JPS59181836A - Optical repeater - Google Patents

Abstract

PURPOSE:To improve the reliability as a monitoring signal by multiplexing an output light of an active and a spare semiconductor laser by a polarized plane optical multiplex circuit to extract the light as the monitoring signal. CONSTITUTION:The changeover of the operation of the active and the spare semiconductor lasers 305 and 306 is performed by switching driving circuits 301 and 302 driving respectively these semiconductor lasers by means of a changeover circuit 311. Further, the optical signal being an output of the semiconductor lasers 305 and 306 is multiplexed at the polarized plane optical multiplex circuits 314 and outputted from an output terminal 4. On the other hand, in monitoring the system, an optical shutter 501 is opened, the optical signal at the 2nd output terminal 316 of the polarized plane optical multiplex circuit reaches the 2nd optical receiving section 6, is transmitted to a device being a downstream on an outgoing line and supervised.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical repeater, and particularly to an optical repeater for an optical fiber transmission system having a failure monitoring function.

When a semiconductor laser is used as a light source in an optical fiber transmission system, the lifespan of the semiconductor laser is generally the shortest among the devices used in this system.
System reliability is often determined by the semiconductor laser.

For this reason, in optical repeater equipment for submarine optical fiber transmission systems, which are particularly difficult to maintain, it has traditionally been the case that the system is equipped with a spare semiconductor laser in order to improve the reliability of the entire system. It is considered. Conventional failure monitoring methods for optical repeaters equipped with standby semiconductor lasers include: ■ Using an optical switch to switch the output light from the working and standby semiconductor lasers into a multi-line transmission optical signal; In the Showa era, a method was proposed in which part of the backside light of the laser was received by an optical fiber, and the output light from this optical fiber was passed through an optical shutter and then guided to a lower multi-line photodetector to generate a monitoring signal. 1981 published by the Institute of Electronics and Communication Engineers, published by the Institute of Electronics and Communication Engineers on March 5, 1958] Separate volume 4 of the lecture papers from the 1958 General National Conference of the Institute of Electronics and Communication Engineers. No. 2229, Mr. Nishimoto, and other papers, 3001VIb/s Optical Submarine Device, describe the following. In addition, ■The output lights of the working and standby semiconductor lasers are multiplexed using a polarization plane optical multiplexing circuit to create the top 9 transmission optical signal, and the monitoring signal is sent from the optical receiver of the top multiline to the electric switch. A method has been proposed in which the signal is guided to the input end of the downlink optical transmitter. In these conventional methods, a part of the center surface of the semi-integrated laser is used as a monitoring signal, but a semiconductor is used for the back surface signal. Since it does not include characteristics such as changes over time, the back side original signal has a similarity with the transmitted nine bonds, so there is a drawback that the reliability of fault 1 monitoring is low, and the optical switch is an active element, so the optical switch The drawback was that there was a problem with reliability.

In addition, in ■, since the monitoring signal is looped back at the electric circuit part, a flat electric signal flows through the electric switch for replacing ψ, so the electric signal waveform in this part is likely to deteriorate. However, since the minimum possible interval for each monitoring pupil is a combination of a 2-care 5-ton optical repeater and one section of optical transmission line, it is difficult to identify the failure point.The purpose of this invention is to solve the above-mentioned drawbacks. An object of the present invention is to provide an optical repeater for an optical fiber transmission system that is improved.

The optical repeater of the present invention includes a first optical receiver and a first optical transmitter for the upper line, and a second optical receiver and a second optical transmitter for the lower multiline, Above 1. The second optical transmitter is provided with a pair of working and standby semiconductor lasers, and the output light from these working and standby semiconductor lasers is transmitted to the first and second light transmitters.
In the optical repeater which multiplexes the multiplexed light with a second polarization plane optical multiplexing circuit and sends out the multiplexed light to the first optical output terminals connected to the optical transmission lines of the upper multi-line and the downlink, respectively, the first. Each of the second polarization plane optical multiplexing circuits is provided with a second optical output terminal, and the output light from these second optical output terminals is transmitted to the first... After passing through the second optical shutter, the signal is inputted to the second optical receiving section and the first optical receiving section.

In the optical repeater of the present invention, the output light No. 16 of the active and standby semiconductor lasers is multiplexed by a polarization plane optical multiplexing circuit by driving the driving circuit. An optical signal similar to the optical signal sent out from the first optical output terminal is output from the second optical output terminal of the 1ji6 v-plane Moto East circuit. If you do not want to monitor the system, please refer to the first option. The second light shutter is closed and the first
．． The optical signals output from the second optical output terminal of the second polarization plane optical multiplexing circuit do not reach the second optical receiver or the first optical receiver, respectively. On the other hand, when monitoring the system, for example, the first optical shutter is opened and the optical signal output from the second optical output terminal of the first polarization plane optical multiplexing circuit is sent to the second optical receiver. reach In this case, no signal light is sent from the upstream device on the downlink, and other optical shutters are closed. Therefore, the monitoring signal sent from the upstream device of the upper multi-line passes through the first polarization plane optical multiplexing circuit, the first optical shutter, and the second optical receiver, and is sent to the lower nine by the second optical transmitter. The signal is sent to the equipment downstream of the line, that is, the equipment upstream of the upper line, and is monitored. Similarly, a monitoring signal is sent from the upstream device of the lower multiline, and is reflected back by the second optical output terminal of the second polarization plane optical multiplexing circuit, the second original shutter, and the first optical receiver. If you return it to the device downstream of the upper line,
It is possible to monitor whether the optical repeater is out of order.

In the optical repeater of this invention, the output lights of the active and standby semiconductor lasers are multiplexed using a polarization plane optical multiplexing circuit, which is a passive device, so it is more reliable than when using an active device, which is an original switch. . 1. The monitoring signal is obtained as an optical signal output from the second optical output terminal of the polarization optical multiplexing circuit, that is, as a polarization multiplexed optical signal, so it is similar to the optical signal sent to the optical transmission line. It is. Therefore, the reliability of the monitoring signal is higher than that in the case where the backside lights of the active and spare semiconductor lasers are used as the monitoring signal. Since the original shutter simply opens and closes light and does not handle high-speed electrical signals, masculinization of the signal waveform does not occur.

Unfortunately, the minimum section that can be monitored and identified is one optical repeater or the optical transmission line of section i1, so it is easy to identify the fault location.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a preferred embodiment of the present invention. The optical signal output from the first optical transmission line 1 is
The bit rate is 430 Mb/s, the wavelength is 13 μm, and the first optical receiver 2 performs photoelectric conversion and amplification.

Timing extraction, @=chemical fiber identification and reproduction reception, and sent to the first optical transmitter 3. The light receiving section 2 with a ratio of 1 includes a first photodetector 201. First preamplifier circuit 202゜first AG
C amplifier circuit 203. First equalization circuit 204, first timing extraction circuit 205. First identification circuit 206. It is composed of a first AGC control circuit 207. Ge-APD was used for the first photodetector 201. First reception 1
The operation of the receiver 2 is similar to that of a conventional optical receiver. The first optical transmitter 3 transmits the signal from the first optical receiver 2 to the first optical transmitter 3. control circuits 301 and 302 of control circuit 2. The first and second control circuits 301 and 302 are sent. 1st. The output signals of the second control circuits 301 and 302 are the first and second control circuits, respectively.
drive circuits 303 and 304, respectively. The second semiconductor lasers 305 and 306 are driven. The first semiconductor laser 305 works as a working device, and the average power of its back surface light is detected by the first monitor photodetector 307, and the average power of the output signal of the first control circuit 301 and the first comparison circuit are detected. 308, the DC bias current applied to the first semiconductor laser 305 is compared with the first semiconductor laser 305 so that the peak value of the original pulse output from the first semiconductor laser 305 is constant.
It is controlled by a drive circuit 303.

The second semiconductor laser 306 works as a backup, and similarly to the first semiconductor laser 305, the average power of its back surface light is detected by a second monitor photodetector 309, and the output signal of the second control circuit 302 is detected by the second monitor photodetector 309. The average value of and the second comparison circuit 31
0, and the DC bias current applied to the second half-integrated laser 306 is controlled in the second drive circuit 304. In the switching control circuit 311, first, the first control circuit 3
A signal is output from 01, and a signal is output from the second control circuit 302, thereby causing the first semiconductor laser 305, which is currently in use, to oscillate, and the second semiconductor laser 306, which is a backup, to oscillate. will not be excavated. When the first semiconductor laser 305 deteriorates, the DC bias current required to obtain a predetermined optical output variation increases. When the value of the DC bias of the first semiconductor laser 305 becomes larger than the fixed value indicating the life of the first semiconductor laser 305, the switching control circuit 311 is activated and a signal is sent from the control circuit 302 of the first semiconductor laser 305. is output, and the first control circuit 301 switches so that no signal is output.By this switching, the first semiconductor laser 305 stops oscillating, and the second semiconductor laser 306 starts oscillating. The first semiconductor laser 305 in use is replaced by the second semiconductor laser 306 in reserve.
The operation is switched to 1st. Second semiconductor laser 3
1,306 output optical signals respectively. The light is input to the second Chisaka plane-preserving fibers 312 and 313, and polarization multiplexed by the polarization plane optical multiplexing circuit 314. In the polarization plane optical multi-plate circuit 314, about 9596 of the polarization multiplexed optical power is sent to the first optical fiber 315 which is the optical output terminal of Ml, and the remaining about 596 is sent to the second optical output terminal. It is input to a second optical fiber 316 which is . The first optical fiber 315 is a single mode fiber with a core diameter of 10 μm, a primary fiber outer diameter of 125 μnt, and a cutoff wavelength of 115 μm, and its output end is used for multiple lines. It is connected to a single mode optical fiber cable, which is the second optical transmission line 4. The second optical fiber 316 connects the first optical shutter 501 of the first optical controller 5
9, and the output light of this first optical shutter 501 is guided by a third optical fiber 503 to a second photodetector 601 of a second optical receiver 6 used for the lower multiline. I'm being chased. This second photodetector 601 is configured to also input an optical signal from the third optical transmission line 7 used for the lower multi-line. Second. third original fiber 316,
503 has a core diameter of 100 μm and an optical fiber outer diameter of 2
A stenop index type material with a diameter of 5 μm and N of 03 was used. The second optical receiver 6 has a structure similar to that of the first optical receiver 2, and the second
A signal is output from the identification circuit 606. The first light control circuit 502 of the first light control section 5 receives the output signal of the first light reception section 2 and opens the first light shutter 501;
1 '& do. That is, if the failure monitoring signal is not output from the first optical receiver 2, the first optical receiver control circuit 50
2 shows the first optical shutter 501 in detail, and the optical signal from the polarization plane optical multiplexing circuit 314 is not sent to the third optical fiber 503. Therefore, the optical signal from the third optical transmission line 7 is
When received by the optical receiver 6 of the third optical fiber 503
The quality of the optical signal from the source will not be degraded. On the other hand, when performing fault monitoring, the terminal station located upstream of the upper line transmits a fault monitoring signal, and the terminal station located upstream of the lower line stops sending signals. . No. 15 for fault monitoring connects the first optical transmission line l and the first 7 to the receiving unit 2.
, the first light control circuit 502 is operated, and the first light shutter 501 is opened.

In this case, the fault monitoring signal manually inputted to the second optical fiber 316 of the first optical transmitter 3 passes through the first optical shutter 501 and is detected by the second optical detector of the second pre-receiver 6. 601, and is looped back to the second pre-receiver 1g section 6, second light-speed receiver 8, and fourth optical transmission line 9, and is sent to the terminal station located downstream of the lower nine lines. They are sent to camp and monitored.

In this case, the fault monitoring signal uses a signal that does not cause any unspecified light control units other than the first light control unit 5, such as the second light control unit 10, to open the optical shack. Therefore, fault monitoring can be performed without error. If such fault monitoring is performed for each optical repeater and the fault monitoring signal is transmitted from both the upper 9 lines and the downlink side, it will be possible to determine which optical repeater is the faulty location or which optical It can be determined whether it is a transmission line or not. Note that the second optical transmitter 8 operates in the same manner as the first optical transmitter 3 with a 1 mJ configuration, and is the first optical output terminal of the second polarization plane optical multiplexing circuit 814. Fourth
The optical fiber 815 is connected to the third optical transmission line 9, and the fifth optical fiber 816, which is the second optical output terminal, is connected to the second optical shirt 7101. The output signal of the second optical receiver 6 is transmitted to the third optical receiver 8 of the 20th optical transmitter 11. Fourth control circuit 80
1.802 and the second light weight 1'' is sent to the second light control circuit 102 of the onion l510. The second light control section 0 has the configuration of the first light control section 5 and Mr.
The signal for opening the second optical control circuit 10275E is different from the first optical signal μ5.

The optical signal output from the second optical shutter 101 is configured to be input to the first photodetector 201 of the first optical receiver 2 through the sixth optical finer (103).

FIG. 2 is a sectional view showing the configuration of the first polarization plane optical multiplexer A (circuit 314) used in the above embodiment, and the second polarization plane optical multiplexer circuit 8.
14 also has a similar configuration. The output optical beams of the 1st and 2nd polarization preserving fibers/<312, 313 are @1, respectively.
．． It is converted into a parallel light beam by the second focusing rod 31 and 318, and enters the polarizing filter 324 at an angle of about 45 degrees.

The polarizing filter 324 is installed at lff1 between the first right-angled nosm 321 and the parallelogram glass block 323. 1st IIM Board Preservation File/<312
The output light of is linearly polarized light with a polarization Uii perpendicular to the plane of the paper in FIG. Both output lights are reflected and transmitted through a polarizing filter 324, respectively, and multiplexed. The multiplexed light enters the semi-transparent film 325 disposed between the glass block 323 and the second one-piece nosm, and about 95% of the optical power is transmitted, while about p% of the 'ND' Light reflects. The original beam reflected from the semi-transparent film 325 is focused by the third focusing rod lens 319 and input to the second optical fiber (316).On the other hand, the light beam transmitted through the semi-transparent film 325 is focused by the third focusing rod lens 319. The light is focused by the four converging rod lenses 320, and the light is transmitted to the first optical fiber 31
5 is entered.

Note that in the above embodiment, the first. Second light detection upper tongue 201
．． Crab using G e -A P D in 601, InG
Other types of photodetectors such as aAs-APD, InGaAs-PD, etc. may also be used. Also, 1st. Second semiconductor layer 8305.306 and first polarization plane optical multiplexing circuit 31
4 means 1st. Second polarization maintaining fiber 312, 313
However, the first connection was made without first connecting the fiber. The second semiconductor lasers 305 and 306 may be directly connected to the polarization plane optical multiplexing circuit. Also, 1st. Second polarization plane optical multiplexing circuit 3
14,814 used the configuration shown in Figure 2, but as long as there are two optical output terminals for polarization multiplexed optical signals, other configurations, such as the one shown in Figure 3, may be used. But that's fine.

Still, the first one. The second optical shutters 501 and 101 may be provided with level adjustment means for fully adjusting the level of the output light from the third optical fiber 503 and the level of the output light from the sixth optical fiber 103.

[Brief explanation of the drawing]

Figure 1 is a fruit of the present invention! A block diagram showing the configuration of Example i, and FIGS. 2 and 3 are cross-sectional views showing the configuration of the polarization plane optical multiplexing circuit used in this embodiment. 1.4, 7.9... Optical transmission line, 2, 6... Optical receiving section, 3.8... Optical transmitting section, 5, 10... Preemptive wholesale section,
201゜601... Photodetector, 202... Preamplifier circuit, 2o3-*cc amplification circuit, 204... Equalization circuit, 205... Timing extraction circuit, 206, 606
...Identification circuit, 207...A cx c ■++ control circuit, 301, 302. 801.802--control circuit, 303,304...
Drive circuit, 305, 306.805.806... Semiconductor laser, 307° 309... Monitor source detector, 3
08,310... Comparison circuit, 312. '313,81
2,813...Polarization maintaining fiber, 311...Switching control circuit, 314,814...Polarization plane optical multiplexing circuit, 3
15,316,503,815,816°103...
・Optical fiber, 501, 101... Former shutter, 50
2.102...Light control circuit. 18,2, a1. l□42.2.48, ,('ゝ＼-
' Figure 2 3/6 3rd port

Claims (1)

[Claims] The first optical receiving section and the first optical transmitting section are provided for the upper line, and the second optical receiving section and the second optical transmitting section are for the lower line. Each of the second optical transmitters is equipped with a pair of working and standby semiconductor lasers, and output light from these working and standby semiconductor lasers is transmitted to the first and second light transmitters. In the optical repeater which multiplexes the multiplexed light using the second polarization plane optical multiplexing circuit and sends the multiplexed light to the optical output terminals connected to the optical transmission lines of the upper multiline and the downlink, respectively, the first. Each of the second polarization plane optical multiplex circuits is provided with a second optical output terminal, and the output light from these second optical output terminals is transmitted to the first and second polarization plane optical multiplex circuits, respectively. An optical repeater characterized in that the input is transmitted to a second optical receiver and a first optical receiver after passing through a second original shutter.