Abstract: An optical waveguide path and an optical branch path branching from the waveguide path are formed in an optical material which is variable in refractive index with the variation of temperature. A heat generator is provided in the vicinity of the branching portion of the waveguide path. The heat of the generator produces in the optical material a temperature gradient in a direction parallel with a plane including the waveguide path and the branch path. The temperature gradient gives the optical material a temperature gradient, by which a light beam propagating through the waveguide path is deflected for switching.

Abstract: A semiconductor mechanical-electrical transducer is obtained by providing a mechanical force applying means on a semiconductor composite comprising a semiconductor substrate, an insulating film formed on said semiconductor substrate and a film of tin oxide deposited on said insulating film and having a barrier having a rectifying characteristic. Preferably, the material of said insulating film may be selected from a group consisting of SiO.sub.2, Si.sub.3 N.sub.4 and GeO.sub.2 and the thickness of the film may be chosen to be 15 to 80A, but preferably to be 20 to 60A and more preferably to be 20 to 40A. It was discovered that such composite shows an increased reverse current response to mechanical force applied to the composite in case where the thickness of the SiO.sub.2 film has been chosen to the said particular value range. Preferably, the main surface of the substrate is made uneven.