Method of gain setting in wavelength division multiplexing transmission system

The present invention relates to a gain setting method in a wavelength division multiplexing transmission device. In particular, the present invention relates to a gain setting method using spontaneous emission light (ASE) generated by excitation light for an optical fiber amplifier.

[0002] [Conventional Technology] In recent years, in optical transmission technology, wavelength division multiplexing (WDM) technology for multiplexing and transmitting a plurality of optical signals having different wavelengths has been put into practical use, and the technology is becoming more and more practical. We are making progress.

[0003] FIG. 1 is a configuration example of a WDM transmission device as two adjacent relay devices in a plurality of relay devices connected in tandem in a wavelength division multiplexing (WDM) optical transmission system.

[0004] In the WDM transmission device, in the adjacent stations A and B, the signal light output from the station A to the station B is transmitted by the transmission line 202, and the receiving amplifier (Pre-) of the receiving amplifier unit 120 of the station B is transmitted. Input to Amp) 111.

[0005] The signal light amplified by the receiving amplifier 111 is separated into signal lights for each wavelength by the wavelength separator (DMUX) 112, and the path is selected (passing Thru / insertion Add / branch Drop) by the optical switch 113. ..

[0006] Further, the wavelength light passed (Thru) by the optical switch 113 is level-adjusted for each wavelength by the optical variable attenuator (VOA) 114 and input to the wavelength division multiplexing (MUX) 115 of the transmission amplifier unit 130. Will be done. Then, it is wavelength-multiplexed by the wavelength division multiplexing (MUX) 115, amplified by the transmission amplifier (Post-Amp) 116 of the transmission amplifier unit 130, and transmitted to a further next station (not shown) on the EAST side by the transmission line 203. Will be done.

[0007] Here, the receiving amplifier (Pre-Amp) 111 and the transmitting amplifier (Post-Amp) 116 use an optical fiber amplifier that uses excitation light from a laser diode (LD), and the laser diode (LD). The amplification factor is controlled by the magnitude of the current.

[0008] On the other hand, the wavelength branched by the optical switch 113 is transmitted to another network by the transmission line 207. In addition, for the wavelength newly inserted (Add) from the transmission line 206 by the optical switch 113, the level is adjusted by the optical variable attenuator (VOA) 114 in the same manner as the passed wavelength, and the wavelength division multiplexing (MUX) is performed. ) 115 wavelength division multiplexing. Then, it is amplified by the transmission amplifier 116 and transmitted to the next station (not shown) on the EAST side by the transmission line 203.

Similarly, the signal light output from the B station to the A station is transmitted by the transmission line 212 and input to the receiving amplifier 141 of the receiving amplifier unit 230 of the A station. The signal light amplified by the receiving amplifier 141 of station A is separated for each wavelength by the wavelength separator (DMUX) 142, and the path is selected (passing Thru / insertion Add / branch Drop) by the optical switch 143. The signal light from the transmission line 216 inserted by the pass (Thru) and the optical switch 143 is level-adjusted by the optical variable attenuator (VOA) 144, and is adjusted by the wavelength division multiplexing (MUX) 145 of the transmission amplifier unit 240. It is wavelength-multiplexed, amplified by the transmission amplifier 146, and transmitted to the next station (not shown) on the WEST side by the transmission line 213.

[0010] As described above, as a conventional example, a WDM transmission device is connected in tandem, optical transmission is performed in both directions, and a branch insertion of an optical signal is performed in each relay device (see, for example, Patent Document 1).

[0011] [Patent Document 1] Japanese Patent No. 3241337 Here, in a WDM transmission apparatus, it is necessary to amplify an optical signal so that the level per wave becomes constant in a receiving amplifier and a transmitting amplifier. For that purpose, it is necessary to set an appropriate gain (amplification degree) for each amplifier.

[0012] Taking the transmission amplifier 106 in the transmission amplifier unit 110 of station A and the reception amplifier 111 of the reception amplifier unit 120 of station B as an example, the level of each wavelength is adjusted by the optical variable attenuator (VOA) 104. Since the optical signal is input to the transmission amplifier 106, the gain can be uniquely determined.

However, in station B, since the input light level of the receiving amplifier 111 depends on the transmission line loss of the transmission line 202 and the like, when the power of the receiving amplifier 111 is turned on, the fiber of the transmission line 202 is replaced, and the fiber is used. When recovering from a disconnection, it is necessary to determine the gain of the receiving amplifier 111 according to the input level to the receiving amplifier 111.

[0014] Here, in order to correctly set the gain of the receiving amplifier 111, input light having a constant wavelength number and a stable level is input to the receiving amplifier 111 while the gain of the receiving amplifier 111 is being set. It is necessary.

[0015] Therefore, by setting the input light to the transmission amplifier 106 as the input light having a constant wavelength and a stable light level, the output light of the transmission amplifier 106 is stabilized and the wavelength is constant with respect to the reception amplifier 111. It is necessary to provide a stable number of input lights.

[0016] As a countermeasure for this, in the method of using the input light to the transmission amplifier 106 as the input light having a constant wavelength and a stable light level, the passing light transmitted from the previous station to the A station is used. It is conceivable to stop and set the add light by the optical switch 103 of the A station, or prepare a light source 107 for the reference light and input the constant light to the transmission amplifier 106.

[0017] Further, as a method of stopping the passing (Thru) light from the previous station of the station A, a method of dropping all the passing (Thru) light to the transmission line 205 at the optical switch 103 of the station A is also considered. Be done. Alternatively, the variable light attenuator (VOA) 104 can attenuate the thru light.

However, in any of the above methods, an insertion light source connected to the transmission line 204 and a light source 107 for reference light must be prepared, and all stations connected in tandem must be prepared. In the above, there is a problem that a large cost is required to prepare such a light source.

[0019] When the gain of the receiving amplifier is set by using the light source for starting up the receiving amplifier, the gain of the receiving amplifier of the previous span is obtained for the receiving amplifier of the span for which the light source is not prepared. After the setting is completed, it is conceivable to set the gain using the output light of the transmission amplifier of the previous span.

However, there is a problem that the gain is set in order from the receiving amplifier of the span in which the light source is set, and it takes time for the span to complete the gain setting of the receiving amplifier of all spans. ..

[0021] Further, when setting the gain of the receiving amplifier of the span without the light source, if the other span is in the service state, the light source is set from the span with the light source in order to set the receiving amplifier gain of the span without the light source. There is a problem that the service up to the span without a light source must be suspended.

Further, when the light passing through to the transmission amplifier 106 is stopped by the light variable attenuator (VOA) 104, the light variable attenuator 104 cannot completely attenuate the passing light, and leakage light is generated. When leakage light occurs, the input to the receiving amplifier 111 is not stable, and there arises a problem that the gain cannot be set correctly. Therefore, it is an issue to completely block the leaked light to the transmission amplifier 106.

Further, when it is necessary to set the gain of the receiving amplifier 111, the maintenance person must recognize the necessity of the gain setting of the receiving amplifier 111 and set the input light for the gain setting of the receiving amplifier 111. It doesn't become. Further, even after the gain setting of the receiving amplifier 111 is completed, the input light for gain setting of the receiving amplifier 111 must be returned to the original state and the signal light must be set. Therefore, there is a problem that a lot of maintenance personnel intervene until the gain setting of the receiving amplifier is completed, which imposes a burden on the maintenance operator and may cause a human error.

[0024] Further, when the gain of the receiving amplifier 111 is set, there is a problem that the signal light of that wavelength is crushed (cannot be used as the signal light) with respect to the wavelength in which the light for gain setting is set. Occurs. Therefore, when setting the gain of the receiving amplifier 111, it is necessary to input the input light having a stable light level to the receiving amplifier 111 without changing the existing signal light setting.

[0025] Therefore, an object of the present invention is to provide a gain setting method for a receiving amplifier in a WDM transmission device that solves the above-mentioned problems.

[Means for Solving the Problems] The first aspect of the gain setting method of the receiving amplifier in the WDM transmission device that achieves the above-mentioned problems of the present invention is to obtain a wavelength division multiplexing optical signal from the front station side. It is a gain setting method of the reception amplifier in a network in which a plurality of wavelength division multiplexing transmission devices having a reception amplifier for receiving amplification and a transmission amplifier for outputting a wavelength division multiplexing optical signal on the rear station side are connected in multiple stages. When the power of the receiving amplifier of the own station device is turned on, the necessity of gain setting of the receiving amplifier is detected, and the wavelength division multiplexing transmission device of the previous station is requested to ASE optical output, and the ASE optical output is requested. Based on this, the wavelength division multiplexing transmission device of the previous station blocks the passing light and the insertion light, outputs ASE light corresponding to a predetermined number of wavelengths of the signal light, and the receiving amplifier of the own station device is the ASE light. After the gain setting is completed, the own station device receives the optical signal and the wavelength division multiplexing transmission device of the previous station switches to the output of the optical signal.

[0027] The second aspect of the gain setting method of the receiving amplifier in the WDM transmission device that achieves the above-mentioned object of the present invention is the receiving amplifier that receives and amplifies the wavelength division multiplexing optical signal from the front station side, and the rear. It is a gain setting method of the receiving amplifier in a network in which a plurality of wavelength division multiplexing transmission devices having a transmission amplifier for outputting a wavelength division multiplexing optical signal on the station side are connected in multiple stages, and is used between the wavelength division multiplexing transmission devices. When recovering from the disconnection of the connected fiber or when replacing the fiber, the necessity of gain setting of the receiving amplifier is detected, and the wavelength division multiplexing transmission device of the previous station is requested to ASE optical output, and the ASE optical output is requested. Based on this, the wavelength division multiplexing transmission device of the previous station blocks the passing light and the insertion light, outputs ASE light corresponding to a predetermined number of wavelengths of the signal light, and the receiving amplifier of the own station device is the ASE light. After the gain setting is completed, the own station device receives the optical signal and the wavelength division multiplexing transmission device of the previous station switches to the output of the optical signal.

[0028] The third aspect of the gain setting method of the receiving amplifier in the WDM transmission device that achieves the above-mentioned object of the present invention corresponds to a predetermined number of wavelengths of the signal light in the first or second aspect. The ASE light is characterized by being ASE light corresponding to one wavelength of signal light.

[0029] The fourth aspect of the gain setting method of the receiving amplifier in the WDM transmission device that achieves the above-mentioned problem of the present invention is, in the first or second aspect, the plurality of wavelength division multiplexing transmission devices are the devices. It is characterized in that it includes a network element that controls the whole, and detects the necessity of gain setting of the receiving amplifier by the network element of the own station when the power of the receiving amplifier of the own station is turned on.

[0030] The fifth aspect of the gain setting method of the receiving amplifier in the WDM transmission device that achieves the above-mentioned object of the present invention is arranged on the input side of the transmitting amplifier in the first or second aspect. It is characterized in that the passing light and the insertion light are blocked by closing the shutter.

[0031] The sixth aspect of the gain setting method of the receiving amplifier in the WDM transmission device that achieves the above-mentioned problem of the present invention is, in the fifth aspect, when the transmitting amplifier of the previous station outputs ASE light. It is characterized in that the state of the shutter arranged on the input side of the transmission amplifier is monitored, and when an abnormality occurs, the maintenance person is notified of the abnormality.

[0032] In the first or second aspect, the seventh aspect of the gain setting method of the receiving amplifier in the WDM transmission device that achieves the above-mentioned problem of the present invention is the transmission amplifier of the previous station in the own station device. If the stable state of the ASE optical output is monitored and the unstable state of the transmission amplifier of the previous station is detected during the gain setting of the reception amplifier of the own station, the gain of the reception amplifier of the own station is detected. The feature is that the setting is canceled, the stable state of the ASE optical output of the transmission amplifier of the previous station is detected again, and then the gain of the reception amplifier of the own station is reset.

[0033] The features of the present invention will be further clarified from the examples of embodiments of the invention described below with reference to the drawings.

[0034] FIG. 2 is an example of an embodiment of a WDM transmission device as a relay device in a wavelength division multiplexing (WDM) optical transmission system according to the present invention. 3 to 9 are operation flows of an embodiment using the configuration of FIG. 2, and FIG. 10 is a diagram showing the relationship of FIGS. 3 to 9.

That is, as shown in FIG. 10, the operation of the embodiment has, for example, the flow of FIGS. 3 and 7 to 9, and by changing only the part of FIG. 3, FIGS. 4 and 5 , Or a different embodiment of FIG.

First, the operation of the first embodiment in FIG. 2 will be described with reference to FIGS. 3 and 7 to 9.

[0037] In FIG. 2, the network element (NEM) 311 of station B is a device that controls the entire station B. When the power is turned on to the receiving amplifier (preamplifier) unit 120 of the own (B) station (processing step P0), the control unit (not shown) of the receiving amplifier unit 120 sends the network element (NEM) 311 to the network element (NEM) 311 for gain setting. , Request provisioning information (processing process P1).

[0038] In response to this, provisioning information is sent from the network element (NEM) 311 to the control unit of the receiving amplifier unit 120 (processing step P2).

[0039] In the receiving amplifier unit 120, the control unit instructs the receiving amplifier 120 to make settings corresponding to the provisioning information (processing step P3).

When gain control by ASE optical is required for the receiving amplifier 111, conditions such as an output target value (Provisioning) are set in the receiving amplifier 111 of the WDM transmission device of station B.

When the provisioning setting for the receiving amplifier 111 is completed, the gain setting by ASE optical is ready (processing process P4), the AMP mode is notified to the control unit (processing process P4-1), and the receiving amplifier 111 is set. If it is set within the support range, the transmission amplifier unit 110 of station A is required to output ASE optical (processing process P5, Yes).

[0042] Here, the ASE light is spontaneous emission light (ASE: Amplified Spontanous Emission) induced by excitation light by a laser diode (LD) supplied to an optical fiber amplifier as a transmission amplifier 106.

Further, the gain control by ASE light is as shown in FIG. 11, and in the AGC control mode, the LD current (vertical axis) that excites the receiving amplifier 111 increases when the input wavelength number (horizontal axis) increases. growing. On the other hand, in ASE mode control, the number of wavelengths of the optical signal sent from the transmitting amplifier 106 is fixed to one wave, and therefore the LD current for excitation to the receiving amplifier 111 is constant, making it easy to set the gain. is there.

[0044] When gain control by ASE light is required, the optical signal control circuit (OSC) 312 of the WDM transmission device of station B passes through the transmission line 212 and the optical signal control circuit (OSC) 302 of station A. The transmission amplifier unit 110 of station A is notified of the information ASEREQ = 1, which means an ASE optical output request, by an OSC signal (processing steps P6-1, 6-2, 6-3).

Further, in FIG. 7, when the control unit of the transmission amplifier unit 110 of the station A detects the information signal ASEREQ = 1 (processing step P7), the transmission amplifier ShutDownX = 1 for shutting down the information signal ShutDownX = 1. Send to 106 (processing process P8).

Further, the shutter 108 is controlled so as to block the passing (Thru) light and the inserting (Add) light input to the transmission amplifier 106 (processing step P9).

[0047] The closing of the shutter 108 is confirmed by the closing control of the shutter 108 in the processing step P9, and if it is not in the closed state (processing steps P10, No), the network element (NEM) 301 of the station A is abnormal. Is notified (processing process P11).

[0048] When the network element (NEM) 301 receives an abnormality notification from the control unit of the transmission amplifier unit 110, it issues an alarm and notifies the maintenance person of the abnormality (processing step P12).

On the other hand, when the closed state of the shutter 108 is confirmed in the processing step P10 (processing step P10, Yes), the above information signal ASEREQ = 1 is sent to the transmission amplifier 103 (processing step P13).

[0050] Based on the information signal ASEREQ = 1, the transmission amplifier 106 generates the information signal ASE = 1 in a state where the ASE optical output preparation is completed (processing step P14), and notifies the control unit of the transmission amplifier unit 110 of this. (Processing process P15).

Upon receiving the information signal ASE = 1, the control unit of the transmission amplifier unit 110 sends the information signal ShutDownX = 0 to release the shutdown to the transmission amplifier 106 (processing step P17). The transmission amplifier 106 starts outputting ASE light corresponding to n wave fractions of signal light (processing step P18).

[0052] When the output of the ASE light corresponding to n wave fractions of the signal light becomes stable, the transmission amplifier 106 generates an information signal ASE_NORMOP = 1 which means output stability (processing step P19), and this information signal ASE_NORMOP = 1 Is notified from the optical signal control circuit (OSC) 302 to the reception amplifier unit 120 of station B via the transmission line 202 and the optical signal control circuit (OSC) 312 of station B by an OSC signal (processing step). P20-1,20-2,20-3,20-4).

[0053] When the control unit of the receiving amplifier unit 120 of the B station detects the information signal ASE_NORMOP = 1, it requests the receiving amplifier 111 to start the gain setting of the receiving amplifier 111 (processing step P21). This request is notified as the information signal ShutDownX = 0 (processing step P22).

As a result, the profit receiving amplifier 111 starts gain setting (processing step P23). On the other hand, the control unit of the transmission amplifier unit 110 of station A monitors the stability of the ASE optical output level of the transmission amplifier 106, and if it becomes unstable (processing steps P24, N0), sets the information signal ASE_NORMOP = 0. The reception amplifier unit 120 of station B is notified by an OSC signal from the optical signal control circuit (OSC) 302 via the transmission line 202 and the optical signal control circuit (OSC) 312 of station B (processing step P25). -1,25-2,25-3,25-4).

Next, the process proceeds to FIG. 8, and the control unit of the receiving amplifier unit 120 of station B detects whether the information signal ASE_NORMOP = 1 remains (processing step P26). When the information signal ASE_NORMOP = 0 is changed (processing step P26, No), the information signal ShutDownX = 1 is sent to the receiving amplifier 111 (processing step P27), and the process returns to processing step P21 (see FIG. 8).

The receiving amplifier 111 detects whether the information signal ShutDownX = 1 has changed (processing step P29), and when the information signal ShutDownX = 1 (processing step P29, Yes), the gain control is stopped. (Processing process P30).

[0057] When the gain control is completed, the information signal AGC / ALC = 1 is notified (processing step P31). The information signal AGC / ALC = 1 is notified to the control unit of the receiving amplifier unit 120 (processing step P32). In response to this, the control unit further requests the transmission amplifier 106 of the transmission amplifier unit 110 of station A to stop the ASE optical output (processing step P33).

[0058] For this request, the information signal ASEREQ = 0 is transmitted by the OSC signal from the optical signal control circuit (OSC) 312 via the transmission line 212 and the optical signal control circuit (OSC) 302 of station A. Notify the control unit of unit 110 (processing steps P34-1,34-2,34-3,34-4).

When the control unit of the transmission amplifier unit 110 of station A receives the information signal ASEREQ = 0, it controls the transmission amplifier 106 to end the ASE optical output and switch to the signal light (processing step P35). .. This control is performed by shifting to FIG. 9 and sending the information signals ShutDownX = 1 and ASEREQ = 0 from the control unit of the transmission amplifier unit 110 to the transmission amplifier 106 (processing steps P36 and P37).

[0060] Based on this, when the signal light output preparation is completed, the transmission amplifier 106 outputs the information signal ASE = 0 (processing step P38) and notifies the control unit of the transmission amplifier unit 110 of station A (processing). Process P39).

[0061] The control unit of the transmission amplifier unit 110 controls to open the shutter 108 when the information signal ASE = 0 is received from the transmission amplifier 106 (processing step P40). The control unit confirms that the shutter 108 is open (processing process P41, Yes), sends the information signal ShutDownX = 0 to the transmission amplifier 106 (processing process P42), and starts the signal light output (processing process P43). ).

[0062] Returning to FIG. 4, the operation of the second embodiment will be described. In the embodiment shown in FIG. 4, the network element 311 of station B asks the control unit of the receiving amplifier unit 120 whether or not the power is turned on by polling (processing step P0-1). On the other hand, the information signal RMV indicating that the power is not turned on is returned until the power is turned on to the receiving amplifier 111 (processing step P0-2).

[0063] When the power is turned on to the receiving amplifier 111 (processing process P0), the information signal RMV_Clear indicating the power-on is returned in response to the question of whether or not the power is turned on (processing process P0-1) (processing process). P0-3). As a result, the network element 311 detects that the power is turned on to the receiving amplifier 111 (processing step P0-4).

On the other hand, when the information signal RMV_Clear indicating the power-on is returned to the network element 311 while the power is turned on to the receiving amplifier 111, the gain from the control unit of the receiving amplifier unit 120 to the network element 311. Request conditional (provisioning) information for configuration (processing process P1).

[0065] On the other hand, provisioning information is sent from the network element (NEM) 311 to the control unit of the receiving amplifier unit 120 (processing step P2).

[0066] In the receiving amplifier unit 120, the control unit instructs the receiving amplifier 120 to make settings corresponding to the provisioning information (processing step P3).

When gain control by ASE optical is required for the receiving amplifier 111, conditions such as an output target value (Provisioning) are set in the receiving amplifier 111 of the WDM transmission device of station B.

On the other hand, the receiving amplifier 111 notifies the control unit of the AMP mode (processing process P4-1), and the control unit further notifies the network element (NEM) 311 of the AMP mode (processing process P4-2). ..

[0069] Therefore, in the network element (NEM) 311 it is determined whether or not the receiving amplifier 111 is set in the support (processing step P5-1), and the receiving amplifier 111 is set in the support. For example, the network element (NEM) 311 sends an information signal ASEREQ = 1, which means an ASE optical output request, to the control unit.

[0070] When the control unit receives the information signal ASEREQ = 1, it generates a gain setting request signal XALCREQ = 0 by the ASE term for the receiving amplifier 111 (processing step P5-3), and notifies the receiving amplifier 111 of this. (Processing process P5-4).

Therefore, the receiving amplifier 111 transitions to the ready state for gain setting by ASE optical (processing step P4).

From the control unit, the transmission amplifier of station A is further passed through the optical signal control circuit (OSC) 312 of the WDM transmission device of station B, the transmission line 212, and the optical signal control circuit (OSC) 302 of station A. The information ASEREQ = 1, which means an ASE optical output request, is notified to the unit 110 by an OSC signal (processing steps P6-1, 6-2, 6-3).

The operation flow following FIG. 4 is the same as the processing of FIGS. 7 to 9 described above.

By performing the operation processing of the embodiments shown in FIGS. 3, 4, and 7 to 9, the gain of the receiving amplifier 111 is automatically obtained without a light source when the receiving amplifier unit 120 is turned on. It is possible to complete the setting. Further, since a light source is not required, it is possible to set the gain of the receiving amplifier at the same time for all stations and independently for each span.

[0075] Here, consider a case where recovery from fiber disconnection of the transmission line 202 and fiber exchange are performed between station A and station B in FIG. 2.

[0076] FIGS. 5 and 6 show an example in such a case, and is an example operation flow of gain control of the receiving amplifier 111 when the transmission line 202 connecting the A station and the B station is restored from the disconnection state. ..

[0077] In the embodiment of FIG. 5, when a fiber break occurs (processing step P100), the optical signal control circuit (OSC) 312 of station B detects the break state of the transmission line 202 based on the break of the OSC signal (processing step P100). Processing process P101).

[0078] When the optical signal control circuit (OSC) 312 detects the disconnected state of the transmission line 202, it notifies the control unit of the receiving amplifier unit 120 of the information signal APSD_OSC = 1 indicating the disconnected state (processing step P102). ).

[0079] When the control unit of the receiving amplifier unit 120 receives the information signal APSD_OSC = 1, it considers it as a fiber break or replacement, and generates a gain setting request XALCREQ = 0 by ASE optical for the receiving amplifier 111 ( Processing process P103), this is notified (processing process P5-4). Therefore, the receiving amplifier 111 transitions to the forward state of the gain setting by the ASE light (processing step P4).

On the other hand, when the fiber break is restored (processing process P104), this is detected by the optical signal control circuit (OSC) 312 (processing process P105), and the information signal APSD_OSC = 0 indicating that the fibers are correctly connected. Is notified to the control unit of the receiving amplifier unit 120 (processing step P107).

[0081] As a result, the transmission amplifier of station A from the control unit via the optical signal control circuit (OSC) 312 of the WDM transmission device of station B, the transmission line 212, and the optical signal control circuit (OSC) 302 of station A. The information ASEREQ = 1, which means an ASE optical output request, is notified to the unit 110 by an OSC signal (processing steps P6-1, 6-2, 6-3).

The operation flow following FIG. 5 after that is the same as the processing of FIGS. 7 to 9 described above.

[0083] When the optical signal control circuit (OSC) 312 detects a fiber break and a fiber break recovery, the operation of the embodiment shown in FIG. 6 is notified to the network element 311 instead of the control unit of the receiving amplifier unit 120 ( The processing steps P1-2-1, P106-1) are different from the operation of the embodiment shown in FIG.

[0084] Correspondingly, the information ASEREQ = 1, which means the ASE optical output request, is emitted from the network element 311 (processing step P6-0), the control unit of the receiving amplifier unit 120, and the WDM transmission device of station B. The transmission amplifier unit 110 of station A is notified by an OSC signal via the optical signal control circuit (OSC) 312, the transmission line 212, and the optical signal control circuit (OSC) 302 of station A (processing step P6-). 1,6-2,6-3).

[0085] The subsequent processing is the same as that of the previous example, and is the same as the processing of FIGS. 7 to 9 described above.

[0086] Here, the opening / closing control of the shutter 102 in each of the above embodiments will be further described. In the transmission amplifier unit 110 of station A, the information ASEREQ that is an ASE optical output request from the reception amplifier unit 120 of station B via the optical signal control circuit (OSC) 312, the transmission line 212, and the optical signal control circuit (OSC) 302. When = 1 is received, the shutter 105 in front of the transmission amplifier 106 is closed.

Further, when the information ASEREQ = 0 indicating that the gain setting is completed is received from the reception amplifier unit 120 of the B station by the OSC signal, the shutter 108 in the front stage of the transmission amplifier unit 106 is opened and the signal is sent to the transmission amplifier 106. Enter the light.

That is, by closing the shutter 108 while outputting the ASE light of the transmitting amplifier 106, the leakage light to the transmitting amplifier 106 is completely blocked, and the transmitting amplifier 106 is stabilized only by the ASE light. It can output light. As a result, the reception amplifier 111 of station B can set the gain at a stable light level.

Here, in the transmission amplifier unit 110 of station A, the state of the shutter 108 in front of the transmission amplifier 106 is monitored, and if the state (open / closed) of the shutter 108 is different from the request, reception is performed. The ASE optical output of the amplifier 106 is not performed, and the network element 301 is notified of the abnormality of the shutter 108.

[0090] As a result, it is possible to prevent the gain of the receiving amplifier 111 of the B station from being set to an invalid value.

Further, the network element 301 notifies the maintenance person of the abnormality of the shutter 108 by a display device (not shown), so that the maintenance person can recognize the abnormality of the shutter 108.

(Appendix 1) A plurality of wavelength-divided multiplex transmission devices having a receiving amplifier that receives and amplifies a wavelength-divided multiplex optical signal from the front station side and a transmission amplifier that outputs a wavelength-divided multiplex optical signal to the rear station side. This is a method of setting the gain of the receiving amplifier in a network in which the above are connected in multiple stages. When the power of the receiving amplifier of the own station device is turned on, the necessity of the gain setting of the receiving amplifier is detected, and the wavelength of the previous station is divided. The ASE optical output is requested from the multiplex transmission device, and the ASE corresponding to a predetermined number of wavelengths of the signal light is blocked by the wavelength division multiplex transmission device of the previous station based on the request for the ASE optical output. The receiving amplifier of the own station device outputs light, and the gain setting is performed by the ASE light, and after the gain setting is completed, the own station device receives an optical signal and the wavelength division multiplex transmission device of the previous station. A gain setting method for a receiving amplifier in a wavelength division multiplexing transmission device characterized by switching to an optical signal output.

(Appendix 2) A plurality of wavelength-divided multiplex transmission devices having a receiving amplifier for receiving and amplifying a wavelength-divided multiplex optical signal from the front station side and a transmission amplifier for outputting a wavelength-divided multiplex optical signal on the rear station side. It is a method of setting the gain of the receiving amplifier in a network in which the above are connected in multiple stages, and it is necessary to set the gain of the receiving amplifier at the time of recovery from the fiber disconnection connecting the wavelength division multiplex transmission devices or at the time of fiber replacement. Is detected, the ASE optical output is requested from the wavelength division multiplex transmission device of the previous station, and the signal light is blocked by the wavelength division multiplex transmission device of the previous station based on the request of the ASE optical output, and the passing light and the insertion light are blocked. The receiving amplifier of the own station device outputs the ASE light corresponding to the predetermined number of wavelengths of the above, sets the gain by the ASE light, and after the gain setting is completed, the own station device receives the optical signal and the above. A gain setting method for a receiving amplifier in a wavelength division multiplexing transmission device, which comprises switching to an optical signal output in the wavelength division multiplex transmission device of the previous station.

(Appendix 3) In Appendix 1 or 2, wavelength-divided multiplexed transmission is characterized in that the ASE light corresponding to a predetermined number of wavelengths of the signal light is the ASE light corresponding to one wavelength of the signal light. How to set the gain of the receiving amplifier in the device.

(Appendix 4) In Appendix 1 or 2, the plurality of wavelength division multiplex transmission devices include a network element that controls the entire device, and when the power of the reception amplifier of the own station is turned on, the network element of the own station is provided. A method for setting a gain of a receiving amplifier in a wavelength division multiplexing transmission device, which comprises detecting the necessity of setting a gain of the receiving amplifier.

(Appendix 5) In Appendix 1 or 2, the wavelength division multiplexing transmission apparatus according to Appendix 1 or 2, wherein the passing light and the insertion light are blocked by closing the shutter arranged on the input side of the transmission amplifier. How to set the gain of the receiving amplifier.

(Appendix 6) In Appendix 5, when the transmitting amplifier of the previous station outputs ASE light, the state of the shutter arranged on the input side of the transmitting amplifier is monitored, and if an abnormality occurs, A method of setting a gain of a receiving amplifier in a wavelength division multiplex transmission device, which comprises notifying a maintenance person of an abnormality.

(Appendix 7) In Appendix 1 or 2, the local device monitors the stable state of the ASE optical output of the transmission amplifier of the previous station, and the previous station is set while the gain of the reception amplifier of the own station is set. When the unstable state of the transmission amplifier of the previous station is detected, the gain setting of the reception amplifier of the own station is stopped, the stable state of the ASE optical output of the transmission amplifier of the previous station is detected again, and then the own station is detected. A method of setting a gain of a receiving amplifier in a wavelength division multiplexing transmission device, which comprises resetting the gain of the receiving amplifier of.

[Effects of the Invention] The following effects can be obtained by the present invention as described above with reference to the embodiments of the invention.

[0100] Since the gain of the receiving amplifier is set by the ASE light of the transmitting amplifier, a light source for setting the gain of the receiving amplifier is not required. This makes it possible to reduce the cost of preparing a light source for all stations.

[0101] Since the gain of the receiving amplifier is set by the ASE light of the transmitting amplifier, the gain of the receiving amplifier can be set at the same time for each span independently. Therefore, the reception amplifier gain setting time for all spans does not depend on the number of spans, and the setting time can be shortened. Moreover, since each span can set the receiving amplifier gain independently without depending on other spans, even if the other spans are in the service state, the receiving amplifier gain can be set without affecting the service. Is possible.

[0102] By providing a shutter in front of the transmission amplifier, the leakage light to the transmission amplifier can be completely blocked, so that the reception amplifier sets the gain at a stable input level and sets the correct gain. It becomes possible to do.

[0103] Regarding the gain setting of the receiving amplifier, since the necessity of the gain setting is detected and the signal light is passed through automatically after the gain setting is completed, the burden on the maintenance person is reduced and the reliability is improved. To do.

Further, since the gain of the receiving amplifier is set using the ASE light of the transmitting amplifier, the gain can be set without changing the existing signal light setting.

BRIEF DESCRIPTION OF THE DRAWINGS [Fig. 1] Fig. 1 is a diagram showing a configuration example of a WDM transmission device as two adjacent relay devices.

FIG. 2 is a diagram showing an example of an embodiment of a WDM transmission device as a relay device in a wavelength division multiplexing (WDM) optical transmission system according to the present invention.

FIG. 3 is a first embodiment operation flow (No. 1) using the configuration of FIG.

FIG. 4 is a second embodiment operation flow (No. 1) using the configuration of FIG.

FIG. 5 is a third embodiment operation flow (No. 1) using the configuration of FIG.

FIG. 6 is a fourth embodiment operation flow (No. 1) using the configuration of FIG.

FIG. 7 is an operation flow (No. 2) common to the first to fourth embodiments.

FIG. 8 is an operation flow (No. 3) common to the first to fourth embodiments.

FIG. 9 is an operation flow (No. 4) common to the first to fourth embodiments.

10 is a diagram showing the relationship between FIGS. 3 to 9. FIG.

FIG. 11 is an LD current comparison diagram in the AGC mode and in the ASE mode embodiment.

[Code description] 110 Transmitter amplifier unit 120 Receiving amplifier unit 106 Transmitting amplifier 111 Receiving amplifier 105 Shutter 311, 301 Network element 302, 312 Optical signal control circuit (OSC)