Non-blocking optical space switch

Details Non-blocking optical space switch Non-blocking optical space switch

1987-08-18

1989-06-06

Griffin, Robert L.

Telecommunications

Receiver or analog modulated signal frequency converter

Signal selection based on frequency

455612, 370 1, 370 54, 3408258, 34082589, H04B 900

Patent

active

048378550

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION

1. Technical Field
The present invention relates to a structure of an n.times.n non-blocking optical space switch formed by n.sup.2 switch elements having two inputs and two outputs, and in particular, it relates to a structure of an optical space switch which can be compactly integrated on a single substrate.
2. Background Art
Today, high speed information services such as high precision images, motion video, and a high definition motion video, in addition to conventional low speed information services such as voice and data up to 64 kb/s, are required for communication networks. For this purpose, optical transmission lines including subscriber lines have been applied to communication networks. Further, in an electric switching system, optical transmission lines have been applied between modules, for example, an interface between a time switch module and a highway switch module. But, in a present switching system, since the switching is realized by an electric logic circuit, highly expensive opto/electrical and electric/optical conversions are required for converting the information from an optical transmission line into electrical information, and vice versa. Further, if an electric device is operated at a high speed, the operation speed of the system is restricted due to capacitance loads or impedance mismatching in the electric circuitry. An optical switching system deals with the optical information from the optical transmission line directly, and therefore, the opto/electrical and electric/optical conversions are not required and thus the ability to handle high speed information is expected. As the optical switching system, a space-division switching system, a time-division switching system, and a wavelength-division switching system are under consideration at present. Among these systems, a space switch is the basic component as well as the existing electrical switching system. A representative space switch, at the present stage, is a matrix switch to realize non-blocking type switching systems. Further, it is able to construct a large size space switch with a combination of a plurality of small size space switches, such as multi-stage switching networks. As well as the electrical matrix switch, the optical matrix switch (optical space switch) is formed by n.sup.2 switching elements arranged in n rows and n columns so that n input highways and n output highways can be accomodated. In this matrix switch, switch elements are, of course, optical switches.


SUMMARY OF THE INVENTION

In the present invention, regardless of which output highway is selected, the optical signal from each input highway is passed through the same number of switch elements respectively, so that the levels of the output optical signals become equal and the loss characteristic and S/N are improved, the switch size can be enlarged, and a smaller size chip can be realized.
In an optical space switch according to the present invention, switch elements having two inputs and two outputs are arranged in an N.times.N matrix form; one of the input terminals of the switch elements arranged in a first column of each row is used as the input highway, and one of the output terminals of the switch elements arranged in the N th column of each row is used as the output highway; one of the switch elements is selectively controlled for connecting between one of the input highways and one of the output highways, so that the output can be obtained from any input highway; and each of the outputs of the switch elements is connected to an input of the next column of the switch elements.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of one example of conventional optic space switch;
FIG. 2 is a diagram for explaining a function of a switch element;
FIG. 3 is a diagram of the switch element;
FIG. 4 is a block diagram of the arrangement of one example of the conventional optical space switch;
FIG. 5 is a block diagram of a first embodiment of an optical space switch of the present invention;
FIG. 6 is a block diagram of a

REFERENCES:
patent: 3593295 (1971-07-01), Joel
patent: 3674938 (1972-07-01), Jacob
patent: 4608682 (1986-08-01), Nagashima
patent: 4679190 (1987-07-01), Dias

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