JP3233204B2 - Wavelength ADM device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to optical communication, optical switching,
Wavelength optical ADM (Add-Drop Mul) in optical networks
The present invention relates to a device, and a fault monitoring method and a network using the device, and more particularly to a wavelength light A that realizes low cost and small size as a node of the network.
It relates to a DM device.

[0002]

2. Description of the Related Art Conventionally, as an optical network, TDM
SONET (Synchronous Op) using (Time Division Multiplexing)
tical Network) / SDH (Synchronous Digital Hierar)
chy) is the mainstream.
In a network based on SONET / SDH, transmission path switching is generally performed by terminating an optical signal in a line layer, performing switching, and then multiplexing the optical signal again.

[0003] At this time, in order to ensure the reliability of link connection, the presence or absence of an optical signal, for example, GR-253-CORE (Issue 1, described in the Bellcore (Bell Communications Research) standard).
As described in December 1994), detecting no signal (hereinafter, LOS: Loss of Signal) or section overhead in a frame (hereinafter, referred to as LOS).
By evaluating SOH: Section Overhead or line overhead (hereinafter LOH: Line Overhead), frame loss (hereinafter, LOF: Loss Of Frame), pointer loss (hereinafter, LOP: Loss of Pointer), code error rate (hereinafter, error rate) , BER: Bit Error Rate) and the like.

In recent years, an OADM capable of switching a transmission path in the form of light without electrically terminating an optical signal.
(Optical Add-Drop Multiplex) device has been proposed and its introduction into the system is being considered. SONE
One of the network elements of T, DCS (Digi
tal Cross-Connect System) includes optical / electrical conversion (hereinafter, O / E conversion), demultiplexer (hereinafter, DEMUX: Demultiplexer), switching,
Multiplexer (hereinafter MUX: Multiplexer)
While optical conversion (hereinafter referred to as E / O conversion) is performed, OADM devices only need to perform switching, and DEMUX and MUX of electrical signals are unnecessary, so that the amount of hardware per transmission optical signal speed can be reduced. In addition, cost reduction and system miniaturization can be expected.

[0005]

When a failure occurs in a network in which an OADM device is arranged, an OAD
The M device is required to detect and determine a failure such as signal light interruption due to a cut of an optical fiber or the like and signal light quality deterioration due to a failure of an optical repeater amplifier and to perform recovery according to the type of the failure. SONET / SD currently used
When network faults are detected using the frame overhead of the H standard, sections or lines need to be terminated in the OADM device.

When a failure occurs in a line including an OADM device, the occurrence of the failure is notified to an end user who uses the line.
AIS: Alarm Indication Signal) read processing and write processing are required. However, in an OADM apparatus that handles optical signals multiplexed at high density, when obtaining network fault information from the frame overhead of a transmitted optical signal, not only large-scale hardware is required, but also fault monitoring information in the network. However, there is a problem that it is necessary to electrically terminate the multiplexed optical signal, read the frame overhead, and multiplex the optical signal again to read only the optical signal.

In order to introduce an OADM device into an existing optical network, a time-division-oriented SONET is required.
The optical layer is defined as an optical layer that treats an optical signal and performs electrical processing in a time-synchronous manner and obtains or does not add information from the optical signal in distinction from the / SDH layer. / SDH provides an automatic protection system (hereinafter referred to as APS: Automatic Protection System), which is a network failure recovery means.
It is necessary to prevent contention with the protection system in the optical layer newly supplied by the ADM device.

[0008] That is, even if SONET / SDH will disappear from the ideal form of the optical network in the future, since at present the SONET / SDH is widely spread worldwide, its assets are used for at least for the time being. Since it is difficult to immediately shift from the APS to the protection system using the OADM device in terms of cost, at least for the time being, it is necessary to make the protection in the optical layer using the OADM device coexist with the APS. Because.

[0009] Considering the introduction into an actual network, the OADM device has the high potential that the amount of hardware per transmitted optical signal can be reduced because of the above-mentioned problems. It cannot be fully demonstrated. In order for an OADM device to fully demonstrate its capabilities, a network fault monitoring and fault recovery method for a network handling high-density multiplexed signals while maintaining compatibility with SONET / SDH, and a method for the same. It is essential to develop hardware.

An object of the present invention is to realize a wavelength optical ADM apparatus capable of dropping and adding signal light of an arbitrary wavelength in a node and competing with a SONET / SDH APS or another framing format transmission apparatus. Not wavelength
An object of the present invention is to define an optical signal interruption failure detection signal in a spatial multiplexing-oriented optical layer, and to realize a reduction in cost and size of an optical ADM device node.

[0011]

[0012]

[0013]

SUMMARY OF THE INVENTION A wavelength light AD according to the present invention is provided .
M apparatus, demultiplexes the multi-wavelength light inputted from the first optical transmission line for each wavelength output from each other three or more multiple terminals, from each other three or more of said plurality terminals a second optical Bungo duplexer you output to the optical transmission path is demultiplexed input light by wavelength multiplexing, and outputs the one hand the light input from the first terminal to the second and third terminals A first optical branch for outputting light input from the second terminal to the first terminal, and an optical receiver for inputting one optical output corresponding to the first optical branch; An optical transmitter having one optical output corresponding to the optical receiver and constituting the wavelength-division multiplexed light, on the one hand outputting light input from a first terminal to a second terminal, and on the other hand the second A second optical branch for outputting light input from the terminal and light input from the third terminal to the first terminal, and a first terminal A third optical branch for outputting light input from the second terminal to the second terminal, and outputting light input from the third terminal to the first terminal, and a light corresponding to the one split light. An optical gate switch for controlling passage and blocking of light,
An optical isolator for passing only one optical output corresponding to the optical gate switch. Further, one of the plurality of terminals of the optical demultiplexer and the first
And the second terminal of the first optical branch and the second terminal.
A first terminal of the first optical branch, a third terminal of the first optical branch, and the optical receiver, a second terminal of the second optical branch, and a third terminal of the third optical branch. 1 terminal and the second terminal
The third terminal of the optical branch is connected to the optical transmitter. Further, a second terminal of each of the plurality of third optical branches formed in a loop and an input terminal of the optical gate switch, an output terminal of the optical gate switch and an input terminal of the optical isolator, The output terminal of the optical isolator is connected to the third terminal of the third optical branch located next. Therefore, the light input to the optical multiplexer / demultiplexer and separated for each wavelength is the first optical branch from one of the other terminals of the optical multiplexer / demultiplexer,
After passing through the second optical branch, the third optical branch, the optical gate switch, and the optical isolator, the separated adjacent third optical branch, the second optical branch, and the first optical branch
Returning to the optical multiplexer / demultiplexer via the optical branch, the optical multiplexer / demultiplexer wavelength-multiplexes the light received from the plurality of first optical branches and outputs the multiplexed light to the optical transmission line.

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of a basic function according to the present invention.
It is a functional block diagram explaining . The wavelength optical ADM apparatus 100 shown in FIG. 1 constitutes a node, and in this node, an optical demultiplexer 11, an optical multiplexer 12, and Light branches 21 to 2n,
Optical gate switches 31 to 3n, optical branches 41 to 4n, optical receivers 51 to 5n, optical transmitters 61 to 6n, control means 70,
And optical signal failure monitoring means 80.

It is assumed that each of the optical demultiplexer 11 and the optical demultiplexer 12 uses an optical demultiplexer or an optical demultiplexer typified by an arrayed waveguide diffraction grating.

The optical branches 21 to 2n are provided for each wavelength obtained by splitting the input wavelength multiplexed light by the optical splitter 11.
It is assumed that the input light is output to each of the optical gate switches 31 to 3n and each of the optical receivers 51 to 5n.

As the optical gate switches 31 to 3n, gate switches having a large on / off ratio are used for switching between branching and insertion, and the EDFA (erbium-doped fiber array) gate switch 30 schematically shown in FIG. I do.

The optical branches 41 to 4n are connected to the optical gate switch 3
1 to 3n and the optical transmitters 61 to 6n
It is assumed that each output is input and output to the optical multiplexer 12.

Optical receivers 51-5n and optical transmitters 61-n
6n, under the control of the control means 70, transmit and receive a predetermined optical signal.

The control means 70 controls the wavelength ADM device 100
, And based on the optical signal interruption monitoring signal received from the optical signal failure monitoring means 80, the target optical gate switch 3n is turned off to interrupt the transmission of the optical signal sent downstream, etc. Each component is controlled so as to realize the following functional operation.

The optical signal failure monitoring means 80 includes the optical receiver 51
5n are monitored, and the result is notified to the control means 70 by a predetermined signal. A specific example of the fault monitoring will be described later with reference to FIG.

Next, the EDFA gate switch 30 will be described with reference to FIG.

EDFA gate switch 3 shown in FIG.
0 is the excitation light source 131, WDM (Wavelength Division)
Multiplex: for wavelength multiplexing) coupler 132 and EDF
(Erbium-doped fiber) 133, and the signal light is input to the EDF 133 from the optical transmission line.
The pump light output from the pump light source 131 is input to the EDF 3 via the wavelength multiplexing coupler 132. In the EDFA gate switch 30, the on / off of the switch and the light level adjustment can be performed on the output signal light by controlling the excitation light intensity of the excitation light source 131.

In the wavelength optical ADM apparatus 100 shown in FIG. 1, the monitoring of the main signal in the optical layer is the information monitoring on the wavelength axis, and the monitoring of the SONET / SDH in units of frames, that is, the information monitoring on the time axis is supported. By doing so, it is possible to handle high-speed optical signals of the Gb / s class.

Next, with reference to FIG. 3, a description will be given of the optical signal interruption failure monitoring signal generated by the optical signal failure monitoring means 80 in FIG. Figure 3 shows the optical layer and SONET / S
It is a target figure which shows and compares the network fault monitoring item in a DH layer.

That is, in the network fault monitoring item in the SONET / SDH layer, a frame loss (LOF: Loss o) for monitoring a time synchronization failure.
f Frame) or pointer loss (LOP: Loss of Poin)
ter), no signal (LOS: Loss o
f Signal) and a bit error rate (BER: Bit Error Rate) for monitoring signal quality deterioration failure.

On the other hand, in the optical layer of the present invention, the wavelength shift signal of the optical signal for monitoring the wavelength shift error of the signal light by the combination of the optical BPF (Band Pass Filter) and the optical S / N ratio or the optical intensity monitoring. (OLOW: Opti
Cal Loss of Wavelength), optical signal interruption signal (OLOS: Optical Loss of Signal) for detecting optical signal interruption failure using monitoring of optical intensity or optical S / N ratio, and optical signal quality by optical S / N monitoring Optical S / N ratio decrease signal (OSD: Optical Signal Degrade) for monitoring deterioration failure
Each of them is newly defined, and the optical signal failure monitoring means 80 in FIG. 1 monitors the optical signal interruption failure in the network.

When a fault occurs in a certain line in the network, the SO is required to notify the fault to the downstream.
In NET / SDH, a line failure detection signal (AIS-L:
LineAlarm Indication Signal).

On the other hand, in the optical layer according to the present invention, the network element detecting the above-mentioned OLOW, OLOS, and OSD, that is, the control means 7 in FIG.
0 and the optical signal failure monitoring means 80 interrupts the optical output to notify the occurrence of a failure by a network failure detection signal (AIS-O: Optical Alarm Indication System).
gnal) to the downstream. That is, when the network element shuts off the optical output, the network element downstream therefrom transmits the OLOS to the AIS.
It is detected as -O and the light output is cut off.

As described above, finally, the SONET / S
The DH line terminator detects the LOS, and this detection allows the optical layer to notify the SONET / SDH layer of a network failure. This series of AIS propagation can be said to be equivalent to that a network element that detects OLOS, OLOW, or OSD converts it into AIS-O in the optical layer and notifies the SONET / SDH layer line terminator. .

The recovery from the failure can be performed by switching the protection switch of each node by receiving the above-mentioned optical signal cutoff monitoring signal. Since the above can be realized with a simple hardware configuration, it is advantageous for reducing the size and cost of the system.

Next, referring to FIG. 1 , the optical gate switch or gate is an EDFA gate switch, and the code value "n" is a value "4", the wavelength is 1548 nm (λ1),
1550 nm (λ2), 1552 nm (λ3), 155
Four signal light of 4 nm (λ4) is wavelength multiplexed.
The details will be described .

[0047]

[0048]

Wavelength 1548 nm (λ1), 1550 nm
The four signal lights of (λ2), 1552 nm (λ3), and 1554 nm (λ4) are input to an optical demultiplexer 11 represented by an arrayed waveguide diffraction grating, and different optical branches 21 to 24, respectively.
Is output to That is, only one wavelength of light is input to each of the optical branches 21 to 24.

Next, passage, branching, and insertion of an optical signal in the operation of the wavelength ADM apparatus 100 will be described.

First, the operation of passing an optical signal will be described. The wavelength 154 input from the optical demultiplexer 11 to the optical branch 21
After passing through the EDFA gate 31, the signal light of 8 nm (λ 1) is input to the optical multiplexer 12 typified by the arrayed waveguide diffraction grating via the optical branch 41.

Next, the branching operation of the optical signal will be described. The wavelength 154 input from the optical demultiplexer 11 to the optical branch 21
The signal light of 8 nm (λ1) passes through the optical branch 21 to the EDFA.
The signal is output to the gate 31 and a part is input to the optical receiver 51 and received.

Finally, the operation of inserting an optical signal will be described. The wavelength 154 input from the optical demultiplexer 11 to the optical branch 21
The signal light of 8 nm (λ 1) emits E
When the optical gate switch 31 of the DFA gate is turned off, the output to the optical branch 41 is cut off. At this time, the signal light having a wavelength of 1548 nm (λ1) output from the optical transmitter 61 under the control of the control means 70 is input to the optical multiplexer 12 by the optical branch 41.

For each of the other wavelengths λ 2 to λ 4, the flowing optical transmission path is changed from the optical demultiplexer 11 to the optical multiplexer 12.
Up to this point, it has the same configuration. Therefore, it is possible to add and drop an optical signal having an arbitrary wavelength in the node.

Next, a difference from the example described above with reference to FIG.
An example in which reflected light also passes through the same transmission path will be described.

The wavelength optical ADM apparatus 200 shown in FIG.
Are optical splitter / demultiplexer 211, optical splitters 221 to 224, optical splitters 231 to 234, EDFA gates 241 to 244, optical receivers 251 to 254, optical transmitters 261 to 264, control means 270, circulator 280, and optical It is assumed that it is constituted by reflection mirrors 281 to 284.

The difference from the above-described example is that the wavelength-multiplexed input light passes through the circulator 280 and is input to the optical demultiplexer / demultiplexer 211, while the input light is multiplexed and wavelength-multiplexed by the optical demultiplexer / demultiplexer 211. The input light passes through the circulator 280 and is output. Further, the signal light demultiplexed for each wavelength by the optical demultiplexer 211 is reflected by the light reflection mirrors 281 to 28.
4 to return to the optical multiplexer / demultiplexer 211.

The signal light input to the wavelength ADM apparatus 200 has wavelengths of 1548 nm (λ1), 1550 nm (λ2),
Four wavelengths of 552 nm (λ3) and 1554 nm (λ4) are multiplexed, and these lights pass through an optical circulator 280 and are input to an optical multiplexer / demultiplexer 211 represented by an arrayed waveguide diffraction grating. Is done.

The optical demultiplexer / demultiplexer 211 demultiplexes the received light and outputs it to different optical branches 221 to 224.
The light received from the light branches 221 to 224 is multiplexed and output to the optical circulator 280. Therefore, optical branch 2
Each of 21 to 224 has only one wavelength of light.

The optical branch 221 outputs the light having a wavelength of 1548 nm (λ 1) received from the optical multiplexer / demultiplexer 211 to the optical branch 231 and the optical receiver 251, respectively.
Is transmitted to the optical multiplexer / demultiplexer 211.

The optical branch 231 outputs the light having the wavelength of 1548 nm (λ 1) received from the optical branch 221 to the EDFA gate 241, and outputs the light received from the EDFA gate 241 and the optical transmitter 261 to the optical branch 221.

The EDFA gate 241 is located between the light branch 231 and the light reflection mirror 281 and under the control of the control means 270, the wavelength of 1548 nm received from the light branch 231.
When passing the light of (λ1), the light is sent to the light reflection mirror 281, and the reflected light is output to the light branch 231.

The components for other wavelengths are connected in the same manner.

Next, passing, dropping, and insertion of signal light in the operation of the wavelength optical ADM apparatus 200 will be described.

The wavelength 15 output from the optical multiplexer / demultiplexer 211
After the signal light of 48 nm (λ1) passes through the EDFA gate 241, it is reflected by the light reflection mirror 281 and the EDF
After passing through the A gate 241 again, it is again input to the optical multiplexer / demultiplexer 211 and passes therethrough. The signal light having a wavelength of 1548 nm (λ1) output from the optical demultiplexer / demultiplexer 211 is
After a part is output to the optical branch 231 connected to 1, it is input to the optical receiver 251 to be received and branched. The wavelength 1548 nm (λ1) output from the optical multiplexer / demultiplexer 211 is used.
When the EDFA gate 241 is turned off under the control of the control means 270, the signal light of EDFA gate 2
The output from 41 is cut off. At this time, the optical transmitter 261
The signal light having a wavelength of 1548 nm (λ1) output from the optical branching unit 231 is connected to the optical branching unit 221 by the optical branching unit 231,
11 and inserted.

For each of the other wavelengths λ 2 to λ 4, the light transmission path through which the light flows has the same configuration from the optical multiplexer / demultiplexer 211 to the light reflecting mirrors 282 to 284. The wavelength-multiplexed light passes through an optical circulator 280 connected to the optical multiplexer / demultiplexer 211 and is output.
Therefore, it is possible to add and drop an optical signal having an arbitrary wavelength in the node.

Next, a description will be given of the onset Ming real施例with reference to FIG. 5.

The wavelength ADM apparatus (30) shown in FIG.
0: not shown) indicates an optical demultiplexer / demultiplexer 311, an optical branch 321
To 224, optical splitters 331 to 334, EDFA gate 34
1 to 344, optical receivers 351 to 354, optical transmitter 361
364, control means 370, optical branches 381 to 384, and optical isolators 391 to 394.

[0069] that the present embodiment is different from the example of the above mentioned is, E
DFA gates 341-344, optical isolators 391-394, respectively, and optical branches 381-384
Each is connected in series, the last optical branch 384 is connected to the first EDFA gate 341 to form a loop, and the optical branches 321 to 224 are further formed.
Each of them is connected to each of the optical branches 334, 331, 332, and 333 with respect to the wavelength in the previous order in the loop configuration.

The signal light input to the wavelength optical ADM apparatus (300) has a wavelength of 1548 nm (λ1) and a wavelength of 1550 nm (λ1).
2), four wavelengths of 1552 nm (λ3) and 1554 nm (λ4) are multiplexed, and these lights are input to an optical multiplexer / demultiplexer 311 typified by an arrayed waveguide diffraction grating.

The optical demultiplexer / demultiplexer 311 demultiplexes the received light and outputs the demultiplexed light to different optical branches 321-324.
The light received from the optical branches 321 to 324 is multiplexed and output. Therefore, each of the optical branches 321 to 324 has only one wavelength of light.

The optical branch 321 outputs the light having a wavelength of 1548 nm (λ 1) received from the optical multiplexer / demultiplexer 311 to the optical branch 334 and the optical receiver 351, respectively.
Is transmitted to the optical multiplexer / demultiplexer 311.

The optical branch 334 receives the light having the wavelength of 1548 nm (λ 1) received from the optical branch
The light having a wavelength of 1554 nm (λ4) received from the optical branch 384 and the optical transmitter 364 is output to the optical branch 321.

Therefore, the optical branch 331 outputs the light having the wavelength of 1550 nm (λ 2) received from the optical branch 322 to the EDFA gate 342 via the optical branch 381, and receives the wavelength 1548 nm (from the optical branch 381 and the optical transmitter 361). λ1)
Is output to the optical branch 322.

The EDFA gate 341 is connected to the control unit 370
When the light received from the optical branch 384 is allowed to pass through, the passed light is sent to the optical isolator 391,
The optical isolator 391 has a wavelength of 1548n out of the received light.
Only the light of m (λ1) is passed and output to the optical branch 381.

The components for other wavelengths are connected in the same manner.

Next, passing, dropping, and insertion of signal light in the operation of the wavelength ADM apparatus (300) will be described.

First, in the case of passing, the wavelength 1548 nm (λ 1) output from the optical multiplexer / demultiplexer 311 is supplied to the optical branch 321.
Signal light passes through the EDFA gate 341 via the optical branches 334 and 384, thereby forming an optical isolator 391.
Through the optical splitters 331 and 322 connected by the optical splitter 381 having a split ratio of 1: 1.

In the case of a branch, the wavelength 1548 nm (λ 1) output from the optical multiplexer / demultiplexer 311 is added to the optical branch 321.
Is transmitted to the optical receiver 351 connected to the optical branch 321.
Is input and received.

In the case of insertion, the wavelength 1548 nm (λ 1) output from the optical multiplexer / demultiplexer 311 is added to the optical branch 321.
The signal light of EDFA gate 341 is turned off under the control of control means 370,
The output from 1 is cut off. At this time, the wavelength 1548 output from the optical transmitter 361 under the control of the control means 370.
The signal light of nm (λ1) is split by the optical branch 331 into the optical branch 3
22 and is input to the optical multiplexer / demultiplexer 311.

For the light of the other wavelengths λ 2 to λ 4, the optical transmission path through which the light flows depends on the optical branches 322 to 324 connected to the optical multiplexer / demultiplexer 311 and the optical branches 381 to 383 forming a loop. Each followed by optical branch 3
82 through 384, 381 and optical branch 322 through
324 and 321 are connected to each other. As described above, it is possible to add / drop an optical signal of an arbitrary wavelength in a node.

Next, referring to FIG. 6, regarding the monitoring of the wavelength ADM apparatus 400 applicable to the present invention , the monitoring items shown in FIG.
The description will be made in the order of W and OSD.

The wavelength optical ADM device 400 shown in FIG.
Has a configuration similar to that of the wavelength ADM apparatus 100 shown in FIG. 1, and only an outline is shown in the figure. That is, the optical demultiplexer 411, the optical branch 424, the gates 431 to 431
434 and an optical multiplexer 412 are illustrated, and an optical branch 424 and an optical layer monitor device 484 are illustrated only for a part of the wavelength of 1554 nm (λ4). This optical layer monitoring device 484 corresponds to the optical signal failure monitoring means 80 shown in FIG. Further, it is assumed that a part of the optical signal input to the wavelength optical ADM apparatus 400 is branched by the optical branch 420 to the optical layer monitor apparatus 480.

The signal light input to the wavelength optical ADM apparatus 400 has wavelengths of 1548 nm (λ1), 1550 nm (λ2),
Four wavelengths of 552 nm (λ3) and 1554 nm (λ4) are multiplexed. These lights are input to an optical multiplexer / demultiplexer 411 typified by an arrayed waveguide diffraction grating, and are also split into an optical branch 420. The monitor light is branched into light and input to an optical layer monitor 480 for monitoring the light intensity of the monitor light.

That is, the optical layer monitor 480 is
The light S / N ratio is determined from the ratio between the light intensity within a certain wavelength range including at least the signal light and the intensity of the spontaneous emission light within a wavelength range having a width equal to the wavelength range and different from the wavelength range. By calculating, the presence or absence of the signal light is determined, or the presence or absence of the signal light is determined from the light intensity within a certain wavelength range including the signal light to monitor the light intensity, and OLOS (Optical Loss Os).
f Signal) to detect a communication failure due to a fiber break or the like.

Next, the wavelength-division multiplexed light is input to an optical demultiplexer 411 represented by an arrayed waveguide diffraction grating and output to different gates 431 to 434, respectively. That is, at each of the gates 431 to 434, only light of one wavelength exists.

Therefore, for example, a part of the signal light having a wavelength of 1554 nm (λ 4) output from the optical demultiplexer 411 to the gate 434 is optically split by the optical splitter 424 as monitor light and input to the optical layer monitor 484. Then, the light intensity is monitored by the optical layer monitor device 484.

The optical layer monitor 484 determines the light intensity within a wavelength range of a predetermined width including at least the signal light, based on the narrow transmission bandwidth characteristics of the arrayed waveguide diffraction grating and the monitored light intensity. Light having a width equivalent to that of the wavelength range and the intensity of the spontaneous emission light in a wavelength range different from the wavelength range.
By calculating the N ratio or monitoring the wavelength shift of the signal light from the light intensity within the wavelength range, the OLOW (Opti
By detecting the cal loss of wavelength, a communication failure due to a wavelength shift of the light source or the optical filter or the like is detected.

Further, the optical layer monitor 484 has a light intensity within a certain wavelength range including at least the signal light and a spontaneous emission within a wavelength range having a width equal to the above wavelength range and different from the above wavelength range. The OSD (Optical Signal) is calculated by calculating the light S / N ratio from the ratio with the light intensity or monitoring that the light S / N ratio has dropped below a predetermined threshold.
nal Degrade) to detect a communication failure due to an abnormality in the communication device.

As described above, monitoring in the optical layer can be realized by the optical layer monitoring device.

Next, the operation of the wavelength ADM apparatus 500 applicable to the present invention when a failure occurs will be described with reference to FIG.

FIG. 7 shows an example in which two of the wavelength ADM devices shown in FIG. 6 are connected by one optical transmission line. Therefore, it is assumed that the configuration of the wavelength optical ADM device is exactly the same.

In the wavelength optical ADM apparatus 500 shown in FIG. 7, an optical demultiplexer 511, an optical branch 524, and gates 531 to 5
34, optical multiplexer 512 and optical layer monitor device 584
Only the optical signal to be input is shown in FIG.
It is assumed that a part is branched to the optical layer monitor device 580 by 20. Similarly, in the wavelength optical ADM device 501, the optical demultiplexer 515, the optical branch 528, the gates 535 to 538,
Only the optical multiplexer 516 and the optical layer monitor 588 are shown, and an optical signal to be input is partly branched by the optical branch 529 to the optical layer monitor 589.

The signal light input to the wavelength optical ADM apparatus 500 has wavelengths of 1548 nm (λ1), 1550 nm (λ2),
Four wavelengths of 552 nm (.lambda.3) and 1554 nm (.lambda.4) are multiplexed. These lights are input to an optical multiplexer / demultiplexer 511 represented by an arrayed waveguide diffraction grating, and are also split into an optical branch 520. The monitor light is branched into light and input to an optical layer monitor 580 that monitors the light intensity of the monitor light. The wavelength multiplexed light described above is input to an optical demultiplexer 511 represented by an arrayed waveguide diffraction grating and output to different gates 531 to 534, respectively. That is, the gate 53
In each of 1 to 534, only light of one wavelength exists.

If a signal light having a wavelength of 1554 nm (λ 4) is output from the optical demultiplexer 511 and a failure occurs in which signal transmission downstream cannot be performed due to disconnection of the optical fiber connected to the optical branch 524. Is assumed.

In this situation, the optical layer monitor device 584 located downstream of the location where the failure occurred cannot detect the optical input, and
Detect OLOS. The optical layer monitor 584
Immediately after the detection of the LOS, by turning off the gate 534 and shutting off the output of the gate, AIS-O is issued downstream to notify the occurrence of a fault.

In the wavelength optical ADM device 501 which becomes the next node connected via the optical transmission line, the input signal light usually has wavelengths of 1548 nm (λ1), 1550 nm (λ2),
Four wavelengths of 1552 nm (λ3) and 1554 nm (λ4) are multiplexed.

However, since the gate 534 is turned off and the gate output is cut off due to the disconnection of the optical fiber in the wavelength light ADM device 500, the wavelength light ADM device 501 is turned off.
OLOS is also detected in the optical layer monitor device 588 of FIG. Accordingly, in the wavelength ADM apparatus 501, the AIS-O is issued downstream by turning off the gate 538.

On the other hand, there is no effect on transmission lines of other wavelengths where no failure has occurred, and the same optical transmission as before the occurrence of the failure can be performed.

As described above, the optical layer monitor of the wavelength ADM apparatus detects the OLOS and turns off the gate switch immediately downstream of the OLOS, thereby affecting the signal light in the optical layer and other wavelengths. Without giving it, it is possible to notify the downstream of a fault occurrence.

Next, another operation different from that in FIG. 7 when the wavelength optical ADM apparatus 500 applicable to the present invention has a failure will be described with reference to FIG.

FIG. 8 shows the two-wavelength light AD shown in FIG.
Wavelength device ADM device 500 out of M devices 500 and 501
Branch 544 between the gate 534 and the optical multiplexer 512
And an optical transmitter 564 are additionally shown.
Therefore, it is assumed that the configuration and the functions of the components in FIG. 8 are exactly the same as those in FIG.

Now, assume that a signal light having a wavelength of 1554 nm (λ 4) is output from the optical demultiplexer 511 and a failure occurs in which signal transmission downstream cannot be performed due to disconnection of the optical fiber connected to the optical branch 524. Is assumed. In this situation, the optical layer monitor device 584 located downstream from the fault location
Cannot detect the light input and detects OLOS. Immediately after the detection of the OLOS, the optical layer monitor device 584 issues an AIS-O downstream to notify the occurrence of a failure by turning off the gate 534 and cutting off the output of the gate.

However, here, the wavelength 1
When the signal light of 554 nm (λ4) is output to the optical multiplexer 516 via the optical branch 534, the wavelength light A of the next node is output.
In the optical layer monitor device 588 of the DM device 501,
OLOS is not detected.

As described above, AIS-O is interrupted on the way by inserting a signal of the same wavelength. However, even during the operation of dropping and adding, the signal light in the optical layer and affecting signal light of other wavelengths is affected. Without giving, it is possible to detect the occurrence of a fault and to notify the details of the fault to the downstream.

Next, with reference to FIG. 9, an operation different from those in FIGS. 7 and 8 when the wavelength optical ADM apparatus 500 applicable to the present invention has a failure will be described.

FIG. 9 shows the two-wavelength light AD shown in FIG.
In the optical transmission line connecting the M devices 500 and 501, the inter-node communication device 591 branched by the optical branch 540 on the wavelength optical ADM device 500 side, and the wavelength optical ADM device 501
Node communication device 5 branched by optical branch 529 on the side
99, each of which is provided.

Now, a case where a signal light having a wavelength of 1554 nm (λ 4) is output from the optical demultiplexer 511 and a failure occurs in which signal transmission to the downstream is impossible due to disconnection of the optical fiber connected to the optical branch 524. Is assumed. In this situation, the optical layer monitor device 584 located downstream from the fault location
Cannot detect the light input and detects OLOS. Immediately after the detection of the OLOS, the optical layer monitor device 584 issues an AIS-O downstream to notify the occurrence of a failure by turning off the gate 534 and cutting off the output of the gate.

In this configuration, the inter-node communication device 5
By using signal light of a different wavelength from the above-mentioned signal light between 91 and 599, network management information can be communicated at the same time as notification of failure occurrence.

Next, referring to FIG. 10, the present invention can be applied.
For it is described self-healing networks utilizing such wavelength light ADM device 600, 601.

FIG. 10 shows a case where two of the wavelength ADM devices shown in FIG.
The M device 601 has an optical layer monitor device 681, and the other wavelength optical ADM device 602 has an optical layer monitor device 681.
2 (not shown).
A signal input to both of the optical layer monitoring devices 681 and 682 is transmitted through the selector switch 600 to the optical receiver 65.
1 are connected.

As shown in FIG. 10, signals are transmitted in opposite directions to the optical transmission lines connected to the wavelength ADM devices 601 and 602, and one of the wavelength ADM devices 601 is used as a working line. And the other wavelength optical ADM device 60
It is assumed that a spare line is connected to 2. Therefore, it is assumed that the selector switch 600 connects the signal of the wavelength optical ADM device 601 to which the working line is connected to the optical receiver 651 with respect to the working line.

In a normal state, the wavelength light A connected to the working line
The signal light branched from the DM device 601 is input to the optical layer monitor device 681, and the wavelength light AD connected to the spare line
The signal light branched from the M device 602 is input to the optical layer monitor device 682.

Each of the optical layer monitoring devices 681 and 682 monitors OLOS, OLOW, OSD or AIS-O due to occurrence of a fault.

Here, when the optical signal interruption failure monitoring signal is detected by the optical layer monitor device 681, the selector switch 600 recognizes that the optical signal interruption failure monitoring signal is not detected by the optical layer monitor device 682. Then, the connection of the optical receiver 71 is switched to receive the signal. By the above method, even when a failure occurs, a self-healing network can be realized in the optical layer.

In the above description, it has been described that light of four wavelengths is multiplexed in all the examples. However, the number of multiplexing is not limited to the number described in the above embodiment. Any number of wavelengths, for example, 8, 16, 32, 64, etc., may be freely set. In addition, the wavelength of the input light 1
It is not limited to the 550 nm band, but can be set freely, such as the 1300 nm band. Also, the signal speed is not particularly limited, and may be 2.5 Gbps, 5 Gbps, 10 Gbps.
Bit rate free setting such as bps is possible.

In addition, here, the description is made by taking an example of an arrayed waveguide diffraction grating such as an optical demultiplexer, a multiplexor, and a multiplexer / demultiplexer. However, a wavelength router having a grating structure having the same function, a wavelength MUX coupler, and the like. For example, the same effects as those described in the above embodiments can be expected as long as they have the same function as the combination of the optical branching and the interference filter.

In addition, since the optical demultiplexing, the optical multiplexing, and the optical demultiplexing device represented by the arrayed waveguide diffraction grating and the like have different insertion loss depending on each wavelength, an optical attenuator may be appropriately inserted into each waveguide. It is also possible to perform light level equalization.

It is also possible to control the gain of each EDFA gate and semiconductor optical amplifier, or to control the reflectivity of the light reflecting mirror described in the second embodiment to equalize the light level for each wavelength. .

The configuration of the EDFA gate is particularly
The structure is not limited to F, but may be replaced by a structure in which aluminum, tellurium, or the like is added as an impurity to the fiber and excited by a pumping light source to perform light amplification.

The same effect can be achieved by using a gate switch such as a mechanical switch having a high on / off ratio, a lithium niobate switch, or a quartz switch instead of the EDFA gate and the semiconductor optical amplifier.

Further, in the above embodiment, the failure occurrence location is described and described in only one location in the wavelength optical ADM apparatus, and
Although each wavelength optical ADM device is illustrated as being provided for each wavelength, the optical layer monitor device according to the present invention can be used in all optical transmission lines, optical transmitters, and the like in a wavelength optical ADM device if there is only one location. It is possible to cope with a case where a fault occurs in several places and a fault in an optical transmission line between wavelength optical ADM devices. Therefore, one device that can identify these faults may be used.

Further, the installation position of the optical layer monitor device is not limited to the position described in the embodiment, and it is possible to freely install the optical layer monitor device and monitor it by using an appropriate optical branch.

Also, when constructing a ring network, an optical layer monitor can be freely installed, and an optical layer monitor can be installed not only in a wavelength optical ADM apparatus but also in an optical regenerative repeater to prevent signal interruption. AI at the time of occurrence
By issuing an SO, self-healing in the optical layer is possible.

As described above, the embodiment has been illustrated and described. However, the block configuration or the block arrangement by dispersing and merging the functions is free as long as the above functions are satisfied, and the above description does not limit the present invention.

[0126]

A first effect of the present invention is that a wavelength optical ADM apparatus capable of dropping / adding signal light of an arbitrary wavelength in a node can be realized.

The reason is that an optical demultiplexer and an optical multiplexer are used to add / drop a signal light in a transmission line installed for each wavelength, and that an optical amplifier and an optical attenuator are used for each wavelength. This is because light level equivalent can be realized.

The second effect is that the amount of hardware to be mounted on the wavelength ADM apparatus can be reduced, and a reduction in the size and cost of the system can be expected.

The reason is that, in response to alarms (LOS, LOF, LOP, BER and AIS-L) in the SONET / SDH layer, optical signal interruption failure detection signals (OLOS, OLOW, OSD and AIS) in the optical layer are newly added. This is because redefining -O) eliminates the need for AIS processing hardware in the wavelength ADM apparatus, and further simplifies the control of the wavelength ADM apparatus because the AIS processing control is not required. It is.

The third effect is that the existing SONET / SDH
It is possible to maintain compatibility with the standard APS.

The reason is that the optical layer uses OLOS, OLO
The network failure detected by at least one of the optical signal interruption failure detection signals of W and OSD is AIS-
O and converted to the conventional LOS for the SONET layer
This is because the line termination is able to recognize the failure detected in the optical layer and recover from the failure.

The fourth effect is that the monitoring system and the failure recovery system in the optical layer can be used without competing not only with the SONET / SDH standard but also with other framing format transmission apparatuses, that is, without using the framing format. It can be introduced to networks. The reason is that AIS-O in the optical layer
Is notified downstream by interrupting the transmission of the optical signal.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating functions according to the present invention.

FIG. 2 is a block diagram showing one configuration of an EDFA gate switch.

FIG. 3 is an explanatory diagram showing the correspondence of an optical signal cutoff detection signal between a SONET / SDH layer and an optical layer.

FIG. 4 is a block diagram showing another example different from FIG.

FIG. 5 is a block diagram showing an embodiment of the present invention.

FIG. 6 is a reference block diagram showing an additional example of a function applicable to the present invention.

FIG. 7 is a reference block diagram showing another example of the functions applicable to the present invention , which is different from FIG. 6 ;

FIG. 8 is a diagram showing another example of the functions applicable to the present invention.
It is a reference block diagram showing an additional example.

FIG. 9 is a diagram showing another example of a function applicable to the present invention;
It is a reference block diagram showing an additional example.

FIG. 10 shows another example of the functions applicable to the present invention.
It is a reference block diagram showing an additional example.

[Explanation of symbols]

11, 411, 511, 515 Optical demultiplexer 12, 412, 512, 516 Optical demultiplexer 21 to 2n, 41 to 4n, 221-224, 231-2
34, 321-324, 331-334, 381-38
4, 420, 424, 520, 524, 528, 529
Optical branch 30, 241-244, 341-344 EDFA gate switch 31-3n Optical gate switch 51-5n, 251-254, 351-354, 651
Optical receivers 61-6n, 261-264, 361-364, 564
Optical transmitters 70, 270, 370 Control means 80 Optical signal failure monitoring means 100, 200, 300, 400, 500, 501, 6
01, 602 wavelength optical ADM device 131 excitation light source 132 WDM coupler 133 EDF (erbium-doped fiber) 211, 311 optical demultiplexer / demultiplexer 281-284 light reflection mirror 280 circulator 391-394 optical isolator 480, 484, 580, 584, 588 , 589, 6
81 Optical layer monitor 591, 599 Communication device between nodes 600 Selector switch

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H04J 14/02 H04Q 3/52 (56) References JP-A-7-245436 (JP, A) JP-A 9-36834 (JP) JP-A-7-326826 (JP, A) JP-A-6-311139 (JP, A) JP-A-5-130044 (JP, A) JP-A-6-284092 (JP, A) JP-A-5-308166 (JP, A) JP-A-11-46030 (JP, A) JP-A-7-226560 (JP, A) JP-A-7-326826 (JP, A) A) JP-A-11-46029 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB name) H04B 10/00-10/28 H04J 14/00-14/08 G02B 6/00 H04Q 3/52

Claims (3)

(57) [Claims] 1. A first wavelength-division-multiplexed optical signals inputted from the optical transmission line and demultiplexed for each wavelength output from each other three or more plural terminals, the other three or more of said plurality terminals, respectively an optical Bungo duplexer you outputs demultiplexed light input to the second optical transmission line by wavelength division multiplexing the one hand outputs light input from the first terminal to the second and third terminals And a first optical branch for outputting light input from the second terminal to the first terminal, and an optical receiver for inputting one optical output corresponding to the first optical branch. An optical transmitter having one optical output corresponding to the optical receiver and constituting the wavelength multiplexed light,
On the one hand, the light input from the first terminal is output to the second terminal, and on the other hand, the light input from the second terminal and the light input from the third terminal are output to the first terminal. 2 and the light input from the first terminal is output to the second terminal, and the light input from the third terminal is output to the first terminal.
, A third optical branch that outputs to the terminal of the optical gate switch, an optical gate switch that controls the passage and cutoff of the light corresponding to the one split light, and passes only one optical output corresponding to the optical gate switch. An optical isolator, wherein one of the plurality of terminals of the optical multiplexer / demultiplexer and a first terminal of the first optical branch are connected to a second terminal of the first optical branch and the second light A first terminal of the branch, a third terminal of the first optical branch, and the optical receiver, a second terminal of the second optical branch, and a first terminal of the third optical branch. And a third terminal of the second optical branch, and a third terminal of the second optical branch and the optical transmitter, respectively, and a second terminal of each of the plurality of third optical branches formed in a loop. An input terminal of the optical gate switch, an output terminal of the optical gate switch and an input terminal of the optical isolator, Further, an output terminal of the optical isolator and a third terminal of the third optical branch located next to the optical isolator,
Respectively connected, the light input to the optical multiplexer / demultiplexer and separated for each wavelength, the first optical branch, the second optical branch from one of the other terminals of the optical multiplexer / demultiplexer. After passing through the optical branch, the third optical branch, the optical gate switch, and the optical isolator, via the separated adjacent third optical branch, the second optical branch, and the first optical branch. Returning to the optical multiplexer / demultiplexer, the optical multiplexer / demultiplexer wavelength-multiplexes the light received from the plurality of first optical branches and outputs the multiplexed light to the optical transmission line. 2. A wavelength optical ADM apparatus according to claim 1 , wherein said optical gate switch includes at least a part of an EDF.
A wavelength optical ADM device, which is an A gate. 3. The wavelength ADM apparatus according to claim 1 , wherein at least a part of said optical gate switch is a semiconductor optical amplifier.