1997-09-26 | 1999-04-14 | Japan Science and Technology Corporation | Apparatus and method for measuring characteristics of light |
| EP0908710A3 (en) * | 1997-09-26 | 2000-05-17 | Japan Science and Technology Corporation | Apparatus and method for measuring characteristics of light |
| JP2002022612A (en) * | 2000-07-10 | 2002-01-23 | Advantest Corp | Equipment and method for measuring optical characteristics, and recording medium |
| JP2002250679A (en) * | 2001-02-23 | 2002-09-06 | Toshio Goto | Measurement instrument for wavelength dispersion |
| JP2002365165A (en) * | 2001-06-08 | 2002-12-18 | Sumitomo Electric Ind Ltd | Wavelength dispersion measuring device and method |
| JP2010513937A (en) * | 2006-12-18 | 2010-04-30 | ザイゴ コーポレーション | Sinusoidal phase shift interferometry |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3237384B2 (en) | 2001-12-10 |
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