JPH03179789A - Alarm circuit - Google Patents
Alarm circuitInfo
- Publication number
- JPH03179789A JPH03179789A JP31919589A JP31919589A JPH03179789A JP H03179789 A JPH03179789 A JP H03179789A JP 31919589 A JP31919589 A JP 31919589A JP 31919589 A JP31919589 A JP 31919589A JP H03179789 A JPH03179789 A JP H03179789A
- Authority
- JP
- Japan
- Prior art keywords
- signal
- circuit
- optical output
- laser diode
- monitors
- 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
Links
- 230000003287 optical effect Effects 0.000 claims abstract description 39
- 238000012544 monitoring process Methods 0.000 abstract description 10
- 239000003990 capacitor Substances 0.000 abstract description 6
- 230000005540 biological transmission Effects 0.000 abstract description 5
- 230000006866 deterioration Effects 0.000 abstract description 4
- 238000000034 method Methods 0.000 abstract 1
- 230000002950 deficient Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 230000007547 defect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES 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
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/068—Stabilisation of laser output parameters
- H01S5/06825—Protecting the laser, e.g. during switch-on/off, detection of malfunctioning or degradation
Landscapes
- Semiconductor Lasers (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は発光素子としてレーザダイオードを使用した光
送信回路における光出力不良のアラーム回路に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an alarm circuit for an optical output failure in an optical transmission circuit using a laser diode as a light emitting element.
従来、この種のアラーム回路は、レーザダイオードのモ
ニタ用受光素子の平均電流を監視し、平均電流がある値
以下になった場合にアラーム信号を送出する回路となっ
ている。Conventionally, this type of alarm circuit monitors the average current of a monitoring light receiving element of a laser diode, and sends out an alarm signal when the average current falls below a certain value.
光送信回路の一般的な構成例を第３図に、従来の光出力
不良のアラーム回路の一例の構成を第４図に示す。FIG. 3 shows a general configuration example of an optical transmitter circuit, and FIG. 4 shows an example configuration of a conventional alarm circuit for a defective optical output.
第３図において、■はレーザダイオードモジュール、２
はＬＤ駆動回路、３はＡＰＣ回路、４はアラーム回路で
あり、１１は送信信号、１２はＬＤ駆動信号、１３は光
出力のモニタ信号、１４はアラーム出力である。In Figure 3, ■ is a laser diode module, 2
1 is an LD drive circuit, 3 is an APC circuit, 4 is an alarm circuit, 11 is a transmission signal, 12 is an LD drive signal, 13 is an optical output monitor signal, and 14 is an alarm output.
次に、第３図に示す光送信回路の動作について説明する
。Next, the operation of the optical transmission circuit shown in FIG. 3 will be explained.
送信信号１１８′！、ＬＤ駆動回路２によりＬＤ駆動信
号１２に変換されレーザダイオードモジュール１内のレ
ーザダイオードＬＤを駆動する。レーザダイオードＬＤ
はＬＤ駆動信号１２に応じて発光し光出力に変換させる
。光出力ＰｈはＬＤモジュール１内の受光素子であるホ
トダイオードＰＤにより電気信号に変換されモニタ信号
１３として出力される。このモニタ信号１３はＡＰＣ回
路３とアラーム回路４へ入力される。ＡＰＣ回路３に入
力されたモニタ信号１３はＡＰＣループによりツ出力信
号の平均値が常に一定となる様にする。アラーム回路４
は入力されたモニタ信号１３を監彩し、光出力不良時に
アラーム信号１４を送出する次に、アラーム回路４の従
来例について第４区を参照して説明する。Transmission signal 118'! , is converted into an LD drive signal 12 by the LD drive circuit 2, and drives the laser diode LD in the laser diode module 1. laser diode LD
emits light in response to the LD drive signal 12 and converts it into optical output. The optical output Ph is converted into an electrical signal by a photodiode PD, which is a light receiving element in the LD module 1, and output as a monitor signal 13. This monitor signal 13 is input to the APC circuit 3 and alarm circuit 4. The monitor signal 13 input to the APC circuit 3 is made to have an average value of the output signal always constant through an APC loop. Alarm circuit 4
monitors the input monitor signal 13 and sends out an alarm signal 14 when the optical output is defective.Next, a conventional example of the alarm circuit 4 will be explained with reference to Section 4.
第４図において、Ｐｈは光信号、ＰＤはＬＤモジュール
ｌ内の光信号モニタ用のホトダイオードＲ，，Ｒ２，Ｒ
３は抵抗、Ｃ１はコンデンサ、２ｈ言演算増幅器であり
、１３はモニタ信号、Ｖｒｅｆ １はアラーム発出レベ
ル設定用の基準電圧、１４ｂはアラーム信号である。ホ
トダイオードＰＤにより電気信号に変換されたモニタ信
号１３は抵抗Ｒ３，コンデンサＣ１により平均値にされ
た後、演算増幅器２１に入力され、基準電圧Ｖｒｅｆ
１により設定したアラーム発出レベルよりモニタ信号平
均レベルが低下した場合にアラーム信号１４ｂを送出す
る。In Fig. 4, Ph is an optical signal, and PD is a photodiode R, , R2, R for monitoring the optical signal in the LD module l.
3 is a resistor, C1 is a capacitor, and 2H operational amplifier, 13 is a monitor signal, Vref 1 is a reference voltage for setting an alarm generation level, and 14b is an alarm signal. The monitor signal 13 converted into an electric signal by the photodiode PD is averaged by a resistor R3 and a capacitor C1, and then inputted to an operational amplifier 21, where the reference voltage Vref
The alarm signal 14b is sent out when the average level of the monitor signal falls below the alarm issuing level set by 1.
上述した従来のアラーム回路は、モニタ信号の平均レベ
ルを監視しているためレーザダイオードの光出力不良と
して光出力の平均レベルが低下した場合のみ検出可能で
あり、レーザダイオードの微分量子効率（Ｄ、Ｑ、Ｅ）
の劣化による光出力不良は検出できない欠点がある。Since the conventional alarm circuit described above monitors the average level of the monitor signal, it can only detect a decrease in the average level of the optical output as a defect in the optical output of the laser diode, and the differential quantum efficiency (D, Q, E)
The disadvantage is that optical output defects due to deterioration cannot be detected.
本発明のアラーム回路は、レーザダイオードを使用した
光送信回路が出力した光出力モニタ電流の平均値を監視
する回路と、前記光出力モニタ電流の直流分を監視する
回路とを備えている。The alarm circuit of the present invention includes a circuit that monitors the average value of the optical output monitor current output by an optical transmitter circuit using a laser diode, and a circuit that monitors the DC component of the optical output monitor current.
次に、本発明について図面を参照して説明する。 Next, the present invention will be explained with reference to the drawings.
第１図は本発明の一実施例回路図である。本実施例が第
３図におけるアラーム回路４として使われるとして以下
説明する。FIG. 1 is a circuit diagram of one embodiment of the present invention. This embodiment will be explained below assuming that it is used as the alarm circuit 4 in FIG.
第１図においてｐｈは光信号、ＰＤはＬＤモジュール１
内の光信号モニタ用のホトダイオード、Ｒｔ、Ｒｔ、Ｒ
３は抵抗、Ｃ，、Ｃ，はコンデンサ、Ｑｌはトランジス
タ、２１．２２は演算増幅器であり、１３はモニタ信号
、Ｖｒｅｆ １ 、 Ｖｒｅｆ ２はアラーム発出レベ
ル設定用の基準電圧、１４ａは演算増幅器２１，２２の
出力のＯＲをとったアラーム信号である。In Fig. 1, ph is an optical signal, and PD is LD module 1.
Photodiodes for optical signal monitoring inside, Rt, Rt, R
3 is a resistor, C, C, is a capacitor, Ql is a transistor, 21.22 is an operational amplifier, 13 is a monitor signal, Vref 1 and Vref 2 are reference voltages for setting the alarm generation level, 14a is an operational amplifier 21 , 22 outputs are ORed together.
第１図に示す実施例の動作について説明する。The operation of the embodiment shown in FIG. 1 will be explained.
ホトダイオードＰＤにより電気信号に変換されたモニタ
信号１３は演算増幅器２１．２２に入力される。演算増
幅器２１側の回路は従来と同様であり、モニタ信号１３
の平均値の低下を検出しアラーム信号１４ａを送出する
。一方、演算増幅器２２ではモニタ信号１３そのものと
、コンデンサＣ２，トランジスタＱ１でパルスクランプ
したモニタ信号１３との差をとることによりモニタ信号
１３の直流信号のみを監視し、基準電圧Ｖｒｅｆ２より
モニタ信号１３の直流信号が増加した場合にアラーム信
号１４ａを出力する。The monitor signal 13 converted into an electrical signal by the photodiode PD is input to operational amplifiers 21 and 22. The circuit on the operational amplifier 21 side is the same as the conventional one, and the monitor signal 13
A decrease in the average value of is detected and an alarm signal 14a is sent out. On the other hand, the operational amplifier 22 monitors only the DC signal of the monitor signal 13 by taking the difference between the monitor signal 13 itself and the monitor signal 13 pulse-clamped by the capacitor C2 and the transistor Q1. An alarm signal 14a is output when the DC signal increases.
第２図を参照して、従来例では検出できず本発明により
可能となる光出力不良モードの例を説明する。１０１は
レーザダイオードＬＤの駆動電流■と光出力りとの関係
を示す曲線、１０２は駆動電流波形、１０３は光出力波
形を示す。又、いずれについても実線は正常時、破線は
劣化時（光出力不良時）を示す。１０１に示す様にレー
ザダイオードの劣化モードには微分量子効率が劣化する
モードがある。このとき駆動電流波形１０２は、ＡＰＣ
ループの動作により直流電流分は増加する（ＩＢＩ→工
、□）が、パルス電流工、は変わらない。With reference to FIG. 2, an example of a light output failure mode that cannot be detected in the conventional example but becomes possible with the present invention will be described. Reference numeral 101 indicates a curve showing the relationship between the drive current (2) of the laser diode LD and the optical output, 102 indicates the drive current waveform, and 103 indicates the optical output waveform. Further, in each case, the solid line indicates the normal state, and the broken line indicates the degraded state (defective optical output). As shown in 101, the deterioration mode of the laser diode includes a mode in which the differential quantum efficiency deteriorates. At this time, the drive current waveform 102 is APC
Due to the operation of the loop, the DC current increases (IBI→work, □), but the pulse current remains unchanged.
このため光出力波形１０３は、正常時は光パルス振幅Ｌ
ＰＩは大きく直流発光分は少ないが、劣化時には光パル
ス振幅は小さくなり（Ｌｐ＋→Ｌ、２）、直流発光分Ｌ
ＤＣが大きくなる。このとき第４図に示す従来例では光
出力の平均値が動いていないため光出力不良のアラーム
信号１４ｂは出力されないが、第１図に示す実施例では
第２図の直流発光分ＬＤｏに比例したモニタ信号１３の
直流値を監視しているため、光出力不良の検出が可能で
ある。For this reason, the optical output waveform 103 has an optical pulse amplitude of L during normal operation.
PI is large and the DC light emission is small, but when it deteriorates, the optical pulse amplitude becomes small (Lp+ → L, 2), and the DC light emission L
DC becomes larger. At this time, in the conventional example shown in FIG. 4, the average value of the optical output does not change, so the alarm signal 14b indicating a defective optical output is not output, but in the example shown in FIG. Since the DC value of the monitor signal 13 is monitored, it is possible to detect a defective optical output.
〔発明の効果〕
以上説明したように本発明は、従来のモニタ信号平均値
を監視する回路に加えてモニタ信号の直流値を監視する
回路を有することにより、従来の光出力平均レベル低下
に加えてレーザダイオードの微分量子効率劣化による光
出力不良の検出が可能であるという効果がある。[Effects of the Invention] As explained above, the present invention has a circuit that monitors the DC value of the monitor signal in addition to the conventional circuit that monitors the average value of the monitor signal. This has the advantage that it is possible to detect optical output defects due to deterioration of the differential quantum efficiency of the laser diode.
第１図は本発明の一実施例の回路図、第２図は本発明に
より検出可能となる光出力不良モードの例を説明するた
めの図、第３図は光送信回路の一般的な構成を示すブロ
ック図、第４図は従来のアラーム回路の一例の回路図で
ある。
■・・・・・・ＬＤモジュール、２・・・・・・ＬＤ駆
動回路、３・・・・・・ＡＰＣ回路、４・・・・・・ア
ラーム回路、２１゜２２・・・・・・演算増幅器、ＬＤ
・・・・・・レーザダイオード、ＰＤ・・・・・・ホト
ダイオード、Ｒ１・・・・・・抵抗、ＣＩ、Ｃ２・・・
・・・コンデンサ、Ｑｌ・・・・・・トランジスタ。FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a diagram for explaining an example of an optical output failure mode that can be detected by the present invention, and FIG. 3 is a general configuration of an optical transmitter circuit. FIG. 4 is a circuit diagram of an example of a conventional alarm circuit. ■...LD module, 2...LD drive circuit, 3...APC circuit, 4...alarm circuit, 21°22... operational amplifier, LD
...Laser diode, PD...Photodiode, R1...Resistance, CI, C2...
...Capacitor, Ql...Transistor.
Claims (1)
力モニタ電流の平均値を監視する回路と、前記光出力モ
ニタ電流の直流分を監視する回路とを備えることを特徴
とするアラーム回路。An alarm circuit comprising: a circuit that monitors an average value of an optical output monitor current output from an optical transmitter circuit using a laser diode; and a circuit that monitors a DC component of the optical output monitor current.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31919589A JPH03179789A (en) | 1989-12-07 | 1989-12-07 | Alarm circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31919589A JPH03179789A (en) | 1989-12-07 | 1989-12-07 | Alarm circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH03179789A true JPH03179789A (en) | 1991-08-05 |
Family
ID=18107475
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31919589A Pending JPH03179789A (en) | 1989-12-07 | 1989-12-07 | Alarm circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03179789A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0756363A2 (en) * | 1995-07-28 | 1997-01-29 | AT&T Corp. | Method and apparatus for monitoring performance of a laser transmitter |
| JP2011009787A (en) * | 2003-01-10 | 2011-01-13 | Avago Technologies Fiber Ip (Singapore) Pte Ltd | Calibration of laser system |
-
1989
- 1989-12-07 JP JP31919589A patent/JPH03179789A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0756363A2 (en) * | 1995-07-28 | 1997-01-29 | AT&T Corp. | Method and apparatus for monitoring performance of a laser transmitter |
| EP0756363A3 (en) * | 1995-07-28 | 1997-11-19 | AT&T Corp. | Method and apparatus for monitoring performance of a laser transmitter |
| JP2011009787A (en) * | 2003-01-10 | 2011-01-13 | Avago Technologies Fiber Ip (Singapore) Pte Ltd | Calibration of laser system |
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