JP2008199450A - Optical access system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable optical access system. <P>SOLUTION: The optical access system is provided with a first device, a first two-wavelength multiplexing/demultiplexing coupler, an optical fiber and a second device which receives an optical signal from the optical fiber, wherein the first device is provided with a first optical transmission means for transmitting an optical signal with first wavelength and a second optical transmission means for transmitting an optical signal with second wavelength and the first two-wavelength multiplexing/demultiplexing coupler outputs a wavelength multiplexing optical signal obtained by multiplexing the optical signals with the first wavelength and the second wavelength transmitted by the first device to the optical fiber. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical access system having a protection against a failure of an optical transceiver.

  The optical access system is a system composed of a node device installed in a communication station, a home device installed in a user's home that uses a communication service, and an optical fiber that connects the node device and the home device. It is used for providing communication services (see Non-Patent Document 1, for example).

“Solutions in the Broadband Era“ Optical Access System ”” [online], Mitsubishi Electric Corporation, [Searched on December 19, 2006], Internet <URL: http://www.mitsubishielectric.co.jp/corporate/ randd / information_technology / communication / com04.html>

  Node devices and in-home devices used in the optical access system have an optical transmission unit and an optical reception unit including a laser diode having a relatively high failure rate, and are serviced by an optical transmission unit or an optical reception unit failure. Interruption occurs. In order to develop high-speed communication services, node devices must be installed in unmanned stations without maintenance personnel. However, when node devices fail in these unmanned stations, or in-home devices fail. When this occurs, the replacement of the faulty part cannot be executed immediately, and there is a problem that service provision remains interrupted until the replacement.

  Accordingly, an object of the present invention is to provide an optical access system that solves the above-described problems and has higher reliability than conventional ones.

According to the optical access system of the present invention,
An optical access system comprising a first device, a first two-wavelength multiplexing / demultiplexing coupler, an optical fiber, and a second device that receives an optical signal from the optical fiber, wherein the first device comprises: , First optical transmission means for transmitting the optical signal of the first wavelength, and second optical transmission means for transmitting the optical signal of the second wavelength, A wavelength multiplexed optical signal obtained by combining the optical signals of the first wavelength and the second wavelength transmitted by the first device is output to the optical fiber.

According to another embodiment of the optical access system of the present invention,
The second two-wavelength multiplexing / demultiplexing coupler demultiplexes the wavelength multiplexed optical signal output to the optical fiber, and outputs the first wavelength optical signal and the second wavelength optical signal, respectively. The second apparatus further includes a wavelength multiplexing / demultiplexing coupler, wherein the second device receives a first optical receiving means for receiving an optical signal of the first wavelength output from the second two-wavelength multiplexing / demultiplexing coupler, It is also preferable to include a second optical receiving unit that receives an optical signal of two wavelengths and a unit that selects an output signal of the first optical receiving unit or the second optical receiving unit.

According to another embodiment of the optical access system of the present invention,
One second optical transmission means is provided for the first optical transmission means of N, where N is an integer of 2 or more, and the second optical transmission means is a 1: M coupler, where And M is an integer greater than or equal to N, and the first two-wavelength multiplexing / demultiplexing coupler is provided for each of the first optical transmission means, each of which corresponds to the corresponding first optical transmission means and 1: It is also preferable to connect with an M coupler.

Furthermore, according to another embodiment of the optical access system of the present invention,
One second optical transmission means is provided for N first optical transmission means, where N is an integer equal to or greater than 2, and the second optical transmission means is controlled by the first device. The first two-wavelength multiplexing / demultiplexing couplers are connected to the first optical transmission means, and each is connected to the corresponding first optical transmission means and the optical switch. It is also preferable.

Furthermore, according to another embodiment of the optical access system of the present invention,
It is also preferable that the first device outputs only the optical signal having the first wavelength or the optical signal having the second wavelength.

  With a simple configuration change such as addition of a passive element with a low insertion loss, at least the optical transmission means on the first device side can be made a standby configuration. When the second device has means for selecting the optical transmission means, the first optical signal and the second optical signal are demultiplexed by the second two-wavelength multiplexing / demultiplexing coupler. After the optical signal is received by the first and second optical receiving means, it is performed by the selecting means, and when the second apparatus does not have the selecting means, the first apparatus transmits the first optical signal. This is performed by controlling the optical signal to be transmitted only from the normal one of the means and the second optical transmission means.

  Further, on the first device side, a 1: M coupler is provided for the second optical transmission means, and a first two-wavelength multiplexing / demultiplexing coupler is provided for each of the first optical transmission means. : N switching configuration can be realized, and the cost for securing the reserve on the first device side can be suppressed. In addition, by using an optical switch controlled by the first device instead of the 1: M coupler, it is possible to suppress the occurrence of loss due to the use of the 1: M coupler and to secure the degree of freedom in network design.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a system configuration diagram of a first embodiment of the present invention. A system according to the present invention includes a node device indicated by reference numeral 1 and a home device indicated by reference numeral 2. Node device 1 and in-home device 2 are connected by a pair of access optical fibers.

  The node device 1 includes a pair of optical transmission / reception units including an optical transmission unit 31 and an optical reception unit 41, and a pair of optical transmission / reception units including an optical transmission unit 32 and an optical reception unit 42. Here, the optical transmitter 31 transmits an optical signal having a wavelength of 1.3 μm, and the optical transmitter 32 transmits an optical signal having a wavelength of 1.5 μm. In the present embodiment, a pair of optical transmission / reception units configured by the optical transmission unit 31 and the optical reception unit 41 and a pair of optical transmission / reception units configured by the optical transmission unit 32 and the optical reception unit 42 are mutually impaired. Use as a spare time. In general, a plurality of optical transmission / reception units are mounted on one interface card, and the node device 1 is configured to be able to mount a plurality of interface cards. The pair is preferably selected from different interface cards in consideration of replacement of the interface card at the time of failure. However, the same interface card may be used when a short-term service interruption accompanying the card exchange can be tolerated.

  The optical transmitters 31 and 32 and the optical receivers 41 and 42 are connected to the switching unit 11. In the present embodiment, since the switching configuration is 1 + 1, the switching unit 11 divides a signal to be transmitted to the in-home device 2 into two branches, transmits the signals to the optical transmission units 31 and 32, and receives from the optical reception units 41 and 42. One of the signals is selected, and the signal is transmitted to the side opposite to the in-home device 2, that is, to the communication network side (not shown). However, the switching unit 11 is configured to transmit a signal only to the optical transmission unit that is currently used, and to switch the signal to the other optical transmission unit when a failure in the active system is detected in a switching sequence that will be described later. May be.

  Similarly to the node device 1, the in-home device 2 includes a pair of optical transmission / reception units configured by the optical transmission unit 33 and the optical reception unit 43 and a pair of optical transmission / reception units configured by the optical transmission unit 34 and the optical reception unit 44. Are used as spares in case of failure. The optical transmitter 33 transmits an optical signal having a wavelength of 1.3 μm, and the optical transmitter 34 transmits an optical signal having a wavelength of 1.5 μm. Further, similarly to the switching unit 11 of the node device 1, the node device 1 includes a switching unit 21 that transmits a signal to at least the active optical transmission unit and selects a signal from the active optical reception unit.

  Further, in FIG. 1, reference numerals 51 to 54 are two-wavelength multiplexing / demultiplexing couplers called 1.3 μm / 1.5 μm multiplexing / demultiplexing couplers. Compared with a 1: 2 coupler that performs demultiplexing, there is a feature that loss due to multiplexing or demultiplexing is small. According to FIG. 1, the two-wavelength multiplexing / demultiplexing coupler 51 installed on the communication station side is connected to the optical transmission unit 31 and the optical transmission unit 32, and the two-wavelength multiplexing / demultiplexing coupler 52 similarly installed on the communication station side is The two-wavelength multiplexing / demultiplexing coupler 54 connected to the optical receiver 41 and the optical receiver 42 and installed on the user's home side is connected to the optical transmitter 33 and the optical transmitter 34 and is also installed on the user home side. The two-wavelength multiplexing / demultiplexing coupler 53 is connected to the optical receiver 43 and the optical receiver 44. Further, the two-wavelength multiplexing / demultiplexing couplers 51 and 53 are connected by a pair of access optical fibers connecting the communication station and the user's home, and the two-wavelength multiplexing / demultiplexing couplers 52 and 54 are connected.

  A signal flow in the configuration of FIG. 1 will be described. The optical signal having a wavelength of 1.3 μm transmitted from the optical transmitter 31 and the optical signal having a wavelength of 1.5 μm transmitted from the optical transmitter 32 are multiplexed by the two-wavelength multiplexing / demultiplexing coupler 51 and transmitted to the access optical fiber. The The wavelength-multiplexed optical signal is demultiplexed by the two-wavelength multiplexing / demultiplexing coupler 53, the optical signal having a wavelength of 1.3 μm is transmitted to the optical receiving unit 43, and the optical signal having a wavelength of 1.5 μm is transmitted to the optical receiving unit 44. The The switching unit 21 selects one of the signals received by the optical receiving unit 43 or the optical receiving unit 44, and sets the signal to be transmitted to the side opposite to the node device 1, that is, the terminal device side (not shown). Similarly, an optical signal having a wavelength of 1.3 μm transmitted from the optical transmitter 33 and an optical signal having a wavelength of 1.5 μm transmitted from the optical transmitter 34 are multiplexed by a two-wavelength multiplexing / demultiplexing coupler 54, and an access optical fiber. The optical signal transmitted and wavelength-multiplexed is demultiplexed by the two-wavelength multiplexing / demultiplexing coupler 52, the optical signal having a wavelength of 1.3 μm is transmitted to the optical receiver 41, and the optical signal having a wavelength of 1.5 μm is transmitted to the optical receiver 42. Sent to each. Then, the switching unit 11 selects any one of the signals received by the optical receiving unit 41 or the optical receiving unit 42 and sets it as a signal to be transmitted to the communication network side.

  FIG. 2 is a switching sequence diagram when a failure occurs in this embodiment. As described above, the optical signal having the wavelength of 1.3 μm transmitted by the optical transmitter 31 is normally received by the optical receiver 43, and the optical signal having the wavelength of 1.3 μm transmitted by the optical transmitter 33 is normally received by the optical receiver 41. Is received by the optical receiving unit 44, and the optical signal transmitted by the optical transmitting unit 34 is received by the optical receiving unit 42. Yes. Note that the switching units 11 and 21 select an optical signal having a wavelength of 1.3 μm.

  When the in-home device 2 detects a failure occurring in the optical transmission unit 31 of the opposite node device 1 from the optical signal level received by the optical reception unit 43, the in-home device 2 uses the optical signal transmitted by the optical transmission unit 34 to The device 1 is notified of failure detection. As a result, both the node device 1 and the in-home device 2 recognize the occurrence of the failure, and the switching unit 11 and the switching unit 21 switch signals so as to use an optical signal of 1.5 μm, respectively. In the present embodiment, the configurations of the node device 1 and the in-home device 2 are symmetrical, and the same sequence is performed when a failure occurs in the optical transmission unit 33 of the in-home device 2.

  The reason why the in-home device 2 performs the failure notification by the optical transmission unit 34 is that there is a high possibility that the optical reception unit 41 is also in a failure state when the optical transmission unit 31 fails. Failure notification may be performed. In addition, the switching is performed in units of a pair of transmission and reception in order not to cause confusion regarding the state of the switching system, but switching may be performed independently between transmission and reception. Further, when switching is performed independently between transmission and reception, and the signal transmitted by the switching units 11 and 21 is always bifurcated, the failure notification to the opposite device is omitted, and the side where the failure is detected is switched by the switching unit. Just do.

  In the present embodiment, by using a low-loss two-wavelength multiplexing / demultiplexing coupler, the loss associated with the switching configuration is suppressed, and thus the degree of freedom in network design is increased, and a simple configuration such as addition of passive elements can cope with a failure. Relief has been realized. In the system according to the present invention, even if a failure occurs in the optical transmission / reception unit, the service can be continuously provided unlike the configuration according to the prior art.

  FIG. 3 is a system configuration diagram of the second embodiment of the present invention. In this embodiment, the node device 1 side is configured to have a switching configuration of 1: N (N is an integer of 2 or more), and FIG. 3 shows the embodiment of 1: 2. Here, the optical transmission / reception unit configured by the transmission unit 32 and the optical reception unit 42 of the node device 1 is normally used as a backup, and the optical transmission / reception unit configured by the transmission unit 31 and the optical reception unit 41 is normally configured. Each time, it is used as a working one. In FIG. 3, reference numerals 61 and 62 denote a 1: M (M is an integer equal to or greater than N) coupler that performs multiplexing / demultiplexing on an optical signal greater than or equal to N for a 1: N switching configuration. 1: 2 coupler. In addition, since the freedom degree of a network design is restrict | limited by the loss generate | occur | produced by 1: M coupler, it is desirable that M is equal to N and N is 4 or less.

  In the present embodiment, the two-wavelength multiplexing / demultiplexing coupler 51 is provided for each optical transmission unit 31, and the 1.3 μm port of the two-wavelength multiplexing / demultiplexing coupler 51 is connected to the corresponding optical transmission unit 31. The 1.5 μm port of the wave coupler 51 is connected to the branch side port of the 1: M coupler 62, and the multiplexing side port of the two-wavelength multiplexing / demultiplexing coupler 51 is connected to the access optical fiber to the corresponding in-home device 2. is doing. Similarly, the two-wavelength multiplexing / demultiplexing coupler 52 is provided for each optical receiving unit 41, and the 1.3 μm port of the two-wavelength multiplexing / demultiplexing coupler 52 is connected to the corresponding optical receiving unit 41. The port for 1.5 μm of 52 is connected to the port on the branch side of the 1: M coupler 61, and the port on the multiplexing side of the two-wavelength multiplexing / demultiplexing coupler 52 is connected to the access optical fiber from the corresponding in-home device 2. Yes.

  A signal flow in the configuration of FIG. 3 will be described. The optical signal having a wavelength of 1.5 μm transmitted from the optical transmitter 32 is first branched by the 1: M coupler 62, and the branched optical signals are respectively input to the two-wavelength multiplexing / demultiplexing coupler 51. The two-wavelength multiplexing / demultiplexing coupler 51 multiplexes an optical signal having a wavelength of 1.3 μm from the connected optical transmitter 31 and an optical signal having a wavelength of 1.5 μm from the 1: M coupler 62, and wavelength multiplexing. To do. The wavelength-multiplexed optical signal is demultiplexed by the two-wavelength multiplexing / demultiplexing coupler 53, the optical signal having a wavelength of 1.3 μm is transmitted to the optical receiving unit 43, and the optical signal having a wavelength of 1.5 μm is transmitted to the optical receiving unit 44. The The switching unit 21 normally selects a signal received by the optical receiving unit 43 and transmits it to the terminal device side. Further, during normal times, the optical transmitter 34 of the in-home device 2 does not transmit an optical signal, and only the optical transmitter 33 transmits an optical signal. An optical signal having a wavelength of 1.3 μm transmitted by the optical transmitter 33 is received by the optical receiver 41 via the two-wavelength multiplexing / demultiplexing couplers 54 and 52, and the switching unit 11 is a signal received by the optical receiver 41. Is used as a signal to be transmitted to the communication network side. Since the optical transmission unit 34 of the in-home device 2 does not normally transmit an optical signal, an optical signal having a wavelength of 1.5 μm is not output from the two-wavelength multiplexing / demultiplexing coupler 52, and the optical reception unit 42 Not receive.

  FIG. 4 is a switching sequence diagram when a failure occurs in this embodiment. As described above, the optical signal having the wavelength of 1.3 μm transmitted by the optical transmitter 31 is normally received by the optical receiver 43, and the optical signal having the wavelength of 1.3 μm transmitted by the optical transmitter 33 is normally received by the optical receiver 41. The optical signal having a wavelength of 1.5 μm transmitted by the optical transmitter 32 is received by the optical receiver 44 of the all-home device 2 in the switching system and transmitted by the all-home device 2 in the switching system. The unit 34 does not transmit an optical signal.

  When the in-home device 2 detects a failure occurring in the optical transmission unit 31 of the opposite node device 1 from the optical signal level received by the optical reception unit 43, the in-home device 2 starts transmission of the optical signal by the optical transmission unit 34, and the wavelength The node device 1 is notified of the failure and its own identifier using the 1.5 μm optical signal. This failure notification is received by the optical receiving unit 42 of the node device 1, and the node device 1 that has recognized the occurrence of the failure uses the optical signal having a wavelength of 1.5 μm transmitted by the optical transmitting unit 42 to generate and protect the failure. The identifier of the household device 2 being used is notified to all the household devices 2 in the switching system. By this notification, all the in-home devices 2 in the switching system recognize that the standby system is used, and thereafter, even if other in-home devices 2 detect other faults, the optical signals from the optical transmission unit 34 are detected. Do not start sending. As a result, it is possible to prevent the communication already performed using the standby system from being disturbed. In addition, the node device 1 performs signal switching in the switching unit 11 so that a transmission / reception signal with the in-home device 2 in which the failure is detected passes through the optical transmission unit 32 and the optical reception unit 42. Further, the node device 2 that has received the failure notification signal including the identifier of the own device from the node device 1 sends the transmission / reception signal to / from the node device 1 through the optical transmission unit 34 and the optical reception unit 44. The signal is switched at 21.

  Further, when a failure occurs in the optical transmission unit 33 of the in-home device 2, the node device 1 that detects this failure uses the optical signal having a wavelength of 1.5 μm transmitted by the optical transmission unit 32 to generate a failure and make a backup. The identifier of the in-home device 2 to be used is notified to all in-home devices 2 in the switching system, and using this as a trigger, the optical transmission unit 34 of the in-home device 2 in which the failure has occurred starts transmission of the optical signal, 11 and the switching unit 21 perform signal switching so that a 1.5 μm optical signal is used.

  In addition, although the description has been given by taking as an example the case of switching a pair of transmission and reception as a unit, transmission and reception may be switched independently as in the first embodiment. In this case, the failure detected by the home device 2 is notified to the node device 1 by the optical transmission unit 33, and the switching unit 11 sends a signal so that the transmission signal to the home device 2 passes through the optical transmission unit 32. The switching unit 21 of the in-home device 2 that has controlled and detected the failure controls the switching unit 21 so that the signal received from the light receiving unit 44 is a signal to be transmitted to the terminal device. Further, the failure detected by the node device 1 is notified to the in-home device 2 by the optical transmission unit 31, and the optical transmission unit 34 of the in-home device 2 in which the failure has occurred starts transmission of an optical signal. Further, the switching unit 11 and the switching unit 21 of the in-home device 2 in which the failure has occurred perform signal switching control so that the optical transmission unit 34 and the optical reception unit 42 become active. When the node device 1 is switched to receive a received signal from the in-home device 2 from the optical receiving unit 42 and a failure from another in-home device 2 is detected, the other in-home device 2 is detected. Since the received signal cannot be remedied, the optical transmitter 31 does not notify the other in-home device 2 of the failure.

  In this embodiment, the number of optical transmitters and receivers on the node device 1 side required as a spare can be suppressed, and a switching system can be realized at a low cost. Although the optical signal power level is 1 / M in this portion due to the use of the 1: M coupler, the use of the 1: M coupler by using an optical signal with a small loss of 1.5 μm on the standby side. Limiting the freedom of network design.

  FIG. 5 is a system configuration diagram of the third embodiment of the present invention. In this embodiment, the 1: M couplers 61 and 62 in the second embodiment are changed to optical switches 71 and 72, and the switching of 1: N is realized as in the second embodiment. In the second embodiment, since the 1: M coupler is used, the in-home device 2 must stop the transmission of the optical signal from the optical transmission unit 34 at the normal time. However, in the present embodiment, the optical switch 71 is used. Since one is selected from a plurality of optical signals having a wavelength of 1.5 μm and transmitted to the optical receiver 42, the optical signal transmission control of the optical transmitter 34 in the in-home device 2 is not required. Further, the optical switch has a lower insertion loss than the 1: M coupler, and can constitute a switching system in which the number of optical transmission / reception units required for the node device 1 is suppressed while ensuring the degree of freedom in network design.

  FIG. 6 is a switching sequence diagram when a failure occurs in the present embodiment. When the in-home device 2 detects a failure that has occurred in the optical transmission unit 31 of the opposite node device 1 from the optical signal level received by the optical reception unit 43, the optical transmission unit 33 notifies the node device 1 of the failure. . The node device 1 that has recognized the occurrence of the failure selects the signal from the two-wavelength multiplexing / demultiplexing coupler 52 connected to the in-home device 2 that has detected the failure for the optical switch 71, The optical switches 71 and 72 are controlled so that signals are output to the two-wavelength multiplexing / demultiplexing coupler 51 connected to the in-home device 2 that has detected the failure, and transmission / reception signals with the in-home device 2 that has detected the failure are The switching unit 11 performs signal switching so as to pass through the transmission unit 32 and the optical reception unit 42. In addition, a switching notification including the identifier of the in-home device 2 is made to the in-home device 2 in which the failure is detected by the optical transmission unit 32. When the in-home device 2 that has detected the failure receives the switching notification including the identifier of the own device at the optical receiving unit 44, the in-house device 2 sends the transmission / reception signal to / from the node device 1 via the optical transmitting unit 34 and the optical receiving unit 44. The signal is switched by the switching unit 21.

  Further, when a failure occurs in the optical transmission unit 33 of the in-home device 2, the node device 1 that has detected this failure receives a signal from the two-wavelength multiplexing / demultiplexing coupler 52 connected to the in-home device 2 in which the failure has occurred. The optical switch 71 is controlled so as to select the optical switch 72 so as to output a signal to the two-wavelength multiplexing / demultiplexing coupler 51 connected to the in-home device 2 where the failure has occurred. The switching unit 11 performs signal switching so that a transmission / reception signal to / from 2 passes through the optical transmission unit 32 and the optical reception unit 42. In addition, a switching notification including the identifier of the in-home device 2 is made to the in-home device 2 in which the failure is detected by the optical transmission unit 32. Furthermore, when the in-home device 2 in which the failure has occurred receives the switching notification including the identifier of the own device at the optical receiving unit 44, the optical transmission unit 34 and the optical receiving unit 44 send the transmission / reception signal to / from the node device 1. The signal is switched by the switching unit 21 so as to pass through.

  In addition, although the description has been given by taking as an example the case of switching a pair of transmission and reception as a unit, transmission and reception may be switched independently as in the first embodiment. In this case, the failure detected by the in-home device 2 is notified to the node device 1 by the optical transmission unit 33, and the node device 1 switches so that the transmission signal reaches the in-home device 2 via the optical transmission unit 32. The in-home device 2 that controls the unit 11 and the optical switch 72 and detects a failure controls the switching unit 21 so that the signal received from the optical receiving unit 44 is a signal to be transmitted to the terminal device. In addition, the failure detected by the node device 1 is notified to the identifier of the in-home device 2 by the optical transmission unit 31, and the node device 1 can receive the signal from the in-home device 2 via the optical reception unit 42. The switching device 11 and the optical switch 71 are controlled, and the in-home device 2 in which the failure has occurred controls the switching unit 21 so that a signal from the optical transmission unit 34 to the node device 1 is output.

  FIG. 7 shows a further embodiment of the present invention. FIG. 7 (a) is obtained by removing the two-wavelength multiplexing / demultiplexing coupler 53 in the first embodiment. For this reason, normally, when the node device 1 transmits an optical signal from only one of the optical transmission units 31 or 32 and receives a failure detection notification from the in-home device 2, the optical signal transmitted by the other optical transmission unit is transmitted. Start sending. In the present embodiment, the in-home device 2 has a configuration in which only an optical transmission unit that is relatively likely to fail is provided with a spare, and the switching unit 21 of the in-home device 2 simply receives the transmission signal in two branches and receives the signal. Switching control for the signal is not required, and the home device 2 can be simplified, and the cost can be suppressed.

  FIG. 7B shows a configuration in which the home device 2 does not have a spare. In the present embodiment, even when the service providing side does not install the in-home device 2 but the user installs the service providing side, it is possible to avoid interruption of service provision due to a failure of the station side equipment. In the present embodiment, the configuration and switching method on the transmission side of the node device 1 are the same as the configuration illustrated in FIG. On the other hand, the in-home device 2 includes one optical transmitter 3 having a wavelength of 1.3 μm or 1.5 μm, and an optical signal transmitted from the in-home device 2 is transmitted by the 1: 2 coupler 63 installed on the station side. The switching unit 11 is branched and selects a normal signal from the signals received by the optical receiving units 41 and 42, respectively. In the present embodiment, it is not necessary to notify the failure between the node device 1 and the home device 2 at the time of switching.

1 is a system configuration diagram of a first embodiment of an optical access system according to the present invention. FIG. It is a switching sequence figure of a 1st embodiment. It is a system block diagram of 2nd Embodiment of the optical access system by this invention. It is a switching sequence figure of a 2nd embodiment. It is a system block diagram of 3rd Embodiment of the optical access system by this invention. It is a switching sequence figure of a 3rd embodiment. It is a system block diagram of other embodiment of the optical access system by this invention.

Explanation of symbols

1 Node device 2 Home device 11, 21 Switching unit 3, 31, 32, 33, 34 Optical transmitting unit 41, 42, 43, 44 Optical receiving unit 51, 52, 53, 54 Two-wavelength multiplexing / demultiplexing coupler 61, 62 1 : M coupler 63 1: 2 coupler 71, 72 Optical switch

Claims (5)

An optical access system comprising a first device, a first two-wavelength multiplexing / demultiplexing coupler, an optical fiber, and a second device that receives an optical signal from the optical fiber,
The first device includes a first optical transmission unit that transmits an optical signal having a first wavelength, and a second optical transmission unit that transmits an optical signal having a second wavelength.
The first two-wavelength multiplexing / demultiplexing coupler outputs a wavelength-multiplexed optical signal obtained by multiplexing the optical signals of the first wavelength and the second wavelength transmitted from the first device to the optical fiber.
Optical access system. The second two-wavelength multiplexing / demultiplexing coupler demultiplexes the wavelength multiplexed optical signal output to the optical fiber, and outputs the first wavelength optical signal and the second wavelength optical signal, respectively. A wavelength multiplexing / demultiplexing coupler is further provided,
The second device includes a first optical receiving unit that receives an optical signal having the first wavelength output from the second two-wavelength multiplexing / demultiplexing coupler, and a second optical signal that receives the optical signal having the second wavelength. Receiving means; means for selecting an output signal of the first optical receiving means or the second optical receiving means;
With
The optical access system according to claim 1. One second optical transmission means is provided for N first optical transmission means, where N is an integer equal to or greater than 2,
The second optical transmission means is connected to a 1: M coupler, where M is an integer greater than or equal to N,
The first two-wavelength multiplexing / demultiplexing coupler is provided for each of the first optical transmission means, and each is connected to the corresponding first optical transmission means and the 1: M coupler.
The optical access system according to claim 1 or 2. One second optical transmission means is provided for N first optical transmission means, where N is an integer equal to or greater than 2,
The second optical transmission means is connected to an optical switch controlled by the first device,
The first two-wavelength multiplexing / demultiplexing coupler is provided for each of the first optical transmission means, and each is connected to the corresponding first optical transmission means and the optical switch.
The optical access system according to claim 1 or 2. The optical access system according to claim 1, wherein the first device outputs only one of an optical signal having a first wavelength and an optical signal having a second wavelength.

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