JPS58161487A - Optical exchange circuit network - Google Patents

Abstract

PURPOSE:To attain optical exchange between optical signals in wavelength split multiplex, by switching an optical wavelength multiplex light with an optical spatial switch after demultiplexing, transmitting the output light to a demultiplexer via an optical wavelength converter and obtaining the optical wavelength multiplex output light again. CONSTITUTION:Inputs of n-wave from the same optical path are seperated into n-set of spatial separation signals at an optical demultiplexing device D and led to an n-set of optical spatial switch S, where different wavelengths are exchanged. The output light is led to an optical wavelength converter CONVi, where n- set of optical signals incoming on the same optical path are converted at first. The replacement of the n-set of waves among the input optical paths is executed by collecting the outputs of the same wavelength lambdai and providing n-group of optical spatial switches Si performing spatial exchange among them only corresponding to each wavelength. The outputs of the switch S are sectioned into in total m-group of optical signals so as to obtain n-set of different wavelength of optical signals. That is, each group of m-set is an optical signal separated for each wavelength spatially. The optical signals are transmitted on output optical paths as n-set of multiple signals at an optical multiplexer M.

Description

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

(2) Background of the Invention The development of optical transmission technology using optical fibers has been remarkable. On the other hand, research on the development and practical application of various optical functional devices and optical integrated circuits is also being vigorously advanced at home and abroad. As a result, optical signals can be directly exchanged. Expectations are also rising for the emergence of optical switching equipment.

The mainstream of multiplex transmission systems using optical fibers is the development and practical use of time division digital multiplex transmission systems that use multimode or single mode light. ...The development and practical application of a wavelength division multiplexing transmission system is underway in which the outputs of nine light sources are multiplexed using an optical multiplexer, transmitted through a single optical fiber, and then demultiplexed using an optical demultiplexer. . In particular, in the latter wavelength division multiplexing transmission system, signals with a very wide band such as image signals can be directly modulated by analog modulation such as intensity modulation in a form that supports one channel and one wave, or the original signal can be converted to -H digital. After encoding and thus digitally modulating the light,
It is considered to be particularly suitable for wavelength division multiplexing transmission systems.

Conventionally, various studies at home and abroad regarding such wavelength division multiplexing systems have mainly focused on multiplex transmission, and there has been no research relating this to switching, making this a completely unexplored field.

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

(4) Key Points of the Invention The optical switching network of the present invention guides a plurality of wavelength-multiplexed input lights to an optical space switch after demultiplexing, and combines the output lights after switching via each optical wavelength converter. It is configured by sending the light to a wavelength multiplexer and sending it out again as output light that has been multiplexed with a plurality of optical wavelengths.

(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, ■1~ImzOt~OIA is each n wave (λ
1. wavelength-multiplexed input optical fiber and output optical fiber. The n-wave optical signals on each wavelength-multiplexed input optical fiber are each passed through an optical demultiplexer and are converted into a total of n spatially separated optical signals in the form of 1 fiber (1 optical path) 1 optical signal. The total amount of n optical signals output from the optical space switch S, which is guided to the space switch S and spatially switches (exchanges) the optical path here, is again converted into m groups of light consisting of n optical signals in each group. It is divided into signal groups. Here, the n optical signals of the same group are guided to a total of n optical wavelength converters C0NVL (L=1 to N). As will be described later, the optical wavelength converter CON VL receives an arbitrary optical wavelength signal as input and converts it into an optical signal of a specific wavelength of wavelength λB. As a result, the n optical signals in the same group are converted into optical signals with different wavelengths of λ]...λ^, and sent out to the output optical fiber as n-wavelength multiplexed signals at the optical multiplexer M. Ru.

Here, optical branching devices, optical multiplexers, etc. can be realized using techniques such as prisms, diffraction gratings, mole wave filters, etc., which are well known to those in the optical technology industry. On the other hand, for optical space switches, there is also a method of switching optical transmission lines by mechanical operation + LtN&
A method is known in which a switch matrix is constructed by arranging directional optical couplers made of materials such as 03 using optical IC technology. Optical wavelength converters are the most difficult part to realize based on current technology. As shown in Figure 2 (a), the currently extremely simple method is to convert the light into an electrical signal using a photoreceiver PD that receives light of any wavelength, and then drive the light emitting element LD of a specific wavelength again with this signal. . Although this method involves some electrical signals, PD is generated using optical IC technology.
If the LD section and LD section are formed within the same IC, it will appear as a direct light-to-light conversion element, and it 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, when the predecessor power signal λt and the control light power λC are simultaneously applied to the nonlinear optical crystal NOC, the wavelength λJ becomes
An optical signal of J λ[ input C is obtained at the output.

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 exchange n waves λ1 to λ wavelength-multiplexed on the same fiber (same optical path), mutual wavelength swapping (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 a time division switching network is broken down into a time slot conversion switch function (time switch function) and a space switch function of different highways, and by combining these functions, various time division networks can be formed. It is easy to understand if you think about it.

In the example shown in Figure 3, the n-wave predecessor power signal from the same fiber (optical path) is separated into If's spatially separated signals by the optical demultiplexer as before, and is divided into n×n signals. Mutual exchange between different wavelengths is performed using a capacitive optical space switch. Optical space switch 4. The output lights of the n pieces are transmitted through an optical wavelength converter C0NVL (i-=1
~N). As a result, the same fiber (optical path)
First, the n-wave optical signals that arrive are exchanged with each other.

That is, the above-mentioned optical wavelength conversion switch function A (lambda) is realized.

Next, the exchange between human-powered optical fibers (optical paths) is performed by collecting optical signal outputs of equal wavelength input from each human-powered optical fiber (optical wavelength conversion switch section A corresponding to optical U This is done by providing n groups of optical space switches S (for each wavelength (λ1...to input)) for performing optical exchange.

That is, this is the realization of the optical space switch function S mentioned above.

The optical signal output from the optical space switch section S 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 λL from each optical space switch St are distributed to two different groups, and as a result, each group of wires has wavelengths λ1 . λ
2. . . . becomes a spatially separated optical signal of n waves. This is an optical multiplexer MT! It is sent to an output optical fiber (optical path) 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. 4 shows a third embodiment of the invention. In the second embodiment, there is uniquely only one path that connects optical signals of a certain wavelength between input and output fibers (optical paths), and on this path, there is a If the optical link between the two parts is being used by another call, the connection cannot be made. 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 optical multiplexer M are cut out, and in between, one stage A is added. It is okay to insert a stage. As a result, the number of paths that connect a given input/output fiber (optical path) and a given wavelength increases to n types, and the degree of freedom in connection is greatly improved, creating a so-called small optical switching circuit network with a good internal cooling rate. is obtained.

Second. In the third embodiment, when the basic exchange functions A and S explained earlier are combined, they are A-8 type and A-8-A type, respectively.
It can be expressed as a type of optical switching network configuration. What can be easily inferred from this is that by combining the basic exchange functions A and S in various ways, various formats such as % type, % S-A type, etc. can be obtained. The fourth embodiment of FIG. 6 shows a 5-A-S type optical switching network among these.

(6) Effects of the Invention As explained above, the present invention enables the organization of the optical space switch function into the above-mentioned optical wavelength conversion switch function by simply combining the optical wavelength converter C0NV and the optical space switch S. By combining the two wavelength division multiplexed optical signals, 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, FIGS. 2(a) and 2(b) are diagrams showing an example of an optical wavelength converter in the first embodiment, and FIG. 3 to 5 are block diagrams showing second to fourth embodiments of the optical switching network of the present invention, respectively. 11～ ■ 賎: Optical wavelength division multiplexing manual optical fiber〇, ~0□:
Optical wavelength multiplex output optical fiber D = Optical demultiplexer S, JA: Optical space switch C0NV: Optical wavelength converter A: Optical wavelength conversion switch function! S: Optical space switch function

Claims (1)

[Claims] A plurality of wavelength-multiplexed human-powered lights are demultiplexed and then guided to an optical space switch, and the output light after switching is sent to a multiplexer via each optical wavelength converter, where the output light is again wavelength-multiplexed. An optical switching network characterized by transmitting signals as