JP2947161B2 - Optical connector disconnection detection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical connector disconnection detection circuit, and more particularly to a detection circuit for detecting an optical connector disconnection or an optical transmission line abnormality in an optical communication system.

[0002]

2. Description of the Related Art Hitherto, in an optical communication system, a high output power of a light source and an optical amplifier have been required for a long distance and a low distortion in an analog system. If the output light becomes high due to the high output of the light source or the optical amplifier, a high level of light may be emitted into the space when the connector is disconnected or the optical transmission path is disconnected. Etc. may occur.

For this reason, it is necessary to detect disconnection of the connector or the like at an early stage. As shown in FIG. 2, the level comparator 15 uses an optical transmission line (not shown) or an optical connector (not shown). Return light level 1 of return reflected light 114
By comparing 15 with the reference value 116, disconnection of the optical connector or the like is detected.

That is, an output light 111 in which an electric signal is converted into an optical signal by a light source or an optical fiber amplifier (hereinafter referred to as a light source) 11 or an output light 111 which is optically amplified.
Is split by the optical splitter 12, and one of the split optical outputs 112 is output to the optical transmission line side. The other optical output 113 is terminated at the non-reflection terminal 13.

In this case, if an optical transmission path disconnection or disconnection of the optical connector occurs on the optical transmission path side, the optical output 112 output to the optical transmission path side returns as reflected light due to the optical transmission path disconnection or disconnection of the optical connector. The light is input to the optical demultiplexer 12, and the optical demultiplexer 1
Demultiplexed at 2.

[0006] One return reflected light split by the optical splitter 12 returns to the light source 1, and the other return reflected light 114 is input to the return light level detector 14. Return light level detector 14
Detects the level of the return reflected light 114 and outputs the detected level as a return light level 115 to the level comparator 15.

[0007] The level comparator 15 has its return light level 11
5 is compared with a preset reference value 116, and a reference value 1
When it is detected that there is more than 16 return reflected lights, an optical connector disconnection signal 117 is output. The control unit (not shown) uses the optical connector disconnection signal 117 to cut off the output of the light source and shut down the optical fiber amplifier.

In the radio field, there is a method of monitoring the transmission power and monitoring the reflected power only at the time of transmission to prevent the antenna and the radio transmitter from being damaged. This method is disclosed in JP-A-5-136747.

[0009]

In the above-mentioned conventional optical communication system, the return light level of the return reflected light split by the optical splitter is compared with a predetermined reference value, and the return light level exceeding the reference value is returned. When detecting the presence of reflected light, the optical connector disconnection signal is output, but since the absolute value of the return light level of the return reflected light is used as the reference value, if the optical output rises, the optical transmission line Even if disconnection or disconnection of the optical connector does not occur, return reflected light increases, disconnection of the connector and the like are erroneously detected, and there is a possibility that the line is disconnected.

Further, when the optical output is reduced, the return reflected light is reduced even when the optical transmission path is broken or the optical connector is disconnected, so that it is possible to detect the optical transmission path disconnected or the optical connector being disconnected. Therefore, there is a risk that an accident or the like may occur due to the light output without shutting down the output of the light source or shutting down the optical fiber amplifier.

Further, in any of the above cases, even a slight change in the level of the output light may cause an erroneous detection such as disconnection of the optical transmission line or disconnection of the optical connector. Become.

Furthermore, in the radio field, there is a method of monitoring transmission power and monitoring reflected power only at the time of transmission. In this case as well, the absolute value of reflected power is used as a reference value, so that the output power is reduced. If it becomes stronger, there is a risk of erroneous detection.

An object of the present invention is to solve the above-mentioned problems and to provide an optical connector disconnection detection circuit capable of reliably detecting disconnection of an optical transmission line, disconnection of an optical connector, or the like irrespective of level fluctuation of output light. To provide.

[0014]

The optical connector detachment detecting circuit according to the present invention comprises: a branching means for branching an output light to be sent to an optical transmission line and a return reflected light from the optical transmission line with respect to the output light; The light increases and decreases in conjunction with a change in the optical output level of the output light branched by the branching means, and
By comparing a judgment value obtained by multiplying the output level by a preset ratio with a return light level of the return reflected light branched by the branching means, when the return light level exceeds the judgment value, an optical connector disconnection signal is output. Comparing means for outputting.

Another optical connector disconnection detecting circuit according to the present invention may further comprise, in addition to the above-described configuration, an optical output level detecting means for detecting an optical output level of the output light branched by the branching means; A return light level detecting means for detecting a return light level of the branched return reflected light.

Another optical connector disconnection detection circuit according to the present invention, in addition to the above configuration, further comprises a setting means for setting the judgment value by multiplying the light output level detected by the light output level detecting means by the ratio. I have it.

Still another optical connector detachment detection circuit according to the present invention, in the above-described configuration, wherein the output light is emitted light emitted from the light source to the optical transmission line.

In still another optical connector detachment detection circuit according to the present invention, in the above configuration, the output light is amplified light that is amplified by an optical amplifier and output to the optical transmission line.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the operation of the present invention will be described below.

An optical output level detector detects one level of the optical output to the optical transmission line branched by the optical demultiplexer, and multiplies the detected optical output level by a preset ratio to obtain an optical connector. While generating a departure determination value, the level of the return reflected light from the optical transmission path branched by the optical demultiplexer is detected by a return light level detector, and the detected return light level and the optical connector departure determination value are determined. Are compared by a comparator, and when the return light level exceeds the optical connector detachment determination value, an optical connector detachment signal is output.

As a result, when the optical output level fluctuates, the optical connector disconnection determination value also varies in conjunction with the variation of the optical output level. Therefore, regardless of the output light level variation, the optical transmission path disconnection or optical connector disconnection occurs. Etc. can be reliably detected.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. In the drawing, an optical connector disconnection detection circuit according to an embodiment of the present invention includes an optical splitter 2, an optical output level detector 3, a return optical level detector 4, a judgment value setting unit 5, a level comparator 6, and the like. It is composed of

An output light 10 in which an electric signal is converted into an optical signal by a light source or an optical fiber amplifier (hereinafter referred to as a light source) 1.
1 or the optically amplified output light 101 is split by the optical splitter 2, and one of the split optical outputs 102 is output to the optical transmission line (not shown).

The other optical output 103 split by the optical demultiplexer 2 is input to the optical output level detector 3, and the optical output level detector 3 detects the optical output level 105.
Light output level 105 detected by light output level detector 3
Is input to the judgment value setting unit 5 and is multiplied by the ratio set in advance by the judgment value setting unit 5 to determine the optical connector disconnection judgment value 107.
Is output to the level comparator 6. The determination value setting device 5 is configured so that the ratio can be freely set from outside.

On the other hand, the return reflected light from the optical transmission line enters the optical splitter 2 and is split by the optical splitter 2. One return reflected light split by the optical splitter 2 returns to the light source 1, and the other return reflected light 104 is input to the return light level detector 4. The return light level detector 4 detects the level of the return reflected light 104 and outputs the detected level to the level comparator 6 as a return light level 106.

The level comparator 6 compares the return light level 106 from the return light level detector 4 with the optical connector disconnection determination value 107 from the determination value setting device 5, and returns the return light exceeding the optical connector disconnection determination value 107. When the level 106 is detected, an optical connector disconnection signal 108 is output. The control unit (not shown) uses the optical connector disconnection signal 108 to shut off the output of the light source and shut down the optical fiber amplifier.

As described above, the optical output level 105 detected by the optical output level detector 3 from the optical output 103 demultiplexed by the optical demultiplexer 2 is multiplied by the ratio preset by the judgment value setting device 5. The level comparator 6 compares the optical connector disconnection determination value 107 with the return light level 106 detected by the return light level detector 4 from the return reflected light 104 split by the optical splitter 2, and returns the return light level 106. Is the optical connector detachment judgment value 10
By outputting the optical connector disconnection signal 108 when the value exceeds 7, it is possible to reliably detect disconnection of the optical transmission line, disconnection of the optical connector, and the like irrespective of the level fluctuation of the output light.

That is, even if the optical output 101 rises and the return reflected light increases even if the optical transmission path disconnection or the optical connector disconnection does not occur, the optical connector disconnection determination value 1
Since 07 changes in conjunction with the rise of the optical output 101, disconnection of the optical transmission path or disconnection of the optical connector can be reliably detected without erroneously detecting disconnection of the optical connector.

Further, even when the optical output is reduced and the return reflected light is reduced even if the optical transmission path is disconnected or the optical connector is disconnected, the optical connector disconnection determination value 107 is set to the optical output 1.
01, it is possible to reliably detect the disconnection of the optical transmission line, disconnection of the optical connector, etc. It is possible to avoid the danger of an accident or the like occurring.

[0030]

As described above, according to the present invention, the determination value obtained by multiplying the light output level of the branched output light by a preset ratio is compared with the return light level of the branched return reflected light. By outputting the optical connector disconnection signal when the return light level exceeds the judgment value, the disconnection of the optical transmission line or disconnection of the optical connector can be reliably detected irrespective of the level fluctuation of the output light. There is.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source or optical fiber amplifier 2 Optical demultiplexer 3 Optical output level detector 4 Return optical level detector 5 Judgment value setting device 6 Level comparator

Claims (5)

(57) [Claims] A splitter for splitting output light to be sent out to the optical transmission line and return reflected light from the optical transmission line with respect to the output light; and a light output level of the output light split by the splitter . Increase and decrease in conjunction with the change
A comparison value of the power level multiplied by a preset ratio is compared with a return light level of the return reflected light branched by the branching unit, and when the return light level exceeds the determination value, an optical connector disconnection signal is generated. An optical connector disconnection detection circuit, comprising: a comparing unit that outputs the signal. 2. A light output level detecting means for detecting an optical output level of the output light branched by the branching means, and a return light level detection for detecting a return light level of the return reflected light branched by the branching means. 2. The optical connector disconnection detection circuit according to claim 1, further comprising: 3. The optical connector disconnection detection circuit according to claim 2, further comprising setting means for setting the determination value by multiplying the light output level detected by the light output level detecting means by the ratio. 4. The optical connector detachment detection circuit according to claim 1, wherein the output light is light emitted from a light source to the optical transmission path. 5. The optical connector disconnection detection circuit according to claim 1, wherein the output light is amplified light which is amplified by an optical amplifier and output to the optical transmission line. .