1987-05-08
1989-05-16
Lee, John D.
G02B 642
Patent
active
048304506
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to optical fiber terminations, and finds particular application in substrates for opto-electronic transducers.
It is often necessary that the end of an optical fiber be mounted so that it is aligned along a particular axis. For instance, if light is to be transferred between an optical fiber and another component such as a photodiode, the light transfer efficiency may be maximised by alignment of the optical fiber end along a particular axis in relation to the other component.
It is known to mount the end portion of an optical fiber in a termination comprising a block of ceramic material having an aperture therethrough. The wall of the aperture at least substantially aligns the fiber end portion along a known axis in the block of material.
Before being placed in the aperture, the fiber end portion is stripped down to the outermost surface of the glass cladding layer or layers. There are two reasons for this. Firstly, the fiber end portion can be aligned with much greater accuracy and, secondly, it can be much more effectively sealed at the aperture if the seal can be made directly to the glass cladding. This second feature is particularly useful where the aperture provides a path for the fiber end portion into an otherwise hermetically sealed optical package.
Because the aperture must be suitable to align a stripped fiber end, its diameter must be only slightly greater than the diameter of a stripped fiber. With fibers commonly having diameters of about 125 .mu.m or 150 .mu.m, significant manufacturing difficulties present themselves: it is not at all easy to construct an aperture accurately to a predetermined diameter when working at such small dimensions.
Two methods of constructing such an aperture are known. In a first method, the aperture is bored through a block of material in a single operation while in a second method, grooves are made in each of two half blocks of material then brought into register to form the aperture about the fiber end portion.
The first method suffers not only from the difficulty of making such a fine aperture but also from a risk of damage to the stripped fiber during its insertion into the bored aperture. A fiber end without its protective coverings is extremely sensitive to damage which can cause considerable light loss from the fiber in use. To compound the difficulty, the ceramic materials which can be most suitable for use in this context, for other reasons, tend to be extremely abrasive as well as being difficult to machine.
The second method largely avoids the possibility of damage to the stripped fiber end but still suffers from disadvantages. The accurate formation of two grooves of suitable dimensions and their being brought into register still present difficulties. Additionally, if the termination is to be used to couple an optical fiber to a photodiode, then problems arise in holding the two half blocks together. Two alternatives are to use epoxy resin or solder between the two half blocks. However, a particularly convenient arrangement is to mount the photodiode directly on the termination so that it overlies one end of the aperture. This means that it is difficult to avoid creating an interface between the resin or the solder and the photodiode. If epoxy resin is used to hold the half blocks together, contact between it and the photodiode can affect the material of the photodiode and consequently damage its action. If solder is used instead of epoxy resin, it can cause electrical difficulties such as earthing of the photodiode.
It is an object of the present invention to provide an improved optical fiber termination in which an end portion of an optical fiber may be mounted and accurately located, and a method of making the termination.
According to a first aspect of the present invention, there is provided a method of manufacturing an optical fiber termination, for receiving and locating an end portion of an optical fiber, which comprises the steps of:
(i) preparing a plurality of platelets of material, each platelet having a lase
REFERENCES:
patent: 4268113 (1981-05-01), Noel, Jr.
patent: 4398796 (1983-08-01), Palgoutte et al.
Patents Abstracts of Japan, vol. 9, No. 101, (P353), (1824), 2 May 1985, & JP, A. 59226308, (Kiyoshi Hajikano), 19 Dec. 1984.
Patents Abstracts of Japan, vol. 6, No. 229(P-155, (1107), 16 Nov. 1982, & JP, A 57132110, (Fujitsu), 16 Aug. 1982.
Connell Ian M.
MacDonald Brian M.
Stanghan Christopher J.
British Telecommunications public limited company
Lee John D.
Ngo John
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