JPH049730A - Reflecting point measuring apparatus for optical waveguide - Google Patents

Reflecting point measuring apparatus for optical waveguide

Info

Publication number
JPH049730A
JPH049730A JP11403890A JP11403890A JPH049730A JP H049730 A JPH049730 A JP H049730A JP 11403890 A JP11403890 A JP 11403890A JP 11403890 A JP11403890 A JP 11403890A JP H049730 A JPH049730 A JP H049730A
Authority
JP
Japan
Prior art keywords
light
frequency
power
laser
receiving element
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.)
Pending
Application number
JP11403890A
Other languages
Japanese (ja)
Inventor
Shinichi Kaneko
進一 金子
Junichiro Yamashita
純一郎 山下
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Electric Corp
Original Assignee
Mitsubishi Electric Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Priority to JP11403890A priority Critical patent/JPH049730A/en
Publication of JPH049730A publication Critical patent/JPH049730A/en
Pending legal-status Critical Current

Links

Abstract

PURPOSE:To easily measure to a reflection point of a long distance by providing means for measuring power spectrum of a photodetected signal or power of predetermined band, and means for frequency-modulating an emitted laser light. CONSTITUTION:A laser light is emitted from a laser emitting device 2, and the light emitted from the device 2 is branched to a photodetector 4 and an optical waveguide 5 to be measured by branch coupling means 6. The means 6 couples the light of the branched laser light to a reflected return light from the waveguide 5, photodetects 4 the light emitted from the device 2, and measures the power spectrum of the signal or power of predetermined band by a spectrum analyzer 7. When the light emitted from the device 2 is frequency-modulated by a synthesizer 9, the power spectrum of the photodetected 4 signal or the power of the predetermined band is so altered in modulation frequency as to become the same as the power spectrum of the photodetected 4 signal or the power of the predetermined band when the laser light is not frequency-modulated.

Description

【発明の詳細な説明】 [産業上の利用分野コ この発明は、光通信などに用いられる光ファイバや光部
品の保守・検査に用いられる先導波路の反射点測定装置
に関するものである。
DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a reflection point measuring device for a guided waveguide used for maintenance and inspection of optical fibers and optical components used in optical communications and the like.

[従来の技術] 第7図は、例えば、ERECTRONtC3LETTE
I?S 9thMa、y 1985 Vol、21 N
o、lOpp434−435に示された従来の光導波路
の反射点測定装置の構成を示すブロック図であり、光導
波路の反射点測定装置(1)は、レーザ光(1,00)
を発射する半導体レーザ発射装置(2)を有しており、
半導体レーザ発射装置(2)には鋸歯状の電流を給電し
て周波数変調を行うランプジェネレータ(3)が接続さ
れている。
[Prior art] FIG. 7 shows, for example, an ERECTRONtC3LETTE.
I? S 9th Ma, y 1985 Vol, 21 N
It is a block diagram showing the configuration of the conventional optical waveguide reflection point measuring device shown in Opp 434-435, and the optical waveguide reflection point measuring device (1) is a laser beam (1,00).
It has a semiconductor laser emitting device (2) that emits
A ramp generator (3) that supplies sawtooth current to perform frequency modulation is connected to the semiconductor laser emitting device (2).

そして、半導体レーザ発射装置(2)のレーザ光発射方
向には、発射されたレーザ光(100)を受光素子(4
)方向と被測定光導波路(5)方向とに分波すると共に
受光素子(4)方向に分波されたレーザ光(100)と
被測定光導波路(5)からの反射戻り光(100)とを
結合する分波結合手段(6)が配置されており、受光素
子(4)にはスペクトラムアナライザ(7)が接続され
てオリ、この光学系はマイケルソン干渉計を構成してい
る。
In the laser beam emitting direction of the semiconductor laser emitting device (2), the emitted laser beam (100) is transmitted to a light receiving element (4).
) direction and the optical waveguide to be measured (5) direction, and the laser beam (100) that is split in the direction of the light receiving element (4), and the reflected return light (100) from the optical waveguide to be measured (5). A demultiplexing/coupling means (6) for coupling the two is arranged, and a spectrum analyzer (7) is connected to the light receiving element (4), and this optical system constitutes a Michelson interferometer.

なお、図中(8)で示すものは光導波路(5)の反射点
である。
Note that what is indicated by (8) in the figure is a reflection point of the optical waveguide (5).

次に動作について説明する。Next, the operation will be explained.

ランプジェネレータ(3)から半導体レーザ発射装置(
2)へ第8図に示すような波形の電流が入力されると、
半導体レーザ発射装置(2)の発振光周波数は第9図の
ように変化する。
From the lamp generator (3) to the semiconductor laser emitting device (
When a current with a waveform as shown in Fig. 8 is input to 2),
The oscillation light frequency of the semiconductor laser emitting device (2) changes as shown in FIG.

そして、半導体レーザ発射装置(2)から発射されるレ
ーザ光(100)は分波結合手段(6)により受光素子
(4)方向と被測定光導波路(5)方向とへ分波され、
被測定光導波路(5)方向とへ分波されたレーザ光(1
00)は光導波路(5)の反射点(8)でその一部が反
射されて反射光(101)となる。
The laser beam (100) emitted from the semiconductor laser emitting device (2) is demultiplexed by the demultiplexing coupling means (6) into the direction of the light receiving element (4) and the direction of the optical waveguide to be measured (5),
The laser beam (1) split in the direction of the optical waveguide (5) to be measured
00) is partially reflected at the reflection point (8) of the optical waveguide (5) and becomes reflected light (101).

反射点(8)におけるレーザ光(100)の透過率は第
10図に示すような関係にあり、FSR(マイケルソン
干渉計のフリースペクトラルレンジ)は、光速Cと2つ
のレーザ光の光路差(空気換算距離)ΔLを用いて、 FSR−c/ΔL        ・・・110と表わ
せる。
The transmittance of the laser beam (100) at the reflection point (8) has the relationship shown in Figure 10, and the FSR (free spectral range of the Michelson interferometer) is determined by the speed of light C and the optical path difference between the two laser beams ( Using air conversion distance) ΔL, it can be expressed as FSR-c/ΔL...110.

更に、この反射光(101)は分波結合手段(6)によ
り受光素子(4)方向へ分波されたレーザ光(100)
と結合されて受光素子(4)に受光される。
Furthermore, this reflected light (101) is split into a laser beam (100) by the splitting/coupling means (6) toward the light receiving element (4).
The light is combined with the light receiving element (4) and received by the light receiving element (4).

そして、受光素子(4)で受光して信号はスペクトルア
ナライザ(7)で測定され、第11図のような電力スペ
クトルを得る。
Then, the light is received by the light receiving element (4) and the signal is measured by the spectrum analyzer (7) to obtain a power spectrum as shown in FIG.

第9図において1つの鋸歯状の波形で周波数はΔfだけ
変化し、1つの鋸歯状の波形でΔf/FSR個の明暗が
生じる。
In FIG. 9, the frequency changes by Δf in one sawtooth waveform, and Δf/FSR brightnesses and darkness occur in one sawtooth waveform.

更に、鋸歯状の波形は単位時間あたり1/T個発生し、
第11図における電力スペクトルには周波数 F、。、に−1/T・Δf/FSR・・・11]にピー
クを持ち、第111式を用いて反射点(8)までの距離
を求める。
Furthermore, 1/T sawtooth waveforms occur per unit time,
The power spectrum in FIG. 11 has a frequency F. , -1/T·Δf/FSR...11], and the distance to the reflection point (8) is determined using Equation 111.

[発明が解決しようとする課題] 従来の光導波路の反射点測定装置は、以上のように構成
されているので、干渉現象を利用して反射点までの距離
を測定しているので、半導体レーザのコヒーレント長に
よる反射点の測定には限界があり(10m位)、かつ被
測定光導波路の反射点を求めるにあたって、予めΔfを
求める必要があるという課題があった。
[Problems to be Solved by the Invention] The conventional optical waveguide reflection point measurement device is configured as described above, and since it measures the distance to the reflection point using an interference phenomenon, There is a limit to the measurement of the reflection point using the coherent length (approximately 10 m), and there is a problem in that Δf must be determined in advance in determining the reflection point of the optical waveguide to be measured.

この発明は、上記のような課題を解消するためになされ
たもので、長距離の反射点まで容易にII定できる先導
波路の反射点1IrlJ定装置を得ることを目的とする
The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a device for determining the reflection point 1IrlJ of a leading waveguide, which can easily determine II up to a long-distance reflection point.

[課題を解決するための手段] この発明に係わる光導波路の反射点測定装置は、レーザ
光を発射するレーザ発射手段と、レーザ発射手段より発
射されるレーザ光を受光する受光素子と、レーザ発射手
段より発射されるレーザ光を受光素子と被測定光導波路
とに分波する分波手段と、受光素子に分波されたレーザ
光の出射光と被11PI定光導波路からの反射戻り光を
結合する結合手段と、受光素子により受光した信号の電
力スペクトルまたは所定帯域の電力を測定する測定手段
と、レーザ発射手段より発射されるレーザ光を周波数変
調する周波数変調手段を備えている。従って、周波数変
調手段は、レーザ発射手段より発射されるレーザ光を周
波数変調する際、受光素子にて受光した信号の電力スペ
クトルまたは所定帯域の電力が、レーザ光を周波数変調
しないときに受光素子により受光した信号の電力スペク
トルまたは所定帯域の電力と同じになるように変調周波
数を変えることを特徴とするものである。
[Means for Solving the Problems] An optical waveguide reflection point measuring device according to the present invention includes: a laser emitting means for emitting a laser beam; a light receiving element for receiving the laser beam emitted from the laser emitting means; a demultiplexing means for demultiplexing a laser beam emitted from the means into a light receiving element and an optical waveguide to be measured; and a demultiplexing means for combining the emitted light of the laser beam demultiplexed by the light receiving element and the reflected return light from the 11PI constant optical waveguide to be measured. A measuring means for measuring the power spectrum of the signal received by the light receiving element or the power in a predetermined band, and a frequency modulating means for frequency modulating the laser light emitted from the laser emitting means. Therefore, when the frequency modulation means frequency modulates the laser light emitted from the laser emitting means, the power spectrum of the signal received by the light receiving element or the power in a predetermined band does not modulate the frequency of the laser light. It is characterized by changing the modulation frequency so that it becomes the same as the power spectrum of the received signal or the power of a predetermined band.

[作用〕 この発明における光導波路の反射点nl定装置は、レー
ザ発射手段よりレーザ光を発射し、レーザ発射手段より
発射されるレーザ光を分波手段により受光素子と被測定
光導波路とに分波し、受光素子に分波されたレーザ光の
出射光と被測定光導波路からの反射戻り光を結合手段に
より結合し、レーザ発射手段より発射されるレーザ光を
受光素子により受光し、受光素子により受光した信号の
電力スペクトルまたは所定帯域の電力を測定手段により
測定し、周波数変調手段によりレーザ発射手段より発射
されるレーザ光を周波数変調する際、受光素子にて受光
した信号の電力スペクトルまたは所定帯域の電力が、レ
ーザ光を周波数変調しないときに受光素子により受光し
た信号の電力スペクトルまたは所定帯域の電力と同じに
なるように変調周波数を変える。
[Operation] The device for determining the reflection point nl of an optical waveguide according to the present invention emits a laser beam from a laser emitting means, and separates the laser beam emitted from the laser emitting means into a light receiving element and an optical waveguide to be measured by a demultiplexing means. The output light of the laser beam which has been waved and split into the light receiving element and the reflected return light from the optical waveguide to be measured are combined by the coupling means, the laser light emitted from the laser emitting means is received by the light receiving element, and the light receiving element When the power spectrum of the signal received by the light receiving element or the power in a predetermined band is measured by the measuring means, and the frequency modulation means frequency modulates the laser light emitted from the laser emitting means, the power spectrum of the signal received by the light receiving element or the power in a predetermined band is measured by the measuring means. The modulation frequency is changed so that the power in the band becomes the same as the power spectrum of the signal received by the light receiving element or the power in the predetermined band when the laser beam is not frequency modulated.

[実施例コ 以下、この発明の一実施例を図について説明する。[Example code] An embodiment of the present invention will be described below with reference to the drawings.

光導波路の反射点測定装置(1)は、第1図に示すよう
に、レーザ光(100)を発射するレーザ発射手段とし
ての半導体レーザ発射装置(2)を有しており、半導体
レーザ発射装置(2)には周波数変調を行う周波数変調
手段としてのシンセサイザ(9)が接続されている。
As shown in FIG. 1, the optical waveguide reflection point measuring device (1) has a semiconductor laser emitting device (2) as a laser emitting means for emitting a laser beam (100). (2) is connected to a synthesizer (9) as a frequency modulation means for performing frequency modulation.

そして、半導体レーザ発射装置(2)のレーザ光発射方
向には、発射されたレーザ光<100)を受光素子(4
)方向と被測定光導波路(5)方向とへ分波すると共に
受光素子(4)方向に分波されたレーザ光(100)と
被測定光導波路(5)からの反射戻り光(1,00)と
を結合する分波手段かつ結合手段としての分波結合手段
(6)が配置されており、受光素子(4)にはi’ll
l定手段と定石段スペクトラムアナライザ(7)が接続
されており、この光学系はマイケルソン干渉計を構成し
ている。
In the laser beam emission direction of the semiconductor laser emitting device (2), the emitted laser beam <100 is sent to the light receiving element (4).
) direction and the optical waveguide to be measured (5), and the laser beam (100) which is split in the direction of the light receiving element (4) and the reflected return light from the optical waveguide to be measured (5) (1,000 ) is arranged, and a demultiplexing means (6) is arranged as a demultiplexing means and a combining means for combining the i'll
The optical system constitutes a Michelson interferometer.

なお、図中(8)で示すものは先導波路(5)の反射点
である。
In addition, what is indicated by (8) in the figure is a reflection point of the leading waveguide (5).

ついで、本実施例の作用について説明する。Next, the operation of this embodiment will be explained.

第2図は、シンセサイザ(9)により周波数変調された
半導体レーザ装置(2)の発振光スペクトルの変化を示
す図であり、シンセサイザ(9)から正弦波状の電流を
半導体レーザ装置(2)に給電すると、半導体レーザ装
置(2)の発振光周波数は正弦波状に変化する。
FIG. 2 is a diagram showing changes in the oscillation light spectrum of the semiconductor laser device (2) frequency-modulated by the synthesizer (9), in which a sinusoidal current is supplied from the synthesizer (9) to the semiconductor laser device (2). Then, the oscillation light frequency of the semiconductor laser device (2) changes sinusoidally.

そして、半導体レーザ発射装置(2)から発射されるレ
ーザ光(100)は分波結合手段(6)により受光素子
(4)方向と被測定光導波路(5)方向とへ分波され、
被測定光導波路(5)方向とへ分波されたレーザ光(1
00)は光導波路(5)の反射点(8)でその一部が反
射されて反射光(101)となる。
The laser beam (100) emitted from the semiconductor laser emitting device (2) is demultiplexed by the demultiplexing coupling means (6) into the direction of the light receiving element (4) and the direction of the optical waveguide to be measured (5),
The laser beam (1) split in the direction of the optical waveguide (5) to be measured
00) is partially reflected at the reflection point (8) of the optical waveguide (5) and becomes reflected light (101).

更に、この反射光(101)は分波結合手段(6)によ
り受光素子(4)方向へ分波されたレーザ光(100)
と結合されて受光素子(4)に受光される。
Furthermore, this reflected light (101) is split into a laser beam (100) by the splitting/coupling means (6) toward the light receiving element (4).
The light is combined with the light receiving element (4) and received by the light receiving element (4).

レーザ光(100)と反射光(101)とには遅延時間
τ(τ−ΔL / c )がある。
There is a delay time τ (τ−ΔL/c) between the laser beam (100) and the reflected light (101).

ところで、半導体レーザの発振瞬時光周波数は所定の分
布を持っており、光スペクトル線幅として表わせる。
Incidentally, the instantaneous oscillation optical frequency of a semiconductor laser has a predetermined distribution, which can be expressed as an optical spectral linewidth.

レーザ光(100)を分波し、一方に遅延をかけた後に
再び合成して受光素子(4)で受光すると、分波された
それぞれの光の瞬時光周波数のビートが測定される。
When the laser beams (100) are demultiplexed, one of them is delayed, and then combined again and received by the light receiving element (4), the beat of the instantaneous optical frequency of each of the demultiplexed lights is measured.

そして、半導体レーザを周波数変調した場合に、受光素
子(4)で受光したこのビートをスペクトラムアナライ
ザ(7)で測定したときに測定される電力スペクトルは
次式で表わすことができる。
When the semiconductor laser is frequency modulated, the power spectrum measured when the beat received by the light receiving element (4) is measured by the spectrum analyzer (7) can be expressed by the following equation.

C5in2(2yr f  r) (t+e−4πΔντ−2e−2πΔντ。。、2、(
f−nfFM) rl + cos  (2πfoT)
(1−e−’πΔしτ−2e−2πΔντ、Δ1/ (
f  n fpM) 5in2yr (f  n fp
M) N )・・・112 但し、R:反射点の反射率 fo :半導体レーザの発振光周波数 J ω:ベツセル関数 Δf:光周波数の変化 Δシ:スペクトル線幅(半値全幅) fPH’変調周波数 a : 0 h:oa それから、第112式により半導体レーザを周波数変調
しないときに、スペクトラムアナライザ(7)で測定さ
れる電力スペクトルを計算すると、第3図のようになり
、第112式により半導体レーザを周波数変調したとき
に、スペクトラムアナライザ(7)で測定される電力ス
ペクトルを計算すると、第4図のようになる。
C5in2(2yr f r) (t+e-4πΔντ-2e-2πΔντ.., 2, (
f−nfFM) rl + cos (2πfoT)
(1-e-'πΔ and τ-2e-2πΔντ, Δ1/ (
f n fpM) 5in2yr (f n fp
M) N)...112 However, R: Reflectance of the reflection point fo: Semiconductor laser oscillation optical frequency J ω: Betssel function Δf: Change in optical frequency Δshi: Spectral line width (full width at half maximum) fPH' Modulation frequency a: 0 h:oa Then, when the power spectrum measured by the spectrum analyzer (7) is calculated using the equation 112 when the semiconductor laser is not frequency modulated, it becomes as shown in Figure 3. When frequency modulated, the power spectrum measured by the spectrum analyzer (7) is calculated as shown in Fig. 4.

第4図の場合、周波数変調の変調周波数が150MHz
のときに、遅延時間と半導体レーザの発振周波数の変化
する周期(シンセサイザ(9)の発生する正弦波状の電
流の周波数の逆数)が等しくなり、この場合、合成され
る2つのレーザ光の発振光周波数は等しくなる。
In the case of Figure 4, the modulation frequency of frequency modulation is 150MHz
When , the delay time and the period of change of the oscillation frequency of the semiconductor laser (the reciprocal of the frequency of the sinusoidal current generated by the synthesizer (9)) are equal, and in this case, the oscillation light of the two combined laser lights The frequencies will be equal.

また、遅延時間と半導体レーザの発振周波数の変化する
周期が異なると、スペクトラムアナライザ(7)で測定
される電力スペクトルは複雑な形となるが、合成される
2つのレーザ光の発振光周波数は等しくなる。
Furthermore, if the delay time and the period of change of the oscillation frequency of the semiconductor laser differ, the power spectrum measured by the spectrum analyzer (7) will have a complicated shape, but the oscillation optical frequency of the two combined laser beams will be equal. Become.

これにより、第3図の周波数変調しないときの電力スペ
クトルと、第4図の遅延時間と半導体レーサの発振周波
数の変化する周期が等しくなる周波数で周波数変調した
ときの電力スペクトルは等しくなる。
As a result, the power spectrum when frequency modulation is not performed in FIG. 3 becomes equal to the power spectrum when frequency modulation is performed at a frequency where the delay time and the period of change of the oscillation frequency of the semiconductor laser are equal to each other in FIG. 4.

第4図のように受光素子で受光した信号のスペクトルが
周波数変調しないときの信号の電力スペクトルと同じ形
になるような周波数の変調周波数f は、光路差をΔL
とすると、 「 f  −c/ΔL         ・・・113と表
わせ、第113式より反射点の位置が求まる。
As shown in Figure 4, the modulation frequency f is such that the spectrum of the signal received by the light receiving element has the same shape as the power spectrum of the signal when no frequency modulation is performed.The optical path difference is ΔL.
Then, the position of the reflection point can be found from Equation 113, which is expressed as f −c/ΔL...113.

なお、上述実施例においては、受光素子(4)で受光し
た信号の全体的な電力スペクトルの形からf を求めて
いたが、これに限らず、受光素子■ (4)で受光した信号の所定帯域の電力を測定し、周波
数変調しないときの電力と同じになるように周波数変調
の変調周波数を変えてf を求めてもよい。
In the above embodiment, f was determined from the shape of the overall power spectrum of the signal received by the light receiving element (4), but the present invention is not limited to this. f may be obtained by measuring the power in the band and changing the modulation frequency of frequency modulation so that it becomes the same as the power when no frequency modulation is performed.

このようにした場合、周波数変調の変調周波数を変えた
時、受光素子(4)で受光した信号の75MHz以下の
電力を計算すると、第5図のようになり、縦軸は周波数
変調しないときの電力で規格化した電力であり、この電
力は75MHz以下の周波数の電気信号を通すローパス
フィルタを用いて、電力計で測定することができる。
In this case, when the modulation frequency of frequency modulation is changed, the power of the signal received by the light receiving element (4) below 75 MHz is calculated as shown in Figure 5, and the vertical axis is the power when no frequency modulation is performed. This is power normalized to electric power, and this power can be measured with a wattmeter using a low-pass filter that passes electrical signals with a frequency of 75 MHz or less.

そして、第4図及び第5図によると、f の決定精度は
±0.25MHz以下であり、光路差ΔLは、3.4m
m程度の精度で求めることができる。なお、光路差ΔL
は反射点までの往復の距離なので、光導波路の反射点測
定装置の反射点までの距離の精度は2mm以下である。
According to FIGS. 4 and 5, the determination accuracy of f is ±0.25 MHz or less, and the optical path difference ΔL is 3.4 m.
It can be determined with an accuracy of about m. In addition, the optical path difference ΔL
Since is the round trip distance to the reflection point, the accuracy of the distance to the reflection point of the optical waveguide reflection point measuring device is 2 mm or less.

また、第112式より、受光素子(4)で受光した信号
の大きさは、反射率に比例するため、周波数変調しない
ときの受光素子で受光した信号の電力スペクトルまたは
所定帯域の電力の大きさから反射点の反射率がわかる。
Also, from Equation 112, the magnitude of the signal received by the light receiving element (4) is proportional to the reflectance, so the power spectrum of the signal received by the light receiving element when frequency modulation is not performed or the magnitude of the power in a predetermined band. The reflectance of the reflection point can be found from .

受光素子で受光した信号は−155(db/Hz)のレ
ベルまで容易に測定でき、第3図よりスペクトル線幅I
MHzの光源での反射率の測定限界は10−5程度であ
る。
The signal received by the photodetector can be easily measured up to a level of -155 (db/Hz), and from Figure 3, the spectral linewidth I
The measurement limit of reflectance with a MHz light source is about 10-5.

次いで、本発明の他の実施例を第6図により説明する。Next, another embodiment of the present invention will be described with reference to FIG.

なお、前述した部分と同じ部分には同一符号を付して説
明を省略する。
Note that the same parts as those described above are given the same reference numerals and the description thereof will be omitted.

先導波路の反射点測定装置(1)は、分波結合手段(6
)と被測定光導波路(5)との間に、基端側が二股にな
った希土類ドープ光ファイバ(10)を有しており、二
股の一方からはレーサービームが入射され、かつ他方か
らは励起用LDモジュール(12)からの励起光(1,
02)が入射されるようになっている。
The reflection point measuring device (1) of the leading wavepath includes a demultiplexing and coupling means (6
) and the optical waveguide to be measured (5), there is a rare earth-doped optical fiber (10) whose base end is bifurcated, and a laser beam is input from one of the bifurcations, and an excitation beam is input from the other. excitation light (1,
02) is made incident.

そして、希土類ドープ光ファイバ(10)の先端には、
励起光(102)を反射すると共にレーザ光(100)
を透過する誘電体多層膜フィルタ(13)がレーザ光軸
に対して所定角度傾斜して配置されている。
At the tip of the rare earth doped optical fiber (10),
While reflecting the excitation light (102), the laser light (100)
A dielectric multilayer filter (13) that transmits the laser beam is arranged at a predetermined angle with respect to the laser optical axis.

ついで、本実施例の作用について説明する。Next, the operation of this embodiment will be explained.

希土類ドープ光ファイバ(10)は、励起光を吸収する
ことにより、内部に反転分布が生じる。
The rare earth-doped optical fiber (10) absorbs excitation light, thereby causing population inversion inside.

このように反転分布が生じている希土類ドープ光ファイ
バ(10)に、共鳴波長に対応するレーザ光(100)
が入射すると、誘導放出が生じ、光導波路の反射点測定
装置(1)から出射されるレーザ光(100)の光強度
は増幅される。
A laser beam (100) corresponding to the resonant wavelength is applied to the rare earth-doped optical fiber (10) in which population inversion has occurred in this way.
When the laser beam is incident, stimulated emission occurs, and the light intensity of the laser beam (100) emitted from the reflection point measuring device (1) of the optical waveguide is amplified.

光導波路の反射点(8)で反射されて光導波路の反射点
測定装置(1)に戻ってくる光も同様に増幅される。
The light reflected at the reflection point (8) of the optical waveguide and returned to the optical waveguide reflection point measurement device (1) is similarly amplified.

このため、先導波路の反射点(8)の反射率が大きくな
ることと同じになり、反射率の低い反射点を測定するこ
とができる。
Therefore, this is equivalent to increasing the reflectance of the reflection point (8) of the leading waveguide, and it is possible to measure a reflection point with a low reflectance.

[発明の効果コ 以上説明したように、この発明によれば、レーザ発射手
段より発射されるレーザ光を周波数変調する際、受光素
子にて受光した信号の電力スペクトルまたは所定帯域の
電力が、レーザ光を周波数変調しないときに受光素子に
より受光した信号の電力スペクトルまたは所定帯域の電
力と同じになるように変調周波数を変えるように構成し
たので、干渉現象を利用せず、反射点の1fllj定限
界距離を長くすることができ、またΔfを求めることな
く、容品に反射点の測定を行うことができる。
[Effects of the Invention] As explained above, according to the present invention, when frequency modulating the laser light emitted from the laser emitting means, the power spectrum of the signal received by the light receiving element or the power in a predetermined band is Since the configuration is such that the modulation frequency is changed so that it becomes the same as the power spectrum of the signal received by the light receiving element or the power of a predetermined band when the light is not frequency modulated, the 1fllj constant limit of the reflection point is The distance can be increased, and reflection points on the product can be measured without determining Δf.

【図面の簡単な説明】[Brief explanation of the drawing]

第1図はこの発明の一実施例による光導波路の反射点測
定装置の構成を示すブロック図、第2図はレーザ光の発
振光スペクトルの変化を示す図、第3図及び第4図は本
発明の動作を示す図、第5図は周波数変調の変調周波数
を変えたときの75MHz以下の電力計算結果を示す図
、第6図はこの発明の他の実施例の構成を示す図、第7
図は従来の光導波路の反射点測定装置の構成を示すブロ
ック図、第8図は半導体レーザ発射装置に給電される電
流を説明するだめの図、第9図は周波数変調されたレー
ザ光の発振光周波数を説明する図、第10図は透過率の
光り周波数依存性を説明する図、第11図は電力スペク
トルを示す図である。 図において、(1)は光導波路の反射点測定装置、(2
)は半導体レーザ発射手段、(4)は受光素子、(5)
は先導波路、(6)は分波手段および結合手段、(7)
は測定手段、(9)は周波数変調手段である。 なお、図中、同一符号は同一または相当部分を示す。
FIG. 1 is a block diagram showing the configuration of an optical waveguide reflection point measuring device according to an embodiment of the present invention, FIG. 2 is a diagram showing changes in the oscillation light spectrum of a laser beam, and FIGS. 3 and 4 are in accordance with the present invention. Figure 5 is a diagram showing the operation of the invention; Figure 5 is a diagram showing the power calculation results below 75 MHz when the modulation frequency of frequency modulation is changed; Figure 6 is a diagram showing the configuration of another embodiment of the invention; Figure 7 is a diagram showing the configuration of another embodiment of the invention.
The figure is a block diagram showing the configuration of a conventional optical waveguide reflection point measurement device, Figure 8 is a diagram for explaining the current supplied to the semiconductor laser emitting device, and Figure 9 is the oscillation of frequency-modulated laser light. FIG. 10 is a diagram explaining the optical frequency dependence of transmittance, and FIG. 11 is a diagram showing the power spectrum. In the figure, (1) is an optical waveguide reflection point measurement device, (2)
) is a semiconductor laser emitting means, (4) is a light receiving element, (5)
is a leading wavepath, (6) is a demultiplexing means and a coupling means, (7)
(9) is a measuring means, and (9) is a frequency modulation means. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

【特許請求の範囲】[Claims] レーザ光を発射するレーザ発射手段と、レーザ発射手段
より発射されるレーザ光を受光する受光素子と、レーザ
発射手段より発射されるレーザ光を受光素子と被測定光
導波路とに分波する分波手段と、受光素子に分波された
レーザ光の出射光と被測定光導波路からの反射戻り光を
結合する結合手段と、受光素子により受光した信号の電
力スペクトルまたは所定帯域の電力を測定する測定手段
とを備える光導波路の反射点測定装置において、レーザ
発射手段より発射されるレーザ光を周波数変調する周波
数変調手段を備え、周波数変調手段は、レーザ発射手段
より発射されるレーザ光を周波数変調する際、受光素子
にて受光した信号の電力スペクトルまたは所定帯域の電
力が、レーザ光を周波数変調しないときに受光素子によ
り受光した信号の電力スペクトルまたは所定帯域の電力
と同じになるように変調周波数を変えることを特徴とす
る光導波路の反射点測定装置。
A laser emitting means for emitting laser light, a light receiving element for receiving the laser light emitted from the laser emitting means, and a demultiplexer for splitting the laser light emitted from the laser emitting means into the light receiving element and the optical waveguide to be measured. a coupling means for coupling the emitted light of the laser beam split by the light receiving element and the reflected return light from the optical waveguide to be measured; and a measurement method for measuring the power spectrum of the signal received by the light receiving element or the power in a predetermined band. The reflection point measuring device for an optical waveguide includes a frequency modulation means for frequency modulating the laser light emitted from the laser emitting means, the frequency modulation means frequency modulating the laser light emitted from the laser emitting means. At this time, the modulation frequency is adjusted so that the power spectrum of the signal received by the light receiving element or the power of the predetermined band is the same as the power spectrum of the signal received by the light receiving element or the power of the predetermined band when the laser beam is not frequency modulated. A reflection point measuring device for an optical waveguide, which is characterized by the ability to change the reflection point.
JP11403890A 1990-04-27 1990-04-27 Reflecting point measuring apparatus for optical waveguide Pending JPH049730A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP11403890A JPH049730A (en) 1990-04-27 1990-04-27 Reflecting point measuring apparatus for optical waveguide

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP11403890A JPH049730A (en) 1990-04-27 1990-04-27 Reflecting point measuring apparatus for optical waveguide

Publications (1)

Publication Number Publication Date
JPH049730A true JPH049730A (en) 1992-01-14

Family

ID=14627477

Family Applications (1)

Application Number Title Priority Date Filing Date
JP11403890A Pending JPH049730A (en) 1990-04-27 1990-04-27 Reflecting point measuring apparatus for optical waveguide

Country Status (1)

Country Link
JP (1) JPH049730A (en)

Similar Documents

Publication Publication Date Title
US5844235A (en) Optical frequency domain reflectometer for use as an optical fiber testing device
US6850318B1 (en) Polarization mode dispersion measuring device and polarization mode dispersion measuring method
JPH079386B2 (en) Optical fiber dispersion characteristics measurement method
JP7152748B2 (en) Rangefinder, distance measuring method, and optical three-dimensional shape measuring machine
US6008487A (en) Optical-fiber inspection device
JP3428067B2 (en) Displacement measuring method and displacement measuring device used therefor
JPH049730A (en) Reflecting point measuring apparatus for optical waveguide
JP2626099B2 (en) Optical transmission line measuring instrument
JPH06186337A (en) Laser distance measuring equipment
JPS63196829A (en) Method and apparatus for searching fault point of light waveguide
JP2923770B2 (en) Method and apparatus for measuring return loss in optical fiber components
JP3223439B2 (en) Fiber inspection equipment
JPH11118928A (en) Electrooptical distance meter
KR100947731B1 (en) Apparatus for and method of measuring chromatic dispersion of optical fiber and otical waveguide using spectral interferometer
JPH0658293B2 (en) Method and apparatus for measuring wavelength dispersion of optical fiber
JP3149421B2 (en) Reflectometer
JP3453746B2 (en) Optical fiber inspection equipment
JPH02140639A (en) Backscattering light measuring instrument
JPH0313835A (en) Method and apparatus for measuring backward scattering light
JPH0716982Y2 (en) Optical frequency change measuring device
KR100335244B1 (en) An apparatus and a method for the measurement of phase fluctuation of optical fiber
JPH07270842A (en) Optical com generator
JPH01307640A (en) Gas detecting device
KR100335243B1 (en) An apparatus for the measurement of nonlinear refractive index of optical fiber
JP3446851B2 (en) Optical fiber inspection equipment