JPS58161486A - Optical exchange circuit network - Google Patents

Abstract

PURPOSE:To attain the optical exchange of optical signals performed mutually for wavelength split and multiplex, by combining a light wavelength conversion switch circuit and an optical spatial switch circuit performing spatial transition among plural optical paths. CONSTITUTION:Optical signals of n-wave on each optical wavelength multiplex input optical fiber are demultiplexed at the optical demultiplexers D and as the optical signals separated spatially in total mn-set in the form of one optical signal per one optical path, they are led to an optical spatial switch S, where spatial conversion of the optical path is done. The output of the switch S is sectioned into m-group of optical signal groups comprising n-set of optical signals each again. The optical signals of each group are led to an optical wavelength converter CONVi, where they are converted into the optical signals of different wavelength and transmitted as n-wave of optical wavelength multiplex signals at an optical synthesizer M. In the optical wavelength converter, the signals are converted into electric signals once at a photodetector PD, and the signals drive light emitting elements LD of a specific wavelength again. Or, an optical input signal lambdai and a control optical input lambdac are applied to a nonlinear optical crystal NOC at the same time, to obtain optical signals of lambdaj, as 1/lambdaj=1/lambdai 1/lambdac.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of the Invention The present invention relates to optical exchanges, and particularly to the construction of a call switch network of an optical exchange.

(2) Background of the Invention The development of optical transmission technology using optical fibers is remarkable, and research on the development and practical application of various optical functional elements and optical integrated circuits is also being vigorously advanced both at home and abroad. As a result, expectations are increasing for the emergence of optical switching equipment that directly exchanges optical signals.

The mainstream of multiplex transmission systems using optical fibers is the development and practical use of time division digital multiplex transmission systems that utilize multi-mode or single mode light. ...Development and practical application of a wavelength division multiplexing transmission system in which the outputs of input light sources are multiplexed using an optical multiplexer, transmitted through a single optical fiber, and then demultiplexed using an optical demultiplexer. It is progressing. In particular, in the latter wavelength division multiplexing transmission system, a signal with a very wide band such as an image signal can be directly modulated by intensity modulation in a form that supports one channel and one wave, or the original signal can be directly modulated by intensity modulation.
It is thought that this method is particularly suitable for a method in which light is digitally encoded using the ``1'' digital encoding, digitally modulated, and then transmitted using wavelength division multiplexing.

Up until now, various domestic and international studies on such wavelength division multiplexing systems have mainly focused on multiplex transmission, and no research has been found that has mistaken this for switching, making this a completely unexplored field.

(3) Object of the Invention An object of the present invention is to provide an optical switching network of wavelength division multiplexed optical signals as described above.

(4) Key Points of the Invention The optical switching network of the present invention includes an optical wavelength conversion switch circuit that arbitrarily replaces a plurality of optical input signals with different wavelengths with the same number of optical output signals with different wavelengths; It is constructed by combining an optical space switch circuit that performs spatial switching between optical paths.

(Examples of 51 inventions Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a block diagram showing a first embodiment of the present invention. In the figure, h to Im, O+ to 0 and each n wave (input 1.
λ5. ...λ7) optical wavelength multiplexing input optical fiber and output optical fiber. The n-wave optical signals on each wavelength-division multiplexed optical fiber are each passed through an optical splitter and guided as l-fiber (l-optical path) optical signals to an optical space switch S, where the optical paths are spatially switched (exchanged). ), a total of n optical signal outputs from the optical space switch S are again divided into m optical signal groups each consisting of rl optical signals in each group. Here, the n optical signals of the same group are guided to a total of n optical wavelength converters C0NV; (=1 to N). As described later, the optical wavelength converter coNvL receives an arbitrary optical wavelength signal as input and converts it into an optical signal of a specific wavelength larger than the wavelength. As a result, the n optical signals of the same group are converted into optical signals of different wavelengths λ...λ, and are sent to the output optical fiber as 11 optical wavelength multiplexed signals at the optical multiplexer M. Ru.

Here, the optical demultiplexer, optical multiplexer, etc. can be realized using techniques such as prisms, diffraction gratings, 9-wavelength filters, etc., which are well known to those in the optical technology field. On the other hand, regarding optical space switches, LLN is a method that switches optical transmission paths by mechanical operation.
A method is known in which a switch matrix is constructed by arranging directional optical couplers made of materials such as bO, etc. using optical IC technology. The optical wavelength converter is the most difficult part to realize based on current technology. The simplest method at present is to convert the light into an electrical signal using a photoreceiver PD that receives light of an arbitrary wavelength, as shown in FIG. Although this method involves some electrical signals, it uses optical IC technology to
If the D and LD sections are formed within the same IC, it will look like a direct light-to-light conversion element and is currently the easiest to realize.

FIG. 2(b) shows a method that is currently being researched to directly convert optical wavelengths without intervening electrical signals. Specifically, the optical input signal λ- and the control optical input λC can be simultaneously applied to the nonlinear optical crystal NOC.

FIG. 3 is a block diagram showing a second embodiment of the invention. In the first embodiment shown in FIG. 1, all optical signals are spatially separated and exchanged using an optical space switch, which has the disadvantage that the size of the optical space switch becomes large.

However, the purpose of optical exchange, that is, exchanging arbitrary optical inputs, is to mutually exchange wavelengths of n-liquids 1 to λ7 wavelength-multiplexed on the same fiber (same optical path) (optical wavelength conversion switch function), It can also be broken down into spatial switching between different fibers (different optical paths) (optical space switching function). This is in contrast to the fact that the time division switching network is broken down into a time slot conversion switch function, a two-time switch function, and a space switch function of inter-highway interleaving, and by combining these, various time division circuit networks can be formed. It's easy to understand if you think about it.

In the example shown in Figure 3, n
As before, the optical input signal of the wave is separated into n spatially separated signals by an optical demultiplexer, and guided to an optical space switch with a capacity of n×n, which separates the signals between different wavelength phases h. An exchange takes place. The n output lights of the optical space switch 旙 are connected to an optical wavelength converter CON V 'c (L
” 1 to N), resulting in the same fiber (
Interchanging (exchanging) the optical signals of the l'1 waves arriving on the optical path) is first performed.

Namely 1. This is the realization of the optical wavelength conversion switch function A (lambda) described above.

Next, mutual exchange between input optical fibers (optical paths) is performed by collecting optical signal outputs of mutually equal wavelength λL from the above-mentioned optical wavelength conversion switch section A corresponding to each manually operated optical fiber (optical path), and spatially exchanging only between these mutually. This is accomplished by providing an optical space switch St corresponding to each wavelength (λ1...λ6).

In other words, the above-mentioned optical space switch function $ is realized.

The optical signal output from the optical space switch unit $ is divided into optical signal groups of total quantity groups so that each group has n optical signals of different wavelengths. That is, the optical signal outputs of n wavelengths λ° C. from each optical space switch S are distributed to different groups, so that each of the m groups has a wavelength input of 1. Input t, . . . become spatially separated optical signals of n waves to the input. This is sent to an output optical fiber (light N) by an optical multiplexer M as an optical wavelength multiplexed signal of n waves. As a result, according to this embodiment, compared to the first embodiment, an optical switching network with a smaller total number of switching points can be realized by linking smaller optical space switches.

FIG. 11 shows a third embodiment of the present invention. In the second embodiment mentioned above, there is only one path that connects optical signals of a certain wavelength of a certain output fiber (optical path), and on this path, If the optical link of the 8th part is being used for another call, the connection will not be possible. In order to eliminate this drawback, as shown in Fig. 4, in the optical switching network configuration of the second embodiment (Fig. 3), section 8 and the optical multiplexer M are cut out, and during this time, the other stage is Just insert a step. As a result, the number of paths that connect certain wavelengths of a given human output fiber (optical path) increases to n types, and the degree of freedom in connections is greatly improved, creating what is called a small optical switching network with a good internal blockage rate. can get.

Second. In the third embodiment, when the basic exchange functions A and S described above are combined, the A-8 type and the A-! type, respectively. 6-
It can be expressed as an A-type optical switching network configuration. What can be easily inferred from this is that various types of optical switching networks can be created by combining the basic switching functions A and S in various ways. That is, for example, S-to $1 type, $-5-A-5-8 type, A-$-B-A type, etc. The fourth embodiment shown in Figure 5 is one of these! 9-A-! I; shows an optical switching network of the form;

(6) Effects of the Invention The present invention provides the following effects by simply combining the optical wavelength converter C0NV and the optical space switch S as described above, or by converting the optical space switch function s1 into the above-mentioned optical wavelength conversion switch function. By systematically combining these, it is possible to realize an optical switching network between wavelength division multiplexed optical signals.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of an optical switching network according to the present invention, and FIGS. 2(a) and (b) are diagrams showing an example of an optical wavelength converter in the first embodiment. 3 to 5 are block diagrams showing second to fourth embodiments of the optical switching network of the present invention, respectively. l, ~l, -Light wavelength light wave type multiplexed manual optical fiber 01~
0IR = Optical wavelength multiplexing optical fiber - +1: yt demultiplexer S, A: Optical space switch C0NV: To optical wavelength converter Dual optical wavelength conversion switch function $: Optical space switch function

Claims (1)

[Claims] An optical wavelength conversion switch circuit that arbitrarily replaces a plurality of seller power signals with different wavelengths with the same number of optical output signals with different wavelengths, and an optical space switch circuit that performs space switching between multiple optical paths. An optical switching network consisting of a combination of