JP2003174417A - Optical relay system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the detecting precision of the failure of a laser diode for excitation. <P>SOLUTION: In an optical multiplexer/demultiplexer CPL<SB>1</SB>, the demultiplex rate of an excitation light 1 and the demultiplex rate of an excitation light 2 are respectively set so as to be asymmetrical (for example, 8:2 and 2:8). A detecting means (not indicated in a figure) judges that a laser diode LD<SB>1</SB>breaks down when the optical output decreasing quantity of an incoming optical transmission path is α, and judges that a laser diode LD<SB>2</SB>breaks down when the optical output decreasing quantity of an outgoing optical transmission path is α. Also, the above mentioned α is set as the specific value of the optical output decreasing quantity of each optical transmission path when the demultiplex rate of the excitation light 1 and the demultiplex rate of the excitation light 2 are respectively 8:2 and 2:8 which is larger than the optical output decreasing quantity when the demultiplex rate of the excitation light 1 and the demultiplex rate of the excitation light 2 is 1:1. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical repeater for relaying light transmitted by optical communication, and in particular,
The present invention relates to an optical repeater that detects a failure of a pumping laser diode from an output fluctuation of an optical signal.

[0002]

2. Description of the Related Art Recently, with the increase in the distance and capacity of optical communication, for example, a failure of a pumping laser diode of an optical repeater for relaying transmitted light is detected from a fluctuation in output of an optical signal. It is required to improve the monitoring characteristics of the entire optical transmission system including the optical repeater. However, the output accuracy of the optical repeater deteriorates as the optical communication becomes longer, and the current system has a problem that it becomes difficult to detect the pump LD failure due to the above-mentioned output fluctuation.

[0003]

As described above, in the optical repeater, the output accuracy of the optical signal deteriorates as the optical communication becomes longer, and in the existing system, the excitation due to the above-mentioned output fluctuation is caused. There is a problem in that it is difficult to detect a failure of the laser diode for use.

It is an object of the present invention to provide an optical repeater capable of improving the accuracy of detecting a failure of a pumping laser diode.

[0005]

In order to solve the above-mentioned problems, in the optical repeater of the present invention, a first optical transmission line having a first optical amplifying means for amplifying the transmitted light and the optical transmission line are provided. A second optical transmission line having a second optical amplifying means for amplifying the light, an excitation light source for outputting the excitation light, and an excitation light output from the excitation light source for the first excitation light and the second excitation light. Demultiplexing into excitation light, transmitting the first excitation light to the first optical amplification means,
Based on the optical multiplexing / demultiplexing means for transmitting the second pumping light to the second optical amplifying means, and the optical output reduction amount in the first optical transmission path and the second optical transmission path, each pumping In the optical repeater including a detector for detecting a failure of a light source, the optical multiplexer / demultiplexer has an asymmetric demultiplexing ratio m: n of the first pump light and the second pump light (m> n). n, m,
n is a positive number), and the detecting means detects a failure of the pumping light source based on the amount of decrease in the optical output of the first optical transmission line.

In the optical repeater of the present invention, the demultiplexing ratio of the first pumping light and the second pumping light is set to m: n (m: n) so that the first pumping light and the second pumping light The demultiplexing ratio of light is 1: 1
Than that, it is possible to increase the amount of decrease in the optical output of the first optical transmission line when the pump light source fails. Therefore, the optical repeater of the present invention can improve the accuracy of detecting a failure of the pumping light source.

Further, in another optical repeater of the present invention, a first optical transmission line having a first optical amplifying means for amplifying the transmitted light and a second optical amplification for amplifying the transmitted light. A second optical transmission line having a means, a plurality of pumping light sources for outputting pumping light, and pumping light output from each of the pumping light sources are demultiplexed into first pumping light and second pumping light, respectively. , At least one optical multiplexing / demultiplexing means for transmitting each of the first pumping lights to the first optical amplifying means and for transmitting each of the second pumping light to the second optical amplifying means, and the first Optical transmission line and the second
An optical repeater including a detection unit for detecting a failure of each of the pumping light sources based on the amount of decrease in optical output in the optical transmission line of the optical transmission line, at least one of the optical multiplexing / demultiplexing units. Is a demultiplexing ratio of the first pumping light and the second pumping light in each of the pumping light sources, the ratio being different for each of the pumping light sources, and the detector is configured to detect the first optical transmission line and the first optical transmission line. One of the pumping light sources, which pumping light source is out of order, is detected based on the amount of decrease in the optical output in the second optical transmission line.

In another optical repeater of the present invention, the demultiplexing ratio between the first pumping light and the second pumping light is changed for each pumping light. By doing so, the amount of output reduction in the transmission line can be made different for each pumping light source that fails, and the detecting means can determine which pumping light source has failed and the first optical transmission line and The determination can be made based on the output reduction amount in the second optical transmission line.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an optical repeater according to an embodiment of the present invention will be described in detail with reference to the drawings.

(First Embodiment) First, an optical repeater according to a first embodiment of the present invention will be described. FIG. 1 is a block diagram showing the configuration of the optical repeater of this embodiment. As shown in FIG. 1, the optical repeater of the present embodiment has upstream and downstream optical transmission lines that are first and second optical transmission lines, and two laser diodes L that are pumping light sources.
D ₁ and LD ₂ , two erbium-doped fiber (EDF) amplifiers EDF ₁ and EDF ₂ , wavelength division multiplexing optical couplers WDM ₁ and WDM _2, and an optical multiplexer / demultiplexer CPL ₁ .

In the optical repeater shown in FIG. 1, the pumping light output from the laser diodes LD ₁ and LD ₂ passes through the optical multiplexer / demultiplexer CPL ₁ and then wavelength division multiplexing optical couplers WDM ₁ and WD.
The optical signals in the upstream and downstream optical transmission lines are amplified by being injected from M ₂ into the EDF amplifiers EDF ₁ and EDF ₂ . The wavelength division multiplexing optical coupler WDM ₁ and the EDF amplifier EDF ₁ are amplifying means for amplifying the light transmitted through the upstream optical transmission line, and the wavelength division multiplexing optical couplers WDM ₂ and EDM ₁ are provided.
The DF amplifier EDF ₂ is an amplification unit that amplifies the light transmitted through the downstream optical transmission line.

The optical multiplexer / demultiplexer CPL ₁ demultiplexes the pumping light 1 sent from the laser diode LD ₁ into the pumping light 1a and the pumping light 1b which are the first or second pumping light, and the laser diode LD _The pumping light 2 sent from 2 is split into pumping light 2a and pumping light 2b. Excitation light 1a and excitation light 2
a is transmitted to the wavelength division multiplexing optical coupler WDM ₁ as pumping light for the upstream optical transmission line, and the pumping light 1b and the pumping light 2b are wavelength division multiplexing optical coupler WDM ₂ as the pumping light for the downstream optical transmission line. Be transmitted to. Therefore, the sum of the pumping lights contributing to the signal amplification for the upstream optical transmission line is the sum of the pumping light 1a and the pumping light 2a, and the sum of the pumping lights contributing to the signal amplification for the downstream optical transmission line is the pumping light 1b. It becomes the sum with the excitation light 2b.

Further, the optical repeater of this embodiment measures the amount of optical output signals in the upstream and downstream optical transmission lines, and based on the amount of decrease in those optical output signals, the laser diode L
Detection means (not shown) for detecting the failure of D ₁ and LD _2.
Is equipped with.

FIG. 2 is a graph showing the relationship between the demultiplexing ratio of the optical multiplexer / demultiplexer CPL ₁ in the optical repeater of this embodiment and the optical output reduction amounts of the upstream and downstream optical transmission lines. As shown in FIG. 2, when the demultiplexing ratio of the optical multiplexer / demultiplexer CPL ₁ is 5: 5, the sizes of the pumping light 1a and the pumping light 1b are the same, and when the laser diode LD ₁ fails. The amount of decrease in the optical output becomes equal. However, the optical multiplexer / demultiplexer CPL
The demultiplexing ratio of ₁ is set to, for example, 8: 2 and the excitation light 1
When the size of a is made larger than the size of the pumping light 1b, the amount of decrease in the optical output when the laser diode LD ₁ fails becomes larger in the upstream optical transmission line than in the downstream optical transmission line. The optical output reduction amount of the transmission line is larger than the optical output reduction amount of the upstream optical transmission line when the demultiplexing ratio of the optical multiplexer / demultiplexer CPL ₁ is 5: 5 (1: 1).

In the optical repeater of this embodiment, the demultiplexing ratio of the pumping light 1 in the optical multiplexer / demultiplexer CPL ₁ is not 1: 1 but asymmetrical (m: n, m> n, m, n is a positive number). ). As a result, the ratio between the excitation light 1a and the excitation light 1b becomes m: n. Further, in the optical repeater of the present embodiment, the demultiplexing ratio of the pumping light 2 in the optical multiplexer / demultiplexer CPL ₁ is set to n: m instead of 1: 1. Thereby, the excitation light 2a and the excitation light 2b
The ratio with is n: m.

In this state, the above-mentioned detecting means measures the optical output reduction amount of the upstream and downstream optical transmission lines. In the optical repeater of this embodiment, the pumping light 1 in the optical multiplexer / demultiplexer CPL ₁ is
Since the demultiplexing ratio of 1 is not a 1: 1 but asymmetrical (m: n), the size of the pumping light 1a that is the first pumping light is as follows when the demultiplexing ratio of the pumping light 1 is 5: 5. Is bigger than Therefore, the amount of decrease in the optical output of the upstream optical transmission line when the laser diode LD ₁ fails becomes larger than when the demultiplexing ratio of the pumping light 1 is 5: 5. Similarly, in the optical repeater of the present embodiment, since the demultiplexing ratio of the pumping light 2 in the optical multiplexer / demultiplexer CPL ₁ is not 1: 1 but asymmetric (n: m), the size of the pumping light 2b is , And is larger than when the demultiplexing ratio of the excitation light 2 is 5: 5. Therefore, the amount of decrease in the optical output of the downstream optical transmission line when the laser diode LD ₂ fails becomes larger than when the demultiplexing ratio of the pumping light 2 is 5: 5.

From the above, in the optical repeater of this embodiment, the amount of decrease in the optical output when the laser diode fails can be made larger than when the demultiplexing ratio of the pumping light is set to 1: 1. It is possible to increase the detection sensitivity of the laser diode failure.

Further, the detecting means compares the optical output reduction amount of the upstream optical transmission line with the optical output reduction amount of the downstream optical transmission line, and when the optical output reduction amount of the upstream optical transmission line is larger, It is possible to determine that the laser diode LD ₁ has failed, and if the amount of decrease in the optical output of the downstream optical transmission line is larger, it can be determined that the laser diode LD ₂ has failed.

For example, in the optical repeater of this embodiment, the demultiplexing ratio of the pumping light 1 in the optical multiplexer / demultiplexer CPL ₁ is 8: 2, and the demultiplexing ratio of the pumping light 2 is 2: 8. Then,
As shown in FIG. 2, a laser diode LD is caused by an obstacle.
_{When 1} fails, the amount of decrease in the optical output of the upstream optical transmission line is α
And the optical output of the downstream optical transmission line becomes β (α>
β). These α and β are eigenvalues of the light output reduction amount when the excitation light of the laser diode LD ₁ is cut off. In addition,
When the laser diode LD ₂ fails, the optical output reduction amount of the upstream optical transmission line becomes β and the optical output amount of the downstream optical transmission line becomes α (α> β). Therefore, in the optical repeater of the present embodiment, when the laser diode LD ₁ fails, the output reduction amount of the optical signal on the upstream optical transmission line becomes α.
From this, the detection means determines that the laser diode LD ₁ has failed. When the laser diode LD ₁ fails, the output reduction amount of the optical signal on the downstream optical transmission line becomes α. From this, the detection means determines that the laser diode LD ₂ has failed.

As described above, in the optical repeater of the present embodiment, which of the laser diodes LD ₁ and LD ₂ has a failure is determined from the comparison of the optical output reduction amounts of the upstream transmission line and the downstream transmission line. It is possible to detect what has been done.

(Second Embodiment) Next, an optical repeater according to a second embodiment of the present invention will be described. FIG. 3 is a block diagram showing the configuration of the optical repeater of this embodiment. As shown in FIG. 3, the optical repeater according to the present embodiment has a wavelength division multiplexing optical coupler WD with respect to the traveling direction of light in each optical transmission line.
The optical repeater of FIG. 1 differs from the optical repeater of FIG. 1 in that M ₁ and WDM ₂ are so-called front-position type optical repeaters arranged upstream of the EDF amplifiers EDF ₁ and EDF ₂ . Also in the optical repeater of this embodiment, the demultiplexing ratio of the pumping light 1 in the optical multiplexer / demultiplexer CPL ₁ is asymmetrical (m: n), and the demultiplexing ratio of the pumping light 2 in the optical multiplexer / demultiplexer CPL ₁ is asymmetrical ( n: m), the same effect as that of the optical repeater of the first embodiment can be obtained. Also, the present invention can be applied to a bidirectional pumping type optical repeater in which wavelength division multiplexing optical couplers WDM _{1 to} WDM ₄ are arranged before and after the EDF amplifiers EDF ₁ and EDF ₂ as shown in FIG. You can In this case, the demultiplexing ratio of only the optical multiplexer / demultiplexer CPL ₁ or only the optical multiplexer / demultiplexer CPL ₂ may be asymmetric, or the demultiplexing ratios of both the optical multiplexer / demultiplexers CPL ₁ and CPL ₂ may be asymmetrical. May be

(Third Embodiment) Next, an optical repeater according to a third embodiment of the present invention will be described. FIG. 5 is a block diagram showing the configuration of the optical repeater of this embodiment. As shown in FIG. 5, the optical repeater of the present embodiment has laser diodes LD ₃ and LD ₄ and optical multiplexers / demultiplexers CPL ₂ and CPL ₃
Is newly provided, which is different from the optical repeaters of the first and second embodiments. The optical multiplexer / demultiplexer CPL ₂ demultiplexes the pumping light output from the laser diode LD ₁ and the pumping light output from the laser diode LD ₃ with a predetermined demultiplexing ratio, and among the demultiplexed pumping light, One of the pump lights is multiplexed and output to the optical multiplexer / demultiplexer CPL ₁ . The optical multiplexer / demultiplexer CPL ₃ demultiplexes the pumping light output from the laser diode LD ₂ and the pumping light output from the laser diode LD ₄ with a predetermined demultiplexing ratio, and among the demultiplexed pumping light, One of the pump lights is multiplexed and output to the optical multiplexer / demultiplexer CPL ₁ . The optical multiplexer / demultiplexer CPL ₁ demultiplexes the excitation light output from the optical multiplexer / demultiplexer CPL ₂ and the excitation light output from the optical multiplexer / demultiplexer CPL ₃ at a predetermined demultiplexing ratio and demultiplexes them. Wavelength division multiplexing optical couplers WDM ₁ , WD
Transmit to M ₂ .

In the optical repeater of the present embodiment, some of the optical multiplexers / demultiplexers CPL _{1 to} CPL ₃ have different demultiplexing ratios of the input pumping light for each pumping light. Ratio. By doing so, the output reduction amount of the transmission line becomes different for each failed laser diode, so that the detection unit can easily determine which laser diode is defective from the output reduction amount. it can.

Similarly, in the forward-positioning type and bidirectional-positioning type optical repeaters shown in FIGS. 6 and 7, the optical multiplexing / demultiplexing means are also hierarchically connected, and FIGS. In the optical repeater connected in multiple stages than the optical repeater shown,
By making the demultiplexing ratios of some optical multiplexers / demultiplexers asymmetric, it is possible to identify a failed laser diode from the amount of output reduction.

[0025]

As described above, in the optical repeater of the present invention, the first pumping light and the second pumping light are made asymmetric by making the demultiplexing ratio of the first pumping light and the second pumping light asymmetric. The amount of reduction in the optical output of the first optical transmission line when the pumping light source fails can be made larger than when the demultiplexing ratio of the pumping light is set to 1: 1. Therefore, the optical repeater of the present invention can improve the accuracy of detecting a failure of the pumping light source.

Further, in the optical repeater of the present invention, when there are a plurality of pumping light sources, the demultiplexing ratio between the first pumping light and the second pumping light is changed for each pumping light source. By doing so, the amount of output reduction in the transmission line is different for each pumping light source that fails, so in the optical repeater of the present invention,
The detecting means can determine which pump light source is out of order on the basis of the amount of output reduction in the first optical transmission line and the second optical transmission line.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical repeater according to a first embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the demultiplexing ratio of the optical multiplexer / demultiplexer in the optical repeater according to the first embodiment of the present invention and the optical output reduction amount of the upstream and downstream optical transmission lines.

FIG. 3 is a block diagram showing a configuration of an optical repeater according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a bidirectional pumping type optical repeater according to a second embodiment of the present invention in which wavelength division multiplexing optical couplers are arranged before and after an EDF amplifier.

FIG. 5 is a block diagram showing a configuration of an optical repeater according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of an optical repeater of a front arrangement type according to a third embodiment of the present invention.

FIG. 7 is a block diagram showing the configuration of a bidirectional arrangement type optical repeater according to a third embodiment of the present invention.

[Explanation of symbols]

CPL _{1 to} CPL ₆ optical multiplexer / demultiplexer EDF _{1 to} EDF ₂ EDF amplifier LD _{1 to} LD ₈ laser diode WDM _{1 to} WDM ₄ wavelength division multiplexing optical coupler

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04B 10/17

Claims (6)

[Claims] 1. A first optical transmission line having a first optical amplifying means for amplifying transmitted light by pumping light, and a second optical amplifying means for amplifying transmitted light by pumping light. 2 optical transmission lines, a pumping light source that outputs pumping light, and pumping light that is input are demultiplexed into first pumping light and second pumping light, and the first pumping light is divided into the first pumping light and the first pumping light. Optical multiplexer / demultiplexer for transmitting the second pumping light to the second optical amplifier and transmitting the second pumping light to the second amplifier, and detecting the failure of each pumping light source based on the amount of decrease in the optical output of the optical transmission line. In the optical repeater, the optical multiplexing / demultiplexing means asymmetrically divides the demultiplexing ratio m: n between the first pumping light and the second pumping light (m> n, m, n). Is a positive number), and the detection means detects a failure of the pumping light source based on the amount of decrease in the optical output of the first optical transmission line. An optical repeater characterized by the above. 2. A first optical transmission line having a first optical amplifying means for amplifying the transmitted light by the pumping light, and a second optical amplifying means having a second optical amplifying means for amplifying the transmitted light by the pumping light. 2 optical transmission lines, a plurality of pumping light sources that output pumping light, and at least one optical demultiplexer that splits the input pumping light into first pumping light and second pumping light An optical repeater comprising: means, and a detection means for detecting a failure of each of the pumping light sources based on an amount of decrease in optical output in the first optical transmission path and the second optical transmission path. Among the optical multiplexing / demultiplexing means, some optical multiplexing / demultiplexing means
The demultiplexing ratio of the input pumping light is different for each of the pumping lights, and the detection means is based on the optical output reduction amount in the first optical transmission line and the second optical transmission line, An optical repeater which detects which pump light source is out of the pump light sources. 3. The optical repeater according to claim 2, wherein each of the optical multiplexing / demultiplexing means is hierarchically configured between the first amplifying means and the second amplifying means and each of the pumping light sources. apparatus. 4. The first and second optical amplifying means, wherein the wavelength division multiplexing optical coupler is a backward pumping type arranged behind the erbium-doped optical amplifying fiber. The optical repeater described. 5. The wavelength division multiplexing optical coupler in each of the first and second optical amplification means is a forward pump type arranged in front of an erbium-doped optical amplification fiber. The optical repeater described. 6. The bidirectional pumping type wherein the wavelength division multiplexing optical couplers are arranged in front of and behind the erbium-doped optical amplifying fiber in the first and second optical amplifying means, respectively. The optical repeater according to claim 1.