KR100317133B1 - Bi-directional wavelength division multiplex self-developed fiber optic network with bidirectional add / drop multiplexer - Google Patents

Abstract

The present invention relates to a bidirectional wavelength division multiplexing self-healing optical communication network having a bidirectional add / drop multiplexer, and an object of the present invention is to implement a bidirectional add / drop multiplexer having a simple structure using a single N × N multiplexer. It is to provide a bidirectional self-healing optical communication network using only two fibers.

A first embodiment of the present invention for this purpose, in the optical communication network interconnected by two strands of optical fibers between the nodes, each node, at least two optical signal receiving means for detecting whether or not to receive the optical signal; At least two switching means for switching to a preliminary optical fiber when the operational optical fiber is cut; At least two switching control means for controlling the switching means; Multiplexing / demultiplexing means connected to the switching means to simultaneously perform multiplexing and demultiplexing; And a plurality of optical amplification means connected to the operation ring and the preliminary ring, wherein the multiplexing / demultiplexing means is connected in a fold-back form to simultaneously perform multiplexing and demultiplexing of the wavelength-divided signals. One multiplexer, at least two circulators, and at least two filtering means for filtering the multiplexed signal output from the multiplexer.

Description

Bidirectional wavelength division multiplexing self-healing optical communication network with bidirectional add / drop multiplexer

The present invention relates to a WDM (wavelength division multiplexing) self-healing optical communication network having a bidirectional add / drop multiplexer (B-ADM). The present invention relates to a bidirectional wavelength division multiplex self-healing optical communication network using an add / drop multiplexer (B-ADM) to improve the utilization efficiency of an optical fiber by about 2 times compared to the conventional method.

In the optical communication network using the wavelength division multiplexing method, it is possible to transmit and receive desired information at each node without optical / electric and all / optical conversion, thus suggesting the possibility of the large-capacity optical communication era of several Tb / s or more. As the speed of the communication network increases significantly, a new problem is the reliability of the optical communication network. For example, an 80 Gb / s optical transmission system allows a million people to talk simultaneously over a pair of optical fibers. Thus, if such a system fails and communication is disrupted, urban or national functions can be paralyzed. Therefore, it is very important to improve the reliability of the communication network in parallel with increasing the communication speed. To increase the reliability of the network, it must have a self-healing function that prevents the network from interrupting service even in the event of a system or transmission line failure.

Currently proposed wavelength-division multiplex optical networks with self-healing features include unidirectional annular optical networks using two fibers, bidirectional annular optical networks using four fibers, and mesh networks. There is an all-optical transmission network.

The ring-shaped optical communication network can implement self-healing function by a relatively simple method compared to the all-optical transmission network, and research has been actively conducted since it has an advantage that it can be easily linked with the existing SONET network. A bidirectional annular fiber network using four fiber optics requires twice as much fiber as a unidirectional fiber optic network using two fiber optics, but it is necessary to connect (N2-1) / 8 Since the wavelength is required, the utilization efficiency of the wavelength is about 4 times higher than that of the unidirectional annular optical communication network requiring N (N-1) / 2 wavelength. In addition, in the bidirectional annular optical network, the maximum number of nodes that must pass before the transmitted signal is received is (N-1) / 2 so that the signal distortion is reduced compared to the unidirectional annular optical network that must pass through (N-1) nodes. There is this. Therefore, it is advantageous to use a bidirectional annular optical communication network as an optical communication network connecting all nodes. In the existing bidirectional optical communication network using four optical fibers, bidirectional optical communication is performed through two optical fibers, and the other two strands are for protection. Therefore, in order to receive (drop) or transmit (ad) a signal in each direction, a unidirectional add / drop multiplexer is separately required for each node.

In recent years, bidirectional optical communication using only one strand of optical fiber has been realized to improve optical fiber utilization efficiency. In addition, a multiplexer capable of adding / dropping signals transmitted in both directions has been proposed, and it has been reported that a bidirectional annular optical communication network can be realized using two fibers. However, the existing bidirectional add / drop multiplexer uses two 1 × N multiplexers, uses an optical amplifier for each channel, or uses fiber grating filters for each channel to be added / dropped with the circulator. The number of parts was large.

Accordingly, the present invention has been made to solve the problems of the prior art as described above, an object of the present invention is to implement a bidirectional add / drop multiplexer of a simple structure using a single N × N multiplexer, using 2 It is to provide a bidirectional self-healing optical communication network using only stranded optical fiber.

1 is a block diagram of a node of a self-healing optical communication network according to a first embodiment of the present invention.

2 is a block diagram of a bidirectional add / drop multiplexer according to the present invention;

3 is a block diagram of a node of a self-healing optical communication network according to a second embodiment of the present invention;

Figure 4 is a block diagram of a node of a self-healing optical communication network sharing a multiplexed area according to a third embodiment of the present invention.

5 is an exemplary diagram of a bidirectional wavelength division multiplexing self-healing optical communication network using the first embodiment;

6 is a graph showing the bit error rate measured according to the reception strength of a signal transmitted using the present invention.

7 is a graph showing self-healing characteristics of a bidirectional wavelength division multiplexing self-healing optical communication network;

8 is a graph showing the measured bit error rate of the recovered signal using the present invention.

Fig. 9 is a graph showing the relative intensity noise generated in the present invention and the penalty due to the accumulation of ASE noise of the amplifier.

* Explanation of symbols for main parts of the drawings

10, 19: coupler

11, 15, 18, 30, 35, 39, 40, 41, 49, 50: bidirectional erbium-doped fiber amplifier

12, 17: control unit

13, 16, 31, 32, 37, 38, 42, 43, 47, 48: switch

14, 34, 45, 46: bidirectional add / drop multiplexer

33, 36: Attenuator

44: switch box

A first embodiment of the present invention for achieving the above object, a bidirectional wavelength division multiplex self-healing comprising a plurality of nodes, the node and the node is interconnected by using two optical fibers to form an operating ring and a preliminary ring An optical communication network, each node comprising: at least two optical signal receiving means for detecting whether an optical signal is received, including an optical coupler, for monitoring a cutting state of an operating optical fiber; At least two switching means for transferring to the preliminary optical fiber when the operational optical fiber is cut; At least two switching control means for controlling the switching means when recognizing that the optical signal is not received by the optical signal receiving means; Multiplexing / demultiplexing means connected between the switching means for multiplexing to add a signal to be transmitted at each node and demultiplexing to drop a signal to be received; And a plurality of optical amplification means connected to the operation ring and the reserve ring to amplify the optical signal, wherein the multiplexing / demultiplexing means, when the number of input and output ports are divided in half, the upper and lower sides correspond to each other. A multiplexer that is connected in a fold-back form to simultaneously connect and multiplexes and demultiplexes wavelength-divided signals, and is connected to the multiplexer to separate bidirectional signals and remultiplexed bidirectional signals And at least two optical signal separation / merge means for merging them, and at least two filtering means for filtering the multiplexed signal output from the multiplexer.

In addition, a second embodiment of the present invention for achieving the above object, a bidirectional wavelength division multiplexing method comprising a plurality of nodes, the node and the node is interconnected using two strands of optical fibers to form an operating ring and a spare ring In the self-healing optical communication network, each node comprises: at least two optical signal receiving means for detecting whether or not to receive an optical signal including an optical coupler to monitor the cutting state of the operating optical fiber; At least two switching means for switching to a preliminary optical fiber when the operational optical fiber is cut; Two optical attenuator means for compensating for the difference in gain of the optical amplifier when switching from the operational optical fiber to the spare optical fiber; At least two switching control means for controlling the switching means when recognizing that the optical signal is not received by the optical signal receiving means; And multiplexing / demultiplexing means connected to the switching means and multiplexed to add a signal to be transmitted from each node, and demultiplexed to drop a signal to be received. When the number of input and output ports is divided in half, the multiplexing means is connected in a fold-back form in which upper and lower portions are connected to each other to simultaneously perform multiplexing and demultiplexing of wavelength-divided signals. A multiplexer, at least two optical signal separation / merge means connected to the multiplexer to separate bidirectional signals and merge remultiplexed bidirectional signals, and at least two to filter the multiplexed signal output from the multiplexer And filtering means, and a plurality of optical amplification means for amplifying the optical signal.

In addition, a third embodiment of the present invention for achieving the above object is provided with a plurality of nodes, between the node and the node between the interconnect using a two-fiber optical fiber to configure the operating ring and the spare ring, the normal time In the bidirectional wavelength division multiplex self-healing optical communication network for transmitting the optical signal through the operating ring and the spare ring, each node, including an optical coupler to monitor the state of the cutting of the operating optical fiber, whether or not to receive the optical signal At least two optical signal receiving means for sensing; At least two switching means for switching to a preliminary optical fiber when the operational optical fiber is cut; At least two switching control means for controlling the switching means when recognizing that the optical signal is not received by the optical signal receiving means; At least two multiplexing / demultiplexings each connected to a spare fiber and an operating fiber between the switching means to multiplex to add a signal to be transmitted from each node and to demultiplex to drop a signal to be received. Way; A plurality of optical amplification means connected to said operating ring and said reserve ring to amplify an optical signal; And a switch box connected to the multiplexing / demultiplexing means connected on the spare ring to block all signals transmitted through the spare ring in the event of a communication failure, wherein the multiplexing / demultiplexing means includes the number of input and output ports. When divided in half, one multiplexer connected in a fold-back form in which the upper part and the lower part correspond to each other and simultaneously perform the multiplexing and demultiplexing of the wavelength-divided signals. And at least two optical signal separation / merge means for separating the bidirectional signals and merging the remultiplexed bidirectional signals, and at least two filtering means for filtering the multiplexed signal output from the multiplexer. .

In the present invention, by implementing a bidirectional add / drop multiplexer using one N × N multiplexer, a bidirectional self-healing optical communication network can be economically implemented as compared to the conventional bidirectional add / drop multiplexer. In the bidirectional add / drop multiplexer according to the present invention, a noise due to crosstalk between signals traveling in opposite directions (due to Rayleigh backscattering and reflection at an optical fiber fusion splicing point) in a bidirectional optical communication, Noise caused by crosstalk can be removed using a simple bandpass filter.

Therefore, in the present invention, the number of nodes that can be accommodated in the bidirectional optical communication network is similar to that of the unidirectional optical communication network. In addition, the present invention by using a separate bi-directional add / drop multiplexer and the optical switch, it is possible to improve the utilization efficiency of the optical fiber by using the protective optical fiber to transmit information that can stop the service in the event of a failure.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

1 is a block diagram of a bidirectional wavelength division multiplexing self-healing optical communication network node according to a first embodiment of the present invention. Erbium-Doped Fiber Amplifier), 12 and 17 are switching controllers, 13 and 16 are switches, and 14 are bidirectional add / drop multiplexers (B-ADMs).

Each node is equipped with one bi-directional add / drop multiplexer (B-ADM) 14, two 2 × 2 switches (13, 16), three bi-directional amplifiers (11, 15, 18), and communication faults. 1:99 couplers 10 and 19 and control units 12 and 17 for recovery in the area.

The 1:99 couplers 10 and 19 perform a function of branching the received optical signal in order to confirm the existence of the received optical signal.

The control unit 12 or 17 checks whether an optical signal is input from the coupler 10 or 19, and checks whether the light beam is cut, thereby switching the switches 13 and 16.

Erbium-added optical fiber amplifiers 11, 15, and 18 are bidirectional amplifiers, which serve to amplify and transmit optical signals.

The 2x2 switches 13 and 16 are in charge of switching by the control part 12 and 17 to a spare optical path, or switching to an operating optical path.

The bidirectional add / drop multiplexer 14 is responsible for adding a signal to be transmitted or dropping a signal to be received at each node, and a detailed configuration thereof is shown in FIG.

2 is a detailed configuration diagram of a bidirectional add / drop multiplexer according to the present invention, in which 20, 28 are circulators, 21, 22, 26, and 27 are unidirectional erbium-doped fiber amplifiers, and 23 is N × N. The multiplexers 24 and 25 represent optical band pass filters (OBPFs), respectively.

The bi-directional add / drop multiplexer is described in detail in "Bi-Directional Add / Drop Optical Amplifier Module Using One Waveguide Grating Multiplexer," filed Jan. 5, 1998, filed by the same applicant. Will be outlined.

The bidirectional add / drop multiplexer includes one N × N multiplexer 23, two circulators 20 and 28, and two bandpass filters 24 and 25.

One N × N multiplexer 23 is a waveguide type diffraction grating, which is operated in a fold-back form to simultaneously perform multiplexing and demultiplexing of wavelength division multiplexed signals. That is, in the 8x8 multiplexer, as shown in the figure, when the number of input and output ports is divided in half, the upper and lower portions are symmetrically connected to each other so that multiplexing and demultiplexing can be simultaneously performed. As shown in the figure, port 5 is connected to port 1 for both input and output ports, port 2 and port 6 are used as add or drop ports, and port 3 is connected to port 7 respectively. Ports 4 and 8 are used for transmission. Here, port 4 is a port for receiving, demultiplexes a received signal, and port 8 is a port for transmitting, and multiplexes a signal to be transmitted. Therefore, ports 1, 2, and 3 of the input stage are multiplexed to port 8 of the output stage, port 4 of the input stage is demultiplexed to ports 1, 2, and 3 of the output stage, and port 4 of the output stage is 5 of the input stage. Demultiplexed to ports 6 and 7, and ports 5, 6 and 7 of the output stage are multiplexed to 8 ports of the input stage.

The circulators 20 and 28 are responsible for separating and demultiplexing bidirectional signals and merging the remultiplexed bidirectional signals.

In a bidirectional optical transmission system using one strand of optical fiber, relative intensity noise occurs due to Rayleigh backscattering, optical reflection, or crosstalk of multiplexers, thereby limiting the performance of the system. Limit scalability In the present invention, band pass filters (OBPF) 24 and 25 are used to suppress the accumulation of relative intensity noise. That is, when the wavelength division multiplexed signal is transmitted in both directions through port 8, the band pass filters 24 and 25 are connected to limit the band of the transmitted signal.

The unidirectional erbium-doped fiber amplifiers 21, 22, 26, and 27 indicated by ruled lines and double ruled lines in FIG. 2 represent a method of using an amplifier in a bidirectional add / drop multiplexer instead of a bidirectional amplifier of an operating ring. That is, an example of using a unidirectional optical amplifier in the bidirectional add / drop multiplexer without using the bidirectional optical amplifier in the operating ring is shown. Therefore, this unidirectional amplifier is generally not used when using a bidirectional amplifier on the operating ring.

In the bidirectional wavelength division multiplexing self-healing optical communication network according to the present invention, by using the node of the structure as shown in FIG. That is, by detecting the presence or absence of a signal of the operation ring by using the 1:99 coupler (10, 19), when the communication is cut off by the optical fiber cut (that is, when no signal is received through the operation ring) the control unit 12 , 17) by switching the switch (13, 16) and transmitting the signal transmitted through the operating ring through the spare ring, it is possible to automatically recover the disconnection of the communication by cutting the optical fiber. The optical amplifier 15 used in the protection ring is used to compensate for the optical fiber transmission loss of the preliminary ring and device loss such as a switch.

3 is a block diagram of a node of a bidirectional wavelength division multiplexing self-healing optical communication network according to a second embodiment of the present invention, wherein 30, 35, and 39 are bidirectional erbium-doped fiber amplifiers, 31, 32, 37, and 38. Silver switch, 33 and 36 are attenuators, and 34 are bidirectional add / drop multiplexers, respectively.

The optical amplifier in the spare ring compensates for the loss of the spare fiber, whose gain equals the loss of fiber between nodes. If the fiber is disconnected between nodes and the communication network fails, the two nodes adjacent to the failed area switch the optical switch to switch the signal from the operating ring to the spare ring. In this case, the gain of the optical amplifier in the spare ring of two adjacent nodes is {(fiber loss [dB]-insertion loss [dB] of add / drop multiplexer) / 2} higher than the gain of the optical amplifier in the operating ring. . Therefore, in the node structure of FIG. 3, instead of using 2x2 switches as shown in FIG. 1, two excess 1x2 switches 31, 32 or 37 and 38 and attenuators 33 or 36 are used to obtain this excess gain. Compensated. If the insertion loss of the bidirectional add / drop multiplexer 34 is greater than the loss of the fiber, this is compensated by increasing the gain of the optical amplifier 35 in the spare ring of two nodes adjacent to the failure of the spare ring.

In FIG. 3, a part for checking an abnormality of the optical path and a controller for controlling the 1 × 2 switch are not shown, but this is the same as the configuration of FIG. 1.

4 is a block diagram of a node of a self-healing optical communication network sharing a multiplexing area using a bidirectional add / drop multiplexer according to a third embodiment of the present invention, wherein 40, 41, 49, and 50 are bidirectional optical amplifiers, 42, 43, 47, and 48 are switches, 44 are switch boxes, and 45 and 46 are bidirectional add / drop multiplexers, respectively.

Self-healing optical networks that share a multiplexed area are those that transmit signals over a spare ring in steady state. However, signals transmitted over the spare ring do not have self-healing. That is, in the normal state, the signal is transmitted through the operating ring and the spare ring, and when a communication failure occurs, only the signals transmitted through the operating ring are recovered. Such a communication network has an advantage that the optical fiber can be used more efficiently than other self-healing optical communication networks.

4 further includes a bidirectional add / drop multiplexer 45 in a spare ring to implement a self-healing optical communication network sharing a multiplexing area. In addition, the bidirectional add / drop multiplexer 45 used in the spare ring uses a switch box 44 to block all signals transmitted through the spare ring when a communication failure occurs.

In the third embodiment of the present invention of Fig. 4, four bidirectional optical fiber amplifiers 40, 41, 49, and 50 are provided on each ring, and bidirectional add / drop multiplexers 45, 46 are formed on the operating ring and the spare ring. It is equipped with each. In addition, four 1 × 2 switches 42, 43, 47, and 48 for switching between the operation ring and the spare ring are connected to the front and rear ends of the bidirectional add / drop multiplexers 45 and 46, respectively. The switch 42 installed at is connected to the switch 48 installed at the rear end of the operation ring, and the switch 47 installed at the rear end of the spare ring is connected to the switch 43 installed at the front end of the operation ring.

Operation of the control unit and circulator not shown in the configuration of FIG. 4 is the same as that of FIG. In addition, the switch shown in FIG. 4 may use the switch shown in FIG. 1 as it is, or various switches other than the above may be used.

FIG. 5 shows an example of implementing a self-healing optical communication network of a bidirectional wavelength division multiplexing method using a node according to the first embodiment of the present invention shown in FIG.

One of the two optical fibers is provided as a spare, and in a normal state, bidirectional communication is performed through one of the operating rings. Each node was annularly connected using 40km of single mode fiber between nodes.

In order to confirm the performance of the bidirectional self-healing optical communication network proposed in the present invention, two signals in each direction are modulated at 2.5 Gb / s and transmitted. The wavelengths of the signals used were 1549.32 nm and 1550.92 nm in the counterclockwise direction and 1555.75 nm and 1557.36 nm in the clockwise direction. In order to confirm the bidirectional add / drop function of the optical network, one of the signals in each direction was dropped at node 2 (counterclockwise: 1549.32 nm) and node 3 (clockwise: 1557.36 nm), respectively. The node dropping the signal adds a signal having the same wavelength as the dropped signal in the same direction and transmits it to Node 1. In addition, in order to confirm the performance of the bidirectional transmission, one signal in each direction (counterclockwise: 1550.92 nm, clockwise: 1555.75 nm) was received at the node 1 in a circular network. The signals around the annular network without add / drop are signals transmitted through six bidirectional amplifiers and three bidirectional add / drop multiplexers.

6 is a graph illustrating bit error rates measured according to the strength of a received signal when transmitting wavelength-division multiplexed signals through a bidirectional wavelength division multiplexing self-healing optical communication network according to the present invention.

As can be seen from the figure, it can be seen that the signal strength penalty of six signals transmitted through each path is less than 0.5 dB at a bit error rate of 10 ⁻⁹ .

In order to confirm the self-healing function of the bidirectional optical communication network according to the present invention, a communication failure (that is, optical fiber cutting) was generated using an acoustic-optic modulator between nodes 1 and 3.

7 shows self-healing characteristics measured in a bidirectional wavelength division multiplex self-healing optical communication network according to the present invention.

The upper line of the two lines shown in the figure represents the electrical signal applied to the acoustic-optic modulator. Thus, the low level of the electrical signal corresponds to a communication failure condition. The bottom line shows the 1550.92 nm signal received at node 1 before and after recovery of the communication failure. Before a communication failure occurs (normal state), this signal is received by circumnavigating the annular network through the operating ring. However, when fiber cleavage occurs, these signals can no longer be transmitted through the operating ring. Thus, these signals are sent from node 3 to the spare ring and then received at node 1 via the spare ring (nodes 1-2-3-2-1). As can be seen in Figure 7, the communication failure recovery of the optical communication network according to the present invention is made within 2 ms.

8 is a graph showing measurement bit error rates of signals recovered through a bidirectional wavelength division multiplexing self-healing optical communication network according to the present invention.

The maximum sensitivity penalty of the recovered signals, i.e., the penalty of the recovered signal over three nodes of the operating ring and three nodes of the spare ring, is less than 0.5 dB.

9 is a result of calculating a penalty due to the accumulation of relative intensity noise and ASE noise of an amplifier generated in a bidirectional wavelength division multiplexing self-healing optical communication network according to the present invention in order to predict the scalability of the optical communication network.

In this calculation, it is assumed that the signal gain of the bidirectional optical amplifier is equal to the transmission loss between nodes, and that the relative intensity noise is mainly caused by Rayleigh backscattering. The values used in the calculation are as follows. Noise figure of optical amplifier = 5.5 dB; Measured Rayleigh reflection coefficient = -28 dB; Extinction ratio of the bandpass filter = 35 dB; Fiber loss = 0.275 dB / km.

The results of Fig. 9 show the effect of suppressing the relative intensity noise by the bandpass filter. As can be seen from the figure, when the bandpass filter is not used, it is difficult to implement a bidirectional wavelength division multiplexing self-healing optical communication network having three or more nodes even when the distance between nodes is 40 km. On the other hand, when using a bandpass filter like the optical communication network according to the present invention, the influence of the relative intensity noise can be negligibly enjoyed, and the size of the optical communication network is limited by the ASE noise of the optical amplifier. . In other words, when using a band pass filter, an optical communication network having more than 40 nodes can be implemented. As the spacing between nodes increases, the ASE noise of the optical amplifier increases, which limits the scalability of the optical network. That is, when the distance between nodes increases to 80km, the bidirectional optical communication network according to the present invention can be extended to 14 nodes (assuming that a spare ring occurs in case of communication failure). As the size of the optical communication network is expanded, the passband of the equivalent multiplexer is reduced as the optical signals transmitted through the communication network pass through multiple nodes while passing through multiple nodes. The narrowing of the passband of the multiplexer also becomes a limiting factor in the scalability of the optical communication network. However, this limiting factor can be easily overcome by using a multiplexer having flat passband characteristics.

The bidirectional wavelength division multiplexing optical network is suitable for connecting all nodes. In a typical bidirectional self-healing optical network using four fiber optics, two-way fiber optics are used for bidirectional communication (the remaining two are redundant) and the same wavelength is used to connect any two nodes. Communication can be performed. In addition, when connecting between nodes, it is possible to select a direction in which connection is possible while passing a small number of nodes from a clockwise direction and a counterclockwise direction. Therefore, in the optical communication network having N nodes, (N2-1) / 8 wavelengths are required to connect all the nodes. This corresponds to one quarter of the number of wavelengths N (N-1) / 2 required in a unidirectional self-healing network. In the bidirectional wavelength division multiplex self-healing optical communication network according to the present invention, since one strand of optical fiber is used for bidirectional communication, the same wavelength cannot be used for bidirectional communication. Therefore, in the proposed optical network, the wavelength required to connect all the nodes is doubled to be approximately (N2-1) / 4 compared with the case of using 4 optical fibers. However, it can be seen that the optical communication network according to the present invention reduces the number of wavelengths in half compared to the unidirectional self-healing optical communication network.

According to the present invention made as described above, by using a simple and economical bidirectional add / drop multiplexer, the number of optical fibers required to implement a bidirectional self-healing optical communication network can be reduced by half. That is, two-way self-healing optical communication network can be realized by using two-fiber optical fiber like unidirectional self-healing optical communication network, and the number of wavelengths required to connect all nodes between nodes is doubled than when using four-fiber optical fiber. However, there is an effect that all nodes can be connected by using half the wavelength than the unidirectional self-healing optical communication network.

Claims (20)

In the bidirectional wavelength-division multiplex self-healing optical communication network comprising a plurality of nodes, and configured by ring-connecting two fibers (operation optical fiber and preliminary optical fiber) between the node and the node, Each node is At least two optical signal receiving means for detecting whether an optical signal is received, including an optical coupler, for monitoring a cutting state of the operating optical fiber; At least two switching means for switching to the preliminary optical fiber when the operational optical fiber is cut; At least two switching control means for controlling the switching means when recognizing that the optical signal is not received by the optical signal receiving means; Multiplexing / demultiplexing means connected between the switching means for multiplexing to add a signal to be transmitted at the node and demultiplexing to drop a signal to be received; And A plurality of optical amplification means connected to the operating ring and the backup ring to amplify the optical signal, The multiplexing / demultiplexing means, When dividing the number of input and output ports in half, the upper and lower ports are connected in a fold-back form so as to simultaneously perform multiplexing and demultiplexing of the wavelength-divided signals that proceed in both directions. With one multiplexer, At least two optical signal separation / merging means connected to the multiplexer to separate bidirectional signals and merge remultiplexed bidirectional signals; and At least two filtering means for filtering the multiplexed signal output from the multiplexer Bidirectional wavelength division multiple self-healing optical communication network comprising a. The method of claim 1, And each switching means is a 2 × 2 switch. The method of claim 1, Each of the switching means comprises at least two 1 × 2 switches respectively connected to the preliminary optical fiber and the operational optical fiber; And attenuators connected between the 1 × 2 switches to compensate the gain difference between the optical amplification means installed in the preliminary ring and the optical amplification means installed in the operating ring. The method of claim 1, The plurality of optical amplification means, A first bidirectional optical amplifier provided between the switching means of the preliminary ring; And a second and a third bidirectional optical amplifier respectively installed between the switching means and the coupling means of the operating ring. The method of claim 1, The optical signal separation / merge means includes a circulator bidirectional wavelength division multiple self-healing optical communication network. In the bidirectional wavelength-division multiplex self-healing optical communication network comprising a plurality of nodes, and configured by ring-connecting two fibers (operation optical fiber and preliminary optical fiber) between the node and the node, Each node is At least two optical signal receiving means for detecting whether an optical signal is received, including an optical coupler, for monitoring a cutting state of the operating optical fiber; At least two switching means for switching to the preliminary optical fiber when the operational optical fiber is cut; At least two switching control means for controlling the switching means when recognizing that the optical signal is not received by the optical signal receiving means; And And multiplexing / demultiplexing means connected to the switching means for multiplexing to add a signal to be transmitted from each node and demultiplexing to drop a signal to be received, The multiplexing / demultiplexing means, When dividing the number of input and output ports in half, the upper and lower ports are connected in a fold-back form so as to simultaneously perform the multiplexing and demultiplexing of the wavelength-divided signals proceeding in both directions. With one multiplexer, At least two optical signal separation / merge means connected to the multiplexer for separating bidirectional signals and merging the remultiplexed bidirectional signals; At least two filtering means for filtering the multiplexed signal output from the multiplexer, and Multiple optical amplifiers for amplifying optical signals Bidirectional wavelength division multiple self-healing optical communication network comprising a. The method of claim 6, And each switching means is a 2 × 2 switch. The method of claim 6, Each of the switching means comprises at least two 1 × 2 switches respectively connected to the preliminary optical fiber and the operational optical fiber; And attenuators connected between the 1 × 2 switches to compensate for gain differences between the optical amplification means installed in the preliminary ring and the operating ring, respectively. The method of claim 6, The optical signal separation / merge means includes a circulator bidirectional wavelength division multiple self-healing optical communication network. The method of claim 6, The plurality of optical amplification means, First and second unidirectional optical amplifiers connected between the circulator and the multiplexer, respectively, for amplifying and receiving the received optical signals; Bidirectional wavelengths, each of which is connected between the circulator and the filtering means, and includes third and fourth unidirectional optical amplifiers for amplifying an optical signal filtered by the filtering means and transmitting the amplified optical signal to another node through the circulator. Split multi-self-healing optical communication network. In the bidirectional wavelength-division multiplex self-healing optical communication network comprising a plurality of nodes, and configured by ring-connecting two fibers (operation optical fiber and preliminary optical fiber) between the node and the node, Each node is At least two optical signal receiving means for detecting whether an optical signal is received, including an optical coupler, for monitoring a cutting state of the operating optical fiber; At least two switching means for switching to the preliminary optical fiber when the operational optical fiber is cut; At least two switching control means for controlling the switching means when recognizing that the optical signal is not received by the optical signal receiving means; At least two multiplexing / demultiplexings each connected to a spare fiber and an operating fiber between the switching means to multiplex to add a signal to be transmitted from each node and to demultiplex to drop a signal to be received. Way; A plurality of optical amplification means connected to said operating ring and said reserve ring to amplify an optical signal; And A switch box connected to the multiplexing / demultiplexing means connected to the spare optical fiber to block all signals transmitted through the spare optical fiber when a communication failure occurs Provided with The multiplexing / demultiplexing means, When dividing the number of input and output ports in half, the upper and lower ports are connected in a fold-back form so as to simultaneously perform the multiplexing and demultiplexing of the wavelength-divided signals proceeding in both directions. With one multiplexer, At least two optical signal separation / merging means connected to the multiplexer to separate bidirectional signals and merge remultiplexed bidirectional signals; and At least two filtering means for filtering the multiplexed signal output from the multiplexer Bidirectional wavelength division multiple self-healing optical communication network comprising a. The method of claim 11, And each switching means is a 2 × 2 switch. The method of claim 11, Each switching means, At least four 1 × 2 switches connected to each other with multiplexing / demultiplexing means connected to the operational ring and the spare ring, respectively, The 1 × 2 switch installed in the spare ring is connected to the 1 × 2 switch installed in the operation ring, and is connected between the 1 × 2 switches to compensate the gain difference between the optical ring and the optical amplification means respectively installed in the operation ring. Bidirectional wavelength division multiple self-healing optical communication network comprising attenuators for. The method of claim 11, The plurality of optical amplification means, A bidirectional wavelength division multiple self-healing optical communication network comprising at least four bidirectional optical amplifiers respectively installed in the preliminary ring and the operating ring. The method of claim 11, The optical signal separation / merge means includes a circulator bidirectional wavelength division multiple self-healing optical communication network. In the bidirectional wavelength-division multiplex self-healing optical communication network comprising a plurality of nodes, and configured by ring-connecting two strands of optical fibers (operating optical fiber and spare optical fiber) between the node and the node, Each node is At least two optical signal receiving means for detecting whether an optical signal is received, including an optical coupler, for monitoring a cutting state of the operating optical fiber; At least two switching means for switching to the preliminary optical fiber when the operational optical fiber is cut; At least two switching control means for controlling the switching means when recognizing that the optical signal is not received by the optical signal receiving means; At least two multiplexing / demultiplexings each connected to a spare fiber and an operating fiber between the switching means to multiplex to add a signal to be transmitted from each node, and to demultiplex to drop a signal to be received. Way; And A switch box connected to the multiplexing / demultiplexing means connected to the spare optical fiber to block all signals transmitted through the spare optical fiber when a communication failure occurs Provided with The multiplexing / demultiplexing means, When dividing the number of input and output ports in half, the upper and lower ports are connected in a fold-back form so as to simultaneously perform the multiplexing and demultiplexing of the wavelength-divided signals proceeding in both directions. With one multiplexer, At least two optical signal separation / merge means connected to the multiplexer for separating bidirectional signals and merging the remultiplexed bidirectional signals; At least two filtering means for filtering the multiplexed signal output from the multiplexer, and A plurality of optical amplification means connected to the operating ring and the backup ring to amplify the optical signal Bidirectional wavelength division multiple self-healing optical communication network comprising a. The method of claim 16, And each switching means is a 2 × 2 switch. The method of claim 16, Each switching means, At least four 1 × 2 switches connected to each other with multiplexing / demultiplexing means connected to the operational ring and the spare ring, respectively, The 1 × 2 switch installed in the spare ring is connected to the 1 × 2 switch installed in the operation ring, and is connected between the 1 × 2 switches to compensate the gain difference between the optical ring and the optical amplification means respectively installed in the operation ring. Bidirectional wavelength division multiple self-healing optical communication network comprising attenuators for. The method of claim 16, The optical signal separation / merge means includes a circulator bidirectional wavelength division multiple self-healing optical communication network. The method of claim 16, The plurality of optical amplification means, First and second unidirectional optical amplifiers connected between the circulator and the multiplexer, respectively, for amplifying and receiving the received optical signals; Bidirectional wavelengths, each of which is connected between the circulator and the filtering means, and includes third and fourth unidirectional optical amplifiers for amplifying an optical signal filtered by the filtering means and transmitting the amplified optical signal to another node through the circulator. Split multi-self-healing optical communication network.