JP4413248B2 - Wavelength division multiplexing passive optical network - Google Patents

Description

  The present invention relates to a wavelength division multiplexing passive optical network. In particular, a wavelength division multiplexing passive optical network using a wavelength division multiplexing optical communication light source that outputs an optical signal wavelength-locked to incoherent light minimizes optical loss and improves transmission quality and transmission distance. Related to technology.

  The wavelength division multiplexing passive optical network includes a central base station, a plurality of optical subscribers, and an optical distribution network that connects the central base station to each optical subscriber. The optical distribution network is composed of a remote branch node having no power supply and comprising light receiving elements such as a wavelength division multiplexer / demultiplexer and an optical divider, and an optical cable. A wavelength division multiplexed optical signal is transmitted between the central base station and the remote branch node through a single optical cable, and a specific wavelength is assigned to the optical subscriber by the remote branch node.

  In the case of a wavelength division multiplexing passive optical network, a plurality of light sources having different wavelengths are required to assign one or more wavelengths to subscribers. Moreover, a means for recovering when a failure occurs in the optical transmission line between the central base station and the remote branch node is required.

  FIG. 1 is a diagram illustrating a conventional wavelength division multiplexing passive optical network, and FIG. 2 is a diagram illustrating a conventional wavelength division multiplexing passive optical network having a failure recovery function.

  FIG. 1 shows a low-cost light source that outputs an optical signal wavelength-locked to injected incoherent light and a wavelength-division-multiplexing passive optical network as described in “A low-cost WDM source with an ASE”. Injected Fabry-Perot semiconductor laser ”and“ Wavelength Division Multiplexing Passive Optical Network ”of Patent Document 1 by Tsugan Wook, Yi Fan, Wu Taiyuan.

Figure 2 shows the proposed method for disaster recovery presented in "ITU-T G.983.1 Broadband optical access systems based on passive optical networks", which is a standard proposed by the International Telecommunication Union. It is the Example applied to.

  A light source that outputs an optical signal that is wavelength-locked to the injected incoherent light is an incoherent and wide line-width spontaneous emission light source, Fabry-Perot laser diode, optical multiplexer / demultiplexer, and optical modulation function Means a light source that always outputs a wavelength division multiplexed optical signal that matches the multiplexed / demultiplexed wavelength of the optical multiplexer / demultiplexer.

Referring to FIG. 1, incoherent light from the B-band spontaneous emission light source 112 is transmitted as a downward signal from the central base station to the optical subscriber by the 2 × 2 3db optical splitter 113, 1 × N optical multiplexer / demultiplexer 110, and the A band and B A wavelength-locked optical signal that is injected into an optical transmitter 101-103 having a Fabry-Perot laser diode of a central base station through an optical multiplexer / demultiplexer 107-109 that multiplexes / demultiplexes the band is output. , An optical signal wavelength-locked in the B band is transmitted to the optical receivers 122-124 of the optical subscribers. As an upward signal from the optical subscriber to the central base station, the incoherent light from the A-band spontaneous emission light source 111 multiplexes the 2 × 2 3db optical splitter 113, the optical cable 114, the remote branch node 115, and the A and B bands. A wavelength-locked optical signal injected into an optical transmitter 119-121 having a Fabry-Perot laser diode of an optical subscriber is output through an optical multiplexer / demultiplexer 116-118 that performs demultiplexing, and wavelength-locked within the A band. The transmitted optical signal is transmitted to the optical receivers 104-106 of the central base station.
Korean Patent No. 10-2002-0003318 Specification Hyun Deok Kim, Seung-Goo Kang, Chang-Hee Lee, “IEEE Photonic Technology Letters, vol.12, no.8” , P.1067-1069

  As described above, in the case of a light source that outputs an optical signal that is wavelength-locked to the injected incoherent light, the wavelength locking phenomenon is more efficiently performed as the intensity of the incoherent light injected into the optical transmitter increases. Is called. Therefore, the incoherent light from the A-band spontaneous emission light source 111 and the B-band spontaneous emission light source 112 needs to be transmitted to the optical transmitters 101-103 and 119-121 as much as possible.

  In the case of the wavelength division multiplexing passive optical network as described above, the 2 × 2 optical splitter 113 is used to inject incoherent light. The 2 × 2 optical splitter 113 divides the optical signal 50 to 50 with respect to the A band and the B band. Therefore, when incoherent light from the A-band spontaneous emission light source 111 is transmitted to the optical cable 114 through the 2 × 2 optical splitter 113, a 3 dB optical loss occurs, and the incoherent light from the B-band spontaneous emission light source 112 is also 1 × N optical multiplexer / When transmitted to the demultiplexer 110, an optical loss of 3 db occurs. Further, since the 2 × 2 optical splitter 113 is located on the optical transmission line, unnecessary optical loss is caused for the upward signal and the downward signal.

  When a failure occurs in the optical cable between the central base station and the remote branch node, communication of all optical subscribers is interrupted, so a failure recovery function is essential. Referring to FIG. 2, in addition to the 1 × N optical multiplexer / demultiplexer 201, the A-band spontaneous emission light source 202, the B-band spontaneous emission light source 203 and the 2 × 2 optical splitter 204, a 1 × 2 spatial optical switch 205 is installed in the central base station. An optical splitter 208 is installed in the remote branch node 209, and when a failure occurs in the first optical cable 206, communication is possible by detouring to the second optical cable 207. In the case of the method described above, the use of the optical splitter 208 in the remote branch node 209 adds an additional 3 db of optical loss.

  As described above, in the wavelength division multiplexing passive optical network, it is necessary to minimize the loss that occurs when incoherent light is injected. In addition, the optical loss that occurs before the signal transmitted by the optical transmitter reaches the optical receiver greatly affects the transmission quality or expandability. Therefore, the optical loss is minimized or compensated for. A method is needed.

  The present invention has been devised to solve the above-described problems of the prior art, and is a wavelength division multiplexing passive method using a wavelength division multiplexing optical communication light source that outputs an optical signal wavelength-locked to incoherent light. It aims at minimizing optical loss by an optical network and improving transmission quality and transmission distance.

  As a technical idea for achieving the above-described object of the present invention, the present invention improves the wavelength locking phenomenon of the wavelength division multiplexing optical communication light source by increasing the injection amount of incoherent light. The present invention also provides a method for reducing optical transmission line loss and compensating for optical transmission line loss. In addition, the present invention provides a failure recovery method using a four-terminal optical path setter without any additional loss.

Wavelength division multiplexing passive optical network according to the present invention, between the central office and a remote branch node having a failure recovery function, using an optical signal wavelength-locked to injected incoherent light Oite the WDM passive optical network, the central base station, a 1 2xN light multiplexer / demultiplexer having two input terminals, the 1 1x2 space type having one input terminal and two output terminals An optical switch, a second 1x2 spatial optical switch having one input terminal and two output terminals , and a four-terminal optical path setter having first to fourth terminals, and two input terminals at a remote branch node comprising a second 2xN light multiplexer / demultiplexer having, between the central office and a remote branch node includes a first optical cable and second optical cable, the four terminals An A-band light source that emits an A-band optical signal is connected to the first terminal of the path setting device, and a B-band light source that emits a B-band optical signal is connected to the second terminal of the 4-terminal optical path setting device. The third terminal of the terminal optical path setting device is connected to the input terminal of the second 1 × 2 spatial optical switch, and the fourth terminal of the four terminal optical path setting device and the input terminal of the first 1 × 2 spatial optical switch are connected to each other. And the first optical cable is normal, the input terminal of the first 1 × 2 spatial optical switch is connected to one of the first 2 × N optical multiplexer / demultiplexer via its one output terminal. One of the second 2xN optical multiplexer / demultiplexer via one output terminal of the second 1x2 spatial optical switch and the first optical cable. When the first optical cable is faulty, the input terminal of the first 1 × 2 spatial optical switch is connected to the input terminal via the other output terminal of the first 2 × N light. Connected to the other input terminal of the multiplexer / demultiplexer, and the input terminal of the second 1 × 2 spatial optical switch is connected to the second 2 × N optical multiplexer / demultiplexer via its other output terminal and the second optical cable. The second input terminal is connected to switch the connection of the first 1x2 spatial optical switch and the second 1x2 spatial optical switch when a failure occurs in the first optical cable , Optical cable and input of the first 2 × N optical multiplexer / demultiplexer and the second 2 × N optical multiplexer / demultiplexer Wherein the force terminal settings are to be changed by the synchronization.

Wavelength division multiplexing passive optical network according to the present invention, the first 1 2xN light multiplexer / demultiplexer and the second 2 2xN light multiplexer / demultiplexer array waveguide grating wavelength division multiplexer / demultiplexer that used It is characterized by.

Wavelength division multiplexing passive optical network according to the present invention is characterized in that the fault recovery time in the first optical cable, wavelength by wavelength change of the injected incoherent light is automatically assigned.

  According to the present invention, the optical loss of a wavelength division multiplexing passive optical network using a light source that outputs an optical signal that is wavelength-locked to the injected incoherent light can be reduced, and the optical loss is compensated. can do. The four-terminal optical path setter according to the present invention can be realized at low cost by using a conventional optical element. Further, the wavelength division multiplexing passive optical network having the failure recovery function according to the present invention can be realized without additional optical loss.

  According to the present invention, the optical loss in the wavelength division multiplexing passive optical network is an important factor that limits the transmission distance and the number of subscribers that can be accommodated. The economics of the wavelength division multiplexing passive optical network can be improved by increasing the transmission distance and the number of subscribers by reducing and compensating the optical loss.

Hereinafter, the present invention will be described in detail with reference to the drawings showing the configuration and operation of the embodiment.
FIG. 3 is a diagram showing operating characteristics of the four-terminal optical path setting device.

  The A-band optical signal input to the first terminal of the four-terminal optical path setter is output to the third terminal. The A-band optical signal input to the third terminal of the four-terminal optical path setter is output to the fourth terminal. The B-band optical signal input to the second terminal of the four-terminal optical path setter is output to the fourth terminal. The B-band optical signal input to the fourth terminal of the four-terminal optical path setting device is output to the third terminal.

  As shown in FIG. 3, the 4-terminal optical path setter is replaced with the 2 × 2 optical splitter 113 of FIG. 1 to reduce optical loss.

  The four-terminal optical path setting device is realized by using a single optical element using a micro-Optics technique or an integrated-Optics technique, or an existing optical element.

  FIG. 4 is a diagram showing an embodiment of a four-terminal optical path setting device. Referring to FIG. 4, the four-terminal optical path setter operates in a first band, a first optical multiplexer / demultiplexer 401 and a second optical multiplexer / demultiplexer 402 that multiplex / demultiplex A band and B band. And an A-band optical circulator 403 having three terminals and a B-band optical circulator 404 having three terminals that operate in the B band.

  The A-band optical signal input to the first terminal of the four-terminal optical path setter passes through the A-band optical circulator 403 and the second optical multiplexer / demultiplexer 402 and is output to the third terminal.

  The A-band optical signal input to the third terminal of the four-terminal optical path setter passes through the second optical multiplexer / demultiplexer 402, the A-band optical circulator 403, and the first optical multiplexer / demultiplexer 401 to the fourth terminal. Is output.

  The B-band optical signal input to the second terminal of the four-terminal optical path setter passes through the B-band optical circulator 404 and the first optical multiplexer / demultiplexer 401 and is output to the fourth terminal.

  The B-band optical signal input to the fourth terminal of the four-terminal optical path setter passes through the first optical multiplexer / demultiplexer 401, the B-band optical circulator 404, and the second optical multiplexer / demultiplexer 402, and the third terminal. Is output.

  Preferably, the first optical multiplexer / demultiplexer 401, the second optical multiplexer / demultiplexer 402, the A-band optical circulator 403, and the B-band optical circulator 404 presented from the embodiment of the four-terminal optical path setter each have three terminals. In consideration of this, the first optical multiplexer / demultiplexer 401 and the second optical multiplexer / demultiplexer 402 output the A-band optical signal input to the first terminal to the second terminal and input to the second terminal. The A-band optical signal is output to the first terminal. The B-band optical signal input to the first terminal is output to the third terminal, and the B-band optical signal input to the third terminal is output to the first terminal.

  In the A-band optical circulator 403, the A-band optical signal input to the first terminal is output to the second terminal, and the A-band optical signal input to the second terminal is output to the third terminal. In the B-band optical circulator 404, the B-band optical signal input to the first terminal is output to the second terminal, and the B-band optical signal input to the second terminal is output to the third terminal.

  At this time, the first terminal of the 4-terminal optical path setter is the first terminal of the A-band circulator 403, and the second terminal of the 4-terminal optical path setter is the first terminal of the B-band optical circulator 404. The third terminal of the 4-terminal optical path setter is the first terminal of the first optical multiplexer / demultiplexer 401, and the fourth terminal of the 4-terminal optical path setter is the first terminal of the second optical multiplexer / demultiplexer 402. Terminal.

  The second terminal of the A-band optical circulator 403 is connected to the second terminal of the first optical multiplexer / demultiplexer 401, and the third terminal of the A-band optical circulator 403 is connected to the second terminal of the second optical multiplexer / demultiplexer 402. Is done. The second terminal of the B-band optical circulator 404 is connected to the third terminal of the second optical multiplexer / demultiplexer 402, and the third terminal of the B-band optical circulator 404 is connected to the third terminal of the first optical multiplexer / demultiplexer 401. Is done.

  Since the four-terminal optical path setter has no theoretical light loss except for the additional loss caused by the manufacturing process of the individual optical elements, the theoretical 3 db light loss due to the 2 × 2 light splitter 113 can be eliminated.

  Therefore, when the 4-terminal optical path setter and the 2 × 2 optical splitter 113 described above are replaced, the injection rate of the spontaneous emission light source can be improved by 3 db. Further, the optical loss of 3 db can be reduced for the upward signal and the downward signal, respectively.

  FIG. 5 is a diagram showing an embodiment of a four-terminal optical path setting device. Referring to FIG. 5, the 4-terminal optical path setter operates in the A band, the first optical multiplexer / demultiplexer 501 and the second optical multiplexer / demultiplexer 502 that multiplex / demultiplex A band and B band. And an A-band optical circulator 503 having three terminals, a B-band optical circulator 504 operating in the B-band, an A-band optical amplifier 505, and a B-band optical amplifier 506.

  The 4-terminal optical path setter that compensates for the optical loss in FIG. 5 is replaced with the 2 × 2 optical splitter 113 described above.

  The A-band upward signal is input to the third terminal of the 4-terminal optical path setter, and the second optical multiplexer / demultiplexer 502, the A-band optical circulator 503, the A-band optical amplifier 505, and the first optical multiplexer / demultiplexer 501 are input. Pass through and output to terminal 4. As the A-band optical amplifier 505, a rare earth doped optical fiber amplifier, a rare earth doped optical waveguide amplifier, a semiconductor optical amplifier, and an optical fiber amplifier using optical nonlinearity of an optical fiber are used. The A-band optical amplifier 505 compensates for the optical loss of the upward signal.

  The B-band downward signal is input to the 4th terminal of the 4-terminal optical path setter, and the first optical multiplexer / demultiplexer 501, the B-band optical circulator 504, the B-band optical amplifier 506, and the second optical multiplexer / demultiplexer 502 are input. Pass through and output to terminal 3. As the B-band optical amplifier 506, a rare-earth doped optical fiber amplifier, a rare-earth doped optical waveguide amplifier, a semiconductor optical amplifier, and an optical fiber amplifier using optical nonlinearity of an optical fiber are used. The B-band optical amplifier 506 compensates for the optical loss of the downward signal.

  By compensating for the optical loss of the upward signal and the downward signal, optical subscribers can be accommodated, and the transmission distance between the central base station and the optical subscribers can be increased.

  Preferably, the first optical multiplexer / demultiplexer 501, the second optical multiplexer / demultiplexer 502, the A-band optical circulator 503, and the B-band optical circulator 504 presented in the four-terminal optical path setter embodiment are three terminals. In view of this, the first optical multiplexer / demultiplexer 501 and the second optical multiplexer / demultiplexer 502 output the A-band optical signal input to the first terminal to the second terminal and input to the second terminal. An A-band optical signal is output to the first terminal. The B-band optical signal input to the first terminal is output to the third terminal, and the B-band optical signal input to the third terminal is output to the first terminal.

  In the A-band optical circulator 503, the A-band optical signal input to the first terminal is output to the second terminal, and the A-band optical signal input to the second terminal is output to the third terminal. In the B-band optical circulator 504, the B-band optical signal input to the first terminal is output to the second terminal, and the B-band optical signal input to the second terminal is output to the third terminal.

  At this time, the first terminal of the 4-terminal optical path setter is the first terminal of the A-band optical circulator 503, and the second terminal of the 4-terminal optical path setter is the first terminal of the B-band optical circulator 504. . The third terminal of the 4-terminal optical path setter is the first terminal of the first optical multiplexer / demultiplexer 501, and the fourth terminal of the 4-terminal optical path setter is the first terminal of the second optical multiplexer / demultiplexer 502. Terminal.

  The second terminal of the A-band optical circulator 503 is connected to the second terminal of the first optical multiplexer / demultiplexer 501, and the third terminal of the A-band optical circulator 503 is connected to the input terminal of the A-band optical amplifier 505. The output terminal of the optical amplifier 505 is connected to the second terminal of the second optical multiplexer / demultiplexer 502.

  The second terminal of the B-band optical circulator 504 is connected to the third terminal of the second optical multiplexer / demultiplexer 502, and the third terminal of the B-band optical circulator 504 is connected to the input terminal of the B-band optical amplifier 506. The output of the optical amplifier 506 is connected to the third terminal of the first optical multiplexer / demultiplexer 501.

  FIG. 6 is a diagram illustrating a wavelength division multiplexing passive optical network having a failure recovery function according to the present invention. Referring to FIG. 6, the wavelength division multiplexing passive optical network includes 2 × N optical multiplexer / demultiplexers 610 and 618, a first 1 × 2 spatial optical switch 614, a second 1 × 2 spatial optical switch 615, and a second optical cable 617 at the time of detour. And wavelength-locked optical signals are used.

  That is, the central base station includes a 2 × N optical multiplexer / demultiplexer 610, a first 1 × 2 spatial optical switch 614, a second 1 × 2 spatial optical switch 615, and a four-terminal optical path setter 613, and the central base station, the remote branching node, The first optical cable 616 for normal connection and the second optical cable 617 for detouring at the time of failure recovery are provided, and the 2 × N optical multiplexer / demultiplexer 618 is provided at the remote branch node.

  At this time, the first 1 × 2 spatial optical switch 614 of the central base station connects one terminal out of the two terminals of the 2 × N optical multiplexer / demultiplexer 610 of the central base station to the four-terminal optical path setting device 613, and the second 1 × 2 The spatial optical switch 615 connects one end of the first optical cable 616 or the second optical cable 617 and the four-terminal optical path setting device 613.

  The 2 × N optical multiplexer / demultiplexer 610, 618 uses optical elements utilizing integrated optical technology, micro-optical technology, and optical fiber technology. In general, an arrayed-waveguide grating multiplexer (AWG) is used. The operating characteristics of AWG are H. Described in “Transmission characteristics of arrayed-waveguide NxN wavelength multiplexer” published by H. Takahashi et al., “IEEE Photonic Technology Letters,” vol.13, p. 447-455. Yes.

The wavelength division multiplexing passive optical network having the failure recovery function shown in FIG. 6 can reduce the optical loss of 3 db since the 1 × 2 optical splitter can be removed from the remote branch node.

  Referring to FIG. 6, the operation and effect of the apparatus according to the present invention will be described below. If the first optical cable 616 fails on the optical network using the first optical cable 616, the first 1x2 spatial optical switch 614 of the central base station is connected to another terminal of the 2xN optical multiplexer / demultiplexer 610, At the same time, the second 1 × 2 spatial optical switch 615 is connected to the second optical cable 617. Thereafter, as a downward signal from the central base station to the optical subscriber, incoherent light from the B-band spontaneous emission light source 612 is converted into a 4-terminal optical path setter 613, a first 1 × 2 spatial optical switch 614, and a 2 × N optical multiplexer / demultiplexer. 610 and an optical multiplexer / demultiplexer 607-609 for multiplexing / demultiplexing the A band and the B band, and then injected into an optical transmitter 601-603 having a Fabry-Perot laser diode of a central base station and wavelength-locked. The optical signal is output, and the optical signal wavelength-locked in the B band is transmitted to the optical receiver 625-627 of the optical subscriber. As an upward signal from the optical subscriber to the central base station, incoherent light from the A-band spontaneous emission light source 611 is converted into a 4-terminal optical path setter 613, a second 1 × 2 spatial optical switch 615, a second optical cable 617, and a 2 × N optical multiplexer. / Demultiplexer 618 and optical multiplexer / demultiplexer 619-621 that multiplexes / demultiplexes the A band and the B band and is injected into an optical transmitter 622-624 having an optical subscriber Fabry-Perot laser diode. The locked optical signal is output, and the optical signal wavelength-locked within the A band is transmitted to the optical receivers 604 to 606 of the central base station.

  When the connection terminal of the 2 × N optical multiplexer / demultiplexer 610, 618 is changed, since the pass wavelength characteristic between the input end and the output end of the 2 × N optical multiplexer / demultiplexer 610, 618 changes, the optical transmission of the central base station It is necessary to newly set the output wavelengths of the optical transmitters 601-603 and the optical transmitters 622-624 of the optical subscribers. However, since the light source of the optical transmitter of the present invention uses the wavelength locking phenomenon caused by the injected incoherent light, the wavelength is synchronized even if the connection terminals of the 2 × N optical multiplexer / demultiplexers 610 and 618 are changed. Has the advantage of being automatically assigned.

  While the invention has been described in terms of preferred embodiments, such embodiments are intended to illustrate rather than limit the invention. It will be apparent to those skilled in the art to which the present invention pertains that various changes, modifications or adjustments can be made to the above-described embodiments without departing from the spirit of the present invention. Therefore, the protection scope of the present invention should be limited only to the appended claims, and should be construed to include all the various modifications or adjustments.

It is the figure which showed the conventional wavelength division multiplexing passive optical network. It is the figure which showed the wavelength division multiplexing system passive optical network which has the conventional failure recovery function. It is the figure which showed the operating characteristic of 4 terminal optical path setting device. It is the figure which showed the Example of 4 terminal optical path setting device. It is the figure which showed the Example of 4 terminal optical path setting device. 1 is a diagram illustrating a wavelength division multiplexing passive optical network having a failure recovery function according to the present invention. FIG.

Explanation of symbols

401, 501 First optical multiplexer / demultiplexer 402, 502 Second optical multiplexer / demultiplexer 403, 503 A-band optical circulator
404, 504 B-band optical circulator 505 A-band optical amplifier 506 B-band optical amplifier 610, 618 2xN optical multiplexer / demultiplexer 613 4-terminal optical path setting device 614 1st 1x2 spatial optical switch 615 2nd 1x2 spatial optical switch 616 First optical cable 617 Second optical cable

Claims (3)

Has a fault recovery function between the central office and a remote branch nodes, wavelength division using an optical signal wavelength-locked to injected incoherent light multiplexing Oite the passive optical network,
In the central base station, a first 2xN optical multiplexer / demultiplexer having two input terminals, a first 1x2 spatial optical switch having one input terminal and two output terminals, one input terminal and two output terminals, the 2 1x2 space type optical switch having, and, equipped with a four-terminal optical path setting device having 1 to 4 pin,
The remote branch node comprises a second 2xN optical multiplexer / demultiplexer having two input terminals ;
A first optical cable and a second optical cable are provided between the central base station and the remote branch node,
An A-band light source that emits an A-band optical signal is connected to the first terminal of the 4-terminal optical path setting device, and a B-band light source that emits a B-band optical signal is connected to the second terminal of the 4-terminal optical path setting device. The third terminal of the four-terminal optical path setting device and the input terminal of the second 1 × 2 spatial optical switch are connected, and the fourth terminal of the four-terminal optical path setting device and the first 1 × 2 spatial optical switch are connected. Is connected to the input terminal of
When the first optical cable is normal, the input terminal of the first 1x2 spatial optical switch is connected to one input terminal of the first 2xN optical multiplexer / demultiplexer via its one output terminal. The input terminal of the second 1 × 2 spatial optical switch is connected to one input terminal of the second 2 × N optical multiplexer / demultiplexer via one output terminal of the second 1 × 2 spatial optical switch and the first optical cable. Yes,
If the first optical cable is faulty, the input terminal of the first 1 × 2 spatial optical switch is connected to the other input terminal of the first 2 × N optical multiplexer / demultiplexer via its other output terminal. The input terminal of the second 1 × 2 spatial optical switch is connected to the other input terminal of the second 2 × N optical multiplexer / demultiplexer via its other output terminal and the second optical cable. Yes,
When a failure occurs in the first optical cable , the connection of the first 1x2 spatial optical switch and the second 1x2 spatial optical switch is switched, and the second optical cable, the first 2xN optical multiplexer / demultiplexer, and the first optical cable are switched . 2 2xN light multiplexer / de WDM passive optical network, wherein the multiplexer and the input terminal settings are to be changed by the synchronization. The wavelength division multiplexing passive method according to claim 1, wherein an arrayed waveguide grating wavelength division multiplexer / demultiplexer is used for the first 2xN optical multiplexer / demultiplexer and the second 2xN optical multiplexer / demultiplexer. optical network. The failure recovery in the first optical cable, WDM passive optical network of claim 1, wavelength by wavelength change of the injected incoherent light is characterized in that it is automatically assigned.

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