JPS6147533A - Method and apparatus for measuring group delay time difference of optical fiber - Google Patents
Method and apparatus for measuring group delay time difference of optical fiberInfo
- Publication number
- JPS6147533A JPS6147533A JP16904884A JP16904884A JPS6147533A JP S6147533 A JPS6147533 A JP S6147533A JP 16904884 A JP16904884 A JP 16904884A JP 16904884 A JP16904884 A JP 16904884A JP S6147533 A JPS6147533 A JP S6147533A
- Authority
- JP
- Japan
- Prior art keywords
- group delay
- delay time
- optical fiber
- time difference
- light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
- G01M11/33—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face
- G01M11/333—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face using modulated input signals
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
- G01M11/33—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face
- G01M11/331—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face by using interferometer
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- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Light Guides In General And Applications Therefor (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、光ファイバを伝搬する光信号の群遅延特性を
測定する方法および装置に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for measuring group delay characteristics of an optical signal propagating through an optical fiber.
光フアイバ内を伝搬する光信号の群遅延特性には、光信
号の波長の変化による群遅延特性(色分子ik特性)、
温度や長さ方向の引っ張りまたは圧縮応力に起因する群
遅延特性、光フアイバ断面内に複屈折が存在する光ファ
イバの直交偏波モード間の群遅延特性(群遅延時間差)
などがある。The group delay characteristics of an optical signal propagating within an optical fiber include group delay characteristics due to changes in the wavelength of the optical signal (color molecule ik characteristics),
Group delay characteristics caused by temperature, longitudinal tensile or compressive stress, and group delay characteristics between orthogonal polarization modes of optical fibers where birefringence exists within the optical fiber cross section (group delay time difference)
and so on.
これらの群遅延特性を求めるために、群遅延時間差の測
定が行われる。群遅延時間差を測定する方法としては、
時間領域で測定するパルス法、周波数領域で測定する位
相法または周波数掃引法、さらに、光の干渉縞の鮮明度
が最大となる位置を検出する干渉法などが利用される。In order to obtain these group delay characteristics, group delay time differences are measured. The method to measure the group delay time difference is as follows:
The pulse method that measures in the time domain, the phase method or frequency sweep method that measures in the frequency domain, and the interferometry that detects the position where the clarity of the interference fringes of light is maximum are used.
パルス法や位相法あるいは周波数掃引法による群遅延時
間差の測定では、測定系の時間分解能や周波数帯域の制
限により、小さい時間差を測定できない欠点があった。Measuring group delay time differences using the pulse method, phase method, or frequency sweep method has the disadvantage that small time differences cannot be measured due to limitations in the time resolution and frequency band of the measurement system.
例えば、パルス法により測定できる群遅延差は数十ピコ
秒が限度である。For example, the group delay difference that can be measured by the pulse method is limited to several tens of picoseconds.
また、光の干渉を利用する干渉法は、測定可能な群遅延
時間差が0.1ピコ秒程度であり、極めて高い時間分解
能を実現できる。しかし、干渉に用いる光の周波数が同
一であり、干渉縞の鮮明度を光路差の関数として測定す
る必要がある。このため、多数のサンプリング点で逐次
測定を行う必要があり、自動的に短時間で測定すること
ができない欠点があった。Further, in the interferometry method that uses optical interference, the measurable group delay time difference is about 0.1 picosecond, and extremely high time resolution can be achieved. However, the frequencies of the lights used for interference are the same, and it is necessary to measure the clarity of the interference fringes as a function of the optical path difference. For this reason, it is necessary to sequentially perform measurements at a large number of sampling points, and there is a drawback that measurements cannot be performed automatically in a short period of time.
本発明は、以上の問題点を解決し、時間分解能が高くし
かも自動測定を行うことが可能な、光ファイバの群遅延
時間差測定方法および装置を提供することを目的とする
。SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide a method and apparatus for measuring group delay time differences of optical fibers, which have high time resolution and are capable of automatic measurement.
本発明の光ファイバの群遅延時間差測定方法は、光源か
ら出射された光を空間的に二つの光束に分離し、この二
つの光束の少なくとも一方を周波数偏移させてこの二つ
の光束に周波数差を与え、この周波数差を与えた二つの
光束の少な(とも一方を被測定光ファイバに伝搬させ、
この光ファイバに伝搬させた後に上記二つの光束を干渉
させ、この干渉によるビート信号の強度を測定し、上記
二つの光束の少なくとも一方の光路長を変化させて測定
を繰り返して、上記二つの光路長の差に対する群遅延時
間差を測定する。The optical fiber group delay time difference measurement method of the present invention spatially separates light emitted from a light source into two light beams, and shifts the frequency of at least one of these two light beams to create a frequency difference between the two light beams. is given, and one of the two beams with this frequency difference is propagated into the optical fiber to be measured,
After propagating through this optical fiber, the above two light beams are made to interfere, the intensity of the beat signal due to this interference is measured, and the measurement is repeated by changing the optical path length of at least one of the above two light beams. Measure the group delay time difference for the length difference.
また、本発明の光ファイバの群遅延時間差測定装置は、
一つの光源と、この光源の出射光を空間的に二つの光束
に分離するとともに、この二つの光束の少な(とも一方
を周波数偏移させてこの二つの光束に周波数差を与える
手段と、この周波数を与えた二つの光束の少なくとも一
方を被測定光ファイバの一端に入射させる手段と、この
光ファイバの他端で上記二つの光束を干渉させる手段と
、この干渉によるビート信号の強度を測定する手段と、
上記二つの光束の少なくとも一方の光路長を変化させる
手段とを備えたことを特徴とする。Further, the optical fiber group delay time difference measuring device of the present invention includes:
A light source, a means for spatially separating the light emitted from this light source into two light beams, and a means for giving a frequency difference to the two light beams by shifting the frequency of one of the two light beams; means for making at least one of the two light beams given a frequency enter one end of an optical fiber to be measured; means for interfering the two light beams at the other end of the optical fiber; and measuring the intensity of the beat signal caused by this interference. means and
It is characterized by comprising means for changing the optical path length of at least one of the two light beams.
本発明の光ファイバの群遅延時間差測定方法は、空間的
に分離された二つの光束の一方を周波数偏移させ、この
二つの光束の少なくとも一方を被測定光ファイバに伝搬
させ、この後に二つの光束を干渉させる。光路長に対す
る干渉の強度を観測することにより、群遅延時間差を測
定することができる。The optical fiber group delay time difference measurement method of the present invention frequency-shifts one of two spatially separated light beams, propagates at least one of the two light beams to the optical fiber to be measured, and then Interfering with light flux. By observing the intensity of interference with respect to the optical path length, the group delay time difference can be measured.
第1図は本発明第一実施例光ファイバの群遅延時間差測
定装置のブロック構成図である。FIG. 1 is a block diagram of an optical fiber group delay time difference measuring device according to a first embodiment of the present invention.
本実施例は、偏波保持光ファイバ8の直交偏波モード間
の群遅延時間差を測定する方法の例である。This example is an example of a method for measuring the group delay time difference between orthogonal polarization modes of the polarization-maintaining optical fiber 8.
光a、1から出力された光は、偏光子2を通過し、光分
岐素子3により二つの光束に分割される。この二つの光
束の一方は、固定鏡4により反則され、半透鏡7を透過
して偏波保持光ファイバ8に入射する。二つの光束の他
方ば、半透鏡7およびA波長板5を通過して可動鏡6に
より反射され、再びA波長板5を通過し、半透鏡7によ
り反射されて偏波保持光ファイバ8に入射する。偏波保
持光ファイバ8を透過した光束は、偏光子9を通過して
光検出器10に入射する。光検出器10は選択レベルメ
ータ11に接続される。選択レベルメータ11ば記録装
置12に接続される。The light output from light a, 1 passes through a polarizer 2, and is split into two light beams by a light branching element 3. One of these two light beams is reflected by the fixed mirror 4, passes through the semi-transparent mirror 7, and enters the polarization-maintaining optical fiber 8. The other of the two beams passes through the semi-transparent mirror 7 and the A-wave plate 5, is reflected by the movable mirror 6, passes through the A-wave plate 5 again, is reflected by the semi-transparent mirror 7, and enters the polarization-maintaining optical fiber 8. do. The light beam transmitted through the polarization-maintaining optical fiber 8 passes through a polarizer 9 and enters a photodetector 10 . Photodetector 10 is connected to a selection level meter 11 . The selection level meter 11 is connected to the recording device 12.
光H,1が出力した可干渉性の光は、偏光子2により、
光分岐素子3の主軸に偏光方向が一致した直線偏光とな
る。光分岐素子3は、音響光学的効果等により周波数偏
移を行うことができる。この光分岐素子3により、偏光
子2を透過した直線偏光が、周波数偏移を受けた第一の
光束と、周波数偏移を受けない第二の光束とに空間的に
分離される。The coherent light outputted by the light H,1 is polarized by the polarizer 2,
It becomes linearly polarized light whose polarization direction coincides with the main axis of the optical branching element 3. The optical branching element 3 can shift the frequency by an acousto-optic effect or the like. This light branching element 3 spatially separates the linearly polarized light that has passed through the polarizer 2 into a first light beam that has undergone a frequency shift and a second light beam that has not undergone a frequency shift.
第一の光束の光路上には固定鏡4が配置されており、第
一の光束がこの固定鏡4により反射される。固定鏡4に
より反射された第一の光束は、半透鏡7を透過して偏波
保持光ファイバ8に入射する。ここで、第一の光束の偏
光方向は、偏波保持光ファイバ8の二つの複屈折軸の一
方と一致している。A fixed mirror 4 is arranged on the optical path of the first light beam, and the first light beam is reflected by this fixed mirror 4. The first light beam reflected by the fixed mirror 4 passes through the semi-transparent mirror 7 and enters the polarization-maintaining optical fiber 8 . Here, the polarization direction of the first light beam coincides with one of the two birefringence axes of the polarization-maintaining optical fiber 8.
第二の光束は、半透鏡7を透過し、A波長板を透過し、
可動鏡6により反射される。可動鏡6は支持台に固定さ
れており、この支持台はパルスモータあるいはステップ
モータにより移動可能である。可動鏡6により反射され
た光束は、再びA波長板5を透過し、半透鏡7により反
射され、C1前波保持光フアイバ8に入射する。The second light beam passes through the semi-transparent mirror 7, passes through the A wavelength plate,
It is reflected by the movable mirror 6. The movable mirror 6 is fixed to a support base, and this support base can be moved by a pulse motor or a step motor. The light beam reflected by the movable mirror 6 passes through the A wavelength plate 5 again, is reflected by the semi-transparent mirror 7, and enters the C1 front wave holding optical fiber 8.
上述の二つの光束は、偏波保持光ファイノ\8の複屈折
軸方向に一致した偏光方向で、偏波イ呆1青光ラブイバ
8に入射する。The above-mentioned two light beams are incident on the polarization maintainer 1 blue light lover 8 with the polarization direction coinciding with the direction of the birefringence axis of the polarization maintaining optical fiber 8.
偏光子9は、その主軸方向を調整することGこより、偏
波保持光ファイバ8の出射した二つの)し束を干渉させ
る。光検出器10は、シリコン・アノ\′ランシェ光ダ
イオードまたはゲルマニューム・アノくランシエ光ダイ
オード等で構成されており、二つの光束間の干渉で生じ
るビート信号を検出1−る。By adjusting the direction of its principal axis, the polarizer 9 causes the two beams emitted from the polarization-maintaining optical fiber 8 to interfere with each other. The photodetector 10 is composed of a silicon anno\'-Ranchet photodiode or a germanium anno-rancier photodiode, and detects a beat signal generated by interference between two light beams.
選択レベルメータ11は、このビー1−信号の数ヲ定量
的に測定する。記録装置12はこの測定値を言己ε朶す
る。記録装置12は、例えばX−Yレコーダ等を用いる
。The selection level meter 11 quantitatively measures the number of B1-signals. The recording device 12 records this measured value. The recording device 12 uses, for example, an X-Y recorder.
群遅延時間差は、二つの光束間の光路差G二対するビー
ト信号の数を測定することにより求められる。The group delay time difference is determined by measuring the number of beat signals for the optical path difference G2 between two light beams.
まず、偏波保持光ファイバ8に入射される二つの光束の
偏光方向が直交するように、A波長手圧5の軸を回転さ
せる。これらの直交する二つの光束の偏光方向は、偏波
保持光ファイ、バ8の二つの複屈折軸方向と一致する。First, the axis of the A-wavelength manual pressure 5 is rotated so that the polarization directions of the two light beams incident on the polarization-maintaining optical fiber 8 are orthogonal. The polarization directions of these two orthogonal beams coincide with the two birefringence axes directions of the polarization-maintaining optical fiber 8.
このため二つの光束は、偏波保持光フアイバ8内を伝搬
中に群遅延時間差(偏波分散)を生じる。この群遅延時
間差の生じた二つの光束を干渉させ、これにより生じる
ビート信号の数を記録する。この測定を、可動鏡6の位
置を移動させながら繰り返す。Therefore, a group delay time difference (polarization dispersion) occurs between the two light beams while propagating within the polarization-maintaining optical fiber 8. The two light beams with the difference in group delay time are caused to interfere, and the number of beat signals generated thereby is recorded. This measurement is repeated while moving the position of the movable mirror 6.
次に、A波長板5の軸を回転させ、二つの光束の偏光方
向を一致させる。すなわち、%波長板5の主軸と、2波
長板5に入射する光束の偏光方向とを一敗させる。これ
により二つの光束は、偏波保持光ファイバ8の同一複屈
折軸方向の偏波モードとして伝搬される。したがって、
この場合には群遅延時間差を生じない。このときのビー
ト信号の測定を、可動鏡6の位置を移動させながら繰り
返す。Next, the axis of the A wavelength plate 5 is rotated to match the polarization directions of the two light beams. That is, the main axis of the % wavelength plate 5 and the polarization direction of the light beam incident on the two-wave plate 5 are made to be the same. As a result, the two light beams are propagated as polarization modes in the same birefringence axis direction of the polarization-maintaining optical fiber 8. therefore,
In this case, no group delay time difference occurs. The measurement of the beat signal at this time is repeated while moving the position of the movable mirror 6.
以上の二つの測定において、ビート信号が最大となる位
置の光路差を測定し、これにより群遅延時間差を求める
ことができる。In the above two measurements, the optical path difference at the position where the beat signal is maximum is measured, and thereby the group delay time difference can be determined.
本測定方法を式を用いて説明する。This measurement method will be explained using equations.
光検出器10で検出される光強度■は、I=11+rz
+2X、(II Iz )”” lγ(τ+2)
1x cosδIzcosΩ −=−(
11(j” =−1)
として表される。ここで、II、Izは二つの光束の光
強度、1γ (τ、2)1は光源により決定されるコヒ
ーレンス度でありτ1□の関数、τ12は二つの光束の
間の光源1から光検出器10までの伝搬時間差、δ1□
は二つの光束の間の位相差、Ωは二つの光束間の偏光面
間の角度である。The light intensity ■ detected by the photodetector 10 is I=11+rz +2X, (II Iz )"" lγ(τ+2)
1x cosδIzcosΩ −=−(
11(j" = -1). Here, II and Iz are the light intensities of the two luminous fluxes, 1γ (τ, 2)1 is the degree of coherence determined by the light source, and is a function of τ1□, τ12 is the propagation time difference between the two light beams from the light source 1 to the photodetector 10, δ1□
is the phase difference between the two beams, and Ω is the angle between the planes of polarization between the two beams.
二つの光束の複素振幅をE+、Ezとすると、E、 =
a、 eXp j (2πft+φ1.1 −(2
1B2=az exp j
×〔2π(f+Δf) t+φ2) −・・=(3)
と表すことができる。ここで、alzazは複素振幅E
+、Ezのそれぞれの振幅、fば光の周波数、Δfは周
波数偏移量、Lは時間、φ1、φ2はそれぞれの位相で
ある。Letting the complex amplitudes of the two luminous fluxes be E+ and Ez, E, =
a, eXp j (2πft+φ1.1 −(2
1B2=az exp j × [2π(f+Δf) t+φ2) −...=(3)
It can be expressed as. Here, alzaz is the complex amplitude E
+ and Ez, f is the frequency of the light, Δf is the amount of frequency deviation, L is time, and φ1 and φ2 are the respective phases.
(2)式および(3)式から(1)弐の位相差δ1□は
、δ、2=2πΔft+(φ2−φ、) ・−−−−−
−(4)となる。ここで、
■1 =αI。From equations (2) and (3), the phase difference δ1□ of (1) 2 is δ, 2=2πΔft+(φ2−φ,) ・−−−−−
-(4). Here, ■1 = αI.
I2= (1−α)■。I2=(1-α)■.
とする(ただしoくαく1)と、(1)式の交流成分1
(t)は、
1(t)=2XI。 1 γ(τ、2)1× (α (
1−α) ) I / Z c o sΩ×cos
〔2πΔft+(φ2−φr ) ) −r5+となる
。各部の配置を調整して
α−0,5
cosΩw1
とすることにより(5)式は、
1(tl=Io l rc t−+z) l”xc
os(27CΔft+(φ2−φ+ ) ) −−(6
)となる。この式は、コヒーレンス度1γ (τ1□)
1で振幅変調されたビート信号を示す。(where o x α x 1), then the AC component 1 of equation (1)
(t) is 1(t)=2XI. 1 γ (τ, 2) 1× (α (
1-α) ) I/Z cosΩ×cos
[2πΔft+(φ2−φr)) −r5+. By adjusting the arrangement of each part to α-0,5 cosΩw1, equation (5) becomes 1(tl=Io lrc t-+z) l”xc
os(27CΔft+(φ2−φ+)) −−(6
). This formula has a coherence degree of 1γ (τ1□)
1 indicates an amplitude modulated beat signal.
したがって、偏波分散が生じている(二つの光束の偏波
方向が直交)ときのビート信号が最大となる位置と、偏
波分散が生じない(二つの光束の偏波方向が一致)とき
のビート信号の強度が最大となる位置との差を求めるこ
とにより、偏波分散による群遅延時間差を求めることが
できる。すなわち、この位置の差を2d、、Xとし、自
由空間の光速をCとし、偏波保持光ファイバ8の長さを
Lとすると、偏波分散による群遅延時間差τ2ば、とし
て算出することができる。Therefore, the position where the beat signal is maximum when polarization dispersion occurs (the polarization directions of the two light beams are orthogonal) and the position where the beat signal is maximum when polarization dispersion does not occur (the polarization directions of the two light beams are the same) By determining the difference from the position where the intensity of the beat signal is maximum, the group delay time difference due to polarization dispersion can be determined. That is, if this positional difference is 2d,,X, the speed of light in free space is C, and the length of the polarization-maintaining optical fiber 8 is L, then the group delay time difference due to polarization dispersion can be calculated as τ2. can.
第2図は、本実施例により実測された光路長に対するビ
ート信号強度を示す図である。FIG. 2 is a diagram showing the beat signal intensity with respect to the optical path length actually measured in this example.
第2図の上部は同一偏波モード間の干渉により得られた
ビート信号強度であり、下部は直交偏波モード間の干渉
で得られたビート信号強度である。The upper part of FIG. 2 shows the beat signal intensity obtained by interference between the same polarization modes, and the lower part shows the beat signal intensity obtained by interference between orthogonal polarization modes.
ビート信号が最大となる光路長差は22.13mmであ
り、実測群遅延時間差は(7)式により、τ、 L=7
3.76 (ピコ秒〕
となる。The optical path length difference at which the beat signal is maximum is 22.13 mm, and the measured group delay time difference is τ, L = 7 according to equation (7).
3.76 (picoseconds).
第3図は本発明第二実施例光ファイバの群遅延時間差測
定装置のブロック構成図である。FIG. 3 is a block diagram of an optical fiber group delay time difference measuring device according to a second embodiment of the present invention.
本実施例は、分散を無視できる空気中を伝搬する光束と
、被測定光ファイバ13中を伝搬する光束との群遅延時
間差を測定する方法の例である。This example is an example of a method for measuring the group delay time difference between a light beam propagating in the air where dispersion can be ignored and a light beam propagating in the optical fiber 13 to be measured.
光源1から出力された光は、光分岐素子3により二つの
光束に分割される。The light output from the light source 1 is split into two light beams by the light branching element 3.
この二つの光束の一方は、被測定光ファイバ13に入射
され、被測定光ファイバ13を伝搬し、半透鏡17およ
び偏光子9を透過して、光検出器10に入射する。One of these two light beams is incident on the optical fiber 13 to be measured, propagates through the optical fiber 13 to be measured, passes through the semi-transparent mirror 17 and the polarizer 9, and enters the photodetector 10.
もう一方の光束は、固定鏡14.15.16により反射
され、半透鏡17を透過し、可動鏡18により反射され
、半透v1.17により反射され、偏光子9を透過して
、光検出器10に入射する。The other beam is reflected by the fixed mirror 14, 15, 16, transmitted through the semi-transparent mirror 17, reflected by the movable mirror 18, reflected by the semi-transparent v1.17, transmitted through the polarizer 9, and detected by light. The light enters the vessel 10.
光検出器10は選択レベルメータ11に接続される。Photodetector 10 is connected to a selection level meter 11 .
選択レベルメータ11は記録装置12に接続される。The selection level meter 11 is connected to a recording device 12.
光分岐素子3は音響光学的効果等により周波数偏移を行
う。The optical branching element 3 performs frequency shift using an acousto-optic effect or the like.
本実施例において、隣接する二つの波長をλ1、λ2と
し、二つの波長に対するビート信号が最大となる可動鏡
18の移動量を2d+zとすると、(7)式の2d−8
に2a+□を代入して群遅延時間差を求めることができ
る。さらに、この群遅延時間差により色分散りを、
として求めることができる。In this embodiment, if two adjacent wavelengths are λ1 and λ2, and the amount of movement of the movable mirror 18 that maximizes the beat signal for the two wavelengths is 2d+z, then 2d-8 of equation (7) is obtained.
By substituting 2a+□ into , the group delay time difference can be obtained. Furthermore, the chromatic dispersion can be obtained from this group delay time difference as follows.
本実施例において、波長を固定し、被測定光ファイバ1
3を高温槽に入れて温度を変化させることにより、温度
変化にともなう群遅延時間差の変化を測定することがで
きる。さらに、引張り試験機等により、被測定光ファイ
バ13に引張り応力や圧縮応力を加え、これらの応力に
よる群遅延時間差の変化を測定することもできる。In this example, the wavelength is fixed and the optical fiber to be measured 1 is
3 in a high-temperature bath and changing the temperature, it is possible to measure changes in the group delay time difference due to temperature changes. Furthermore, it is also possible to apply tensile stress or compressive stress to the optical fiber 13 to be measured using a tensile tester or the like, and measure changes in the group delay time difference due to these stresses.
以上説明したように、本発明光ファイバの群遅延時間差
測定方法により、時間分解能がサブピコ秒程度と極めて
小さく、被測定光ファイバの長さに関わらず、高精度に
群速度を測定できる効果がある。本発明の測定方法は、
種々の群遅延時間差の測定に実施できる。As explained above, the optical fiber group delay time difference measurement method of the present invention has an extremely small time resolution of about sub-picoseconds, and has the effect of being able to measure the group velocity with high precision regardless of the length of the optical fiber to be measured. . The measurement method of the present invention includes:
It can be carried out to measure various group delay time differences.
ii
【図面の簡単な説明】
第1図は本発明第一実施例光ファイバの群遅延時間差測
定装置のブロック構成図。
第2図は光路長に対するビート信号強度の実測値を示す
図。
第3図は本発明第二実施例光ファイバの群遅延時間差測
定装置のブロック構成図。
1・・・光源、2・・・偏光子、3・・・光分岐素子、
4・・・固定鏡、5・・・騒波長板、6・・・可動鏡、
7・・・半透鏡、8・・・偏波保持光ファイバ、9・・
・偏光子、lO・・・光検出器、11・・・選択レベル
メータ、12・・・記録装置、13・・・被測定光ファ
イバ、14.15.16・・・固定鏡、17・・・半透
鏡、18・・・可動鏡。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an optical fiber group delay time difference measuring device according to a first embodiment of the present invention. FIG. 2 is a diagram showing actual measured values of beat signal intensity with respect to optical path length. FIG. 3 is a block configuration diagram of an optical fiber group delay time difference measuring device according to a second embodiment of the present invention. 1... Light source, 2... Polarizer, 3... Light branching element,
4... Fixed mirror, 5... Noise wave plate, 6... Movable mirror,
7... Semi-transparent mirror, 8... Polarization maintaining optical fiber, 9...
- Polarizer, lO... photodetector, 11... selection level meter, 12... recording device, 13... optical fiber to be measured, 14.15.16... fixed mirror, 17...・Semi-transparent mirror, 18...Movable mirror.
Claims (2)
難し、 この二つの光束の少なくとも一方を周波数偏移させてこ
の二つの光束に周波数差を与え、 この周波数差を与えた二つの光束の少なくとも一方を被
測定光ファイバに伝搬させ、 この光ファイバに伝搬させた後に上記二つの光束を干渉
させ、 この干渉によるビート信号の強度を測定し、上記二つの
光束の少なくとも一方の光路長を変化させて測定を繰り
返して、上記二つの光路長の差に対する群遅延時間差を
測定する 光ファイバの群遅延時間差測定方法。(1) Split the light emitted from the light source into two light beams spatially, shift the frequency of at least one of these two light beams to give a frequency difference between the two light beams, and At least one of the two light beams is propagated into the optical fiber to be measured, and after propagating through the optical fiber, the two light beams are made to interfere with each other, the intensity of the beat signal due to this interference is measured, and the optical path of at least one of the two light beams is determined. A method for measuring a group delay time difference of an optical fiber, which measures a group delay time difference with respect to the difference between the two optical path lengths by repeating the measurement while changing the length of the optical fiber.
もに、この二つの光束の少なくとも一方を周波数偏移さ
せてこの二つの光束に周波数差を与える手段と、 この周波数を与えた二つの光束の少なくとも一方を被測
定光ファイバの一端に入射させる手段と、この光ファイ
バの他端で上記二つの光束を干渉させる手段と、 この干渉によるビート信号の強度を測定する手段と、 上記二つの光束の少なくとも一方の光路長を変化させる
手段と を備えたことを特徴とする光ファイバの群遅延時間差測
定装置。(2) one light source; means for spatially separating the light emitted from this light source into two light beams, and frequency-shifting at least one of the two light beams to give a frequency difference between the two light beams; A means for making at least one of the two light beams given this frequency enter one end of the optical fiber to be measured, a means for interfering the two light beams at the other end of the optical fiber, and measuring the intensity of the beat signal due to this interference. An apparatus for measuring a group delay time difference of an optical fiber, comprising: means for changing the optical path length of at least one of the two light beams.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP59169048A JPH0731096B2 (en) | 1984-08-13 | 1984-08-13 | Optical fiber group delay time difference measuring method and measuring apparatus |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP59169048A JPH0731096B2 (en) | 1984-08-13 | 1984-08-13 | Optical fiber group delay time difference measuring method and measuring apparatus |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS6147533A true JPS6147533A (en) | 1986-03-08 |
JPH0731096B2 JPH0731096B2 (en) | 1995-04-10 |
Family
ID=15879354
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP59169048A Expired - Lifetime JPH0731096B2 (en) | 1984-08-13 | 1984-08-13 | Optical fiber group delay time difference measuring method and measuring apparatus |
Country Status (1)
Country | Link |
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JP (1) | JPH0731096B2 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6352034A (en) * | 1986-08-21 | 1988-03-05 | Nippon Telegr & Teleph Corp <Ntt> | Method and device for measuring single mode optical fiber |
WO2001061303A1 (en) * | 2000-02-21 | 2001-08-23 | Japan Science And Technology Corporation | Polarization mode dispersion measuring device and polarization mode dispersion measuring method |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5724836A (en) * | 1980-07-22 | 1982-02-09 | Nippon Telegr & Teleph Corp <Ntt> | Measurement of group delay time difference by mode groups for multimode optical fiber scope |
-
1984
- 1984-08-13 JP JP59169048A patent/JPH0731096B2/en not_active Expired - Lifetime
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5724836A (en) * | 1980-07-22 | 1982-02-09 | Nippon Telegr & Teleph Corp <Ntt> | Measurement of group delay time difference by mode groups for multimode optical fiber scope |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6352034A (en) * | 1986-08-21 | 1988-03-05 | Nippon Telegr & Teleph Corp <Ntt> | Method and device for measuring single mode optical fiber |
WO2001061303A1 (en) * | 2000-02-21 | 2001-08-23 | Japan Science And Technology Corporation | Polarization mode dispersion measuring device and polarization mode dispersion measuring method |
US6850318B1 (en) | 2000-02-21 | 2005-02-01 | Japan Science And Technology Agency | Polarization mode dispersion measuring device and polarization mode dispersion measuring method |
Also Published As
Publication number | Publication date |
---|---|
JPH0731096B2 (en) | 1995-04-10 |
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