JPS61163684A - Driving circuit for laser diode - Google Patents

Driving circuit for laser diode

Info

Publication number
JPS61163684A
JPS61163684A JP425585A JP425585A JPS61163684A JP S61163684 A JPS61163684 A JP S61163684A JP 425585 A JP425585 A JP 425585A JP 425585 A JP425585 A JP 425585A JP S61163684 A JPS61163684 A JP S61163684A
Authority
JP
Japan
Prior art keywords
laser diode
drive circuit
waveform
distributed constant
pattern effect
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
JP425585A
Other languages
Japanese (ja)
Inventor
Isamu Takano
高野 勇
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.)
NEC Corp
Original Assignee
NEC 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 NEC Corp filed Critical NEC Corp
Priority to JP425585A priority Critical patent/JPS61163684A/en
Publication of JPS61163684A publication Critical patent/JPS61163684A/en
Pending legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01SDEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00Semiconductor lasers
    • H01S5/04Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
    • H01S5/042Electrical excitation ; Circuits therefor

Landscapes

  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Semiconductor Lasers (AREA)

Abstract

PURPOSE:To prevent the generation of a pattern effect in an optical output even on modulation at high speed by connecting one terminal of a laser-diode driving circuit to an output terminal to a distributed constant circuit grounded through a terminal resistor. CONSTITUTION:A distributed constant line (a coaxial line) in length (l) for compensating pattern effect is represented by 8 and a terminal resistor R in the line 8 by 9. A laser-diode driving circuit 11 is mounted, and the length of the distributed constant line 8 and the value of the terminal resistor R9 are adjusted thus regulating the retardation time of reflected waves and amplitude thereof at proper values, then changing optical output waveforms into waveforms having no pattern effect. Accordingly,the laser-diode driving circuit in which the pattern effect is not generated in optical outputs even in modulation at high speed can be manufactured.

Description

【発明の詳細な説明】 (産業上の利用分舒) 本発明は、光フ′フィバケーブルを光伝送媒体とする光
通信システム等で用いられるレーザダイオード駆動回路
に関し、特に高速変調が可能なし−ザダイオード駆動回
路に関する。
DETAILED DESCRIPTION OF THE INVENTION (Industrial Application) The present invention relates to a laser diode drive circuit used in an optical communication system using an optical fiber cable as an optical transmission medium. This invention relates to the diode drive circuit.

(従来の技術及び発明が解決しようとする問題点)電気
回路の動作領域は年々高速化、広帯域化する傾向にあり
、例えば数GHzの帯域をもった増幅器、数Gb/sの
高速で動作するディジタル回路等の実現が可能となり、
これに応じてIC化技術も年々と進み、例えばガリウム
ヒ素電界効果トランジスタを用いた、ガリウムヒ素IC
での高速ディジタルIC,高周波アナログICが実現さ
れつつある。
(Prior art and problems to be solved by the invention) The operating range of electric circuits tends to become faster and wider every year. For example, amplifiers with a band of several GHz and those that operate at high speeds of several Gb/s It becomes possible to realize digital circuits, etc.
Correspondingly, IC technology has progressed year by year, such as gallium arsenide ICs using gallium arsenide field effect transistors.
High-speed digital ICs and high-frequency analog ICs are being realized.

一方、光フアイバケーブルは広帯域、低損失、軽量、細
径等多くの優れた特長を持ち、レーザダイオードと光フ
アイバケーブルで構成される光フアイバケーブル伝送シ
ステムは応用範囲も広く画期的な技術に成長しつつある
。したがって、超高速光フアイバケーブル伝送システム
を実現するためには、高速変調が可能なレーザダイオー
ド駆動回路が不可決である。しかし、従来レーザダイオ
ードを高速にパルス変調する場合、レーザダイオード内
のキャリア拡散効果のために光出力パルス列位パターン
効果が現われ、高速変調を行なうにはその変調速度に限
界を生じていた。
On the other hand, optical fiber cables have many excellent features such as broadband, low loss, light weight, and small diameter, and optical fiber cable transmission systems consisting of laser diodes and optical fiber cables have a wide range of applications and have become revolutionary technology. It's growing. Therefore, in order to realize an ultrahigh-speed optical fiber cable transmission system, a laser diode drive circuit capable of high-speed modulation is essential. However, when conventionally pulse-modulating a laser diode at high speed, an optical output pulse alignment pattern effect appears due to the carrier diffusion effect within the laser diode, and there is a limit to the modulation speed for high-speed modulation.

第3図は従来のレーザダイオード駆動回路(50Ω負荷
)を示す回路図であり、第4図は第3図のレーザダイオ
ードの駆動電流波形及び光出力波形を示す図である。次
に、これら両図を参照して従来のレーザダイオード駆動
回路の限界を説明する。なお、第3図の方式のレーザダ
イオード駆動回路については、度板出版から発行きれて
いる技術書1光通侶の実用技術」に詳しい説明がある。
FIG. 3 is a circuit diagram showing a conventional laser diode drive circuit (50Ω load), and FIG. 4 is a diagram showing the drive current waveform and optical output waveform of the laser diode shown in FIG. Next, the limitations of the conventional laser diode drive circuit will be explained with reference to these figures. The laser diode drive circuit of the type shown in FIG. 3 is explained in detail in the technical book 1 "Practical Techniques of Practical Techniques of Practical Techniques" published by Oita Publishing.

第3図において、1は入力端、2はパルス電流駆動回路
、3は同軸線路、4は抵抗値R1の負荷インピーダンス
整合抵抗、5はレーザダイオード、6はファイバケーブ
ル、7はバイアス電流供給回路、10はレーザダイオー
ド駆動回路である。
In FIG. 3, 1 is an input terminal, 2 is a pulse current drive circuit, 3 is a coaxial line, 4 is a load impedance matching resistor with a resistance value R1, 5 is a laser diode, 6 is a fiber cable, 7 is a bias current supply circuit, 10 is a laser diode drive circuit.

光源にレーザダイオードを用いた高速光伝送システムで
は、一般にPCM信号を用いる。そして、レーザダイオ
ードに変調用のパルス信号を加え、レーザダイオードに
流れろ電流を0N10FFすることにより、し・−ザダ
イオードの発光/消光動作を制御し、PCM光信号を光
ファイバに加えている。第3図の従来回路についてより
詳しく述べる。パルス電流駆動回路2への信号入力端1
には変調パルス信号としてRZ信号101が入力きれる
。このRZ信号101には一般に占有率50%の波形が
用いられる。パルス電流駆動回路2は、入力端1に入力
さレタRZM号101(7)ONloFFに従い、同じ
く占有率50%のパルスのレーザダイオード駆動電流1
02を発生する。
A high-speed optical transmission system using a laser diode as a light source generally uses a PCM signal. Then, by applying a modulation pulse signal to the laser diode and setting the current flowing through the laser diode to 0N10FF, the light emission/quenching operation of the laser diode is controlled, and the PCM optical signal is applied to the optical fiber. The conventional circuit shown in FIG. 3 will be described in more detail. Signal input terminal 1 to pulse current drive circuit 2
An RZ signal 101 can be input as a modulated pulse signal. This RZ signal 101 generally uses a waveform with an occupancy rate of 50%. The pulsed current drive circuit 2 receives a pulsed laser diode drive current 1 with a 50% occupation rate in accordance with the letter RZM No. 101 (7) ONloFF input to the input terminal 1.
Generates 02.

この駆動電流102は、レーザダイオード5の発振しき
い値電流の値に応じた大きさのバイアス電流供給回路7
によるオフセットバイアス電流と加え合わされ、レーザ
ダイオード5に導かれる。こうして駆動電流102はレ
ーザダイオード5を変調する。通常、レーザダイオード
5はモジュール化され、なおかつパルス電流駆動回路2
は50Ω負荷条件で設計されているから、パルス電流駆
動回路2には同US路3が接読される。このためレーザ
ダイオード5の前に負荷インピーダンス整合抵抗4を設
け、これを介してパルス電流駆動回路2の負荷インピー
ダンスが50Ωとなるように調整が行なわれる。駆動電
流パルス102により変調されたレーザダイオード5は
、その駆動電流パルス102の0N10FFによりレー
ザ発振を生じ、パルス化した光を出力する。この光出力
はファイバケーブル6へと結合きれる。このレーザダイ
オード5の発光強度は、駆動電流値の大小により変化す
る。一定振幅のRZ電流信号でレーザダイオードを変調
した場合、一般にある時点のレーザダイオード発光波形
は、その前の信号が“1”か“0”かで波形が異なる。
This drive current 102 is supplied to a bias current supply circuit 7 whose magnitude corresponds to the value of the oscillation threshold current of the laser diode 5.
The offset bias current is added to the offset bias current caused by the current and is guided to the laser diode 5. The drive current 102 thus modulates the laser diode 5. Usually, the laser diode 5 is modularized, and the pulse current drive circuit 2
Since it is designed under a 50Ω load condition, the pulse current drive circuit 2 is directly connected to the US path 3. For this purpose, a load impedance matching resistor 4 is provided in front of the laser diode 5, and the load impedance of the pulse current drive circuit 2 is adjusted to 50Ω via this resistor. The laser diode 5 modulated by the driving current pulse 102 generates laser oscillation due to the 0N10FF of the driving current pulse 102, and outputs pulsed light. This optical output can be coupled into fiber cable 6. The light emission intensity of this laser diode 5 changes depending on the magnitude of the drive current value. When a laser diode is modulated with an RZ current signal of constant amplitude, the laser diode light emission waveform at a certain point in time generally differs depending on whether the previous signal was "1" or "0".

これをレーザダイオードのパターン効果と呼んでいる。This is called the laser diode pattern effect.

この現象は、高速変調を行なうときに特に顕著に現れる
This phenomenon is particularly noticeable when performing high-speed modulation.

第4図にその様子を示す、第4図(a)の波形はレーザ
ダイオード駆動電流波形、(b)の波形はレーザダイオ
ードの光出力波形である。レーザダイオードの光応答波
形におけるパターン効果は、信号のない連続した“O″
の状態から信号が連続的に到来した場合、光出力波形(
(b)の波形)において114gが徐々1こ小さくなり
、また立ち上がり時点も速くなる((b)の波形D+ 
、 Da 、 Ds )現象である。これはレーザダイ
オードの内部状態が、信号が入力きれるに従い発光をし
やすい励起状態になるためと考えられる。
The situation is shown in FIG. 4. The waveform in FIG. 4(a) is the laser diode driving current waveform, and the waveform in FIG. 4(b) is the optical output waveform of the laser diode. The pattern effect in the optical response waveform of a laser diode is a continuous “O” with no signal.
If a signal arrives continuously from the state of , the optical output waveform (
In waveform (b)), 114g gradually becomes smaller by 1, and the rise time also becomes faster (waveform D+ in (b)).
, Da, Ds) phenomenon. This is thought to be because the internal state of the laser diode becomes an excited state in which it is more likely to emit light as the signal is inputted.

以上に述べたレーザダイオードの光応答波形におけるパ
ターン効果は、高速変調時において波形歪みとなり伝送
特性を劣化させ、更番こは伝送速度の向上に限界を与え
る要因となっている。
The above-described pattern effect in the optical response waveform of the laser diode causes waveform distortion during high-speed modulation, deteriorating transmission characteristics, and is a factor that limits the improvement of transmission speed.

そこで、゛本発明の目的は高速変調においても光出力ニ
ハターン効果を生じにくいレーザダイオード駆動回路の
提供にある。
SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a laser diode drive circuit that is less likely to cause the optical output Nihaturn effect even in high-speed modulation.

(問題点を解決するための手段) 前述の問題点を解決するために本発明が提供する手段は
、入力される変調パルス信号に応じたパルス電流を出力
するパルス電流駆動回路が備えてあり、そのパルス電流
によりレーザダイオードを変調するレーザダイオード駆
動回路であって、片端が前記パルス電流駆動回路の出力
端番こ接続してあり他端が終端抵抗を介して接地してあ
る分布定数線路が備えてあることを特徴とする。
(Means for Solving the Problems) Means provided by the present invention to solve the above-mentioned problems includes a pulse current drive circuit that outputs a pulse current according to an input modulated pulse signal, A laser diode drive circuit that modulates a laser diode with the pulsed current, and includes a distributed constant line whose one end is connected to the output terminal of the pulsed current drive circuit and whose other end is grounded via a terminating resistor. It is characterized by:

(発明の原理) 本発明においては、以下に述べる原理に基づき本発明の
目的を達成している。すなわち、本発明では、パルス電
流駆動回路の出力端に分布定数線路を接続してレーザダ
イオードの駆動電流波形に反射波を発生させることによ
り、駆動電流波形の後縁にバックスパイクをつくり、レ
ーザダイオードを励起状態から、速やかに定常状態に戻
し、これによりレーザダイオードのパターン効果を補償
し、高速変調時においてもレーザダイオードのパターン
効果が生じていない光波形を出力せしめる。更に、この
手段を用いた場合、レーザダイオード間に特性バラツキ
があっても、分布定数線路あるいは反射波形振幅を調整
する抵抗Rのいずれかを再調整する事により、光応答波
形の特性にバラツキがなく安定な光波形を出力せしめる
(Principle of the Invention) In the present invention, the object of the present invention is achieved based on the principle described below. That is, in the present invention, by connecting a distributed constant line to the output end of the pulse current drive circuit and generating a reflected wave in the drive current waveform of the laser diode, a back spike is created at the trailing edge of the drive current waveform, and the laser diode from the excited state to a steady state, thereby compensating for the pattern effect of the laser diode, and outputting an optical waveform in which the pattern effect of the laser diode does not occur even during high-speed modulation. Furthermore, when this method is used, even if there are variations in characteristics between laser diodes, the variations in the characteristics of the optical response waveform can be eliminated by readjusting either the distributed constant line or the resistor R that adjusts the reflected waveform amplitude. It outputs a stable optical waveform.

(実施例) 以下に図面を参照して本発明の詳細な説明する。(Example) The present invention will be described in detail below with reference to the drawings.

第1図は本発明の一実施例を示す回路図である。回路図
において、1は入力端、2はパルス電流駆動回路、3は
同軸線路、7はバイアス電流供給回路、5はレーザダイ
オード、4は抵抗値R4の負荷インピーダンス調整抵抗
、6はファイバケーブルである。また8は、パターン効
果を補償するための長さ!の分布定数線路(同軸線路)
であるが、例えばペア線あるいは薄膜IC回路等で構成
された分布定数線路であっても良い。9は分布定数線路
8の終端抵抗(抵抗値R)、11は本発明の一実施例の
レーザダイオード駆動回路である。この実施例11を備
えであるから、レーザダイオード5で生じるパターン効
果に従って、分布定数線路の長き2と抵抗値Rの値を調
整することにより、反射波の遅延時間T0およびその振
幅Hが適正な値に調!!、’れ、光出力波形をパターン
効果の無い波形にすることができる。
FIG. 1 is a circuit diagram showing an embodiment of the present invention. In the circuit diagram, 1 is an input terminal, 2 is a pulse current drive circuit, 3 is a coaxial line, 7 is a bias current supply circuit, 5 is a laser diode, 4 is a load impedance adjustment resistor with a resistance value R4, and 6 is a fiber cable. . Also, 8 is the length to compensate for pattern effects! Distributed constant line (coaxial line)
However, it may also be a distributed constant line composed of, for example, a pair of wires or a thin film IC circuit. 9 is a terminal resistor (resistance value R) of the distributed constant line 8, and 11 is a laser diode drive circuit according to an embodiment of the present invention. Since this embodiment 11 is provided, by adjusting the length 2 of the distributed constant line and the value of the resistance value R according to the pattern effect generated in the laser diode 5, the delay time T0 of the reflected wave and its amplitude H can be adjusted appropriately. Value for money! ! , it is possible to make the optical output waveform free from pattern effects.

すなわち、第1図A点に分布定数線路8を付加した状態
での伝達関数S (ui )は(zeは特性インピーダ
ンス) となり、分布定数線路8の長−atにより反射波形の遅
延時間Tゎを、また抵抗9の抵抗値Rによりその振幅の
太きtHをそれぞれ変える事ができる。
That is, the transfer function S (ui) with the distributed constant line 8 added to point A in Fig. 1 is (ze is the characteristic impedance), and the delay time T of the reflected waveform is determined by the length -at of the distributed constant line 8. , and the amplitude tH can be changed by changing the resistance value R of the resistor 9.

この第1図回路の各部信号の波形が第2図(a)。The waveforms of the signals in each part of the circuit in FIG. 1 are shown in FIG. 2(a).

(b)に示してある。第2図(a)は本実施例におけろ
レーザダイオード駆動主流102波形であり、本図(a
)の波形の駆動電流102でレーザダイオード5を駆動
したとき光応答波形は同図(b)の如くになる。
It is shown in (b). FIG. 2(a) shows the main waveform of the laser diode drive 102 in this embodiment.
) When the laser diode 5 is driven with a drive current 102 having a waveform of 102, the optical response waveform becomes as shown in FIG.

このように、レーザダイオードの駆動電流波形を分布定
数線路を付加して第2図(a)のような波形にすること
により、RZ信号101としてパルス波形が連続して到
来しても、1・−ザダイオード5は発光時の励起状態か
ら、すぐに定常状態に落ち着くようにすることができる
。従って、レーザダイオード5の光出力波形(第2図(
b)の波形)にはパターン効果が現れない。
In this way, by adding a distributed constant line to the drive current waveform of the laser diode to create the waveform as shown in FIG. - The diode 5 can be made to quickly settle into a steady state from an excited state during light emission. Therefore, the optical output waveform of the laser diode 5 (Fig. 2 (
No pattern effect appears in waveform b).

なお、レーザダイオードの特性には分散があるから応答
特性も素子こ゛とLこ異なる。しかし、本発明では分布
定数線路の長さ!又は終端抵抗9の抵抗値Rを選択する
ことにより、レーザダイオードごとに最適な駆動回路を
形成できる。このように融通性に優れていることも本発
明の効果の一つである。
Note that since there is dispersion in the characteristics of the laser diode, the response characteristics also differ from element to element. However, in the present invention, the length of the distributed constant line! Alternatively, by selecting the resistance value R of the terminating resistor 9, an optimal drive circuit can be formed for each laser diode. Such excellent flexibility is also one of the effects of the present invention.

(発明の効果) 以上述べた如く、本発明によれば高速変調においても光
出力にパターン効果を生じないレーザダイオード駆動回
路が提供できる。また、本発明を適用すれば、レーザダ
イオードの個別の特性に応じて調整することにより、レ
ーザダイオードの特性に分散があっても最適の波形のパ
ルスレーザ光を得ることができる。
(Effects of the Invention) As described above, according to the present invention, it is possible to provide a laser diode drive circuit that does not cause pattern effects on optical output even in high-speed modulation. Furthermore, by applying the present invention, by adjusting according to the individual characteristics of the laser diode, it is possible to obtain pulsed laser light with an optimal waveform even if there is dispersion in the characteristics of the laser diode.

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

第1図は本発明の一実施例を示す回路図、第2図(a)
 、 (b)は第1図回路の各部信号波形図、第3図は
従来のレーザダイオード駆動回路を示す回路図、第4図
(a) 、 (b)は第3図の回路における各部信号波
形図である。 1・・・入力端、2・・・パルス電流駆動回路、3・・
・同軸線路、4・・・負荷インピーダンス整合抵抗、5
・・・レーザダイオード、6・・・ファイバケーブル、
7・・・バイアス電流供給回路、8・・・分布定数線路
、9・・・終端抵抗、to、ti・・・し・−ザダイオ
ード駆動回路。 47・−1ゝ 代理人弁理士  内 原  晋、パ 〈 第1図 第2図
Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2(a)
, (b) is a signal waveform diagram of each part of the circuit in Figure 1, Figure 3 is a circuit diagram showing a conventional laser diode drive circuit, and Figures 4 (a) and (b) are signal waveforms of each part in the circuit of Figure 3. It is a diagram. 1... Input end, 2... Pulse current drive circuit, 3...
・Coaxial line, 4...Load impedance matching resistance, 5
...Laser diode, 6...Fiber cable,
7... Bias current supply circuit, 8... Distributed constant line, 9... Termination resistor, to, ti... - the diode drive circuit. 47・-1ゝRepresentative Patent Attorney Susumu Uchihara, Pa〈Figure 1Figure 2

Claims (1)

【特許請求の範囲】[Claims] 入力される変調パルス信号に応じたパルス電流を出力す
るパルス電流駆動回路が備えてあり、そのパルス電流に
よりレーザダイオードを変調するレーザダイオード駆動
回路において、片端が前記パルス電流駆動回路の出力端
に接続してあり他端が終端抵抗を介して接地してある分
布定数線路が備えてあることを特徴とするレーザダイオ
ード駆動回路。
A pulse current drive circuit that outputs a pulse current according to an input modulation pulse signal is provided, and in the laser diode drive circuit that modulates a laser diode with the pulse current, one end is connected to the output terminal of the pulse current drive circuit. 1. A laser diode drive circuit comprising a distributed constant line whose other end is grounded via a terminating resistor.
JP425585A 1985-01-14 1985-01-14 Driving circuit for laser diode Pending JPS61163684A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP425585A JPS61163684A (en) 1985-01-14 1985-01-14 Driving circuit for laser diode

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP425585A JPS61163684A (en) 1985-01-14 1985-01-14 Driving circuit for laser diode

Publications (1)

Publication Number Publication Date
JPS61163684A true JPS61163684A (en) 1986-07-24

Family

ID=11579428

Family Applications (1)

Application Number Title Priority Date Filing Date
JP425585A Pending JPS61163684A (en) 1985-01-14 1985-01-14 Driving circuit for laser diode

Country Status (1)

Country Link
JP (1) JPS61163684A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3833695A1 (en) * 1987-10-05 1989-04-20 Gen Electric SIGNAL PROCESSING DEVICE AND METHOD FOR EXTENDING THE FLAT FREQUENCY OF A COMPONENT
JP2016072288A (en) * 2014-09-26 2016-05-09 沖電気工業株式会社 Photoelectric conversion circuit

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5378795A (en) * 1976-12-23 1978-07-12 Fujitsu Ltd Driver circuit of luminous element

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5378795A (en) * 1976-12-23 1978-07-12 Fujitsu Ltd Driver circuit of luminous element

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3833695A1 (en) * 1987-10-05 1989-04-20 Gen Electric SIGNAL PROCESSING DEVICE AND METHOD FOR EXTENDING THE FLAT FREQUENCY OF A COMPONENT
DE3833695C2 (en) * 1987-10-05 1998-01-22 Gen Electric Signal processing device
JP2016072288A (en) * 2014-09-26 2016-05-09 沖電気工業株式会社 Photoelectric conversion circuit

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