JPS6142976B2 - - Google Patents
Info
- Publication number
- JPS6142976B2 JPS6142976B2 JP56085124A JP8512481A JPS6142976B2 JP S6142976 B2 JPS6142976 B2 JP S6142976B2 JP 56085124 A JP56085124 A JP 56085124A JP 8512481 A JP8512481 A JP 8512481A JP S6142976 B2 JPS6142976 B2 JP S6142976B2
- Authority
- JP
- Japan
- Prior art keywords
- signal
- current
- modulation
- optical transmitter
- multiplexed
- 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.)
- Expired
Links
- 230000003287 optical effect Effects 0.000 claims description 10
- 239000004065 semiconductor Substances 0.000 claims description 4
- 238000001514 detection method Methods 0.000 description 5
- 230000010355 oscillation Effects 0.000 description 4
- 238000001228 spectrum Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Communication System (AREA)
Description
【発明の詳細な説明】
本発明は、半導体レーザ（以下LDと略記す
る）を光源とした周波数多重光送信器に関するも
のである。LDを光源として用いる場合、LDの変
調度により、ノイズの発生の様子が変化したり送
信信号の高調波歪み量が変動する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a frequency multiplexed optical transmitter using a semiconductor laser (hereinafter abbreviated as LD) as a light source. When an LD is used as a light source, the degree of modulation of the LD changes how noise is generated and the amount of harmonic distortion of the transmitted signal.
本発明は、これらの変動を抑え安定した光信号
を送信できる周波数多重光送信器を提供すること
を目的とする。 An object of the present invention is to provide a frequency multiplexing optical transmitter that can suppress these fluctuations and transmit stable optical signals.
第１図に従来例として、LD１を光源として
VHF帯のテレビジヨン信号を数波（図中には２
波の場合を示す）多重伝送する場合を示す。端子
２と端子３にそれぞれ搬送周波数f1とf2のVHF帯
テレビジヨン信号を加えたときの波形の一部を第
１図中ａ，ｂに縦軸を振幅の大きさに、横軸を時
間軸として模式的に示した。これらの２波を多重
すると第１図中ｃに示したような多重信号とな
り、これがLD駆動部４に加えられる。LD駆動部
４では、この多重信号を信号電流に変換したの
ち、これにバイアス電流ＩBを加え合わせてLD１
に供給し、LD１を駆動する。第１図中ｄは、LD
１に供給される駆動電流波形の一部を表わしたも
のである。縦軸は電流の大きさ、横軸は時間軸で
ある。 Figure 1 shows a conventional example using LD1 as a light source.
Several waves of VHF television signals (2 waves are shown in the figure)
(shows the case of multiplex transmission). Parts of the waveforms when VHF band television signals with carrier frequencies f 1 and f 2 are applied to terminals 2 and 3, respectively, are shown in a and b in Figure 1, with the vertical axis representing the amplitude and the horizontal axis representing the amplitude. It is shown schematically as a time axis. When these two waves are multiplexed, a multiplexed signal as shown in c in FIG. 1 is obtained, and this is applied to the LD driving section 4. The LD drive section 4 converts this multiplexed signal into a signal current, adds a bias current I B to it, and then outputs the LD1.
and drives LD1. d in Figure 1 is LD
1 represents a part of the drive current waveform supplied to the circuit 1. The vertical axis is the magnitude of the current, and the horizontal axis is the time axis.
第１図中ｄに示したように、時刻によりLD１
に供給される信号電流の大きさは変化している。
これはLD１の変調度が時刻により刻々変化して
いることになるが、変調度が変化すると一般の
LDでは次の様な現象が生じる。 As shown in d in Figure 1, depending on the time, LD1
The magnitude of the signal current supplied to is changing.
This means that the modulation degree of LD1 is changing moment by moment, but when the modulation degree changes, the general
The following phenomena occur in LD.
通常、LDの発振スペクトルの温度変化は２〜
５Å/℃であり、ある温度になると発振スペクト
ルのモードが隣接するモードへジヤンプしたり、
２つ以上のモードが競合したりする。これらの現
象が生じている時、ノイズ量や信号の高調波歪み
量が激増する。特に無変調時または変調度が小さ
い時は、このモードジヤンプの繰り返しやモード
競合が生じ、この時S/Nの急変や高調波歪み量の
変動がみられる。ところが実験的に、変調度を大
きくすれば、モードジヤンプやモード競合が抑圧
される事がわかり、変調度を0.5〜0.7にするとモ
ードジヤンプやモード競合はみられずLDの発振
スペクトルは安定となつた。すなわち、LDの変
調度を大きな値に保つことにより、ノイズ量や歪
み量が急激に増大する現象が抑圧されることがわ
かつた。 Normally, the temperature change in the LD's oscillation spectrum is 2~
5 Å/℃, and at a certain temperature, the mode of the oscillation spectrum jumps to an adjacent mode,
Two or more modes may conflict. When these phenomena occur, the amount of noise and harmonic distortion of the signal increases dramatically. Especially when there is no modulation or when the modulation depth is small, this mode jump repeats and mode competition occurs, and at this time, sudden changes in S/N and fluctuations in the amount of harmonic distortion are observed. However, it has been experimentally found that increasing the modulation depth suppresses mode jumps and mode competition, and when the modulation depth is set to 0.5 to 0.7, no mode jump or mode competition is observed and the LD's oscillation spectrum becomes stable. Ta. In other words, it was found that by keeping the modulation degree of the LD at a large value, the phenomenon in which the amount of noise and distortion increases rapidly can be suppressed.
以上のことから、LDの温度と変調度を常に一
定に保つておくことは、高いS/Nと線形性が要求
されるアナログ通信では、特に必要となる。 From the above, it is especially necessary to keep the temperature and modulation degree of the LD constant at all times, especially in analog communication where high S/N and linearity are required.
本発明のLDを光源とした周波数多重光送信器
は、送信する周波数多重信号の振幅の大きさに比
例したバイアス電流をLDに加えることによつ
て、常にLDの変調度を一定に保ちながら駆動で
きるようにしたものである。 The frequency-multiplexed optical transmitter using the LD of the present invention as a light source is driven while always keeping the degree of modulation of the LD constant by applying a bias current to the LD that is proportional to the amplitude of the frequency-multiplexed signal to be transmitted. It has been made possible.
第２図はその一実施例であり、一例として搬送
周波数f1とf2の２波VHF帯テレビジヨン信号を多
重して送信する場合について示している。 FIG. 2 shows an example of this, and shows, as an example, a case where two-wave VHF band television signals of carrier frequencies f 1 and f 2 are multiplexed and transmitted.
第２図中ｅは、端子５に加えられた多重信号の
波形の一部を表わしたものである。送信するこの
周波数多重信号の振幅の大きさに比例したバイア
ス電流ＩBをLD１に加え、常に変調度を一定に保
つための実施例として、第２図中に示すようにダ
イオードからなる検波回路６と、この検波回路６
からの出力信号を電流に変換するための電圧―電
流変換回路７を用いた場合について説明する。 2 represents a part of the waveform of the multiplexed signal applied to the terminal 5. In FIG. As an example of applying a bias current I B proportional to the magnitude of the amplitude of this frequency multiplexed signal to be transmitted to the LD 1 to keep the degree of modulation constant, a detection circuit 6 consisting of a diode as shown in Fig. 2 is used. And this detection circuit 6
A case will be described in which a voltage-current conversion circuit 7 is used to convert an output signal from the circuit into a current.
端子５からの多重信号の一部を分岐し検波回路
６に加え包絡線検波を行なう。すると第２図中ｆ
に示すような包絡線信号ｆが得られる。この信号
ｆは、電圧―電流変換回路７で包絡線信号ｆの大
きさに比例した信号電流に変換され、LD１のバ
イアス電流ＩBとしてLD駆動部４に供給される。 A part of the multiplexed signal from terminal 5 is branched and added to detection circuit 6 for envelope detection. Then f in Figure 2
An envelope signal f as shown in is obtained. This signal f is converted by the voltage-current conversion circuit 7 into a signal current proportional to the magnitude of the envelope signal f, and is supplied to the LD driving section 4 as a bias current I B of the LD 1.
LD駆動部４では、多重信号を電流に変換した
のちバイアス電流ＩBと加え合わせてLD１に供給
し、LD１を駆動する。この時のLD駆動電流波形
を第２図中ｇに表わしている。バイアス電流ＩB
は図中破線で示したように変化し、信号振幅とバ
イアス電流ＩBの大きさの比は常時一定となる。
すなわち、LD１の変調度は一定に保たれる。 The LD driving section 4 converts the multiplexed signal into a current, adds it to the bias current I B and supplies it to the LD1, thereby driving the LD1. The LD drive current waveform at this time is shown in g in FIG. Bias current I B
changes as shown by the broken line in the figure, and the ratio of the signal amplitude to the magnitude of the bias current I B remains constant.
That is, the modulation degree of LD1 is kept constant.
この時の変調度を05〜0.7と比較的大きく設定
しておけば、LD１のノイズ量や歪み量の変動は
抑圧できる。さらに、LD１の温度制御も行なえ
ば温度による波長シフトなども抑制できるため、
極めて安定した光信号を送信できる。 By setting the modulation degree at this time to a relatively large value of 05 to 0.7, fluctuations in the amount of noise and distortion of LD1 can be suppressed. Furthermore, by controlling the temperature of LD1, wavelength shifts due to temperature can be suppressed.
It can transmit extremely stable optical signals.
以上説明したように本発明によれば、LDの変
調度を一旦比較的大きな値に設定しておけば、あ
とは常に一定に保たれるため、LDの発振スペク
トルは安定となり、ノイズ量や高調波歪み量の変
動を抑圧できる。このため、極めて品質の良い安
定した光信号が送信できる。 As explained above, according to the present invention, once the modulation degree of the LD is set to a relatively large value, it is always kept constant, so the oscillation spectrum of the LD becomes stable, and the amount of noise and harmonics are reduced. Fluctuations in the amount of wave distortion can be suppressed. Therefore, stable optical signals of extremely high quality can be transmitted.
第１図は従来の光送信器の構成図、第２図は本
発明の一実施例における周波数多重光送信器の構
成図である。
１…LD、４…LD駆動部、５…入力端子、６…
検波回路、７…電圧―電流変換回路。
FIG. 1 is a block diagram of a conventional optical transmitter, and FIG. 2 is a block diagram of a frequency multiplexing optical transmitter according to an embodiment of the present invention. 1...LD, 4...LD drive section, 5...input terminal, 6...
Detection circuit, 7... Voltage-current conversion circuit.
Claims (1)
器において、周波数多重信号の振幅の大きさに比
例したバイアス電流を前記半導体レーザに供給す
る回路を設けて前記半導体レーザを駆動すること
を特徴とする周波数多重光送信器。1. A frequency multiplexed optical transmitter using a semiconductor laser as a light source, characterized in that a circuit is provided to supply the semiconductor laser with a bias current proportional to the magnitude of the amplitude of the frequency multiplexed signal to drive the semiconductor laser. Multiplex optical transmitter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56085124A JPS57199347A (en) | 1981-06-02 | 1981-06-02 | Frequency multiplex optical transmitter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56085124A JPS57199347A (en) | 1981-06-02 | 1981-06-02 | Frequency multiplex optical transmitter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57199347A JPS57199347A (en) | 1982-12-07 |
| JPS6142976B2 true JPS6142976B2 (en) | 1986-09-25 |
Family
ID=13849884
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56085124A Granted JPS57199347A (en) | 1981-06-02 | 1981-06-02 | Frequency multiplex optical transmitter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57199347A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6338335A (en) * | 1986-08-02 | 1988-02-18 | Fujitsu Ltd | Optical transmission equipment |
| JPH04256392A (en) * | 1991-02-08 | 1992-09-11 | Sumitomo Electric Ind Ltd | Frequency multiplexing optical transmission equipment |
| CN101836380B (en) * | 2007-10-24 | 2013-06-05 | 欧力天工股份有限公司 | Infrared transmitter |
-
1981
- 1981-06-02 JP JP56085124A patent/JPS57199347A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57199347A (en) | 1982-12-07 |
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