JP2015115675A - Optical transmission system, optical transmission method, and optical transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption of an optical communication station in the case that a failure occurs in a transmission path; and automatically perform recovery from a low power consumption state to a normal state in the case of failure recovery while reducing the power consumption.SOLUTION: An optical transmission system includes: a first relay station; a second relay station connected to the first relay station; and a third relay station connected to the second relay station. The first relay station is connected to a terminal station or a fourth relay station. When a transmission path failure occurs on a first transmission path connecting the first relay station to the terminal station or the fourth relay station, the first relay station transmits an optical signal to the second relay station. When detecting the optical signal, the second relay station transmits an optical signal to the third relay station. When receiving the optical signal from the second relay station, the third relay station stops an excitation light source of an optical amplifier for amplifying an optical signal for the second relay station.

Description

  The present invention relates to a power saving method for an optical transmission system.

  When optical transmission is performed between a plurality of optical communication stations on a bidirectional optical transmission path, it is determined whether or not the input signal optical power to the optical amplifying means in the optical communication station is within a predetermined set value range. If out of the set value range, output change instruction information is sent to the optical communication station in the opposite direction to the optical transmission direction, and the pumping optical power supplied to the optical amplifying means of the optical communication station in the opposite direction is adjusted. Patent Document 1 discloses that the output signal optical power of the optical communication station in the opposite direction is adjusted.

JP 2003-69501 A

  In Patent Document 1, when a plurality of optical communication stations are connected in series to form an optical transmission line, the first optical communication station is connected to the preceding stage of the own apparatus adjacent to the own apparatus. The optical signal of the second optical communication station can be controlled, but the optical signal of the third optical communication station connected adjacent to the own apparatus upstream of the second optical communication station cannot be controlled. Therefore, when the technique described in Patent Document 1 is used, if a transmission path failure occurs in the transmission path subsequent to the first communication station, the first optical communication station is connected to the preceding stage of the first optical communication station. Although the transmission optical signal of the second optical communication station can be reduced, the transmission optical signal of the third optical communication station connected to the preceding stage of the second optical communication station cannot be reduced. Therefore, the third optical communication station continues to transmit an optical signal toward the subsequent transmission path, although a transmission path failure has occurred in the subsequent transmission path. In addition, when the technique disclosed in Patent Document 1 is used, the first optical communication station continues to transmit an optical signal toward the subsequent transmission path although a transmission path failure has occurred in the subsequent transmission path. . Therefore, the optical communication station wastes power. Accordingly, an object of the present invention is to reduce the power consumption of an optical communication station when a transmission path failure occurs. Another object of the present invention is to automatically recover from a low power consumption state to a normal state at the time of failure recovery while reducing power consumption.

An optical transmission system including a first relay station, a second relay station connected to the first relay station, and a third relay station connected to the second relay station, The first relay station is connected to a terminal station or a fourth relay station, and a transmission path failure occurs on a first transmission path connecting the terminal station or the fourth relay station and the first relay station. Occurs, the first relay station transmits an optical signal to the second relay station, and when the second relay station detects the optical signal, the first relay station transmits the optical signal to the third relay station. When the third relay station receives the optical signal from the second relay station, the third relay station uses an excitation light source of an optical amplifier that amplifies the optical signal directed to the second relay station. Characterized by stopping

  When an optical transmission line failure occurs, it is possible to provide a low power consumption optical transmission system that can reduce the power consumption of normal devices constituting the transmission section and can automatically recover when the optical transmission line failure is recovered.

Configuration diagram example of this example Optical amplifier block diagram Block diagram of optical amplifier Block diagram of optical multiplexer / demultiplexer 1 Block diagram of optical multiplexer / demultiplexer 2 Block diagram of control unit Flow chart of control that operates in the light control unit The block diagram of the control part in Example 2 Flowchart of control that operates in the light control unit according to the second embodiment. Diagram showing relay station operation without transmission line failure The figure which showed the relay station operation | movement immediately after the transmission line failure generate | occur | produced between relay station CD The figure which showed the relay station operation | movement at the time of the power consumption reduction after the transmission line failure generate | occur | produced between relay station CD The figure which showed the relay station operation | movement at the time of the power consumption reduction after the transmission line failure generate | occur | produced between relay station CD Figure showing relay station operation immediately after recovery from transmission line failure Diagram showing relay station operation after recovery from transmission line failure Diagram showing relay station operation after recovery from transmission line failure Figure showing the relay station operation after the impact of power consumption reduction after recovery from transmission line failure has converged

  Hereinafter, embodiments of the present invention will be described using examples with reference to the drawings.

  In the present embodiment, an example of an optical transmission apparatus 2000 that reduces the power consumption of devices constituting a normal transmission path constituting the transmission section when an optical transmission path failure occurs will be described.

  FIG. 1 shows an example of the configuration of this embodiment. In FIG. 1, an optical transmission system 1000 includes a transmitting station 2000 of a terminal station A, a receiving station 4000 of a terminal station B, and 3000-1 and 3000-2 of relay stations B, C, and D that connect the terminal stations A and B. , 3000-3. Relay stations B, C, and D are stations having the same function, although the installed stations are different. Each device is connected using an optical fiber.

  Transmitting station 2000 inputs signals from user devices 1 to N (not shown) to transmitters 2100-1 to 2100-N, and receiving station 4000 receives receivers 4100-1 to 4100- to user devices 1 to N (not shown). By transmitting a signal from N, communication between the terminal station A and the terminal station B is enabled.

  Transmitters 2100-1 to 2100-N of transmitting station 2000 perform wavelength conversion into communication light suitable for light transmission to the transmission path.

  The wavelength multiplexing unit 2200 receives the light received from the transmitters 2100-1 to 2100 -N and performs wavelength multiplexing so that it can be transmitted through one optical fiber.

  The wavelength demultiplexing unit 4200 of the receiving station 4000 demultiplexes the optical signal for each wavelength so that the optical signal received from the relay station D can be received by the receivers 4100-1 to 4100-N. Send.

Although long distance transmission represented by a loss of 100 km or 30 dB is considered between the transmission station 2000 and the relay station 3000-N, this control can be applied regardless of the distance because the control does not depend on the distance between the stations.
FIG. 2 is a block diagram of relay stations 3100-1 to 3100-3. Each of the relay stations 3100-1 to 3100-3 has the same function, and an optical multiplexing / demultiplexing unit-1 3110, an optical amplifying unit 3120, an optical multiplexing / demultiplexing unit-2 3130, a monitor light receiving unit 3140, an excitation light source 3170, and optical transmission It comprises a machine 3180, a control unit 3190, and a reflected light receiver 3200.

  The optical multiplexer / demultiplexer-1 3110 demultiplexes the input light from the IN side to the monitor light receiver 3140 and the optical amplifying unit 3120. Further, the optical multiplexer / demultiplexer-1 3110 multiplexes the light from the optical transmitter 3180 so as to be occupied by the dotted-line arrow and sends it to the IN side.

  The optical amplifying unit 3120 amplifies the received light demultiplexed from the optical multiplexer / demultiplexer-1 3110 using the light of the excitation light source 3170, and sends the amplified light to the optical multiplexer / demultiplexer-2 3130.

  The optical multiplexer / demultiplexer-2 3130 transmits the light received from the optical amplifying unit 3120 to the OUT side. Further, the optical multiplexer / demultiplexer-2 3130 transmits the light received from the OUT side to the reflected light receiver 3200 as indicated by a dotted line. The optical multiplexer / demultiplexer-2 3130 receives the received optical signal when a fiber break occurs in the transmission line on the OUT side or when an optical signal output from the optical transmitter of the relay station connected to the OUT side is received. Is transmitted to the reflected light receiver 3200. The monitor light receiver 3140 measures the light intensity of the light received from the optical multiplexer / demultiplexer-1, and transmits the measured monitor light intensity to the control unit 3190.

  The excitation light source 3170 controls transmission / stop of excitation light by a control signal from the control unit 3190. Further, the excitation light source 3170 performs control so that the transmission light level of the excitation light becomes constant according to a control signal from the control unit 3190.

  The optical transmitter 3180 transmits light. The transmitted light is used as a control signal. The optical transmitter 3180 controls transmission and stop of light according to a control signal from the control unit 3190. The control unit 3190 receives the received light intensity from the reflected light receiver 3200 and the monitor light intensity from the monitor light receiver 3140, and based on the received received light intensity and the monitor light intensity, the excitation light source 3170 and the optical transmitter 3180. Control the behavior.

  The reflected light receiver 3200 measures the light intensity received from the optical multiplexer / demultiplexer-2 3130 and transmits the measured received light intensity to the control unit 3190.

  FIG. 3 is a block diagram of the optical amplification unit 3120. The optical amplification unit 3120 includes isolators 3122 and 3123 and an optical amplification fiber 3121.

  The isolator 3122 attenuates the excitation light from the optical amplification fiber 3121 so as not to be transmitted to the optical multiplexer / demultiplexer 3110, and transmits the optical signal from the optical multiplexer / demultiplexer-1 3110 to the optical amplification fiber 3121.

  The optical amplification fiber 3121 is an optical amplification fiber typified by an Er-doped optical fiber, receives input light from the excitation light source 3170, amplifies the optical signal received from the isolator 3122, and transmits the amplified optical signal to the isolator 3123.

  The isolator 3123 transmits the amplified optical signal from the optical amplification fiber 3121 to the optical multiplexer / demultiplexer-2 3130. The isolator 3123 attenuates the light from the optical multiplexer / demultiplexer-2 3130 so as not to be transmitted to the optical amplification fiber 3121.

FIG. 4 is a block diagram of the optical multiplexer / demultiplexer 1. The optical multiplexer / demultiplexer-1 3110 includes an optical multiplexer / demultiplexer-1-3111. The optical combiner / part-1 3111 is an optical coupler that branches light from the IN side into three. The three branching ratios are ratios in which the optical amplifier 3120 is the main, the monitor light receiver 3140 is the subordinate, and the optical transmitter 3180 is the subordinate, and a typical design example is about 50:25:25. However, depending on the performance of the optical amplifying unit 3120 and the performance of the monitor light receiver 3140, the branching ratio is not limited. FIG. 5 is a block diagram of the optical multiplexer / demultiplexer 2. The optical multiplexer / demultiplexer-2 3130 includes an optical multiplexer / demultiplexer-2-3131.
The optical multiplexing / demultiplexing unit-2 3131 is an optical coupler that branches light from the OUT side into two. The two branching ratios are ratios mainly for the optical amplifying unit 3120 and subordinates for the reflected light receiver 3200, and a typical design example is about 72:25. Depending on the performance of the reflected light receiver 3200, the branching ratio is not limited.

  FIG. 6 is a block diagram of the control unit 3190. The control unit 3190 includes a main signal light determination unit 3191, a reflected light determination unit 3193, and a light control unit 3192.

  The main signal light determination unit 3191 receives the measurement result of the monitor light intensity from the monitor light receiving unit 3140 and determines the presence or absence of the main signal light. The determination threshold value is fixed by the main signal light determination unit 3191 and is set to a value exceeding the light reception determination lower limit optical power of the monitor light receiver. The main signal light determination unit 3191 determines that “light input is present” when the monitor light intensity is greater than or equal to the determination threshold, and determines that “no light input” when the monitor light intensity is smaller than the determination threshold. This threshold value determines only the presence or absence of light. The main signal light determination unit 3191 transmits the main signal light presence / absence determination result to the light control unit 3192.

  The reflected light determination unit 3193 receives the received light intensity measurement result from the reflected light receiver 3200, and makes two types of determination based on the reflected light level.

  The first determination is when the reflected light intensity changes depending on the excitation intensity light, and the reflected light determination unit 3193 reflects the optical signal transmitted from the OUT side of the relay station in conjunction with the optical transmission power. When the light intensity fluctuates, it is determined that “there is reflected light”, and otherwise, it is determined that “there is no reflected light”.

  Another determination is that the reflected light determination unit 3193 detects the reflected light when the reflected light intensity is constant without depending on the excitation intensity light, or when the relationship with the excitation light intensity is unknown. It is determined that “light input is present”, and otherwise “no light input” is determined.

  The reflected light presence / absence determination result and the light presence / absence determination result are transmitted to the light control unit 3192.

  The light control unit 3192 receives the reflected light presence / absence determination result and the light presence / absence determination result from the main signal light determination unit 3191 and the reflected light determination unit 3193, and as a control result based on the control flowchart shown in FIG. An excitation light source control signal is transmitted to the excitation light source 3170, and an optical transmitter control signal is transmitted to the optical transmitter 3180.

  FIG. 7 shows a control flow S710 executed by the light control unit 3192. The control flow starts from S710. In the control flow S711, the light control unit 3192 performs the processing of S712 when determining “with light” based on the main signal light presence / absence determination result transmitted from the main signal determining unit 3191, and S716 when determining “without light”.

  In the control flow S716, the light control unit 3192 transmits a control signal to the excitation light source 3170 to stop the light in order to stop the excitation light source 3170. After finishing the control flow S716, the optical control unit 3192 transmits a control signal to the optical transmitter so as to stop the optical transmitter by the process of the control flow S717. S717 may be performed only when the optical transmitter transmits an optical signal. By this control, the relay station stops optical amplification. Therefore, when the relay station does not receive the optical signal, that is, when the optical signal from the preceding relay station is not received due to fiber breakage in the transmission path, the pumping light source 3170 and the optical transmitter of the relay station are stopped. I can do it.

  In the control flow S 712, the light control unit 3192 performs the processing of S 718 when determining “with reflected light” based on the reflected light presence determination result transmitted from the reflected light receiver 3200, and performing S 713 when determining “without reflected light”. . The determination of “with reflected light” is a case where a fiber break has occurred in the transmission path downstream of the relay station. In order to determine that there is “reflected light” in the present control flow S712, it is necessary to change the excitation light once. Therefore, if S720, which is a process for changing the excitation light, is not performed, this determination is always performed. No.

  In the control flow S718, the light control unit 3192 transmits a control signal that results in a decreased light output to the pumping light source 3170 in order to reduce the light output of the pumping light source 3170. When the OUT side transmission line fiber breaks, the optical amplifying unit 3120 lowers the power consumption of the relay station by reducing the optical amplification factor, and the relay station breaks the OUT side transmission line fiber. Can be monitored to see if it has recovered.

  Further, the light control unit 3192 performs the process of the control flow S719. In control flow S719, the optical control unit 3192 transmits an optical transmitter control signal to the optical transmitter 3180 so as to start optical transmission in order to start transmission light from the optical transmitter 3180. With this control, it is possible to stop the excitation light of the relay station in the preceding stage of the relay station, and it is possible to reduce the power consumption of the relay station in the preceding stage.

  Next, the light control unit 3192 performs the process of the control flow S713.

  In the control flow S713, based on the received light intensity transmitted from the reflected light receiver 3200, the light control unit 3192 performs the processing of S720 when “light is present” is determined, and S714 when “no light” is determined.

  In the control flow S720, the light control unit 3192 transmits a control signal to the excitation light source 3170 to stop the light in order to stop the excitation light source 3170. As a result, the power consumption of the relay station can be reduced when the subsequent relay station detects the fiber breakage by receiving the reflected light.

  After finishing the control flow S720, the optical control unit 3192 transmits a control signal to the optical transmitter so that the optical transmitter emits light by the process of the control flow S721. With this control, it is possible to stop the excitation light of the relay station in the preceding stage of the relay station, and it is possible to reduce the power consumption of the relay station in the preceding stage.

  In the control flow S714, the light control unit 3192 transmits a control signal to the pumping light source 3170 so that the pumping light source 3170 has a normal output in order to set the pumping light source 3170 to a normal output. When the control flow S714 ends, the process of the control flow S715 is performed. By this control, the relay station amplifies the light from the optical multiplexer / demultiplexer-1 3110 and transmits it to the optical multiplexer / demultiplexer-2 3130. As a result, the output of the excitation light source can be stopped, or the low power consumption state can be changed to the normal output state.

  In the control flow S715, the optical control unit 3192 transmits a control signal to the optical transmitter 3180 so as to stop the optical transmission in order to stop the transmission light from the optical transmitter 3180. When the control flow S715 is completed, the process of the control flow S711 is performed again.

  In the present embodiment, an example of an apparatus 2000 using a total reflection mirror instead of the optical transmitter 3180 will be described.

  FIG. 8 is a diagram showing a relay station in this embodiment, and the difference from FIG. 2 is a total reflection mirror 3181. The total reflection mirror 3181 is a mirror that completely reflects the light from the optical multiplexer / demultiplexer-1 3110, and provides the same function as the optical transmitter 3180 in FIG. FIG. 9 shows a control flow of the light control unit 3192 in the present embodiment. Optical multiplexing / demultiplexing unit-1 3110, optical amplification unit 3120, optical multiplexing / demultiplexing unit-2 3130, monitor light receiving unit 3140, excitation light source 3170, main signal light determination unit 3191 of control unit 3190, reflected light determination unit 3193, reflected light reception The machine 3200 is the same as that shown in FIGS.

In FIG. 9, the difference from FIG. 7 is S922 to S925.
In the control flow S922, the light control unit 3192 transmits a control signal for stopping the reflection to the reflection mirror in order to stop the reflection of the total reflection mirror 3181.

  In the control flow S923, the light control unit 3192 transmits a control signal for starting reflection to the reflection mirror in order to start reflection of the total reflection mirror 3181. Next, the process of control flow S912 is performed.

In the control flow S924, the light control unit 3192 transmits a control signal for stopping the reflection to the reflection mirror in order to stop the reflection of the total reflection mirror 3181. Next, the process of control flow S912 is performed.
The control flow S925 performs the same process as the control flow S922.

  In the present embodiment, an example of a relay station will be described in which the power consumption of a device constituting a normal transmission path constituting the transmission section is reduced when an optical transmission path failure occurs, and a transmission path state grasping function at the time of restoration is added.

  The difference from the first embodiment shown in FIGS. 1 to 7 is the logic of the light control unit flowchart shown in FIG. 10, and S1031 to S1034 are added. In the control flow S1011, the light control unit 3192 performs the processing of S1012 when determining “with light” based on the main signal light presence / absence determination result transmitted from the main signal determining unit 3191, and performing S1016 when determining “without light”.

  In the control flow S1011, the light control unit 3192 proceeds to the control flow S1012 when the “light present” determination is made based on the main signal light presence / absence determination result transmitted from the main signal determination unit 3191. On the other hand, when “no light” is determined, a stop signal of the excitation light is transmitted to the excitation light source in S1016. Further, the optical transmitter is stopped in the control flow S1017.

In the control flow S1031, the light control unit 3192 transmits a control signal for increasing the light output to the pumping light source 3170 in order to increase the pumping light output of the pumping light source 3170, and performs the process of the control flow S1032. The light output to be increased depends on the light detection resolution at the reflected light receiver 3200, and an increase amount higher than the resolution is required. However, if the resolution of a general light detector is taken into consideration, the effect can be sufficiently increased by about 1 dB. It is believed that there is.
In the control flow S1032, the light control unit 3192 receives the light increase in the control flow S1031, and when the light reception light intensity increase is seen based on the reception light intensity of the reflected light receiver 3200, the increase is not seen in S1033. In the case, the process of S1014 is performed.
The control flow S1033 performs the same processing as the light control unit S718.
The control flow S1034 performs the same process as the light control unit S719.

  FIGS. 11 to 17 describe the operation of the apparatus when the first, second, or third embodiment of the present invention is implemented.

  FIG. 11 shows a normal operation state before transmission line breakage occurs. In this state, relay station B 3000-1, relay station C 3000-2, and relay station D 3000-3 are all in the same state (reflected light: none, pumping light: normal, monitoring light: detection, optical transmission: stopped. ). The reflected light in the figure is the result of measuring the light intensity in the reflected light receiver 3200, the excitation light is the result of controlling the excitation light intensity in the excitation light source 3170, the monitor light is the measurement result of the monitor light intensity in the monitor light receiver 3140, and the optical transmission is optical transmission The optical transmitter control state and the received light in the device 3180 indicate the received light intensity in the receivers 1 to N 4100-1 to 4100-N. In this state, all of relay station B 3000-1 to relay station D 3000-3 are in the normal operation state with the maximum power consumption. FIG. 11 shows the normal operation state of the apparatus as an initial value with t = 0. In the normal operation state, the relay station 3000 is in a state in which there is no reflected light, pumping light normal operation, input monitor light detection, and control light transmission are stopped. In this state, the pumping light and the optical transmitter are not controlled by the control flow of the light control unit 3192.

  FIG. 12 shows an apparatus state immediately after the fiber of the transmission line between the relay station C3000-2 and the relay station D3000-3 is broken at t = 1.

In relay station C3000-2, due to transmission line fiber breakage, reflected light receiver 3200 receives the reflected light, measures the received light intensity, and transmits the measured received light intensity to control unit 3190. The reflected light determination unit 3193 of the relay station C3000-2 detects the reflected light. The optical control unit 3192 of the relay station C3000-2 transmits a control signal for reducing the pumping light to the pumping light source 3170 in the control flow S718 because the presence / absence of reflected light by the reflected light detection is “present” in the control flow S712. Further, in the control flow S719, a control signal is transmitted to the optical transmitter 3180 so that the optical signal is transmitted from the optical transmitter. Accordingly, the relay station C3000-2 reduces the excitation light and monitors the recovery of the fiber breakage depending on whether or not the reflected light is detected. Also, the control optical signal is transmitted to the relay station B.
At t = 1, the control optical signal from the relay station C has not yet reached the relay station B3000-1, so that the pump light from the relay station B is in a normal output state. Therefore, the input monitor light is still detected for the monitor light receiver 3140 of the relay station C3000-2.

  The relay station D3000-3 does not receive the optical signal from the relay station C3000-2 due to the transmission line fiber breakage, and therefore the monitor light receiver 3140 does not detect the input monitor light. Therefore, the light control unit 3192 determines that there is no light input in the main signal determination unit in the control flow S711, and transmits a control signal for stopping the excitation light to the excitation light source 3170. Thereby, the optical transmission from relay station D3000-3 is stopped. Therefore, the power consumption of relay station D3000-3 can be reduced.

  FIG. 13 shows a state where the control operation of the optical control unit 3192 of the relay station C reaches the relay station B3000-1 at t = 2. In the relay station B 3000-1, the monitor light receiver 3140 detects the input monitor light, but the reflected light receiver 3200 receives the control light from the relay station C 3000-2. Accordingly, the light control unit 3192 determines that the light presence / absence determination result in the reflected light determination unit is “light input present” in the control flow S713, and transmits a control signal to stop the excitation light to the excitation light source 3170 in S720, The light source 3170 stops the excitation light. With this control, it is possible to stop the excitation light of relay station B3000-1 at the preceding stage from the location where the fiber is broken, and it is possible to realize power saving of relay station B3000-1.

FIG. 14 shows a state immediately after the fiber breakage in FIG. 13 is resolved at t = 11.
When the fiber break is eliminated, the reflected light receiver 3200 of the relay station C3000-2 does not receive the reflected light, and the reflected light determination unit 3193 of the control unit 3190 does not detect the reflected light. Therefore, the light control unit 3192 determines that the reflected light determination unit determines whether there is reflected light or not in the control flow S713, and the reflected light determination unit determines whether there is light input or not. In S714, a control signal for controlling the pumping light as a normal output is transmitted to the pumping light source. In S715, a control signal for stopping the control light transmission is transmitted to the optical transmitter 3180. However, at t = 11, the optical transmission for control has reached the relay station B3000-1. For this reason, after the normal output of the pumping light in S714, it is determined that there is no light input by the determination of the presence or absence of the main signal light in the determination in S711, the pumping light is stopped by the processing in S716, and the light does not reach the relay station D3000-3.

  FIG. 15 shows a state where the control operation at t = 11 has reached relay station B 3000-1 at t = 12. In the relay station B 3000-1, the control light of the relay station C 3000-2 is stopped, and in the control flow S713 of the light control unit 3192, it is determined that there is no light input in the reflected light determination unit, and the light control unit 3192 transmits a control signal to the excitation light source 3170 so that the excitation light is normally output. However, at t = 12, the restoration of the main excitation light has not yet reached the relay station 3000-2C.

  FIG. 16 shows a state in which the pumping light recovery of the relay station B3000-1 reaches the relay station C3000-2 at t = 13 at t = 13. In relay station C3000-2, monitor light receiver 3140 has received the input monitor light and has started optical output. FIG. 17 shows that at t = 14, the pumping light recovery of the relay station C3000-2 at t = 13 reaches the relay station D3000-3, and the monitor light receiver 3140 of the relay station D3000-2 detects the input monitor light. In the control flow S711 of the light control unit 3192, the determination result of the received signal determination unit is determined to be “with light input”, and in S714, a control signal is transmitted to the excitation light source 3170 so that the excitation light is normally output. The excitation light source 3170 receives the control signal and resumes normal output of the excitation light. As described above, the normal operation state is restored.

1000 Optical transmission system 2000 Transmitting station 3000-1, 3000-2, 3000-3 Relay station 4000 Receiving station 2100-1, 2100-N Transmitter 2200 Wavelength multiplexing unit 3100-1, 3100-2, 3100-3 Optical amplifier 4200 Wavelength separation unit 4100-1, 4100-N receiver 3110 Optical multiplexing / demultiplexing unit-1
3120 Optical amplification unit 3130 Optical multiplexing / demultiplexing unit-2
3140 Monitor light receiving unit 3170 Excitation light source 3180 Optical transmitter 3190 Control unit 3200 Reflected light receiver 3121 Optical amplification fibers 3122 and 3123 Isolator 3111 Optical multiplexing / demultiplexing unit-1
3131 Optical multiplexing / demultiplexing part-2
3191 Main signal light determination unit 3192 Light control unit 3193 Reflected light determination unit 3181 Total reflection mirror

Claims (8)

An optical transmission system including a first relay station, a second relay station connected to the first relay station, and a third relay station connected to the second relay station, The first relay station is connected to a terminal station or a fourth relay station,
When a transmission path failure occurs on the first transmission path connecting the terminal station or the fourth relay station and the first relay station,
The first relay station is
Transmitting an optical signal to the second relay station;
The second relay station is
Upon detecting the optical signal, the optical signal is transmitted to the third relay station,
The third relay station is
When the optical signal is received from the second repeater station, the optical transmission system stops the pumping light source of the optical amplifier that amplifies the optical signal directed to the second repeater station. The first relay station is
When the reflected light from the first transmission path is detected, the optical amplification factor of its own optical amplifier that amplifies the optical signal directed to the terminal station or the fourth relay station is reduced below a certain value,
2. The optical transmission system according to claim 1, wherein when the reflected light from the first transmission path is not detected, the optical gain is set to the constant value. The optical transmission system according to claim 1, further comprising:
The first relay station is
Decreasing the optical amplification factor of the optical amplifier of its own device that amplifies the optical signal directed to the terminal station or the fourth relay station from a certain value,
The second relay station is
An optical transmission system, wherein an excitation light source of an optical amplifier that amplifies an optical signal directed to the first relay station is stopped. The optical transmission system according to claim 3, further comprising:
The first relay station is
When reflected light from the first transmission line is no longer detected,
Return the optical amplification factor of its own optical amplifier that amplifies the optical signal toward the terminal station or the fourth relay station to a constant value,
Stop transmitting the optical signal to the second relay station;
The second relay station is
When the optical signal from the first relay station is not received,
The output of the pump light source of the optical amplifier that amplifies the optical signal directed to the first relay station is recovered to output a fixed value of pump light,
Stop transmitting optical signals to the third relay station,
The third relay station is
An optical transmission system, wherein an output of an excitation light source of an optical amplifier that amplifies an optical signal directed to the second relay station is recovered so as to output a constant value of excitation light. A first optical multiplexer / demultiplexer for demultiplexing an optical signal received from a first optical transmission device connected via a first transmission path;
An optical amplifier for amplifying an optical signal input from the first optical multiplexer / demultiplexer;
An excitation light source of the optical amplifier;
A control unit for controlling the output of the excitation light source;
A second optical multiplexer / demultiplexer for sending an optical signal output from the optical amplifier toward a second optical transmission device connected via a second transmission path;
A reflected light receiver for receiving reflected light input from the second optical transmission device side to the second optical multiplexer / demultiplexer,
The control unit, the reflected light receiver,
When the reflected light is detected by the reflected light receiver,
Controlling the output of the excitation light source to be smaller than a certain value,
further,
When no reflected light is detected by the reflected light receiver,
An optical transmission apparatus that controls an output of the pumping light source to a constant value. The optical transmission device according to claim 5,
An optical transmitter for inputting an optical signal to the first optical multiplexer / demultiplexer;
In the reflected light receiver, when receiving the optical signal input from the second optical multiplexer / demultiplexer from the second transmission path,
The controller is
Stopping the excitation light source;
Sending a control signal to send an optical signal to the optical transmitter;
The first optical multiplexer / demultiplexer includes:
An optical transmission apparatus for transmitting an optical signal transmitted from the optical transmitter to the first transmission path. The optical transmission device according to claim 5,
A reflection mirror for reflecting an optical signal from the first optical multiplexer / demultiplexer;
In the reflected light receiver, when receiving the optical signal input from the second optical multiplexer / demultiplexer from the second transmission path,
The controller is
Stopping the excitation light source;
Send a control signal to the reflection mirror to start light reflection,
The first optical multiplexer / demultiplexer includes:
An optical transmission apparatus for transmitting an optical signal reflected by the reflection mirror to the first transmission path. An optical transmission method for an optical transmission system, comprising: a first relay station; a second relay station connected to the first relay station; and a third relay station connected to the second relay station. The first relay station is connected to a terminal station or a fourth relay station;
When a transmission path failure occurs on the first transmission path connecting the terminal station or the fourth relay station and the first relay station,
The first relay station is
Transmitting an optical signal toward the second relay station;
The second relay station is
Detecting the optical signal, transmitting the optical signal to the third relay station;
The third relay station is
And a step of stopping an excitation light source of an optical amplifier that amplifies an optical signal directed to the second relay station when the optical signal is received from the second relay station.

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