Optical switch unit

Details Optical switch unit Optical switch unit

2001-02-08

2002-12-10

Patel, Tulsidas (Department: 2839)

Optical waveguides

With optical coupler

Switch

C385S024000

Reexamination Certificate

active

06493481

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to an optical switch unit having input-ports and output-ports for optical signals. Then, the optical switch unit can selectively switch inner switch elements for connecting an optical input port to an optical port.
BACKGROUND OF THE INVENTION
In recent years, large scale optical switch units having comparatively many input ports have been proposed. For example, a 32×32 optical switch unit has 32 input ports and 32 output ports. And, an optical signal inputted in any one of the input ports can be selectively output from any one of the output ports.
These large scale optical switch units are comprised of some smaller scale waveguide-type optical matrix switches, e.g., waveguide-type 8×8 optical matrix switches. In order to increase the number of output ports, these smaller waveguide-type optical matrix switches form multistage-connections.
Regarding these multistage waveguide-type optical matrix switches, a three-stage construction applying to a cross-network is used generally, e.g., “Optical Switch Architectures for Optical Path Cross-Connect”; Tetuya Nishi, Satoshi Kuroyanagi and Tomohiro Ishihara; Proceedings of the 1998 IEICE General Conference, B-10-97(March 1998) discloses these constructions.
Though, these present optical switch units constructed by multistage-connecting of the waveguide-type optical matrix switches have a problem that the present optical switch units have comparative large insertion losses because they need three-stage-connecting of the waveguide-type optical matrix switches and each of them has large insertion loss.
Therefore, the present optical switch units additionally need optical amplifiers for compensating the insertion loss.
For example, each of silica-based 8×8 matrix switches has about 5 dB insertion loss, then three-stage-connecting of the 8×8 matrix switches has more than 15 dB insertion loss totally.
Also in Clos-networks, the present optical switch units need three-stage constructions, and three-stage boards were needed for containing the optical matrix switches. For inter-board connection of the three-stage boards, connections occur at two sections and each of the two sections needs about r
2
lines for inter-board connection, where r is a port number of an optical matrix switch.
Consequently, because a large number lines are centralized in limited area of the optical switch unit, a production process of the optical switch unit is more complicated.
Furthermore, in connection with the complicated production process, when expanding the optical switch unit's scale, each of the three-stages of the optical switch unit needs additional boards.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an large scale optical switch unit having a simple construction and low insertion loss.
To resolve the above problems, a K×K optical switch unit according to the present invention is comprised of an input port, a 1×M optical matrix switch connected with the input port, an N×N optical matrix switch connected with the 1×M optical matrix switch, an M×1 optical matrix switch connected with the N×N optical matrix switch, and an output port connected with the M×1 optical matrix switch, where K=M×N, M and N are integers more than 1.


REFERENCES:
patent: 5048910 (1991-09-01), Caron
patent: 6005698 (1999-12-01), Huber et al.
patent: 6044185 (2000-03-01), MacDonald
patent: 6259834 (2001-07-01), Shani
patent: 6317529 (2001-11-01), Kashima
patent: 10-10588 (1998-01-01), None

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