Methods for making planar waveguides with removal of a sacrifical member which surrounds the core

An optical waveguide is made by forming successively of light transmitting material a first clad layer (13), a core layer (15) and a second clad layer (18). The core layer has a higher refractive index than that of the first and second clad layers such that the core layer (15) can transmit light along its length as an optical waveguide. A sacrificial layer (14, 17) is formed surrounding at least a first end potion of the core layer. The sacrificial layer is selectively removed as by selective etching such that the first end portion of the core layer is separated from the first and second clad layers. With the end portion so isolated, a lens (22) can be formed on it such that light may be more effectively coupled to or from the core layer. Preferably, the lens is formed by heating the structure sufficiently to form a meniscus on the free end and then cooling it before the reminder of the core layer flows or melts. The cooling hardens the meniscus such that it constitutes an optical lens.