Temperature sensitive fiber-optic devices

Claim 1

A wide aperture optical coupler for coupling light beams into and out of an end of a fiber-optic guide, said coupler comprising: a first transparent material having an index of refraction n1 and being dielectric, said first transparent material forming the core of said fiber-optic guide; a second transparent material in contact with said first material and having an index of refraction n2, said second transparent material forming the cladding of said fiber-optic guide, the indices n1 and n2 being substantially the same in value at a particular temperature and having different temperature sensitivities; and temperature control means disposed about the end of said fiberoptic guide where the coupling is to take place for generating a variation in the difference in the indices of refraction of said first and second transparent materials in the vicinity of said end by controlling the temperature of said end, the difference in the indices being substantially zero at said end and gradually increasing in a limited region of said guide away from said end, whereby coupling of light beams into and out of said end of said fiber-optic guide is facilitated.