JP2006196938A - Optical network system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical network system capable of monitoring an optical transmission line not used for signal transmission. <P>SOLUTION: Line measurement apparatuses 24, 44 and dummy light sources 26, 46 are connected to optical cross-connectors 14, 34 of optical signal distributors 12, 32. A network management server 70 can set an optical path passing through a desired optical amplifier line between terminals 10-1 to 10-n and terminals 30-1 to 30-m by remotely controlling the optical cross-connectors 14, 34 of the optical signal distributors 12, 32. The network management server 70 controls the optical cross-connector 14 to deliver dummy light from either of the dummy light sources, e.g., the dummy light source 26 at all times. The line measurement apparatus 24 or 44 monitors the presence / absence of a fault in the optical amplifier line 50 at all times and informs the network management server 70 about a result of monitoring via a control network 22. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical network system.

  In general, an optical amplifier is provided in the optical line of the optical network system. Some optical amplifiers are added with a function of monitoring the presence or absence of input light and shutting down optical amplification when there is no input light.

  Further, in an optical network that can set various optical paths such as a mesh or a ring, or an optical network that can provide a spare optical path in addition to the working optical path, there may be an optical line through which no signal light propagates.

  As a technology for remotely monitoring the optical transmission line, a technology for measuring the presence or absence of signal light at major points, and OTDR (Coherent Optical Time Domain Reflectometry) for monitoring reflected light or backscattered light for monitoring light or signal light Alternatively, C-OTDR (Coherent OTDR) is known.

  When signal light is not input to the optical transmission line in which the optical amplifier with the input light monitoring function is arranged, the input light monitoring function of the optical amplifier operates to stop the excitation light of the optical amplifier. If pump light is continuously supplied to the optical amplifier without operating the input light monitoring function of the optical amplifier, an optical surge will occur in the optical amplifier when signal light is input to the optical amplifier due to switching of the optical path, etc. In the worst case, the optical amplifier and the optical device arranged in the subsequent stage are destroyed. Therefore, an optical amplifier to which no signal light is input should not be held in an excited state.

  When the excitation light of the optical amplifier is stopped, the optical signal is attenuated and cannot be propagated through the optical transmission line. As a result, line faults such as disconnection that may occur in the optical transmission line cannot be monitored by the monitoring function described above. After that, when it becomes necessary to newly use for signal transmission, first, it must be measured whether or not there is a failure in the optical transmission line.

  An object of the present invention is to provide an optical network system capable of monitoring an optical transmission line that is not used for signal transmission.

  An optical network system according to the present invention is an optical network system comprising a plurality of optical signal distribution devices and a plurality of optical lines connecting the plurality of optical signal distribution devices, and capable of switching an optical path, A dummy light is supplied to an unused optical line.

  According to the present invention, by supplying dummy light to an unused optical line, the presence or absence of a line failure can be optically measured by an existing optical measuring device. In addition, since the optical amplifier on the unused optical amplification line can be maintained in a predetermined operation state, it is possible to suppress the occurrence of an optical surge when setting the optical path. In addition, it is possible to monitor the failure of the optical amplification line regardless of the presence or absence of the optical path.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic block diagram of an embodiment of the present invention. A plurality of terminals 10 (10-1 to 10-n) are connected to the optical cross-connect device 14 of the optical signal distribution device 12. The optical cross-connect device 14 includes a plurality of input ports and a plurality of output ports, and is a well-known device capable of distributing each of a plurality of input signal lights to a desired output port. The optical cross-connect device 14 includes WDM (wavelength division multiplexing) multiplexers 16 and 18 that multiplex signal light of different wavelengths to generate WDM signal light, and WDM that separates the WDM signal light into signal light of individual wavelengths. Separating devices 20 and 22, a line measuring device 24 and a dummy light source 26 are connected. The line measuring device 24 includes, for example, an optical measuring device such as an optical power measuring device, an OTDR measuring device, a C-OTDR measuring device, a wavelength dispersion monitor, or a polarization mode dispersion monitor. Although details will be described later, the dummy light source 26 is a wavelength belonging to a signal wavelength band for monitoring an optical line not transmitting signal light by using the line measuring device 24 or the line measuring device of another optical signal distribution device. For example, an ASE (Amplified Spontaneous Emission) light source, a laser diode, a modulated DFB (Distributed Feedback Bragg reflector) light source, or an unmodulated DFB light source.

  Similarly, a plurality of terminals 30 (30-1 to 30-m) are connected to the optical cross-connect device 34 of the optical signal distribution device 32. Connected to the optical cross-connect device 34 are WDM multiplexers 36 and 38, WDM separation devices 40 and 42, a line measuring device 44 having the same function as the line measuring device 24, and a dummy light source 46.

  In the embodiment shown in FIG. 1, the output signal light (WDM signal light) of the WDM multiplexer 16 is input to the WDM separation device 40 via the optical amplification line 50. The optical amplification line 50 includes an optical fiber 52 and an optical amplifier 54. Similarly, the output signal light (WDM signal light) of the WDM multiplexer 36 is input to the WDM separator 20 via the optical amplification line 56. The optical amplification line 56 includes an optical fiber 58 and an optical amplifier 60.

  The output signal light of the WDM multiplexer 18 is supplied to a third optical signal distribution device (not shown) via the optical amplification line 62, and the WDM signal light output from the third optical signal distribution device passes through the optical amplification line 64. To the WDM separator 22. The output signal light of the WDM multiplexer 38 is supplied to a fourth optical signal distribution device (not shown) via the optical amplification line 66, and the WDM signal light output from the fourth optical signal distribution device is transmitted via the optical amplification line 68. To the WDM separator 42.

  The network management server 70 controls and monitors the optical signal distribution devices 12 and 32 via the control network 72. The network management server 70 can also monitor the operation state of the optical amplifiers 54 and 60 on the optical amplification lines 50, 56, 62, 64, 66, and 68, and remotely control the on / off of the excitation light.

  The network management server 70 remotely controls the optical cross-connect devices 14 and 34 of the optical signal distribution devices 12 and 32, so that desired optical amplification is performed between the terminals 10-1 to 10-n and 30-1 to 30-m. You can set up an optical path through the track.

  In such an optical fiber communication network, an alternative line is prepared in advance in preparation for an unexpected failure of the optical amplification line. Such an alternative line is not used at all at normal times, or is used for a low quality service that does not provide an alternative line when a failure occurs. In the latter case, since some signal light flows through the optical amplification line, the line measuring device 24 can always monitor the occurrence of a failure in the optical line. However, in the former case, since no signal light is transmitted, the line measuring devices 24 and 44 cannot monitor the failure of the optical amplification line. There is a possibility that a failure may occur while not in use. When a failure has occurred in the working optical line using the optical amplification line as a backup path, it is understood that the optical amplification line is disconnected only after switching to the optical amplification line as the backup path. This cannot serve as a standby optical line.

  Therefore, in this embodiment, dummy light from any one of the dummy light sources is always allowed to flow through an optical amplification line that does not transmit signal light (hereinafter referred to as an unused optical amplification line). Then, any of the line measurement devices constantly monitors whether there is a failure in the optical amplification line, and notifies the network management server 70 via the control network 72 of the monitoring result.

  For example, when the optical amplification line 50 is a completely spare optical line that does not transmit signal light, the server 70 controls the optical cross-connect device 14 of the optical signal distribution device 12 to output dummy of the dummy light source 26. Light is output to the optical amplification line 50. Then, the server 70 causes the line measuring device 24 or 44 to measure the transmission state of the optical amplification line 50. The line measuring device 24 or 44 notifies the server 70 of the measurement result.

  As described above, in this embodiment, the dummy light is transmitted to the unused optical amplification line, so that the existing optical line monitoring technology is used to constantly measure and monitor whether the unused line is available. can do. By always supplying dummy light to the unused optical amplification line, an optical amplifier that automatically shuts down when there is no optical input can be used as the optical amplifiers 54 and 60 on the optical amplification line. Further, when the optical amplifier is excited even in the absence of optical input, an optical surge is likely to occur due to a sudden input of an optical signal when switching to the current one. In this embodiment, since the optical amplifier on the unused optical amplification line can be made to stand by in an operating state, an optical surge can be prevented even when switched to the current use.

  Thus, in this embodiment, the unused optical amplification line can be constantly monitored without preparing a special wavelength for monitoring the optical amplification line, so that the wavelength utilization efficiency is improved.

  Although the invention has been described with reference to specific illustrative embodiments, various modifications and alterations may be made to the above-described embodiments without departing from the scope of the invention as defined in the claims. This is obvious to an engineer in the field to which the present invention belongs, and such changes and modifications are also included in the technical scope of the present invention.

It is a schematic block diagram of one Example of this invention.

Explanation of symbols

10 (10-1 to 10-n): terminal 12: optical signal distribution device 14: optical cross-connect device 16, 18: WDM (wavelength division multiplexing) multiplexer 20, 22: WDM separation device 24: line measurement device 26: Dummy light source 30 (30-1 to 30-m): terminal 32: optical signal distribution device 34: optical cross-connect device 36, 38: WDM (wavelength division multiplexing) multiplexing device 40, 42: WDM separation device 44: line measuring device 46: Dummy light source 50: Optical amplification line 52: Optical fiber 54: Optical amplifier 56: Optical amplification line 58: Optical fiber 60: Optical amplifiers 62, 64, 66, 68: Optical amplification line 70: Network management server 72: Control network

Claims (5)

  An optical network system comprising a plurality of optical signal distribution devices and a plurality of optical lines connecting the plurality of optical signal distribution devices, wherein the optical path can be switched, and dummy light is applied to an unused optical line An optical network system characterized by being supplied.   The optical network system according to claim 1, wherein the wavelength of the dummy light belongs to a signal wavelength band of the optical line.   The optical network system according to claim 1, wherein a dummy light source that generates the dummy light is connected to one or more of the plurality of optical signal distribution devices.   4. The optical network system according to claim 1, further comprising an optical measuring device that optically detects a failure of the unused optical line supplied with the dummy light. .   The optical network system according to claim 1, wherein the optical line is an optical amplification line.

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