Patent
1989-02-01
1990-11-13
Sikes, William L.
350 9618, G02B 626
Patent
active
049697048
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a positioning device for positioning one or more optical devices relative to a transmissive window.
BACKGROUND OF THE INVENTION
It necessary for many semi-conductor devices to be packaged in a hermetically sealed environment, and so any connections into the package need to pass through a hermetically sealed feed-through. Optical fibres may be used where it is necessary to conduct light to or from a package, in which case the fibre needs to be close to the device and has to pass through the package wall. The fibre itself needs to be sealed to the feed-through because otherwise there is a leakage path along the fibre between the fibre and the usual protecting sheath. Sealing the fibre to the feed-through presents problems; firstly the fibre is delicate and can be damaged by the handling processes of stripping, metalising and soldering that are typical in the preparation of feed-through, and then, once the protecting sheath is removed the fibre may be subject to stress unless the sheath is also secured to the feed-through to maintain continuity of strength and covering for the fibre.
A known method of overcoming these problems is to incorporate a transmissive window with the package device arranged to transmit or receive light through it but this has been found to cause difficulty in aligning the internal and external devices.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a device which largely overcomes the alignment problems.
According to a first aspect of the present invention there is provided a positioning device comprising a single crystal and having a transmissive window portion having first and second sides oppositely disposed, which is transparent to predetermined wavelengths, and a first locating portion for locating a first optical device in a fixed position relative to the first side of the window portion.
By forming the positioning device from a single crystal, the locating portion and the window portion are in a fixed position relative to one another. The first optical device is therefore also located in a fixed position relative to the window portion.
Preferably, there is a second locating portion for locating a second optical device in a fixed position relative to the second side of the window portion.
Two optical devices may thus be located in a fixed position relative to the window portion, and also relative to one another.
The window may subsequently be made into a package such that the first optical device is external to the package, and the second optical device is internal to the package.
This reduces the problems of aligning the first optical device with the window portion and alignment with the second optical device within a package can be obtained by accurate fixing of the positioning device to the package.
Conveniently, the first optical device is an optical fibre, and the second optical device is a semi-conductor device.
The window portion is transparent to wavelengths corresponding to the wavelength response or emission wavelength of the semi-conductor device. The fibre and semi-conductor device may thus be located relative to the window and to one another such that light emitted from the semi-conductor device passes through the window and is coupled to the fibre. Alternatively, light may be emitted from the fibre, pass through the window and be incident on the semi-conductor device.
Where the first optical device is an optical fibre the window portion may conveniently be formed by a thin region at the end of the bore in the single crystal block, the walls of the bore forming the first locating portion. The diameter of the bore is such that the fibre may be push-fitted into it. Once inside the bore, the bore acts as a support for the fibre.
Alternatively, the first locating portion may be in the form of a V-groove in the single crystal block. The groove may be formed by using chemical etching processes, for example.
The device to be sealed in a package is generally mounted on a planar surface. Th
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patent: 4690487 (1987-09-01), Hale et al.
patent: 4768199 (1988-08-01), Heinen et al.
7th European Conference on Optical Communication, Conference Proceedings, Sep. 8th-11th Sep. 1981, Copenhagen, pp. P13-1-P13-4; G. Kuyt et al. , "Metal Sealed Hermetic Laser Diode Package Suitable for Direct Single-Mode Fibre Coupling".
Patent Abstracts of Japan, vol. 6, No. 147 (E-123)[1025], Aug. 6, 1982; & JP-A-57 69 792 (Nippon Denki K.K.).
Patents Abstracts of Japan, vol. 9, No. 56 (E0302)(1779), Mar. 12, 1985 & JP, A, 59197184 (Nippon Denki K.K.) Nov. 8, 1984.
IBM Technical Disclosure Bulletin, vol. 20, No. 5, Oct. 1977, (New York, U.S.), J. D. Crow: "Integral Source/Receiver Package for Optical Data" pp. 2089-2090.
British Telecommunications public limited company
Heartney Phan T.
Sikes William L.
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