JPH0823020A - Measurement of intermodulation distortion of optical receiver - Google Patents
Measurement of intermodulation distortion of optical receiverInfo
- Publication number
- JPH0823020A JPH0823020A JP6176009A JP17600994A JPH0823020A JP H0823020 A JPH0823020 A JP H0823020A JP 6176009 A JP6176009 A JP 6176009A JP 17600994 A JP17600994 A JP 17600994A JP H0823020 A JPH0823020 A JP H0823020A
- Authority
- JP
- Japan
- Prior art keywords
- signal
- light
- optical receiver
- intermodulation distortion
- intensity
- 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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- Testing Or Measuring Of Semiconductors Or The Like (AREA)
- Optical Communication System (AREA)
- Optical Couplings Of Light Guides (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、光２トーン法による光
受信器の相互変調歪測定方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermodulation distortion measuring method for an optical receiver by an optical two-tone method.
【０００２】[0002]
【従来の技術】例えば、映像信号を周波数多重して光で
伝送する光ＣＡＴＶ（ケーブルテレビ）システム等の開
発が行われている。このようなシステムにおいては、ど
うしても、伝送される信号の品質が、周波数多重される
それぞれの搬送波による相互変調歪により劣化するため
に、特に、システムを構成するデバイスは、相互変調歪
の小さいものが求められている。2. Description of the Related Art For example, an optical CATV (cable television) system for frequency-multiplexing a video signal and transmitting it by light has been developed. In such a system, since the quality of the transmitted signal is deteriorated by the intermodulation distortion due to the respective frequency-division-multiplexed carriers, in particular, the devices that constitute the system have a small intermodulation distortion. It has been demanded.
【０００３】ところで、上記光ＣＡＴＶシステムのよう
なシステムを構成するデバイスの１つとして、光受信器
があり、光受信器の相互変調歪の簡易的な評価方法とし
て、図２に示すような、光２トーン法による相互変調歪
測定方法が用いられている。同図において、第１の光源
として機能するレーザダイオード１からの光は、第１の
信号発生器３から発生する周波数ｆ1 の第１の信号に基
づいて、第１の信号発生器３により直接強度変調され、
光カプラ８側に加えられる。また、第２の光源として機
能するレーザダイオード２からの光は、第２の信号発生
器４からの、前記第１の信号の周波数ｆ1 とは異なる周
波数ｆ2 の第２の信号に基づいて、第２の信号発生器４
により直接強度変調され、光カプラ８側に加えられる。By the way, there is an optical receiver as one of the devices constituting the system such as the optical CATV system, and as a simple evaluation method of the intermodulation distortion of the optical receiver, as shown in FIG. An intermodulation distortion measuring method using the optical two-tone method is used. In the figure, the light from the laser diode 1 functioning as the first light source is directly emitted by the first signal generator 3 based on the first signal of the frequency f 1 generated by the first signal generator 3. Intensity modulated,
It is added to the optical coupler 8 side. Also, light from the laser diode 2 functioning as a second light source, from the second signal generator 4, the frequency f 1 of the first signal based on the second signal of a different frequency f 2 , Second signal generator 4
Is directly intensity-modulated by and is added to the optical coupler 8 side.
【０００４】光カプラ８は、レーザダイオード１から加
えられる前記強度変調後の光とレーザダイオード２から
加えられる前記強度変調後の光を合波して光アッテネー
タ９に加える。そして、光アッテネータ９により、光カ
プラ８で合波した光の強度を、予め定められた光強度に
減衰させて測定対象の光受信器10に受信させ、その受信
光を光受信器10により光電変換して出力する。The optical coupler 8 multiplexes the intensity-modulated light applied from the laser diode 1 and the intensity-modulated light applied from the laser diode 2 and adds the multiplexed light to the optical attenuator 9. Then, the optical attenuator 9 attenuates the intensity of the light multiplexed by the optical coupler 8 to a predetermined optical intensity and causes the optical receiver 10 to be measured to receive the received light, and the optical receiver 10 photoelectrically receives the received light. Convert and output.
【０００５】そして、光受信器10は、その出力信号をス
ペクトラムアナライザ11に加え、スペクトラムアナライ
ザにより出力信号を観測し、周波数ｆ1 ＋ｆ2 , ｆ1 −
ｆ2に検出される２次相互変調歪と、周波数２ｆ1 −ｆ
2 ，２ｆ2 −ｆ1 に検出される３次相互変調歪を測定す
ることにより、光受信器10の相互変調歪を測定する。Then, the optical receiver 10 adds the output signal to the spectrum analyzer 11, observes the output signal with the spectrum analyzer, and determines the frequencies f 1 + f 2 and f 1 −.
Second-order intermodulation distortion detected at f 2 and frequency 2f 1 −f
The intermodulation distortion of the optical receiver 10 is measured by measuring the third-order intermodulation distortion detected in 2 , 2f 2 −f 1 .
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、上記の
ように、レーザダイオード１からの光を第１の信号発生
器３により直接強度変調すると、強度変調後の光信号
は、周波数ｆ1 の搬送波の他に、２次高調波成分（歪）
２ｆ1 を有する光信号となって出力される。そうする
と、光カプラ８で合波されて光受信器10に加えられる信
号には、この２次高調波成分２ｆ1 とレーザダイオード
２の搬送波ｆ2 との周波数２ｆ1 −ｆ2 の２次相互変調
歪が生じ、この歪が光受信器10の出力の３次相互変調歪
（周波数２ｆ1−ｆ2 ）に加算される。また、同様に、
レーザダイオード２の２次高調波成分２ｆ2 とレーザダ
イオード１の搬送波ｆ1 との２次相互変調歪（周波数２
ｆ2 −ｆ1 ）が光受信器10の３次相互変調歪（周波数２
ｆ2 −ｆ1 ）に加算されるために、上記のように、スペ
クトラムアナライザ11により光受信器10の３次相互変調
歪を測定しても、光受信器10の３次相互変調歪の真の値
を正確に測定することができなかった。However, when the light from the laser diode 1 is directly intensity-modulated by the first signal generator 3 as described above, the intensity-modulated optical signal is the carrier wave of the frequency f 1 . In addition, the second harmonic component (distortion)
It is output as an optical signal having 2f 1 . Then, in the signal multiplexed by the optical coupler 8 and applied to the optical receiver 10, the secondary intermodulation of the frequency 2f 1 -f 2 between the secondary harmonic component 2f 1 and the carrier wave f 2 of the laser diode 2 is performed. Distortion occurs, and this distortion is added to the third-order intermodulation distortion (frequency 2f 1 -f 2 ) of the output of the optical receiver 10. Similarly,
Second-order intermodulation distortion (frequency 2) between the second-order harmonic component 2f 2 of the laser diode 2 and the carrier f 1 of the laser diode 1
f 2 −f 1 ) is the third-order intermodulation distortion (frequency 2) of the optical receiver 10.
To be added to f 2 -f 1), as mentioned above, be measured third-order intermodulation distortion in the optical receiver 10 by the spectrum analyzer 11, a true third order intermodulation distortion in the optical receiver 10 The value of could not be measured accurately.
【０００７】本発明は上記従来の課題を解決するために
なされたものであり、その目的は、光受信器の３次相互
変調歪を正確に測定することができる光受信器の相互変
調歪測定方法を提供することにある。The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to measure intermodulation distortion of an optical receiver capable of accurately measuring third-order intermodulation distortion of the optical receiver. To provide a method.
【０００８】[0008]
【課題を解決するための手段】上記目的を達成するため
に本発明は次のように構成されている。すなわち、本発
明は、第１の光源からの光を第１の信号発生器からの第
１の信号に基づいて強度調整し、一方、第２の光源から
の光を第２の信号発生器からの前記第１の信号とは異な
る周波数の第２の信号に基づいて強度調整し、然る後に
それらの各強度変調後の光を合波して測定対象の光受信
器に受信させ、然る後に該受信光を該光受信器により光
電変換して出力し、然る後に該出力信号の相互変調歪を
測定する光２トーン法による光受信器の相互変調歪測定
方法において、前記第１の光源からの光は前記第１の信
号に基づいて、２次高調波成分を発生させない第１の外
部変調器により強度変調し、前記第２の光源からの光は
前記第２の信号に基づいて、２次高調波成分を発生させ
ない第２の外部変調器により強度変調することを特徴と
して構成されている。In order to achieve the above object, the present invention is constructed as follows. That is, the present invention adjusts the intensity of the light from the first light source based on the first signal from the first signal generator, while the light from the second light source from the second signal generator is adjusted. Intensity adjustment is performed based on the second signal having a frequency different from that of the first signal, and then the respective intensity-modulated lights are multiplexed and received by the optical receiver to be measured. In the intermodulation distortion measuring method of the optical receiver by the optical two-tone method, which later photoelectrically converts the received light and outputs it, and thereafter measures the intermodulation distortion of the output signal. The light from the light source is intensity-modulated based on the first signal by a first external modulator that does not generate a second harmonic component, and the light from the second light source is based on the second signal. Intensity modulation is performed by a second external modulator that does not generate a second harmonic component. It is configured.
【０００９】[0009]
【作用】上記構成の本発明において、第１の光源からの
光は第１の信号に基づいて、信号に２次高調波成分を発
生させない第１の外部変調器により強度変調され、同様
に、第２の光源からの光は、第２の信号に基づいて、信
号に２次高調波成分を発生させない第２の外部変調器に
より強度変調され、これらの各強度変調後の光が合波さ
れて光受信器に受信される。そのため、第１、第２の光
源からの２次高調波成分に起因する歪が光受信器の出力
信号の３次相互変調歪に加算されることはなく、光受信
器の３次相互変調歪が正確に測定される。In the present invention having the above-mentioned structure, the light from the first light source is intensity-modulated based on the first signal by the first external modulator that does not generate a second harmonic component in the signal. The light from the second light source is intensity-modulated by a second external modulator that does not generate a second harmonic component in the signal based on the second signal, and these intensity-modulated lights are combined. Received by the optical receiver. Therefore, the distortion caused by the second-order harmonic components from the first and second light sources is not added to the third-order intermodulation distortion of the output signal of the optical receiver, and the third-order intermodulation distortion of the optical receiver is generated. Is accurately measured.
【００１０】[0010]
【実施例】以下、本発明の実施例を図面に基づいて説明
する。なお、本実施例の説明において、従来例と同一名
称部分には同一符号を付しその詳細説明は省略する。図
１には、本発明に係わる光受信器の相互変調歪測定方法
の一実施例の要部構成が示されている。本実施例が従来
例と異なる特徴的なことは、レーザダイオード１側に第
１の外部変調器５を設け、レーザダイオード２側に第２
の外部変調器６を設けて、レーザダイオード１からの光
は第１の信号発生器３からの第１の信号に基づいて、２
次高調波成分を発生させない第１の外部変調器５により
強度変調し、レーザダイオード２からの光は、第２の信
号発生器４からの第２の信号に基づいて、２次高調波成
分を発生させない第２の外部変調器６により強度変調す
るようにしたことである。Embodiments of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same names as those in the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted. FIG. 1 shows the main configuration of an embodiment of the intermodulation distortion measuring method for an optical receiver according to the present invention. This embodiment is different from the conventional example in that a first external modulator 5 is provided on the laser diode 1 side and a second external modulator 5 is provided on the laser diode 2 side.
The external modulator 6 is provided so that the light from the laser diode 1 can be adjusted to 2 based on the first signal from the first signal generator 3.
The intensity is modulated by the first external modulator 5 that does not generate the second harmonic component, and the light from the laser diode 2 generates the second harmonic component based on the second signal from the second signal generator 4. That is, the intensity is modulated by the second external modulator 6 that is not generated.
【００１１】第１、第２の外部変調器５，６は、それぞ
れ、レーザダイオード１，２からの光を強度変調すると
きに、２次高調波成分を発生させずに強度変調すること
ができるマッハチェンダ型のＬｉＮｂＯ3 外部変調器に
より形成されており、これらの外部変調器５，６の出力
パワーｐ（伝達特性）は次式（１）のように表される正
弦波となる。The first and second external modulators 5 and 6 can intensity-modulate the light from the laser diodes 1 and 2, respectively, without generating a second harmonic component. It is formed by a Mach-Cendar type LiNbO 3 external modulator, and the output power p (transfer characteristic) of these external modulators 5 and 6 becomes a sine wave represented by the following equation (1).
【００１２】 ｐ＝sin （θ）＝θ−１／６・θ3 ＋１／120 ・θ5 ＋・・・・・──（１）P = sin (θ) = θ−1 / 6 · θ 3 + 1/120 · θ 5 + ・ ・ ・ ・ ・ ─── (1)
【００１３】なお、式（１）において、θ＝π・Ｖ／Ｖ
π（Ｖπは定数）であり、Ｖは電圧を示す。In the equation (1), θ = π · V / V
π (Vπ is a constant), and V represents a voltage.
【００１４】そして、このような外部変調器にＶ＝ａco
s （ωｔ＋φ）の電圧を印加すると、外部変調器の出力
は、次式（２）に示すようになり、πａ／Ｖπ＝Ａとす
ると、外部変調器の出力は次式（３）に示すようにな
る。In such an external modulator, V = aco
When a voltage of s (ωt + φ) is applied, the output of the external modulator becomes as shown in the following expression (2). When πa / Vπ = A, the output of the external modulator becomes as shown in the following expression (3). become.
【００１５】 ｐ＝sin ｛π／Ｖπ・ａcos （ωｔ＋φ）｝──（２）P = sin {π / Vπ · acos (ωt + φ)}-(2)
【００１６】 ｐ＝sin ｛Ａcos （ωｔ＋θ）｝ ＝（Ａ−１／８・Ａ3 ＋１／192 ・Ａ5 ）・cos （ωｔ＋φ）＋（−１／24 ・Ａ3 ＋１／384 ・Ａ5 ）・cos （３ωｔ＋３φ）＋１／1920・Ａ5 ・cos （５ ωｔ＋５φ）──（３）[0016] p = sin {Acos (ωt + θ)} = (A-1/8 · A 3 +1/192 · A 5) · cos (ωt + φ) + (- 1/24 · A 3 +1/384 · A 5)・ Cos (3ωt + 3φ) +1/1920 ・ A 5・ cos (5ωt + 5φ) ── (3)
【００１７】そして、この式は２次高調波成分（２次高
調波歪）の項であるω2 を含まない式となり、したがっ
て、この外部変調器によって強度変調されて出力される
信号は、２次高調波歪の発生のない信号となる。This equation does not include ω 2 , which is the term of the second-order harmonic component (second-order harmonic distortion). Therefore, the signal intensity-modulated and output by this external modulator is 2 The signal has no second harmonic distortion.
【００１８】本実施例は以上のように構成されており、
本実施例でも、従来例と同様に、レーザダイオード１，
２側からの強度変調後の光が光カプラ８で合波されて光
受信器10に受信されるが、本実施例では、レーザダイオ
ード１からの光は、第１の信号発生器３からの周波数ｆ
1 の第１の信号の基づいて、２次高調波成分を発生させ
ない第１の外部変調器５により強度変調されるために、
レーザダイオード１の強度変調後の光信号は、２次高調
波歪２ｆ1 の光信号を含まない状態で周波数ｆ1 の搬送
波となって光カプラ８側に加えられる。また、同様に、
レーザダイオード２からの光は、第２の信号発生器４か
らの周波数ｆ2 の第２の信号に基づいて、２次高調波成
分を発生させない第２の外部変調器６により強度変調さ
れるために、レーザダイオード２の強度変調後の光信号
は、２次高調波歪２ｆ2 を含まない状態で周波数ｆ2 の
搬送波となって光カプラ８に加えられる。This embodiment is constructed as described above,
In this embodiment, the laser diode 1,
Light intensity-modulated from the second side is multiplexed by the optical coupler 8 and received by the optical receiver 10. In this embodiment, the light from the laser diode 1 is emitted from the first signal generator 3. Frequency f
In order to be intensity-modulated by the first external modulator 5 that does not generate the second harmonic component based on the first signal of 1,
The optical signal after the intensity modulation of the laser diode 1 becomes a carrier wave of frequency f 1 in a state where the optical signal of the second harmonic distortion 2f 1 is not included and is applied to the optical coupler 8 side. Similarly,
The light from the laser diode 2 is intensity-modulated by the second external modulator 6 that does not generate the second harmonic component based on the second signal of the frequency f 2 from the second signal generator 4. In addition, the optical signal after the intensity modulation of the laser diode 2 is applied to the optical coupler 8 as a carrier wave of the frequency f 2 in the state where the second harmonic distortion 2f 2 is not included.
【００１９】そして、これらの各強度変調後の光が光カ
プラ８により合波されて光アッテネータ９を介して光受
信器10に受信されるために、本実施例では、従来のよう
にレーザダイオード１，２側から生じる２次高調波成分
に起因する周波数２ｆ1 −ｆ2 ，２ｆ2 −ｆ1 の２次相
互変調歪が光受信器10の３次相互変調歪（周波数２ｆ1
−ｆ2 ，２ｆ2 −ｆ1 ）に加算されることはなく、スペ
クトラムアナライザ11により光受信器10の３次相互変調
歪のみが測定され、光受信器10の３次相互変調歪を正確
に測定することができる。Since each of these intensity-modulated lights is combined by the optical coupler 8 and received by the optical receiver 10 via the optical attenuator 9, in this embodiment, the laser diode is used as in the conventional case. The 2nd-order intermodulation distortion of the frequencies 2f 1 −f 2 and 2f 2 −f 1 caused by the 2nd-order harmonic components generated from the 1 and 2 sides is the 3rd-order intermodulation distortion of the optical receiver 10 (frequency 2f 1
-F 2 , 2f 2 -f 1 ) is not added, and only the third-order intermodulation distortion of the optical receiver 10 is measured by the spectrum analyzer 11, and the third-order intermodulation distortion of the optical receiver 10 is accurately measured. Can be measured.
【００２０】なお、本発明は上記実施例に限定されるこ
とはなく、様々な実施の態様を採り得る。例えば、上記
実施例では、第１、第２の外部変調器５，６は、マッハ
チェンダ型のＬｉＮｂＯ3 外部変調器により構成した
が、第１、第２の外部変調器５，６は、必ずしもマッハ
チェンダ型ＬｉＮｂＯ3 外部変調器とするとは限らず、
レーザダイオード１，２からの光を、それぞれ、第１、
第２の信号発生器３，４からの第１、第２の信号に基づ
いて、信号の２次高調波成分を発生させずに強度変調す
ることができる外部変調器とすればよい。The present invention is not limited to the above-mentioned embodiment, and various embodiments can be adopted. For example, in the above-described embodiment, the first and second external modulators 5 and 6 are Mach-Cendar type LiNbO 3 external modulators. Type LiNbO 3 external modulator is not always
The light from the laser diodes 1 and 2 is respectively fed to the first and
An external modulator capable of performing intensity modulation based on the first and second signals from the second signal generators 3 and 4 without generating the second harmonic component of the signal may be used.
【００２１】また、上記実施例では、第１の信号発生器
３から周波数ｆ1 の第１の信号を発生し、第２の信号発
生器４から周波数ｆ2 の第２の信号を発生するようにし
たが、第１、第２の信号発生器３，４から発生される信
号の周波数は特に限定されるものではなく、第１の信号
の周波数と第２の信号の周波数が異なる周波数となるよ
うに適宜設定されるものである。In the above embodiment, the first signal generator 3 generates the first signal of the frequency f 1 and the second signal generator 4 generates the second signal of the frequency f 2 . However, the frequencies of the signals generated from the first and second signal generators 3 and 4 are not particularly limited, and the frequencies of the first signal and the second signal are different frequencies. Is set as appropriate.
【００２２】[0022]
【発明の効果】本発明によれば、第１の光源からの光
は、第１の信号に基づいて、２次高調波成分を発生させ
ない第１の外部変調器により強度変調し、第２の光源か
らの光は、第２の信号に基づいて、２次高調波成分を発
生させない第２の外部変調器により強度変調するため
に、それらの各強度変調後の光を２次高調波成分を含ま
ない光とすることが可能となり、従来のように、それら
の２次高調波成分に起因する２次高調波歪が光受信器の
３次高調波歪に加算されて光受信器の３次高調波歪を正
確に測定できないといったことはなく、光受信器の３次
高調波歪を正確に測定することができる。According to the present invention, the light from the first light source is intensity-modulated by the first external modulator that does not generate the second harmonic component based on the first signal, The light from the light source is intensity-modulated by the second external modulator that does not generate the second harmonic component based on the second signal, so that the light after each intensity modulation is converted into the second harmonic component. It becomes possible not to include the light, and as in the conventional case, the second-order harmonic distortion caused by those second-order harmonic components is added to the third-order harmonic distortion of the optical receiver to cause the third-order of the optical receiver. It is possible to accurately measure the third-order harmonic distortion of the optical receiver without being unable to accurately measure the harmonic distortion.
【図１】本発明に係わる光受信器の相互変調歪測定方法
の一実施例を示す要部構成図である。FIG. 1 is a main part configuration diagram showing an embodiment of a method for measuring intermodulation distortion of an optical receiver according to the present invention.
【図２】従来の光２トーン法による光受信器の相互変調
歪測定方法を示す説明図である。FIG. 2 is an explanatory diagram showing a conventional intermodulation distortion measuring method of an optical receiver by an optical two-tone method.
１，２ レーザダイオード ３ 第１の信号発生器 ４ 第２の信号発生器 ５ 第１の外部変調器 ６ 第２の外部変調器 10 光受信器 1, 2 Laser diode 3 First signal generator 4 Second signal generator 5 First external modulator 6 Second external modulator 10 Optical receiver
Claims (1)
からの第１の信号に基づいて強度調整し、一方、第２の
光源からの光を第２の信号発生器からの前記第１の信号
とは異なる周波数の第２の信号に基づいて強度調整し、
然る後にそれらの各強度変調後の光を合波して測定対象
の光受信器に受信させ、然る後に該受信光を該光受信器
により光電変換して出力し、然る後に該出力信号の相互
変調歪を測定する光２トーン法による光受信器の相互変
調歪測定方法において、前記第１の光源からの光は前記
第１の信号に基づいて、２次高調波成分を発生させない
第１の外部変調器により強度変調し、前記第２の光源か
らの光は前記第２の信号に基づいて、２次高調波成分を
発生させない第２の外部変調器により強度変調すること
を特徴とする光受信器の相互変調歪測定方法。1. The light from the first light source is intensity adjusted based on the first signal from the first signal generator, while the light from the second light source is from the second signal generator. Intensity adjustment based on a second signal of a frequency different from the first signal,
Then, the respective intensity-modulated lights are combined and received by an optical receiver to be measured, after which the received light is photoelectrically converted by the optical receiver and output, and then the output. In a method of measuring intermodulation distortion of an optical receiver by an optical two-tone method for measuring intermodulation distortion of a signal, light from the first light source does not generate a second harmonic component based on the first signal. Intensity modulation is performed by a first external modulator, and light from the second light source is intensity-modulated by a second external modulator that does not generate a second harmonic component based on the second signal. Measuring method of intermodulation distortion of optical receiver.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6176009A JPH0823020A (en) | 1994-07-05 | 1994-07-05 | Measurement of intermodulation distortion of optical receiver |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6176009A JPH0823020A (en) | 1994-07-05 | 1994-07-05 | Measurement of intermodulation distortion of optical receiver |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0823020A true JPH0823020A (en) | 1996-01-23 |
Family
ID=16006129
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6176009A Pending JPH0823020A (en) | 1994-07-05 | 1994-07-05 | Measurement of intermodulation distortion of optical receiver |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0823020A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2017139642A (en) * | 2016-02-04 | 2017-08-10 | 富士通株式会社 | Photoreceiver evaluation method and light source device |
-
1994
- 1994-07-05 JP JP6176009A patent/JPH0823020A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2017139642A (en) * | 2016-02-04 | 2017-08-10 | 富士通株式会社 | Photoreceiver evaluation method and light source device |
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