JPH04369130A - Optical wavelength multiplex communication system - Google Patents

Abstract

PURPOSE:To facilitate the wavelength selection control corresponding to a receiver side node by adopting a common element structure for a photoelectric conversion module of each switch being a node and to employ a common circuit for all nodes as a wavelength multiplex transmitter-receiver circuit. CONSTITUTION:When a signal inputted to an input port 111a of a switch 10a is not addressed to its own node, a photoelectric conversion module 13a converts the signal into an optical signal having a wavelength corresponding to a destination output port (e.g., 121b) via a connection port 131a. An optical signal outputted from an optical fiber 16a is distributed into optical fibers 15a-15c by an optical star coupler 2 and inputted respectively to modules 13a-13c in switch modules 1a-1c. Since the modules 13a-13c receive only the optical with a wavelength addressed to its own node, only a switch 10b receives a signal via a connection port 132b and the signal is outputted to an output port 121b corresponding to the destination. Other modules than the module 13b cannot receive the signal because the reception wavelength differs. Thus, other switches than the switch 10b cannot be operated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical wavelength division multiplexing communication system using an optical fiber communication system. In particular, the present invention relates to an optical wavelength division multiplexing communication system that transmits and receives optical signals of a plurality of wavelengths corresponding to each node.

0002

2. Description of the Related Art Conventionally, there is a configuration shown in FIG. 5 as an example of such an optical wavelength division multiplexing communication system. The system shown in FIG. 5 is described in the following literature.

[0003] Literature E. Arthurs et al.
．． ”Multiwavelength Optica
l Crossconnect for parallel
el-processing Computers,”
Electron Lett. vol. 24. p
p119-120, 1988

The optical wavelength division multiplexing communication system shown in FIG. 5 has three processors (PU).
and four memories (MEM) are connected using a 3x4 optical star coupler, and bidirectional communication is performed between the processor and the memory.

[0005] This system will be explained. First, it includes three processors 501a, 501b, and 501c, four memories 520a, 520b, 520c, and 520d, and 3×4 optical star couplers 510 and 520 that connect them. In this system, two optical star couplers 510,
By using 520 for uplink and downlink transmission paths, communication is performed through separate routes for uplink and downlink.

The configuration for transmitting signals from the processor 501 to the memory 520 will be explained using tunable laser emitters (TLTs) 502a, 502b, and 50, respectively.
2c, the wavelength tunable laser emitters 502a, 50
The optical signals from 2b and 502c are transmitted through optical fibers 511a,
511b and 511c to the optical star coupler 510, and from the optical star coupler 510 to the optical fiber 51.
2a, 512b, 512c, and 512d, and fixed wavelength receivers (FWRs) provided in each memory
) 521a, 521b, 521c, and 521d and converted into electrical signals.

Similarly, from the memory 520 to the processor 50
1, the optical signal is sent to the wavelength tunable laser emitters 522a, 522b, and 522b provided in each memory.
522c, 522d to optical fibers 521a, 522b
, 522c, 522d to the optical star coupler 520.
from the optical star coupler 520 to the optical fiber 5
Fixed wavelength receivers 503a, 503b, 503c provided in each processor via 22a, 522b, 522c
is received and converted into an electrical signal.

Next, the operation of the system having this configuration will be explained.

[0009] Each processor 501a, 501b, 501
The signals from c are sent to their respective destination memories 520a, 52
λ1 to λ4 corresponding to 0b, 520c, 520d
The wavelength up to
, 502b and 502c perform electro-optical conversion. This optical signal is distributed to all memories by an optical star coupler 510. Each memory 520a, 520b, 520
Fixed wavelength receivers 521a, 521b, 521c, and 521d select only the optical wavelength addressed to the self, and photoelectrically convert only the signal addressed to the memory 520a.
, 520b, 520c, and 520d. Similarly, signals from the memory 520 to the processor 501 are transmitted to the wavelength tunable laser emitters 522a, 522b, 522c, 52.
2d, is received by the fixed wavelength receivers 503a, 503b, and 503c via the optical star coupler 520, and is photoelectrically converted.
01c.

0010

However, in such a configuration, the wavelength tunable laser emitters 502 and 522 are controlled by selecting wavelengths λ1 to λ4 that match the reception wavelengths of the respective fixed wavelength receivers 521 and 503. Therefore, there is a problem that the configuration for controlling the optical wavelength becomes complicated.

An object of the present invention is to provide an optical wavelength division multiplexing communication system that simplifies the configuration of optical wavelength control at each node, allows easy wavelength setting, and improves economic efficiency.

0012

[Means for Solving the Problems] The present invention includes a plurality of nodes, receives an optical signal transmitted from one of the nodes at another node, and each node transmits an optical signal to a specific node in advance. The configuration is such that an optical signal of a predetermined wavelength is transmitted, and each node has an optical element that transmits signals of multiple wavelengths, and a light receiving element that receives only a signal of a specific wavelength set for a specific node. In an optical wavelength division multiplexing communication system including a wavelength division multiplexing transmission/reception circuit, the wavelength division multiplexing transmission/reception circuit is composed of a plurality of optical elements that generate signals of a plurality of wavelengths, and a part of the optical elements serves as a light receiving element. It is characterized by

Note that the wavelength multiplexing optical transmitter/receiver circuit can be a single optical integrated circuit, and a part of the optical element can function as a reception wavelength selection element.

[0014]

[Operation] The present invention realizes a wavelength multiplexing transmitting/receiving circuit provided at each node of an optical wavelength division multiplexing communication system using one optical integrated circuit common to all nodes in which a plurality of optical elements are integrated. Among the optical elements of this optical integrated circuit, for the wavelength set as the reception wavelength of the own node, the optical element is made to function not as a light emitting element but as a light receiving element, specifically, as a wavelength selection element for the received signal addressed to the own node. Receive a received signal addressed to the node. Other optical elements are used as light emitting elements for transmission signals destined for other nodes.

[0015] Furthermore, for transmission to other nodes, optical elements capable of transmitting light of wavelengths corresponding to each node are driven to transmit light to the other nodes.

In this way, by using a circuit common to all nodes as a wavelength multiplexing transmitting/receiving circuit, it is possible to easily control wavelength selection corresponding to the receiving side node, and also to reduce the circuit scale and improve the economical efficiency of the entire system. can.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram illustrating the configuration of an optical wavelength division multiplexing communication system according to an embodiment of the present invention. The configuration of this communication system will be explained. Each node is equipped with a switch module (SWM) 1a, 1b, . . . 1c for performing optical communication, and each node's switch module 1a, 1b, .
1c are connected by optical star couplers 2, respectively. The switch module 1a has input ports 111a, 112
a, 113a and output ports 121a, 122a, 123
a switch (SW) 10a with a connection port 1
It is composed of an opto-electrical conversion module (OEM) 13a connected to a switch 10a through 31a and 132a. This opto-electric conversion module 13a is connected to an optical star coupler (SC) by an input optical fiber 15a and an output optical fiber 16a.

Similarly, the switch module 1 of another node
b and 1c are also connected to the optical star coupler 2. here,
Each of the switches 10a, 10b, and 10c has three input/output ports, and three switch modules 1a, 1b, and 1
Although an example is shown in which the optical star coupler c is connected to the optical star coupler 2, in principle, it functions in the same way regardless of the number of input/output ports and the number of switch modules. In addition, the input/output ports of the switch function equally well with optical signals and electrical signals.

Next, the operation of this embodiment will be explained. As an example, an example will be explained in which a signal input to the input port 111a of the switch 10a is output to the output port 121b of the switch 10b.

The switch 10a determines whether the destination of the input signal is within its own switch (its own node). In this case, since it is not within the own switch, the connection port 131a
is converted into an optical signal having a wavelength λ2 corresponding to the destination output port 121b by the opto-electrical conversion module 13a. The optical signal output from the optical fiber 16a is sent to the optical fibers 15a and 15 by the optical star coupler 2.
b, 15c, switch module 1a,
Photoelectric conversion modules 13a and 13b in 1b and 1c
, 13c, respectively. Since the optical receivers inside each opto-electrical conversion module 13a, 13b, 13c receive only the optical signal of the wavelength addressed to the own switch (own node), here, only the switch 10b receives the signal via the connection port 132b. It is received and output to the output port 121b corresponding to the destination. At this time, the optical signal is input to all the opto-electrical conversion modules, but it cannot be received by any module other than the opto-electrical conversion module 13b because the receiving wavelengths are different. Therefore, the switches other than switch 10b do not perform any operation on the optical signal transmitted from switch module 1a.

FIG. 2 is a diagram illustrating the operating principle of the photoelectric conversion module. Here, the correspondence relationship between optical transmission and optical reception in the opto-electrical conversion module of each switch when the number of switches is four will be explained.

That is, LDA indicates a photoelectric conversion array in the photoelectric conversion module, and LD indicates one of the optical elements. For example, the photoelectric conversion array 210 indicates optical elements provided in the photoelectric conversion module 13a, including LD11, LD12, LD13, and LD14.
It consists of four optical elements. Similarly, other photoelectric conversion modules each include photoelectric conversion arrays 220, 230, and 240 each consisting of four optical elements.

Here, the optical elements designated by group EG1 are a group of elements capable of transmitting or receiving the same wavelength λ1; similarly, group EG2 has the wavelength λ2, group EG3 has the wavelength λ3, Group EG4
is a group of elements capable of transmitting or receiving wavelengths of λ4. In FIG. 2, a downward arrow for each optical element indicates that an optical signal is input, and an upward arrow indicates that an optical signal is output. That is, photoelectric conversion arrays 210, 220, 230,
240 is composed of a group of optical elements with the same wavelength,
Only the reception wavelength is λ1 for the opto-electrical conversion array 210,
The photoelectric conversion array 220 has a wavelength of λ2, the photoelectric conversion array 230 has a wavelength of λ3, and the photoelectric conversion array 240 has a wavelength of λ4.
It is characterized by the fact that it is configured as follows. In other words, the optical element corresponding to the wavelength received by each photoelectric conversion module is characterized in that the optical element that functions as a light emitting element in other photoelectric conversion arrays functions as a receiving element.

FIG. 3 shows the wavelength characteristics (frequency characteristics) of the photoelectric conversion module shown in FIG. 2. Figure 3
301, 302, 303, 30
4 are respective optical element groups EG201, 201, 2
03 and 204 are shown. And, drawing code 311 is an optical element (LD11) 2
11 shows an example of reception wavelength characteristics. That is,
In this case, communication between the photoelectric conversion arrays uses one optical element among a group of optical elements that do not overlap between the arrays as a light receiving element in each photoelectric conversion array. That is, in FIG. 2, the optical elements 211, 222, 233, and 244 are operated as light receiving elements, and the other optical elements are operated as light emitting elements.

FIG. 4 shows the configuration of the photoelectric conversion module.

Reference numeral 401 indicates a photoelectric conversion module, and the photoelectric conversion array LDA includes optical elements (LD) 4
11a, 411b, 411c, and 411d. This optical element is, for example, a semiconductor laser element. The optical elements 411a, 411b, 411c, and 411d are connected to an external optical multiplexer, optical star coupler, etc. via optical fibers 421a, 421b, 421c, and 421d. These optical elements 411a, 411b, 411c, 411d include monitor light receiving elements (DET) 412a, 412b, 412.
c and 412d are optical fibers 422a and 422b, respectively.
, 422c, 422d. Light receiving element 4
12a, 412b, 412c, and 412d are electrical circuits (ELC) 413a, 413b, 413c, and 413, respectively.
d, and its electrical signal output is output to electrical signal output ports 423a, 423b, 423c, and 423d. This photoelectric conversion module 401 is provided with a control circuit for controlling each optical element, and a light receiving element control circuit (
DTC) 415 and light emitting device drive circuit (LDC) 416
a, 416b, and 416c, and each control circuit is connected to each optical element via a matrix switch (MAT) and optical element coupling connections 424a, 424b, 424c, and 424d. In addition, in the drawing, 425
are connections for controlling the light receiving element, 426a, 426b, 426
427 is a light receiving element control input port, and 428a, 428b, 428c, and 428d are input ports for driving a light emitting element.

Next, the operation of the present photoelectric conversion module will be explained.

The optical elements 411a, 411b, 411c
, 411d, an example will be described in which the optical element 411a is operated as a light receiving element and the others are operated as light emitting elements. At this time, the inside of the matrix switch 414 includes an optical element coupling connection 424a, a light receiving element control connection 425, an optical element coupling connection 424b and a light emitting element driving connection 426a, an optical element coupling connection 424c and a light emitting element driving connection 426b. , the optical element coupling wire 424d and the light emitting element driving wire 426c are set to be connected. In this case, the optical fiber 421a is used as the input optical fiber.
b, 421c, and 421d are used as output optical fibers. The light receiving element 412a operates as an optical signal receiving element that receives the input optical signal selected by the optical element 411a functioning as a wavelength selection element. Other light receiving element 41
2b, 412c, and 412d are light emitting elements 411, respectively.
b, 411c, and 411d are used as light receiving elements for monitoring optical outputs.

First, the transmission operation will be explained. Light emitting element drive circuits 416a, 416b, 4 corresponding to the transmission destination
The electrical signal input to 16c is transmitted to optical elements 411b and 4 which are respectively set by matrix switch 414.
11c and 411d, wavelengths λ2, λ3, λ4
The optical fibers 421b and 4
21c and 421d.

Next, the reception operation will be explained. The optical signal input from the optical fiber 421a has 4 wavelengths of λ1 to λ4.
It has different wavelengths. However, the light receiving characteristic of the optical element 411a is different from the receiving characteristic 31 of the optical element group 301 as shown in FIG.
1, only one of the four types of optical signals with wavelengths is selected in advance as the self-destination, and
It outputs to the optical fiber 422a. After that, the light receiving element 41
2a, the received signal is photoelectrically converted by the electric circuit 413a and outputted from the output port 423a.

The operation of the optical element 411a as a reception wavelength selection element will now be explained. Generally, in semiconductor lasers, most of the light emitted from the semiconductor laser is output from the transmitting end facet, but some light is output to the opposite side for monitoring, input to the monitor light receiving element, and then the light receiving element for monitoring. The configuration is such that the output of the semiconductor laser is feedback-controlled based on the output of the element. In the photoelectric conversion module of this embodiment, optical elements are normally used as light emitting elements, and only one optical element is operated as an amplifier having wavelength selection characteristics (for example, in the case of 0 dB, as a filter).

[0033]

Effects of the Invention As described above, in the present invention, all the opto-electrical conversion modules of each switch serving as a node have a common element structure, and only one optical element functions as a light-receiving element. By using a common circuit for the nodes, wavelength selection control corresponding to the receiving side node can be easily performed. Further, the circuit scale of the wavelength division multiplexing transmitter/receiver circuit can be reduced, and the economical efficiency of the entire system can be improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an optical wavelength division multiplexing communication system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the principle of the optical transmitter/receiver circuit configuration of the embodiment.

FIG. 3 is a diagram illustrating characteristics of an optical element group.

FIG. 4 is a diagram showing the configuration of a photoelectric conversion module according to an example.

FIG. 5 is a diagram showing the configuration of a conventional wavelength division multiplexing communication system.

[Explanation of symbols]

1a, 1b, 1c switch module 2, 510
, 520 optical star couplers 10a, 10b, 1
0c switch 13a, 13b, 13c, 4
01 Photoelectric conversion modules 15a, 15b, 15
c, 16a, 16b, 16c, 421a, 42
1b, 421c, 421d, 422a, 422b, 42
2c, 422d Optical fibers 111a, 111b, 1
11c, 112a, 112b, 112c, 113a, 1
13b, 113c input ports 121a, 121b, 121c, 122a, 122b,
122c, 123a, 123b, 123c Output ports 131a, 131b, 131c, 132a, 132b,
132c connection ports 210, 220, 230
, 240 photoelectric conversion arrays 411a, 411b, 41
1c, 411d Optical elements 412a, 412b, 412
c, 412d light receiving elements 413a, 413b, 413
c, 413d Electric circuit 414 Matrix switch 415 Light receiving element control circuit 416a, 416b, 416c Light emitting element drive circuit 4
23a, 423b, 423c, 423d Electrical signal output ports 424a, 424b, 424c, 424d
Optical element coupling connections 425 Light receiving element control connections 426a, 426b, 426c Light emitting element driving connections 427 Light receiving element control input ports 428a, 428b, 428d Light emitting element driving input ports 501a, 501b, 501c Processor 5
02a, 502b, 502d, 522a, 522b, 5
22c, 522d Tunable wavelength laser emitters 520a, 520b, 520c, 520d Memory 5
03a, 503b, 503c, 521a, 521b, 5
21c, 521d fixed wavelength receiver

Claims (2)

[Claims] Claim 1: Comprising a plurality of nodes, an optical signal transmitted from one of the nodes is received by another node, and each node transmits an optical signal of a predetermined wavelength when transmitting to a specific node. Each node includes a wavelength multiplexing transmitting/receiving circuit including an optical element that transmits signals of multiple wavelengths and a light receiving element that receives only signals of a specific wavelength set for a specific node. In the optical wavelength division multiplexing communication system, the wavelength division multiplexing transmitting/receiving circuit is composed of a plurality of optical elements that generate signals of a plurality of wavelengths, and a part of the optical elements serves as a light receiving element. system. 2. The optical wavelength division multiplexing communication system according to claim 1, wherein the wavelength division multiplexing transmitting/receiving circuit is configured as one optical integrated circuit, and some of the plurality of optical elements are used as wavelength selection elements.