Optical waveguides – With optical coupler – Switch
Patent
1994-12-12
1996-06-18
Lee, John D.
Optical waveguides
With optical coupler
Switch
385 17, G02B 635
Patent
active
055287107
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an optical switching device and finds particular application in optical communications systems.
BACKGROUND OF THE INVENTION
Optical switching is expected to play an important role in future high capacity, for instance broadband, optical telecommunications networks. It is desirable to have all-optical switches in a communications network for several reasons, including the avoidance of a bit rate "bottleneck".
Optical switching can offer: equipment than for instance electronic switching. can be switched without optical demultiplexing and multiplexing. processing speeds. of data rates).
The semiconductor laser amplifier gate switch array is an attractive component, offering potential for zero insertion loss, polarisation insensitivity, low wavelength dependence, low crosstalk, high extinction ratio, high switching speed and simple drive conditions. Small size and scope for integration are both important criteria for the practical realisation of optical switches. Switches are known, including a 2.times.2 switch with waveguided Y-branched input and output, and a 2.times.2 switch in which the Y-branching is replaced by reactive ion etched (RIE) total internal reflection (TIR) mirrors instead of the waveguided Y-branching.
Known devices of the prior art which have relevance to the present invention are described in the following published documents: Switch Arrays" by M. Janson et al, Proceedings of the 17th European Conference on Optical Communications, Post Deadline Papers, pp 28-30, 8th Aug. 1990.
The latter is entitled "Integrated Optics Asymmetric Y-Coupler" and provides a description of a fabrication technique for mirrors in optical semiconductor technology.
BRIEF DESCRIPTION OF THE INVENTION
According to the present invention, there is provided a semiconductor optical switching device comprising passive optical input and output stages, each having respectively a plurality of inputs and outputs, and a matrix stage, one or more inputs being selectively coupled to one or more outputs via The matrix stage to provide selective routing for optical signals input to the device, the material of the device in the matrix stage being at least in part active so that said selective routing can be controlled by control inputs to the matrix stage wherein the propagation direction of optical signals in both the input and output stages of the device is substantially the same, and said direction is substantially different from the propagation direction of optical signals in the active part of the matrix.
Thus, by providing that the input and output stages are in a substantially different direction to the active part of the matrix stage, switching devices according to the present invention have an architecture which can be relatively simply adapted to a differing number of input and/or output paths, and which is thus scalable.
The matrix stage can thus be set out between the input and output stages so that virtually any number of optical paths can be "picked off" from the input stage and selectively connected to any one of up to a large number of optical paths in the output stage. For instance, the matrix stage can be provided by optical paths lying generally transverse, for instance, at right angles, to the input and output stages. In the right-angled case, the input and output stages will be offset approximately by the length (in the direction of optical signals propagating in the matrix stage) of the matrix stage, though clearly other configurations might be applicable and advantageous.
Because switching devices according to embodiments of the present invention are part active and part passive, they can provide gain, thereby reducing insertion losses, while only simple drive conditions are required.
Embodiments of the present invention can provide a monolithically integrated amplifier gate switch matrix which provides a small device, compared with like devices of the prior art, and which introduces very low losses in use.
Preferably, changes in direction of propagation of optical signa
REFERENCES:
patent: 5050951 (1991-09-01), Caron et al.
patent: 5255332 (1993-10-01), Welch et al.
patent: 5283844 (1994-02-01), Rice et al.
"Monolithically Integrated Optical Gate 2X2 Matrix Switch Using GaAs/AlGaAs Multiple Quantum Well Structure", A. Ajisawa, et al., Electronics Letters, Oct. 8, 1987, vol. 23, No. 21, pp. 1121-1122.
"Monolithically Integrated 2X2 InGaAsP/InP Laser Amplifier Gate Switch Arrays", M. Janson, et al., ECOC 1991, pp.1-4.
"Monolithically Integrated 2X2 InGaAsP/InP Laser Amplifier Gate Switch Arrays", M. Janson, et al., Electronics Letters, Oct. 9, 1992, vol. 28, No. 8, pp. 776-778.
Burton Julie
Fiddyment Philip J.
Robertson Michael J.
British Telecommunications Public Limited Corporation
Lee John D.
Palmer Phan T. H.
LandOfFree
Optical switching device with passive input and output stages an does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Optical switching device with passive input and output stages an, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical switching device with passive input and output stages an will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-229762