JPH0452674B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Technical Field of the Invention The present invention relates to an optical switch having a function of exchanging information transmitted using light as a medium to a desired route as it is, and particularly to an optical switch that constitutes an optical switch. This invention relates to an optical highway switch with a matrix configuration, which is a basic element.

(2) Technology background With the remarkable progress of semiconductor technology in recent years,
LSI and digitalization are being implemented in communication networks, and furthermore, development is being actively carried out toward the practical application of optical communication systems that use light as the communication medium. In particular, in the transmission technology of the two major cores of communication, such as transmission technology and switching technology, efforts are being made to increase the amount of information transmitted and increase the transmission speed using optical transmission technology. On the other hand, in the area of switching technology, research on optical switching equipment is underway, and although there are still few proposals regarding specific configuration technology, the development of optical switch elements, which are the basic elements that make up optical switching equipment, has been successful.

(3) Prior art and problems As for the application area of such optical switching equipment, due to the limitation of switching operation speed of optical elements, current technology deals only with the exchange of broadband image information (for example, transmission of audio and TV images, etc.). Moreover, since the switching operation speed is relatively slow, a space division switching method is being considered. However, in order to implement an optical switching system using the space division method, the number of cross points required on the communication path is smaller than the time division method or frequency (or wavelength) multiplexing method, since each line has one piece of information (or one communication). The drawback is that it increases dramatically as the number increases, making it economically difficult.

(4) Purpose of the Invention In order to solve these drawbacks, the present invention is a component of an optical multiplex switching system that enables the combination of optical transmission technology and optical switching technology and is also applicable to existing digital switching equipment. The purpose is to provide optical highway switches.

(5) Structure of the Invention In order to achieve the above object, the present invention detects the wavelength of the incoming highway and transmits information for each wavelength in an optical multiplex exchange whose input/output is a highway on which a plurality of pieces of information are wavelength-multiplexed and transmitted. An optical demultiplexing circuit that collects the same wavelength from each highway by the optical demultiplexing circuit, and an optical switch matrix that switches and outputs information for each same wavelength, It is characterized by being composed of an optical multiplexing circuit that optically multiplexes the optical information heading towards the highway, and exchanging optical information between the highways.

(6) Examples of the invention The present invention will be explained in detail below using examples.

FIG. 1 is a block diagram of an optical highway switch according to the present invention. In the figure, S is an optical highway switch, cc is an optical exchange control unit, 11 to 1n are incoming highways, 51 to 5n are outgoing highways, and optical highway switch s is the light (analog) input from the incoming highways 11 to 1n. Optical demultiplexers 21 to 2n that separate optical paths for each wavelength (multiplexed light or time-division multiplexed light); optical switches 31 to 3m that exchange optical paths; It is composed of an optical highway switch control unit CTL that controls wave transmitters 41 to 4n and optical switches 31 to 3m. In this embodiment, the multiplicity m within the same highway is
The number of highways is n, and m×n information can be switched arbitrarily. There, light (wavelength λ
1 to λm), the light from each highway is demultiplexed into wavelengths λ1 to λm by optical demultiplexers 21 to 2n, and the demultiplexed wavelengths λ1 to λm are determined for each same wavelength. The light is input to the optical switches 31 to 3m. That is, the output wavelength λ1 of the optical demultiplexer 21 is transmitted to the optical path 211, the wavelength input 2 is transmitted to the optical path 212... the wavelength λm is separated to the optical path 21m, and similarly the output wavelength λ1 of the optical demultiplexer 2n is transmitted to the optical path 2n1, . . . the wavelength λm is optical path 2nm
The light is divided into . The optical switches 31 to 3m are optical switch elements in which m input ends can be replaced with m output ends.For example, as an optical switch element currently being developed, a mirror is placed at the cross point of the optical path, and the mirror is A mechanical type that determines the output end by rotation, an electronic type that changes the optical path within the optical switch element using an electric field, etc. can be used.

Exchange between highways is performed under the control of the optical highway switch control unit CTL for each of the same wavelengths input to the optical switches 31 to 3m, and input to the optical multiplexers 41 to 4n. Optical multiplexer 41~4n
The light input to the output highways 51 to 5n is multiplexed and output. Note that optical circuit parts such as a diffraction grating and an interference film filter are used for the optical multiplexer and the optical demultiplexer. The optical exchange control unit cc is a storage device (not shown)
It issues a command to the optical highway switch control unit CTL based on the program stored in the controller, line information (or subscriber information), etc.

In this way, it is possible to exchange multiplexed highways input directly from an optical transmission line system (using optical fiber, for example).

FIG. 2 is a configuration diagram when the optical highway switch of the present invention is applied to a time division exchange. In the diagram, the configuration of the optical highway switch S is the same as that shown in FIG. It is rarely read out randomly by the control memory COT. This read call information is converted into light by an electric/optical conversion circuit (for example, a phototransistor etc. can be used) 71 to 7n, and is modulated by an optical wavelength modulation circuit (for example, by applying an electric field to a waveguide) 81 to 8n. The signal is inputted to the input highway, modulated into wavelengths λ1 to λm for each time slot of each highway, and sent to primary links 11 to 1n (same values as the incoming highways shown in FIG. 1).

Then, as explained in FIG. 1, the optical highway switch S exchanges the lights with wavelengths λ1 to λm between each highway, and sends them out to the secondary links 51 to 5n (equivalent to the outgoing highways 51 to 5n in FIG. 1). , optical wavelength demodulators (modulators) 91 to 9n, and optical/electrical conversion circuits 101 to 10n, they are sequentially written, for example, in the communication memories 1021 to 102n on the receiving side, and read out randomly by the control memory COT. That is, in this method, T-S-T
This corresponds to a system in which the space switch section of a time division switch is replaced with an optical highway switch S.

FIGS. 3 and 4 are explanatory diagrams illustrating switching operations when the optical highway switch of the present invention uses an analog multiplexing format and a time division multiplexing format among optical wavelength multiplexing systems.

In FIG. 3, the relationship between the incoming highways 11, 1n and the outgoing highways 51, 5n will be explained as an example. Each of the wavelengths λ1 to λm is represented by the wavelength on the horizontal axis and the light intensity on the vertical axis, and the time axis represents analog multiplexed light when the highway is cut. Here, the distance between each wavelength depends on the accuracy (resolution) of the optical demultiplexer, etc., but it is usually
If you take 20 Å (Angstrom), it is possible to separate the wavelengths sufficiently. Entering highway 11, 1n at wavelength λ1
(A), λ2 (B), λ1 (C), λ2 (D) are output.Wavelengths λ'1 (A)', λ'2 of highways 51 and 5n.
(b)′, λ′1(c)′, λ′2(d)′, each light exiting the optical demultiplexer 21, 2n has a wavelength of λ
1 (a) and λ1 (c) are applied to the optical switch 31 by λ2
(b) and λ2 (d) are input to the optical switch 32. In the optical switch 31, the optical path 211 (λ1 (a))
to 311, optical path 2n1 (λ1 (c)) to 31m
The optical switch 32 switches the optical path 21 to
2 (λ2 (b)) to 32n, optical path 2n2 to 32
1 and multiplexed by optical multiplexers 41 and 4n.

On the other hand, as shown in Fig. 4, the light wavelength λ1~
When λm is input to the input highways 11 and 1n in a time-division manner, the light is exchanged in a time-division manner as in FIG. 3.

(7) Effects of the Invention As explained above, according to the present invention, since light is used as the transmission medium and exchange between highways is performed using optical circuit elements, the transmission speed becomes high.
Accordingly, high-speed switching (substantially only by determining the optical path of the optical switch) is possible, and the switch can be made smaller. Furthermore, since it uses light, it has excellent transmission quality and low power consumption, which has great practical effects.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the optical highway switch of the present invention, Fig. 2 is a block diagram of the optical highway switch of the present invention applied to a time division switch, and Fig. 3 is a block diagram of the optical highway switch of the present invention in analog multiplex format. FIG. 4 is a diagram illustrating the switching operation when the optical highway switch of the present invention is used in a time division multiplex format. S: Optical highway switch, 21-2n: Optical demultiplexer, 31-3m: Optical switch, 41-4n: Optical multiplexer, CTL: Optical highway switch control unit,
cc: Optical exchange control unit.

Claims (1)

[Scope of Claims] 1. In an optical multiplex exchange whose input/output is a highway on which a plurality of pieces of information are wavelength-multiplexed and transmitted, the optical demultiplexer circuit detects the wavelength of the incoming highway and demultiplexes each wavelength; An optical switch matrix that collects the same wavelength from each highway using an optical demultiplexing circuit, switches and outputs information for each same wavelength, and an optical synthesis circuit that optically multiplexes the optical information headed for the same output highway from each of the optical switch matrices. An optical highway switch characterized by exchanging optical information between highways.