Optical waveguides – With optical coupler – Switch
Reexamination Certificate
2000-02-03
2002-07-30
Healy, Brian (Department: 2874)
Optical waveguides
With optical coupler
Switch
C385S017000
Reexamination Certificate
active
06427037
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical switch circuit network for controlling paths for the propagation of optical signals.
2. Description of the Background Art
It has been customary to implement a number of input ports and output ports, i.e., a large-scale architecture with optical switches by sequentially combining the optical switches. Various schemes heretofore proposed for combining optical switches include an optical path cross-connect system taught in T. Nishi, et al. “Optical Switch Architectures for Optical Path Cross-Connect”, Proceedings of the 1998 General Conference of the Institute of Electronics, Information and Communication Engineers of Japan, B-10-97, March 1998. The cross-connect system constitutes an optical switch circuit network with optical matrix switches arranged in three consecutive stages. This, however, brings about a substantial loss in the optical matrix switches. Effective architectures for increasing the number of input ports and output ports with two stages of optical matrix switches have not been reported yet.
An optical switch circuit network using thermo-optical (TO) switches is disclosed in A. Watanabe, etal. “8×16 delivery and coupling switch board for 320 Gbit/s throughput optical path cross-connect system”, Electronics Letters, Vol. 33, No. 1, pp. 67-68, Jan. 2, 1997. The TO switches each include means for switching an optical path by varying the resistance of an optical waveguide with heat. Each TO switch is located at the intersection of one input and one output. The network drives only one of the TO switches connected to a desired input and a desired output for the purpose of saving drive power.
However, the problem with the above TO switch scheme is that it has to serially connect TO switches equal in number to the inputs or the outputs and therefore results in a prohibitive total length. Specifically, when the TO switch scheme is used to construct an N×N optical switch circuit network, it is necessary to switch Nlog
2
N TO switches at the input port side and switch Nlog
2
N TO switches at the output port side. In the worst case, therefore, the network has to switch 2Nlog
2
N TO switches in total.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an optical switch circuit network needing only two stages of optical matrix switches.
It is another object of the present invention to provide an optical switch circuit network capable of scaling down the individual optical matrix switch.
It is a further object of the present invention to provide an optical switch circuit network which is short despite the use of TO switches and capable of reducing power necessary for driving TO switches while stabilizing the power.
In accordance with the present invention, an optical switch circuit network including nr (n and r being positive integers) input ports and nr output ports includes r input optical switches arranged at the input side and each having n of the nr input ports, m (m being a positive integer) 1×r optical switches and an n×m optical switch for selectively connecting the n input ports and m 1×r optical switches, and r output optical switches arranged at the output side and each having n of the nr output ports, m r×1 optical switches and an m×n optical switch for selectively connecting said n output ports and m r×1 optical switches. The i-th (i being an integer between 1 and m) 1×r optical switch of each of the input optical switches is connected to the i-th r×1 optical switch of each of the output optical switches.
Also, in accordance with the present invention, an optical switch circuit network including nr input ports and nr output ports includes r/h (h being a positive integer) input optical switches arranged at the input side and having nh of the nr input ports, m h×r optical switches and h n×m optical switches each being connected to a particular one of n of the nr input ports to thereby switch a path between the n input ports and said m h×r optical switches, and r/h optical output switches arranged at the output side and having nh of the nr output ports, m r×h optical switches and h m×n optical switches each being connected to particular one of n of the nr output ports to thereby switch a path between the n output ports and the m r×h optical switches. The i-th (i being an integer between 1 and m) h×r optical switch of each of the input optical switches is connected to the i-th r×h optical switch of each of the output optical switches by a tape-like optical fiber constituted by h connect lines.
Further, an optical switch circuit network including nr input ports and nr output ports of the present invention includes r/h input optical switches arranged at the input side and having nh of the nr input ports, m/h′ (h′ being a positive integer) nh×h′r optical switches and nh/h′ h′×m/h′ optical switches each being connected to particular one of h′ of the nr input ports to thereby switch a path between the h′ input ports and m/h′ nh×h′r optical switches, and r/h output optical switches arranged at the output side and having nh of the nr output ports, m/h′ h′r×nh optical switches and nh/h′ m/h′×h′ optical switches each being connected to particular one of h′ of the nr output ports to thereby switch a path between the h′ output ports and h′r×nh optical switches. The h′×m/h′ optical switches each are connected to said nh×h′ optical switches by tape-like optical fibers each comprising h′ connect lines. The m/h′ optical switches each are connected to the r
h optical switches by tape-like optical fibers each having h′ connect lines. The input optical switches are connected to the output optical switches by tape-like optical fibers each having h connect lines.
Moreover, in accordance with the present invention, an optical switch circuit network including N input ports and N output ports includes 2
n
input sections each having N/2
n
of the N input ports, 2
n
N/2
n
×N/2
n
input optical switches, and 1×2 optical switches arranged in an n-stage tree configuration and connecting the input ports and input optical switches, and 2
n
output sections each having N/2
n
of the N output ports, 2
n
N/2
n
×N/2
n
output optical switches, and 1×2 optical switches arranged in an n-stage tree configuration and connecting the output ports and output optical switches. The j-th (j being an integer between 1 and 2
n
) input optical switch of the i-th (i being an integer of 2
n
or smaller) input section is connected to the i-th output optical switch of the j-th output section.
REFERENCES:
patent: 5532855 (1996-07-01), Kato et al.
patent: 6044185 (2000-03-01), MacDonald
patent: 0 386 958 (1990-09-01), None
patent: 9-46736 (1997-02-01), None
T. Nishi et al. “Optical Switch Architectures for Optical Path Cross-Connect” Proceedings of the 1998 General Conference of the Institute of Electronics, Information and Communication Engineers of Japan, B-10-97, Mar. 1998.
A. Watanabe et al. “8×16 Delivery and Coupling Switch Board for 320 Gbit/s Throughput Optical Path Cross-Connect System” Electronics Letters, vol. 33, No. 1, pp. 67-68, Jan. 2, 1997.
(1) English Language Abstract No. XP-002142425 of JP 08 251632.
(2) English Language Abstract of JP 08 251632.
(3) English Language Abstract of JP 09 046736.
(4) English Language Abstract of JP 10 257030.
Frank Robert J.
Healy Brian
Oki Electric Industry Co. Ltd.
Sartori Michael A.
Song Sarah U
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