1987-06-12
1989-08-08
Sikes, William L.
G02B 626, G02B 642
Patent
active
048546585
DESCRIPTION:
BRIEF SUMMARY
The invention relates to radiation deflector assemblies of the kind comprising at least three radiation waveguides; a controllable radiation deflector positioned such that when the deflector is in a first position radiation passes between one combination of two of the waveguides, and when the deflector is in a second position radiation passes between another combination of two of the waveguides; and control means responsive to control signals for controlling the position of the deflector. Such assemblies are hereinafter referred to as of the kind described.
Radiation deflector assemblies of the kind described find particular application as switches in optical transmission systems. IBM Technical Disclosure Bulletin Vol 27, No. 2 of July 1984 (pages 11-12) describes a solid-state array of mirrors positioned beneath three groups of optical fibres. In a relaxed position, optical radiation impinging on the mirrors from one group of fibres is reflected towards another group. When the mirrors are in a deflected position, optical radiation is instead reflected towards the third group of fibres.
The major problem with this arrangement is that it is difficult accurately to align the optical fibres with the mirrors. Alignment is important when large arrays of mirrors are concerned so as to maximise the number of mirrors per unit area.
In accordance with the present invention, a radiation deflector assembly of the kind described is characterised in that the waveguides and the deflector are mounted in a common substrate.
The invention deals with the alignment problem by mounting both the waveguides and the deflector in the same substrate.
Preferably, the waveguides are substantially coplanar, and conveniently the direction of movement of the deflector is in substantially the same plane as the plane of the waveguides. In alternative arrangements, however, the waveguides may extend in different planes.
The invention is particularly suitable where the substrate comprises a single crystal of for example silicon, since anisotropic etching techniques may be used to define grooves of the same or different depths into which the waveguides are mounted.
The invention is particularly suitable for deflecting radiation in the optical waveband and typically a large number of radiation deflector assemblies according to the invention will be assembled together to constitute an optical switch array.
In some arrangements, the deflector may comprise a piston member which moves to and fro between the first and second positions. Preferably, however, the deflector comprises a cantilevered arm which is controlled to pivot between the first and second positions.
It is particularly convenient if the deflector is integrally formed with the substrate. This can be achieved using conventional etching techniques or laser etching technology.
Preferably, the deflector is adapted to deflect the radiation in both the first and second positions although in some examples, radiation could pass directly from one waveguide to another when the deflector is in the first position and be deflected towards another waveguide when the deflector is in the second position.
The deflector will typically comprise a radiation reflector but other deflectors are possible such as a refractor or diffractor.
In some examples, the waveguides could be formed by diffusing a suitable material into the substrate but conveniently each waveguide is mounted in a groove formed in a surface of the substrate, typically a V-shaped groove.
As has previously been mentioned, the substrate may comprise silicon but other substrate materials are possible such as silica or lithium niobate or III-V compounds such as gallium arsenide.
The position of the deflector can be controlled using conventional electrostatic techniques or by thermal methods similar to those described in my copending U.S. patent application 080,469 of even date entitled "Movable Member Mounting".
An example of an optical reflection assembly according to the invention for use in an optical switch array will now be described
REFERENCES:
patent: 4182544 (1980-01-01), McMahon
patent: 4657339 (1987-04-01), Fick
patent: 4669817 (1987-06-01), Mori
patent: 4674828 (1987-06-01), Takahashi et al.
patent: 4675521 (1987-06-01), Sugimoto
patent: 4684208 (1987-08-01), Ishikawa et al.
patent: 4705349 (1987-11-01), Reedy
IEEE Transactions on Microwave Theory and Techniques, vol. MTT-30, No. 10, Oct. 1982, (IEEE, New York, U.S.), M. Spitzer et al.: "Development of an Electrostatically Bonded Fiber Optic Connector Technique", pp. 1572-1576.
IBM Journal of Research and Development, vol. 24, No. 5, Sep. 1980, (Armonk, N.Y. U.S.), K. Petersen: "Silicon Torsional Scanning Mirror", pp. 631-637.
IBM Technical Disclosure Bulletin, vol. 27, No. 2, Jul. 1984, "Array Light Valve Switches Information Signals Between Fiber-Optics Signal Conductors", by M. B. Callaway et al.-pp. 1119-1120.
British Telecommunications public limited company
Sikes William L.
Wise Robert E.
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