JP2011211548A - Optical relay amplifier, optical communication system and optical relay amplifier monitoring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical relay amplifier capable of giving a sufficient power budget to a monitoring optical signal, an optical communication system with the same, and an optical relay amplifier monitoring method for monitoring the optical relay amplifier in the optical communication system.SOLUTION: An optical relay amplifier 1 includes: a relay amplifying section 5 for amplifying an optical signal bidirectionally; a first optical directional coupler 7a oriented in a direction (OLT2 direction) away from the relay amplifying section 5 at one side of the relay amplifying section 5; a second optical directional coupler 7b oriented in a direction (OLT2 direction) toward the relay amplifying section 5 at the other side of the relay amplifying section 5; an ONU 6 for transmitting and receiving the monitoring optical signal relating to the relay amplifying section 5; an optical switch 9 for selecting whether to pass the monitoring optical signal which is transmitted and received by the ONU 6 through the first optical directional coupler 7a or through the second optical directional coupler 7b; and a control section 10 for controlling the switching of the optical switch 9 based on the operational state of the relay amplifying section 5 and the communication link state of the ONU 6.

Description

  The present invention relates to an optical repeater amplifier for extending an optical access system, an optical communication system including the same, and an optical repeater amplifier monitoring method for monitoring an optical repeater amplifier in the optical communication system.

  In recent years, an optical access service based on a PON (Passive Optical Network) method has become a mainstream method for providing broadband communication for mass users. In order to further expand the area where the optical access service can be provided and improve the opticalization rate of the communication service, it is necessary to lengthen the optical signal reach of the PON system. For this purpose, a general method is to arrange an optical repeater amplifier in the optical access line to compensate the line optical loss.

  FIG. 1 shows an example of a PON system using an optical repeater amplifier. In the optical repeater amplifier 1, an optical line terminator (OLT) 2 which is a device placed in a telecommunications carrier's office and an optical network unit (ONU) 3 which is an in-home device are respectively optical. They are connected by access lines (4a, 4b). The optical repeater amplifier 1 includes a repeater amplifier 5, an ONU unit 6, and an optical directional coupler 7 directed in the direction of the OLT 2. The relay amplification unit 5 and the ONU unit 6 are connected via a monitoring terminal 8. The ONU unit 6 and the optical access line 4 a are connected by an optical directional coupler 7.

  Transmission / reception of the main signal between the user terminal and the communication network having a connection point in the station is performed by the ONU 3 and the OLT 2, and the optical access line (4 a, 4 b) composed of a single optical fiber that connects between the ONU 3 and the OLT 2. This is done via the amplifier 1. The ONU 3 has a function of transmitting a main signal from the user terminal as a communication optical signal to the optical access line 4b, and conversely, a function of transmitting a communication optical signal received from the optical access line 4b toward the user terminal. Communication optical signals between the OLT 2 and the ONU 3 are time-division multiplexed, and a plurality of ONUs 3 can be connected to one OLT 2. The light transmitted by each of the OLT 2 and the ONU 3 has different wavelength bands, and bidirectional communication is possible even if only one optical fiber is used. In the OLT 2, the time division multiplexing timing of each ONU 3 is controlled and the signals are multiplexed and separated.

  The relay amplification unit 5 optically amplifies communication optical signals transmitted from the OLT 2 and from the ONU 3 to compensate for the optical power level.

  Here, for the purpose, the optical repeater amplifier 1 is installed at a location remote from the communication carrier station. Therefore, it is necessary to monitor and control the optical repeater amplifier 1 from a remote location.

  That is, the monitoring optical signal needs to be communicated between the monitoring terminal 8 that transmits and receives the monitoring optical signal related to the relay amplification unit 5 and the monitoring network having a connection point in the station. An ONU unit 6 that is a block having functions equivalent to those of the ONU 3 with respect to the optical wavelength, signal system, and the like is placed inside the amplifier 1, and a configuration is adopted in which the monitoring optical signal is optically time-division multiplexed onto the optical access line 4a (for example, (See Non-Patent Document 1.)

  The monitoring optical signal is demultiplexed by the station apparatus OLT 2 and is accommodated in the monitoring network via a connection point in the station.

  The monitoring signal emitted from the monitoring terminal 8 of the relay amplification unit 5 is converted into a monitoring optical signal in the ONU unit 6 and transmitted to the optical access line 4 a connecting the OLT 2 and the optical relay amplifier 1. At this time, since the ONU unit 6 is controlled by the OLT 2 and incorporated in the PON system like the other ONUs 3, it is possible to transmit the monitoring optical signal by optical time division multiplexing together with the communication optical signal. In the OLT 2, the monitoring optical signal is time-division demultiplexed and transmitted to the connection point to the monitoring network. Transmission of the monitoring optical signal from the monitoring network to the optical repeater amplifier 1 is performed in the reverse order.

ITU-T Recommendation G. 984.6, Section 6.1

  However, the monitoring optical signal transmitted from the ONU unit 6 is incident on the optical access line 4a immediately before the relay amplifying unit 5, and the monitoring optical signal transmitted from the OLT 2 is not transmitted through the relay amplifying unit 5. Input to unit 6. That is, the monitoring optical signal is not optically amplified even though the optical repeater amplifier 1 is placed at a location remote from the communication carrier station for that purpose. For this reason, the PON system of FIG. 1 has a problem that the power budget of the monitoring optical signal between the OLT 2 and the ONU unit 6 has no margin, and an unstable factor occurs in the communication establishment such as the occurrence of accommodation restriction. .

  Therefore, in order to solve the above-described problems, the present invention provides an optical repeater amplifier capable of providing a sufficient power budget for a monitoring optical signal, an optical communication system including the same, and an optical repeater amplifier in the optical communication system. It is an object of the present invention to provide an optical repeater amplifier monitoring method for monitoring.

  In order to achieve the above object, in the optical repeater amplifier according to the present invention, the monitoring optical signal is also passed through the repeater amplifier during normal operation, and the switch is switched when the repeater amplifier fails, and the repeater amplifier is not passed. It was decided.

  Specifically, an optical repeater amplifier according to the present invention includes a repeater amplifying unit that amplifies an optical signal bidirectionally, and a first that is directed in a direction away from the repeater amplifying unit on one side of the repeater amplifying unit. An optical directional coupler, a second optical directional coupler directed in the direction of the relay amplifying unit on the other side of the relay amplifying unit, and an ONU (Optical Network) that transmits and receives a monitoring optical signal related to the relay amplifying unit Unit), an optical switch for selecting whether the monitoring optical signal transmitted / received by the ONU unit is routed through the first optical directional coupler or the second optical directional coupler, and the relay A control unit that controls switching of the optical switch based on an operation state of the amplification unit and a communication link state of the ONU unit.

  The present optical repeater amplifier can amplify the monitoring optical signal through the repeater amplification unit at the normal time by switching the optical switch. Therefore, the present invention can provide an optical repeater amplifier that can provide a sufficient power budget for the monitoring optical signal. Furthermore, this optical repeater amplifier can divert the monitoring optical signal from the repeater amplifier by switching the switch when the repeater amplifier fails. As a result, the optical communication system equipped with this can maintain the monitoring function of the optical repeater amplifier even if the repeater amplifier section fails.

  Another optical repeater amplifier according to the present invention includes a repeater amplifying unit that amplifies an optical signal in both directions, and a first optical directional coupler oriented in a direction away from the repeater amplifying unit on one side of the repeater amplifying unit A second optical directional coupler directed in the direction of the relay amplifying unit on the other side of the relay amplifying unit, and the first optical directional coupler, and a monitoring optical signal related to the relay amplifying unit A first photoelectric conversion unit that performs transmission and reception, a second photoelectric conversion unit that is connected to the second optical directional coupler, and transmits and receives a monitoring optical signal related to the relay amplification unit, and the monitoring optical signal as the first optical signal. An ONU unit having an electronic switch for selecting whether to pass through an optical directional coupler or through the second optical directional coupler, an operating state of the relay amplifier unit, and a communication link state of the ONU unit Based on the control to control the switching of the electronic switch. It comprises a part, a.

  This optical repeater amplifier can also obtain the same effect as the one optical repeater amplifier described above. In addition, this optical repeater amplifier has high device reliability such as impact resistance and wear resistance by not using an optomechanical switch having a movable part.

  The control unit of the optical repeater amplifier according to the present invention determines an operation state of the repeater amplifier unit by combining information on power consumption of the repeater amplifier unit and information on optical power of optical signals before and after the repeater amplifier unit. be able to.

  An optical communication system according to the present invention is connected to the optical repeater amplifier and the first optical directional coupler of the optical repeater amplifier via an optical access line, transmits and receives a communication optical signal, and the repeater amplification unit An optical line terminal (OLT) that transmits and receives a monitoring optical signal to and from the second optical directional coupler of the optical repeater amplifier via an optical access line, and the optical repeater between the OLT and the OLT An ONU that transmits and receives the communication optical signal via an amplifier.

  Since the optical communication system includes the above-described optical repeater amplifier, it is possible to provide an optical communication system capable of providing a sufficient power budget for the monitoring optical signal.

  The optical repeater amplifier of the optical communication system according to the present invention includes a supervisory optical signal amplifier that amplifies the supervisory optical signal through the second optical directional coupler through the second optical directional coupler by the optical switch or the electronic switch. It has the means.

  The optical repeater amplifier of the optical communication system according to the present invention is configured to bypass the monitoring optical signal by using the optical switch or the electronic switch to route the supervisory optical signal through the first optical directional coupler and bypass the repeater amplification unit. It has the means.

  The optical repeater amplifier can divert the monitoring optical signal from the repeater amplifier by switching the switch when the repeater amplifier fails. As a result, the optical communication system equipped with the optical communication system can maintain the monitoring function of the optical repeater amplifier even if the repeater amplifier section fails.

  In the optical repeater of the optical communication system according to the present invention, when the repeater amplification unit is normal and a communication link with the OLT is established by the supervisory optical signal, the supervisory optical signal amplifying unit uses the supervisory optical signal amplifier to When the transmission / reception of the monitoring optical signal is performed and the communication link is interrupted, the relay amplification unit is estimated to be abnormal, and the monitoring optical signal bypassing means transmits and receives the monitoring optical signal with the OLT, and the monitoring optical signal bypassing After the transmission and reception of the OLT and the monitoring optical signal by the means, if the communication link is broken and no abnormality is detected in the relay amplification unit, the monitoring optical signal amplification means performs the OLT and the monitoring optical signal. The monitoring optical signal is transmitted and received again, and the establishment of the communication link is waited for.

  This optical communication system can maintain the communication link of the optical repeater amplifier by switching the optical switch or the electronic switch depending on the situation.

  An optical repeater amplifier monitoring method according to the present invention is an optical repeater amplifier monitor method for monitoring an optical repeater amplifier disposed between an OLT and an ONU with a monitor optical signal, wherein the optical repeater amplifier monitors the monitor optical signal. A supervisory optical signal amplifying procedure is performed by amplifying by the relay amplifying unit and transmitting and receiving between the OLT and the optical repeater amplifier.

  In the present optical repeater amplifier monitoring method, the monitor optical signal is amplified through the repeater amplifier in a normal state. Therefore, the present invention can provide an optical repeater amplifier monitoring method capable of providing a sufficient power budget for the monitoring optical signal.

  In the optical repeater amplifier monitoring method according to the present invention, when the repeater amplification unit is abnormal, the supervisory optical signal is transmitted and received between the OLT and the repeater amplifier by bypassing the repeater amplifier unit. A detouring procedure is performed.

  The present optical repeater amplifier monitoring method can bypass the monitor optical signal from the repeater amplifier when the repeater amplifier fails. As a result, the monitoring function of the optical repeater amplifier is maintained even if the repeater amplifier section fails.

  The optical repeater amplifier monitoring method according to the present invention performs the supervisory optical signal amplification procedure when the repeater amplification unit is normal and a communication link with the OLT is established by the supervisory optical signal, and the communication link is disconnected. The relay amplification unit is assumed to be abnormal and performs the monitoring optical signal detouring procedure, and the communication link is disconnected and the relay amplification unit is abnormal even after performing the monitoring optical signal detouring procedure. Is not detected, the monitoring optical signal amplification procedure is performed again, and the establishment of the communication link is awaited.

  This optical repeater amplifier monitoring method can maintain the communication link of the optical repeater amplifier by determining whether to amplify the monitor optical signal according to the situation.

  The present invention provides an optical repeater amplifier capable of providing a sufficient power budget for a supervisory optical signal, an optical communication system including the same, and an optical repeater amplifier monitoring method for monitoring an optical repeater amplifier in the optical communication system. be able to.

It is a figure explaining the structure of the conventional optical communication system. It is a figure explaining the structure of the optical communication system which concerns on this invention. 5 is a flowchart illustrating an optical repeater amplifier monitoring method according to the present invention. It is a figure explaining the optical repeater amplifier concerning this invention. It is a figure explaining the optical repeater amplifier concerning this invention.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

  FIG. 2 is a diagram illustrating the optical communication system according to the present embodiment. The optical communication system is connected to the optical repeater amplifier 1 and the first optical directional coupler 7a of the optical repeater amplifier 1 through the optical access line 4a to transmit and receive communication optical signals and to the repeater amplifier 5. Is connected to the second optical directional coupler 7b of the optical repeater amplifier 1 via the optical access line 4b, and the communication optical signal via the optical repeater amplifier 1 is exchanged with the OLT 2. ONU3 which transmits and receives.

  The optical repeater amplifier 1 includes a repeater amplifier 5 that amplifies an optical signal in both directions, and a first optical directional coupler that is directed in a direction away from the repeater amplifier 5 on one side of the repeater amplifier 5 (OLT2 direction). 7a, a second optical directional coupler 7b directed in the direction of the relay amplifying unit 5 (OLT2 direction) on the other side of the relay amplifying unit 5, and an ONU unit 6 that transmits and receives a monitoring optical signal related to the relay amplifying unit 5. An optical switch 9 for selecting whether the monitoring optical signal transmitted / received by the ONU unit 6 is routed through the first optical directional coupler 7a or the second optical directional coupler 7b, and the relay amplification unit 5 And a control unit 10 that controls the switching of the optical switch 9 based on the operation state of the ONU unit 6 and the communication link state of the ONU unit 6.

  A two-way optical switch 9 is connected to the ONU unit 6. The optical switch 9 is an optical switch that switches the path (A, B) of the optical fiber, and can communicate light only in one of the paths. The path A is connected to the optical access line 4a on the side facing the OLT 2 of the relay amplifying unit 5 by the optical directional coupler 7a oriented in the direction of the OLT 2. Further, the path B is also connected to the optical access line 4b facing the ONU 3 of the relay amplifier 5 by the optical directional coupler 7b oriented in the direction of the OLT 2.

  The optical repeater amplifier 1 has supervisory optical signal amplifying means for amplifying the supervisory optical signal by the optical amplifier 9 via the second optical directional coupler 7b and by the repeater amplifier 5. The control unit 10 controls the switching state of the optical switch 9.

  When the optical switch 9 selects the route B, the monitoring optical signal transmitted from the ONU unit 6 is coupled to the optical access line 4b via the optical directional coupler 7b and then to the relay amplification unit 5. Finally, it is optically amplified together with the communication optical signal between the OLT 2 and the ONU 3 and output to the optical access line 4a. The supervisory optical signal transmitted from the OLT 2 passes through the relay amplification unit 5 from the optical access line 4a, is optically amplified there, and reaches the ONU unit 6 through the optical directional coupler 7b. The OLT 2 controls the ONU 3 and the ONU unit 6 so that the monitoring optical signal and the communication optical signal are optical time division multiplexed.

  Further, the optical repeater amplifier 1 has a supervisory optical signal detour unit that causes the optical switch 9 to bypass the repeater amplification unit 5 via the first optical directional coupler 7a.

  When the optical switch 9 selects the route A, the monitoring optical signal transmitted from the ONU unit 6 is directly sent to the optical access line 4a through the optical directional coupler 7a. The monitoring optical signal transmitted from the OLT 2 reaches the ONU unit 6 from the optical access line 4a through the optical directional coupler 7a. That is, the monitoring light signal is communicated without going through the relay amplification unit 5.

  A power budget sufficient for communication of the monitoring optical signal can be obtained by selecting the route B by the optical switch 9 and optically amplifying the monitoring optical signal, so that the optical repeater amplifier 1 is stably monitored and controlled. Will be able to. If the obtained power budget is assigned to the optical access line, the optical access line 4a can be further extended.

  Even if the relay amplification unit 5 breaks down and optical amplification is not performed, switching the path of the optical switch 9 to the A side tries to communicate the monitoring optical signal without going through the relay amplification unit 5 However, although the instability of communication establishment exists, the possibility of continuing monitoring can be increased.

  Here, a switching method of the optical switch 9 will be described. The switching of the optical switch 9 is controlled by the control unit 10. The control unit 10 constantly monitors the operation state of the relay amplifying unit 5 and the optical communication link state of the ONU unit 6, and instructs the switching of the optical switch 9 according to the operation state of these devices. For example, the relay amplifying unit 5 can output a status to the control unit 10 regarding normality and abnormality of the optical amplification function such as the optical input / output power level. The ONU unit 6 can notify the control unit 10 of establishment or disconnection of the optical communication link.

  In the optical repeater amplifier 1, when the relay amplifier 5 is normal and the communication link with the OLT 2 by the monitoring optical signal is established, the monitoring optical signal amplifying means transmits and receives the monitoring optical signal to and from the OLT 2, and the communication link is interrupted. In this case, after the relay amplification unit 5 estimates that there is an abnormality, the monitoring optical signal detouring unit transmits and receives the OLT2 and the monitoring optical signal, and the monitoring optical signal detouring unit transmits and receives the OLT2 and the monitoring optical signal. Is interrupted, and no abnormality is detected in the relay amplifying unit 5, the supervisory optical signal amplifying means transmits / receives the supervisory optical signal to / from the OLT 2 again and waits for establishment of a communication link.

  Usually, the optical switch 9 selects the route B. If the optical amplification is normally performed from the information of the relay amplifying unit 5 and the optical communication link is established in the ONU unit 6, the optical switch 9 continues to maintain the route B. If the control unit 10 receives a notification of the optical communication link disconnection from the ONU unit 6, the control unit 10 switches the optical switch 9 to the route A and expects the ONU unit 6 to establish an optical communication link.

  If the ONU unit 6 cannot establish an optical communication link and does not detect an alarm from the relay amplification unit 5 that indicates an optical communication failure such as an optical amplification function abnormality, the control unit 10 The switch 9 is switched back to the route B, and the optical communication link establishment of the ONU unit 6 is expected again there.

  FIG. 3 is a flowchart for explaining this optical repeater amplifier monitoring method. After starting up the optical repeater amplifier 1 (step 21), the control unit 10 switches the optical switch 9 to the route B (step 22). Next, if the communication link of the ONU unit 6 is established, the control unit 10 continues to maintain that state (route B) (step 23). When the communication link of the ONU unit 6 is down (step 23), the control unit 10 switches the optical switch 9 to the route A side (step 24). If the ONU unit 6 can establish a communication link in the route A or if there is an abnormality alarm in the relay amplification unit 5, the control unit 10 continues to hold (route A) (step 25). When the ONU unit 6 cannot establish a communication link in the route A and there is no abnormality alarm of the relay amplification unit 5 (step 25), the control unit 10 switches the optical switch 9 to the route B, and the link of the ONU unit 6 Attempt to establish (step 22).

  Here, when switching the optical switch 9, in order to avoid an unstable operation due to a sensitive reaction, for example, a timer may be introduced at the time of switching determination of step 23 or step 25, and the situation may be observed for a certain period of time. A counter that counts the number of times of switching in order to avoid repeated switching of the optical switch 9 when the communication link of the ONU unit 6 continues to go down for a long time, such as when the ONU unit 6 fails or when the PON system is abnormal. May be introduced, and after a certain number of times of switching, the state may be held there.

  As described above, the optical communication system according to the present embodiment can obtain a sufficient optical power budget by amplifying the monitoring optical signal of the optical repeater amplifier by the repeater amplification unit. Instability can be eliminated, and the route can be switched by a switch, so that establishment of monitoring optical signal communication can be expected even when the relay amplifier section fails.

(First embodiment of optical repeater amplifier)
FIG. 4 is a diagram for explaining a first embodiment of the optical repeater amplifier 1. The relay amplifier 5 includes an optical amplifier 11, a current monitor 12 that monitors the current consumption of the optical amplifier 11, a power monitor 13 that monitors the input / output optical power level of the optical amplifier 11, and the current monitor 12 and the power monitor 13. It comprises an alarm unit 14 that collects monitor information and generates an alarm. The alarm unit 14 determines whether the operational state of the optical amplifier 11 is abnormal or normal based on the monitor information from the current monitor 12 and the power monitor 13, and outputs each as an alarm. The alarm output from the alarm unit 14 is sent to the ONU unit 6 and the control unit 10 through the monitoring terminal 8. In the ONU unit 6, the alarm is converted into a monitoring light signal and transmitted.

  The control unit 10 determines the operation state of the relay amplifying unit 5 by combining the information on the power consumption of the relay amplifying unit 5 and the information on the optical power of the optical signal before and after the relay amplifying unit 5. The control unit 10 controls switching of the optical switch 9, which is an optomechanical optical switch that switches the path of the optical signal by mechanical means, based on the state of the communication link of the ONU unit 6 and the alarm state of the relay amplification unit 5. To do. As described above, the optical repeater amplifier 1 can switch the optical switch 9 according to the device state.

(Second embodiment of optical repeater amplifier)
FIG. 5 is a diagram for explaining a second embodiment of the optical repeater amplifier 1. The optical repeater amplifier 1 shown in FIG. 5 includes a repeater amplifying unit 5 that amplifies an optical signal in both directions, and a first optical directional coupler 7a oriented in a direction away from the repeater amplifying unit 5 on one side of the repeater amplifying unit 5. And the second optical directional coupler 7b directed in the direction of the relay amplifying unit 5 on the other side of the relay amplifying unit 5 and the first optical directional coupler 7a, and a monitoring optical signal for the relay amplifying unit 5 Are connected to the first photoelectric conversion unit 16a and the second optical directional coupler 7b, and the second photoelectric conversion unit 16b that transmits and receives the monitoring optical signal to the relay amplification unit 5 and the monitoring optical signal to the first optical conversion unit 16a and the second optical directional coupler 7b. The ONU unit 6 having an electronic switch 9b for selecting whether to pass through the one optical directional coupler 7a or the second optical directional coupler 7b, the operating state of the relay amplification unit 5, and the ONU unit 6 Based on the communication link status of the electronic switch 9b. Comprises a section 10, the.

  The ONU unit 6 includes a driver unit 15 that performs alarm signal processing and operation control of the ONU unit 6 itself, and a photoelectric conversion unit (16a, 16b) connected to the optical directional coupler 7a and the optical directional coupler 7b, respectively. 16b) and an electronic optical switch 9b for operating any one of the photoelectric conversion units (16a, 16b).

  The driver unit 15 provides the control unit 10 with information related to the link of the ONU unit 6, and mediates between the control unit 10 and the electronic optical switch 9b. The optical repeater amplifier 1 shown in FIG. 5 does not use an optomechanical switch, and thus has no moving parts, and has excellent device reliability such as impact resistance and wear resistance.

1: Optical repeater amplifier 2: OLT
3: ONU
4a, 4b: Optical access line 5: Relay amplifier unit 6: ONU units 7, 7a, 7b: Optical directional coupler 8: Monitoring terminal 9 of relay amplifier unit: Optical switch 9b: Electronic switch 10: Control unit 11 : Optical amplifier 12: Current monitor 13: Power monitor 14: Alarm unit 15: Driver unit 16a, 16b: Photoelectric conversion unit A, B: Path

Claims (10)

A relay amplifier for amplifying optical signals in both directions;
A first optical directional coupler oriented in a direction away from the relay amplifier on one side of the relay amplifier;
A second optical directional coupler directed in the direction of the relay amplifier on the other side of the relay amplifier;
An ONU (Optical Network Unit) unit for transmitting and receiving a monitoring optical signal related to the relay amplification unit;
An optical switch that selects whether the monitoring optical signal transmitted and received by the ONU unit is routed through the first optical directional coupler or the second optical directional coupler;
A control unit that controls switching of the optical switch based on an operation state of the relay amplification unit and a communication link state of the ONU unit;
An optical repeater amplifier comprising: A relay amplifier for amplifying optical signals in both directions;
A first optical directional coupler oriented in a direction away from the relay amplifier on one side of the relay amplifier;
A second optical directional coupler directed in the direction of the relay amplifier on the other side of the relay amplifier;
A first optical / electrical converter that is connected to the first optical directional coupler and transmits / receives a monitoring optical signal related to the relay amplifier, and a monitoring light that is connected to the second optical directional coupler and is related to the relay amplifier A second photoelectric conversion unit for transmitting and receiving signals, and an electronic switch for selecting whether the monitoring optical signal is routed through the first optical directional coupler or the second optical directional coupler An ONU unit having
A control unit that controls switching of the electronic switch based on an operation state of the relay amplification unit and a communication link state of the ONU unit;
An optical repeater amplifier comprising: The controller is
The operation state of the relay amplification unit is determined by combining information on power consumption of the relay amplification unit and information on optical power of optical signals before and after the relay amplification unit. Optical repeater amplifier. An optical repeater amplifier according to any one of claims 1 to 3,
An OLT (Optical Line Terminal) connected to the first optical directional coupler of the optical repeater amplifier via an optical access line for transmitting / receiving a communication optical signal and transmitting / receiving a monitoring optical signal to / from the repeater amplification unit. )When,
An ONU connected to the second optical directional coupler of the optical repeater amplifier via an optical access line, and for transmitting and receiving the communication optical signal via the optical repeater amplifier to and from the OLT;
An optical communication system comprising: The optical repeater amplifier is:
The monitoring optical signal amplifying means for amplifying the monitoring optical signal through the second optical directional coupler by the optical switch or the electronic switch and amplifying by the relay amplification unit according to claim 4. Optical communication system. The optical repeater amplifier is:
The monitoring optical signal bypassing means for bypassing the relay amplification unit by passing the monitoring optical signal through the first optical directional coupler by the optical switch or the electronic switch, according to claim 4 or 5. The optical communication system described. The optical repeater amplifier is:
When the relay amplification unit is normal and a communication link with the OLT by the monitoring optical signal is established, the monitoring optical signal amplifying means performs transmission and reception of the monitoring optical signal with the OLT,
When the communication link is interrupted, the relay amplification unit is assumed to be abnormal, and the OLT and the monitoring optical signal are transmitted and received by the monitoring optical signal detouring unit,
The supervisory optical signal amplifying means when the communication link is broken and no abnormality is detected in the relay amplifier after the supervisory optical signal detour means transmits and receives the supervisory optical signal with the OLT. 7. The optical communication system according to claim 6, wherein the OLT and the monitoring optical signal are transmitted / received again to wait for establishment of the communication link. An optical repeater amplifier monitoring method for monitoring an optical repeater amplifier disposed between an OLT and an ONU with a monitor optical signal,
An optical repeater amplifier monitoring method for amplifying the supervisory optical signal by a repeater amplifier included in the optical repeater amplifier and performing a supervisory optical signal amplification procedure for transmitting and receiving between the OLT and the optical repeater amplifier.   The monitoring optical signal detouring procedure for transmitting and receiving the monitoring optical signal between the OLT and the optical repeater amplifier by detouring the monitoring optical signal when the relay amplification unit is abnormal is performed. 9. The optical repeater amplifier monitoring method according to 8. When the relay amplification unit is normal and a communication link with the OLT by the monitoring optical signal is established, the monitoring optical signal amplification procedure is performed,
When the communication link is interrupted, the relay amplification unit is assumed to be abnormal and performs the monitoring optical signal bypass procedure,
Even after the monitoring optical signal detouring procedure is performed, if the communication link is broken and no abnormality is detected in the relay amplification unit, the monitoring optical signal amplification procedure is performed again to establish the communication link. 10. The optical repeater amplifier monitoring method according to claim 9, wherein the method waits.

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