JPH11237651A - Optical path switching monitoring system and monitoring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely monitor an optical path switching operation for signal light without exerting any influence on the signal light. SOLUTION: An optical switch 101 is provided so as to perform the optical path switchings of signal light and of monitoring light at the same time, and a monitoring optical receiver 104 detects whether or not the monitoring light is outputted. A switch control and monitoring part 106 monitors a monitor light detection signal to monitor an optical path switching operation for the signal light by the optical switch 101.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical communication system, and more particularly, to a method and system for monitoring optical path switching.

[0002]

2. Description of the Related Art In recent years, a wavelength division multiplexing (WDM) transmission system for directly amplifying a wavelength division multiplexed (WDM) transmission light by widening an optical fiber amplifier and extending a transmission distance by linear relay has been actively researched and developed. In particular, the optical add / drop (ADD) required to construct a flexible network
/ DROP) technology is attracting attention, and various optical ADMs
(Add / Drop Multiplexer) system has been proposed.

Generally, an optical ADM system has a configuration in which an optical switch for outputting an input optical signal of a predetermined wavelength as it is or for branching and inserting a new optical signal of the same wavelength is provided for each wavelength. Have. Accordingly, since the wavelength of the output signal light is the same as the wavelength of the input light irrespective of ON / OFF of the optical switch for performing the optical add / drop, it is determined whether or not these optical switches are operating properly. It is difficult to do so, and therefore, monitoring of the optical switch is regarded as important.

As an example of a monitoring system for an optical matrix switch, Japanese Patent Application Laid-Open No. 64-59220 discloses an optical space division matrix switch having a fault monitoring function. According to this conventional example, the monitoring light is branched into two, and one is used as the reference light, and the other is output from the monitoring output terminal through the entire optical space division matrix switch. Then, a failure or the like in the matrix switch is monitored by comparing the monitoring output light with the reference light.

[0005]

However, the above conventional monitoring method attempts to detect a failure by flowing monitoring light through the entire space division matrix switch, and the signal light is actually correctly switched by each optical switch. It is not intended to identify whether they have been As mentioned above,
In the optical ADM system, the wavelength of the input / output light is the same regardless of whether ADD / DROP is performed or not.
It is extremely difficult to determine whether each optical switch has been normally switched.

It is an object of the present invention to provide a monitoring system and a monitoring method capable of reliably monitoring an optical path switching operation of signal light.

Another object of the present invention is to provide a monitoring system and method capable of monitoring the optical path of signal light with high reliability without affecting the signal light in the optical ADM.

[0008]

An optical path switching monitoring system according to the present invention includes first optical path switching means for switching the optical path of signal light, and switching of the monitoring light optical path in synchronization with the first optical path switching means. It is characterized by comprising a second optical path switching means, and a monitoring means for monitoring the optical path switching operation of the signal light by detecting the monitoring light output from the second optical path switching means.

Since the switching of the optical path of the signal light can be monitored by the switching of the optical path of the monitoring light, the switching of the optical path of the signal light can be reliably monitored without affecting the signal light.

[0010]

FIG. 1 is a schematic block diagram showing one embodiment of an optical switch monitoring system according to the present invention. The optical switch 101 has four input ports and four output ports, and is set to one of an OFF state (normal state) and an ON state according to a switch control signal. As described later, when in the OFF state, the input ports 1 and 4 are optically connected to the output ports 1 and 4, respectively, the input port 2 is optically connected to the output port 3, and the input port 3 is optically connected to the output port 2, respectively. Is done. On the other hand, in the ON state, the input port 1 is optically connected to the output port 4 and the input port 4 is optically connected to the output port 1, respectively.
Are optically connected to output ports 2 and 3, respectively.

The input port 1 of the optical switch 101 receives an input optical signal of a predetermined wavelength λ 1, the input port 3 receives monitoring light from a monitoring light source 102, and the input port 4 receives an optical transmitter 103. , An input optical signal of wavelength λ1 is input. On the other hand, from the output port 1 of the optical switch 101,
Either the input optical signal or the add optical signal from the optical transmitter 103 is output. Output port 2 has monitoring optical receiver 1
04 is connected, and the optical receiver 105 is connected to the output port 4. Here, the input port 2 and the output port 3 of the optical switch 101 are not used.

The switching operation of the optical switch 101 is performed according to a switch control signal from the switch control / monitoring unit 106. The switch control / monitoring unit 106 further checks whether the switching of the optical switch 101 has been performed normally or not. The determination is made by monitoring the output signal of the receiver 104.

In a normal state in which the optical add / drop operation is not performed, the optical switch 101 is set to the OFF state, the input optical signal is transferred as it is as the output optical signal, and the monitoring light is input to the monitoring optical receiver 104 at the same time. When performing optical dropping / addition, after setting the optical switch 101 to the ON state, the station 107 inputs a drop signal from the optical receiver 105 and outputs a new insertion signal to the optical transmitter 103. Hereinafter, the operation of the present embodiment will be described in detail.

FIG. 2 is a diagram schematically showing the connection state of the optical switch 101. FIG.
(B) shows the connection state at the time of ON state.

As shown in FIG. 2A, the optical switch 10
When 1 is in the OFF state, input ports 1 and 4 are optically connected to output ports 1 and 4, respectively, input port 2 is output port 3, and input port 3 is output port 2
Are optically connected to each other. Therefore, the input optical signal input to the input port 1 appears as it is at the output port 1 and is output.

The monitoring light source 1 input to the input port 3
The monitoring light from 02 appears at the output port 2 and enters the monitoring light receiver 104. If the monitoring optical receiver 104 outputs a voltage corresponding to the intensity of the incident light, the switch control / monitoring unit 106 monitors the output voltage of the monitoring optical receiver 104 so that the optical switch 101 operates normally. It is possible to know that it is in the OFF state. That is, switch control
When the monitoring unit 106 sets the optical switch 101 to the OFF state, if the output voltage of the monitoring optical receiver 104 at that time is a voltage level indicating the same OFF state, the optical switch 1
01 can determine that the optical path is normally set.

As shown in FIG. 2B, the optical switch 10
When 1 is ON, the input port 1 is optically connected to the output port 4, the input port 4 is optically connected to the output port 1, and the input ports 2 and 3 are optically connected to the output ports 2 and 3, respectively. You. Therefore, the input optical signal of wavelength λ1 input to the input port 1 appears at the output port 4,
Input to the optical receiver 105. That is, the input optical signal is converted into an electric signal by the optical
07. Conversely, the insertion signal from the station 107 is converted by the optical transmitter 103 into an optical signal of wavelength λ1, and is input to the input port 4 of the optical switch 101 as an insertion optical signal. This inserted optical signal appears at the output port 4 and is transmitted as an output signal.

At the same time, the input port 3 of the optical switch 101
Is not output port 2 but output port 3, no monitoring light is input to monitoring optical receiver 104. Accordingly, the output voltage of the monitoring optical receiver 104 decreases, and the switch control / monitoring unit 106
Can know that the optical switch 101 is in a normal ON state. That is, when the switch control / monitoring unit 106 switches the optical switch 101 to the ON state, if the output voltage of the monitoring optical receiver 104 at that time is the same voltage level indicating the ON state, the optical switch 101 normally operates. Can be determined to have been switched.

The wavelength of the monitoring light may be selected so as not to match the wavelength of the input optical signal. In particular, it is desirable to provide an optical band-pass filter at the input stage of the monitoring optical receiver 104 that allows only the wavelength band of the monitoring light to pass. Hereinafter, a more specific description will be given with reference to FIGS. 3 and 4.

FIG. 3 is a schematic diagram for explaining an optical path when the optical switch according to the present embodiment is in the OFF state. FIG. 4 is a schematic view illustrating an optical path when the optical switch according to the present embodiment is in the ON state. It is a schematic diagram for description.

First, as shown in FIGS. 3 and 4, one example of the optical switch 101 used in the present embodiment is composed of four 2 ×
The monitoring optical receiver 104 is configured using two optical matrix switches 201 to 204, and the monitoring optical receiver 104 is an optical bandpass filter 2
05 and an optical receiver 206.

In the optical switch 101, the upper input port of the optical matrix switch 201 is optically connected to the input port 1 of the optical switch 101, and the lower input port is optically connected to the input port 2 of the optical switch 101. Similarly, the upper input port of the optical matrix switch 202 is optically connected to the input port 3 of the optical switch 101, and the lower input port is optically connected to the input port 4 of the optical switch 101.

The upper input port of the optical matrix switch 203 is connected to the upper output port of the optical matrix switch 201, and the lower input port is connected to the optical matrix switch 202.
The upper input port of the optical matrix switch 204 is optically connected to the lower output port of the optical matrix switch 201, and the lower input port is optically connected to the lower output port of the optical matrix switch 202. ing.

The upper output port of the optical matrix switch 203 is optically connected to the output port 1 of the optical switch 101, and the lower output port is optically connected to the output port 2 of the optical switch 101. Similarly, the optical matrix switch 2
The upper output port of 04 is optically connected to the output port 3 of the optical switch 101, and the lower output port is optically connected to the output port 4 of the optical switch 101.

These 2 × 2 optical matrix switches 201
To 204 are set to the same connection state according to the switch control signal. More specifically, the optical switch 101 is turned off.
In the state, as shown in FIG. 3, each of the optical matrix switches 201 to 204 is in a bar state in which the upper input port and the upper output port, and the lower input port and the lower output port are optically connected. Thus, the input optical signal input to the input port 1 appears at the output port 1 through the optical matrix switches 201 and 203, and the monitoring light input to the input port 3 appears at the output port 2 through the optical matrix switches 202 and 203. The monitoring light output from the output port 2 is input to the optical receiver 206 through the optical bandpass filter 204, and is output to the switch control / monitoring unit 106 as a monitoring light detection signal having a high output voltage level.

On the other hand, when the optical switch 101 is ON, as shown in FIG.
Each of the 204 has a cross state in which the upper input port and the lower output port, and the lower input port and the upper output port are optically connected. This allows input port 1
Is input to the optical matrix switch 201.
And 204 appear as a branch optical signal at output port 4 and the add optical signal input to input port 4 appears at output port 1 through optical matrix switches 202 and 203.

Further, the monitoring light input to the input port 3 appears at the output port 3 through the optical matrix switches 202 and 204. Since no monitoring light is output from the output port 2, the amount of light input to the optical receiver 206 through the optical band-pass filter 204 is extremely small, and the switch control / monitoring unit 1 generates a low-voltage monitoring light detection signal.
06 is output. As described above, the switch control / monitoring unit 106 can reliably monitor the switching state of the optical switch 101 by detecting ON / OFF of the voltage level of the monitoring light detection signal.

FIG. 5 is a block diagram showing another embodiment of the monitoring system according to the present invention. Here, an example is shown in which the present invention is applied to an optical ADM in a WDM transmission system in which a plurality of wavelengths are multiplexed.

The optical fiber transmission line 301 is an optical demultiplexer 302
Multiplexed wavelengths (λ1
To λ5) are respectively connected to five corresponding input ports of the optical multiplexer 303 via five optical switches SW1 to SW5. The output port of the optical multiplexer 303 is connected to the optical fiber transmission line 305. Each of the optical switches SW1 to SW5 corresponds to the optical switch 101 described above and has a similar configuration and function.

Each of the input ports 1 of the optical switches SW1 to SW5 receives a demultiplexed input optical signal (one of the wavelengths λ1 to λ5), and an output optical signal of the same wavelength is output from each output port 1. The signals are output to the input ports of the optical multiplexer 303, respectively. Monitoring light is input from the optical path monitoring optical transmitter 305 to each of the input ports 3 of the optical switches SW1 to SW5. The wavelength of the monitoring light is selected so as not to match the wavelengths λ1 to λ5 of the signal light. Each input port 4 of the optical switches SW1 to SW5 has an insertion optical transmitter TADD1 to TAD.
D5 receives input optical signals of the corresponding wavelengths. Each of the insertion optical transmitters TADD1 to TADD5 corresponds to the optical transmitter 103, and further includes optical switches SW1 to SW
5 are provided at the output ports 2 of the optical path monitoring optical receivers RS1 to RS.
S5 are respectively connected. Optical receiver R for optical path monitoring
Each of S1 to RS5 corresponds to the monitoring optical receiver 104. Lastly, branch optical receivers RDROP1 to RDROP5 are connected to the output ports 2 of the optical switches SW1 to SW5, respectively. RDROP1 for branching optical receiver
To RDROP5 correspond to the optical receiver 105.

In such an optical ADM system, the switch control / monitoring unit 106 includes an optical path monitoring optical receiver RS1.
ON / OFF of the monitoring light detection signal input from RS5
By detecting the OFF state, it is possible to reliably determine whether the corresponding optical switch is in a normal switching state.

The same 1 as the pump light of the optical fiber amplifier is used.
If you use the monitoring light of 480nm or 980nm,
It is not necessary to newly provide the monitoring light source 102.

[0033]

As described above in detail, according to the present invention, since the optical path of the monitoring light is switched in synchronization with the switching of the optical path of the signal light, the signal light is detected by detecting the switching of the optical path of the monitoring light. Switching of the optical path of the signal light can be reliably monitored without affecting the optical path.

[0034]

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing one embodiment of an optical switch monitoring system according to the present invention.

2A is a schematic diagram illustrating a connection state when the optical switch 101 is OFF, and FIG. 2B is a schematic diagram illustrating a connection state when the optical switch 101 is ON.

FIG. 3 is an optical switch according to the embodiment;
It is a schematic diagram for demonstrating the optical path at the time of F state.

FIG. 4 is a schematic diagram illustrating an optical path when an optical switch according to the present embodiment is in an ON state.

FIG. 5 is a block diagram showing another embodiment of the monitoring system according to the present invention.

[Explanation of symbols]

 Reference Signs List 101 optical switch 102 monitoring light source 103 optical transmitter 104 monitoring optical receiver 105 optical receiver 106 switch control / monitoring unit 107 station 201 to 204 2 × 2 optical matrix switch 205 optical bandpass filter 206 optical receiver 301 optical fiber transmission Path 302 Optical demultiplexer 303 Optical multiplexer 304 Optical fiber transmission path 305 Optical path monitoring optical transmitter

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04Q 3/52 H04Q 11/04 L 11/04

Claims (13)

[Claims] 1. A system for monitoring optical path switching, comprising: first optical path switching means for switching an optical path of signal light; and second optical path switching for switching an optical path of monitoring light in synchronization with the first optical path switching means. Means for monitoring the optical path switching operation of the signal light by detecting the monitoring light output from the second optical path switching means. 2. The second optical path switching means has at least one input port and two output ports, and the monitoring light input to the input port is output from one of the output ports. The optical path switching monitoring system according to claim 1, wherein: 3. The optical path switching device according to claim 2, wherein said monitoring means comprises monitoring light detecting means optically connected to one predetermined output port of said second optical path switching means. Monitoring system. 4. A system for monitoring switching of an optical path in an optical add / drop circuit, comprising: a monitoring light generating unit configured to generate monitoring light; a first optical path switching unit configured to switch an optical path of signal light having a predetermined wavelength; A second optical path switching unit for inputting the monitoring light and switching the optical path, wherein the first and second optical path switching units perform an optical path switching operation simultaneously according to a control signal; and the second optical path switching. Monitoring light detection means for detecting the monitoring light output from the unit; and control means for monitoring an optical path switching operation of the signal light based on an output of the monitoring light detection means. Monitoring system. 5. The optical switch, comprising: an input port for inputting the monitoring light; and an input port for outputting the monitoring light to one of the input ports.
5. The optical path switching monitoring system according to claim 4, further comprising: two output ports, wherein the monitoring light detection unit is optically connected to one of the output ports. 6. The optical switch has two connection states of an optical branching / insertion ON state and an optical branching / insertion OFF state, and when the optical switch is in the optical branching / insertion ON state, the monitoring light is supplied to the output port. The optical path switching monitoring system according to claim 5, wherein the monitoring light is output to one of the output ports and the monitoring light is output to the other of the output ports when the optical branching / insertion is in the OFF state. 7. The control means further controls the optical switch, and compares the connection state of the optical switch with the connection state of the optical switch indicated by the output of the monitoring light detection means to thereby control the signal light. The optical path switching monitoring system according to claim 4, wherein an optical path switching operation is monitored. 8. The optical path switching monitoring system according to claim 4, wherein said optical switch comprises a plurality of 2 × 2 optical matrix switches. 9. A method for monitoring switching of an optical path of an optical switch, comprising: simultaneously switching an optical path of a signal light and an optical path of a monitoring light; and detecting the switching of the optical path of the monitoring light to perform an optical path switching operation of the signal light. Monitoring. An optical path switching monitoring method. 10. A method for monitoring switching of an optical path of an optical switch in an optical add / drop circuit, comprising the steps of: generating monitoring light; and simultaneously controlling an optical path of a signal light having a predetermined wavelength and an optical path of the monitoring light according to a control signal. Switching, and monitoring the optical path switching operation of the signal light by detecting the optical path switching of the monitoring light. 11. A system for monitoring optical path switching of an optical add / drop circuit in a wavelength division multiplexing transmission system, comprising: a monitoring light generating means for generating monitoring light; and a signal light corresponding to each of a plurality of multiplexed wavelengths. An optical demultiplexing unit that is provided corresponding to each of the plurality of wavelengths, and a first optical path switching unit that switches an optical path of a corresponding signal light, and a first optical path switching unit that inputs the monitoring light and switches the optical path. An optical switch comprising a second optical path switching unit, wherein the first and second optical path switching units simultaneously perform an optical path switching operation in accordance with a control signal; and a monitoring light for detecting the monitoring light output from the second optical path switching unit. An optical path switching monitoring system, comprising: detecting means; and control means for monitoring an optical path switching operation of the signal light based on an output of the monitoring light detecting means. 12. The optical switch has an input port for inputting the monitoring light, and two output ports to which the monitoring light is output, and the monitoring light detecting means is provided on one of the output ports. The optical path switching monitoring system according to claim 11, wherein the optical path is optically connected. 13. The optical switch has two connection states of an optical branching / insertion ON state and an optical branching / insertion OFF state. When the optical switch is in the optical branching / insertion ON state, the monitoring light is supplied to the output port. 13. The optical path switching monitoring system according to claim 12, wherein the monitoring light is output to one of the output ports and the monitoring light is output to the other of the output ports when the optical branching / insertion is in the OFF state.