JP2674558B2 - Optical communication device - 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 communication device,
For example, the present invention relates to an optical communication device that outputs a high-output optical signal, which is used in a long-distance transmission system and an image distribution system.

[0002]

2. Description of the Related Art In order to construct a long distance transmission system or an image distribution system by an optical fiber communication system,
An optical communication device using an optical amplifier or the like that can output a laser beam of about 0 mW to 100 mW is required. Since laser light of such power is sufficient to damage the human body such as eyes and skin, when the connector of the optical fiber is disconnected or the optical fiber is broken, the end surface of the laser beam may damage the human body. It is desired to prevent laser light irradiation, and optical communication devices as described below have been developed.

FIG. 2 shows an outline of a conventional optical communication device having an optical output blocking function. The optical communication device shown in this figure is a so-called optical amplification repeater, and in this optical communication device, the signal light input from the optical connector 31 is EDF.
(Erbium-doped optical fiber) 11
It is output from the output end 32 via the optical branching circuit 13.

The gain in the EDF 11 is equal to the pump LD (LAS
(ER Diode) 14 is in accordance with the level of the pumping light output, and the pumping light is a wavelength division multiplexing coupler (WD).
M) 13 to the EDF 11. The optical branching circuit 13 branches the light from the EDF 11 side and outputs the branched light to the optical connector 32 and the light receiving element (PD: Photo Diode) 15, and the light input from the optical connector 32 side to the PD.
It is an optical circuit that outputs to the 16 side. The optical signal level detected by the PD 15 is notified to the automatic power control unit 20, and the optical signal level detected by the PD 16 is notified to the reflection alarm detection unit 17.

The automatic power control unit 20 is a control circuit for controlling the pump LD drive unit 21 so that the optical signal level notified from the PD 15 becomes a predetermined level. The pump LD drive unit 21 is an automatic power control unit. The excitation LD 14 is driven according to the control signal from 20.

[0006] PD16 and the connected reflected alarm detecting circuit 17, the level of the signal from PD16 is, when it becomes higher than a predetermined level to a predetermined, to the excitation LD drive section 21, a predetermined control signal It is a circuit that outputs,
The excitation LD drive unit 21 stops driving the excitation LD when detecting the control signal.

That is, in this optical communication device, when the optical fiber is disconnected or the optical fiber is cut at the right side of the optical branch circuit 13, the optical branch circuit 13 side is caused by Fresnel reflection at the end face. It is determined whether or not a failure has occurred by utilizing the fact that the level of the reflected light returning to (3) becomes high. When a failure occurs, high output light is prevented from being sent in that direction.

[0008]

As described above, in the conventional optical communication device, since a high-power signal light is not output to the outside when a failure occurs in the transmission line, the laser leaking from the failure point is present. It is possible to prevent the light from damaging the human body.

However, in the conventional optical communication apparatus, once the optical output is cut off, the optical output cutoff state is maintained. Therefore, in order to restart the service after the recovery of the failure, the optical amplification is performed. There is a problem in that it is necessary to go to the place where the relay device is installed and release the cutoff state (the reset instruction section 25 in FIG. 2 must be operated).

Therefore, an object of the present invention is to provide an optical circuit that automatically shuts off the output of signal light when a failure occurs in the transmission line and automatically releases the shutoff state when the failure is restored. To provide a communication device.

[0011]

Means for Solving the Problems The invention according to claim 1so
Is (a) Optical amplification that amplifies the input signal light and outputs it.
Means, and (b) the output end of this optical amplifying means and the signal light are transmitted.
Output from the optical amplification means provided between the optical transmission line
Optical signal transmission while supplying the signal light to the optical transmission line
The light input from the optical path is not
Direction optical circuit and (c) this optical circuit
Monitor the level of light output towardOptical transmission
Due to fiber breaks or disconnections in the roadPlace
First judging means for judging whether or not a constant level is exceeded
(D) This first determination means determines the level of light from the optical circuit.
When it is determined that the level exceeds the specified level,
Amplify the signal light by controlling the stagesFrom the state that is performed continuously
It is repeated in a short time and in a predetermined cycleTo the stateIts behavior
First control means for changing the state, and (e) this first control means
Amplification of signal light by optical amplification means for a short time
The optical circuit outputs in a predetermined direction when
Determine if the light level exceeds a certain level
Second judging means, and (f) this second judging means from the optical circuit
It was judged that the light level of did not exceed the predetermined level
At this time, the optical amplification means is controlled to continuously amplify the signal light.
The operating stateRecoveryThe second control means
For optical communication equipmentPreparationLet it.

That is, according to the first aspect of the invention, by adding the first determination means and the first control means to the optical communication device having the optical amplification means for amplifying and outputting the input signal light, the transmission is performed. When a failure occurs in the path, the operating state is changed from the state where the signal light is continuously amplified to the state where the signal light is repeated in a short period and in a predetermined cycle, and the level of the reflected light is synchronized with the cycle. By adding the second judging means for judging, it is possible to judge whether or not the failure is restored. Then, when the restoration is completed, the operation state of the device is
The optical communication device is configured so as to be restored to a state in which continuous amplification is performed (return to a normal operation state).

As the optical amplifying means, it is possible to use one using a rare earth-doped optical fiber such as an erbium-doped optical fiber. When a rare earth-doped optical fiber is used, the first control unit and the second control unit control the level of pumping light supplied to the rare earth-doped optical fiber to control whether or not amplification is performed. Any of the above can be used.

[0014] In the second aspect of the present invention, a signal beam generating means for generating a signal beam corresponding to information to be transmitted (b),
(B) The signal light output from the signal light generating means, which is provided between the output end of the signal light generating means and the optical transmission path through which the signal light is transmitted, is supplied to the optical transmission path and is transmitted. An optical circuit that outputs the light input from the optical amplifier in a predetermined direction different from the direction of the optical amplification means, and (c) The level of the light output by the optical circuit in the predetermined direction is monitored and the level is transmitted.
First determining means for determining whether or not a predetermined level is exceeded due to disconnection or disconnection of the optical fiber in the path ; A state in which signal light generation means is controlled to continuously generate signal light when it is determined that the light level exceeds a predetermined level.
A first control means for changing its operating state to a state in which the operation is repeated for a short period of time at a predetermined cycle, and (e) the signal light generation means causes the signal light to be generated for a short time by the control of the first control means. The second determining means determines whether or not the level of the light output from the optical circuit in the predetermined direction exceeds the predetermined level, and (f) the second determining means detects the light from the optical circuit. When it is determined that the level does not exceed a predetermined level, the signal light generating means is controlled to restore its operating state so that the signal light is continuously generated.
A control means is provided in the optical communication device .

That is, according to the second aspect of the invention, the first determining means and the first controlling means are added to the optical communication device having the signal light generating means for generating the signal light according to the information to be transmitted. When the failure occurs in the transmission line, the operating state is changed from the state where the signal light is continuously generated to the state where the signal light is repeated in a short period at a predetermined cycle.
And, second determining the level of the reflected light in synchronization with the cycle
By adding a judging means, it is possible to judge whether or not the failure is restored. When the recovery is completed, the second control means, operating state of the device, so the continuous generation of the signal light is restored <br/> in which is carried out by returning (to the normal operating state As such), an optical communication device is configured.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments.

FIG. 1 shows a schematic configuration of an optical communication apparatus according to an embodiment of the present invention. As shown in the figure, the optical communication device of the embodiment has EDF (erbium-doped optical fiber) 11 and wavelength division multiplexing coupler (WDM) 12 as main elements.
Optical branching circuit 13, pumping LD (LASER Diode) 14, light receiving elements (PD) 15, 16, reflection alarm detector 17, timing generator 18, reflection alarm pulse generator 19, automatic power controller 20, pumping LD drive And a part 21. In the figure, the optical isolator 33 provided in the front stage of the EDF 11 and the rear stage of the WDM 12 is an optical circuit for cutting the light from the opposite direction, and is a circuit not directly involved in the operation of the present invention. Therefore, the optical isolator 33 will be described here as being absent.

The optical communication device of the embodiment is an optical amplification repeater, and its normal operation is to amplify the signal light input from the optical connector 31 and output it from the optical connector 32.

Amplification of the signal light is performed by an EDF (erbium-doped optical fiber) 11. The amplification gain in the EDF 11 corresponds to the level of the pumping light output from the pumping LD (LASER Diode) 14, and the pumping light is
EDF 11 through wavelength division multiplexing coupler (WDM) 12
Is supplied to The optical branching circuit 13 branches the light from the EDF 11 side and outputs it to the optical connector 32 and the PD 15, and the light input from the optical connector 32 side to the PD.
Output to 16 side. Information output from the PD 15 according to the amplified optical signal level is notified to the automatic power control unit 20, and the automatic power control unit 20 drives the pump LD so that the signal level from the PD 15 becomes a predetermined level. Part 21
Output a control signal to the controller.

The reflection alarm detecting circuit 17, the level of the signal from PD16 is output when a predetermined level greater than or equal to a predetermined control signal for instructing the stop of the output of the excitation light to the excitation LD drive unit 21 To do. Then, after outputting the control signal, the mode shifts to a mode for monitoring the output level of the PD 16 in synchronization with the timing signal from the timing generator 18, and when the timing signal is input, the output level of the PD 16 is changed. When the level is below a predetermined level, a control signal for instructing continuous output of the pump light is pumped L
Output to the D drive unit 21.

The timing signal from the timing generation unit 18 is also supplied to the reflection alarm pulse generation unit 19, and the reflection alarm pulse generation unit 19 generates a short pulse signal in synchronization with the input timing signal, The generated short pulse signal is supplied to the excitation LD control unit 21.

The pumping LD driving section 21 is a control circuit for driving the pumping LD 14 to generate pumping light. In a normal state, the pumping light of the pumping LD 14 is generated in response to a control signal from the automatic power control section 20. Control the level. Also,
When a control signal instructing to stop the output of the excitation light is input from the reflection alarm detection unit 17, the drive of the excitation LD 14 is stopped and the excitation is performed according to the short pulse signal from the reflection alarm pulse generation unit 19. When the control signal for instructing the continuous output of the excitation light is input, the LD 14 is driven, and the pump LD 14 is continuously driven.

The pulse width of each short pulse signal generated by the reflection alarm pulse generator 19 is set so that the signal light output by the EDF 11 according to the pulse does not adversely affect the human body. It is set in an extremely short time with reference to the laser light safety standard.

In the optical communication apparatus of the embodiment configured as described above, when the optical fiber is disconnected or the optical fiber is cut at the right side of the optical branch circuit 13, FIG. 2 is used. Like the conventional optical communication device described above,
The transmission of the high-output signal light is stopped, and the adverse effect on the human body due to the leakage of the signal light is prevented.

After shutting off the optical output, the EDF 11 is
Since short-time supply of pumping light is periodically repeated, when the failure in the transmission line is not recovered, large reflected light is periodically input to the PD 16 that monitors the reflected light level. Therefore, the reflection alarm detection unit 17 continues to receive signals of a predetermined level or higher in synchronization with the timing signal from the timing generation unit 18. Therefore, the reflection alarm detection unit 17 does not supply a new control signal to the excitation LD drive unit 21, and the excitation LD drive unit 21 causes the excitation LD 14 to receive the short pulse from the reflection alarm pulse generation unit 19. Control will continue according to the signal.

When the failure is recovered, the PD is synchronized with the timing signal from the timing generator 18.
Since the level of the reflected light incident on 16 is lowered, the reflection alarm detection unit 17 recognizes that the failure has been repaired, and instructs the excitation LD drive unit 21 to continuously output the excitation light. The control signal is output so that continuous amplification is performed by the EDF 11 (that is, the normal operation state is restored).

As described above, in the optical communication apparatus of the embodiment, when the failure is restored, the normal operation state is automatically restored. Therefore, after the failure recovery is completed, the optical amplification repeater is installed. You can restart the service without having to go to the location where you are and remove the blocking status.

Modification

Although the optical communication device of the embodiment uses the erbium-doped optical fiber, it is needless to say that another rare earth-doped optical fiber may be used, and a semiconductor laser amplifier can also be used. Although the optical communication device according to the embodiment is configured to perform optical relay, the present technology may be applied to manufacture an optical transmitter. When manufacturing an optical transmitter, a light emitting source may be provided in front of the EDF to control the gain of the EDF as in the embodiment, and the light emitting source may be directly controlled without providing the EDF or the like. It may be configured to.

[0030]

As described above, according to the present invention,
When a failure occurs in the transmission line, the output of the signal light is automatically cut off, and when the failure is restored, the cutoff state is automatically released. The service can be restarted without going to the place where the service is installed and removing the blocking state, and the time required to restart the service can be shortened.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration of a conventional optical communication device.

[Explanation of Codes] 11 Erbium-doped Optical Fiber 12 WDM (Wavelength Division Multiplexer) 13 Optical Branch Circuit 14 Excitation LD (LASER Diode) 15, 16 Photodetector (PD) 17 Reflection Alarm Detection Circuit 18 Timing Generator 19 Reflection Alarm Pulse Generation unit 20 Automatic power control unit 21 Excitation LD drive unit 25 Reset instruction unit 31, 32 Optical connector 33 Optical isolator

Claims (4)

(57) [Claims] 1. An optical amplifying means for amplifying and outputting the input signal light, and the optical amplifying means provided between an output end of the optical amplifying means and an optical transmission path through which the signal light is sent out. An optical circuit that supplies the signal light output from the means to the optical transmission line and outputs the light input from the optical transmission line in a predetermined direction different from the optical amplification means direction; Monitor the level of light output to the optical fiber
Or a first judging means for judging whether or not a predetermined level is exceeded due to disconnection, and the first judging means judges that the level of light from the optical circuit exceeds the predetermined level. in a first control means for changing the operation state to a state where amplification of the optical amplification means to control the signal light is repeated in a short time and a predetermined period from the state carried out continuously, the first control means When the signal light is being amplified by the optical amplifying means for a short time by the control of, the optical circuit determines whether the level of the light output in the predetermined direction exceeds the predetermined level. When the second determining means determines that the level of the light from the optical circuit does not exceed a predetermined level, the second amplifying means is controlled to continuously amplify the signal light. Its operating state as Optical communication device characterized by comprising a second control means to recover. 2. A signal light generation means for generating signal light according to information to be transmitted, and an optical transmission line to which the signal light is sent and an output end of the signal light generation means. An optical circuit that supplies the signal light output from the signal light generation means to the optical transmission path and outputs the light input from the optical transmission path in a predetermined direction different from the optical amplification means direction, and this optical circuit The level of light output in the predetermined direction is monitored and the level is cut in the optical fiber in the optical transmission line.
Or a first judging means for judging whether or not a predetermined level is exceeded due to disconnection, and the first judging means judges that the level of light from the optical circuit exceeds the predetermined level. The signal light generating means is controlled to continuously generate the signal light .
From the first control means for changing its operating state to a state in which the operation is repeated in a short time and at a predetermined cycle, and the signal light generation means causes the signal light to be generated for a short time by the control of the first control means. At this time, second determining means for determining whether or not the level of the light output from the optical circuit in the predetermined direction exceeds a predetermined level, and the second determining means determines that the level of the light from the optical circuit is And a second control means for controlling the signal light generating means to restore the operating state so that the signal light is continuously generated when it is determined that the predetermined level is not exceeded. Optical communication device. 3. The optical communication device according to claim 1, wherein the optical amplification means uses a rare earth-doped optical fiber. 4. The first control means and the second control means are for controlling whether or not amplification by the optical amplification means is performed by controlling the level of the pumping light. Item 3. The optical communication device according to item 3.