Abstract: A method of producing a substrate for an optical surface mount circuit including the steps of forming an optical wave guide in the substrate, wherein the optical wave guide has a zone of refraction gradient decreasing from a central axis thereof toward surrounding portions thereof, and end surfaces of the optical wave guide are exposed to the front surface of the substrate. Portions of the substrate are masked and salts of metallic cations are contacted to the substrate to form the optical wave guide and the end surfaces thereof.

Abstract: An optical surface mounting circuit is provided which does not necessitate alignment of optical axes of optical parts used therein, reduces greatly the number of production steps, enables mass-production of complicated optical circuits, and facilitates designing of optical circuits and changes in the designing. The optical surface mount circuit includes a substrate having optical wave guides and a first guide means positioned and fixed relative to an end surface of the optical wave guide, and an optical part having an optical terminal and a second guide means at the bottom positioned and fixed relative to the optical terminal. The first and the second guide means are engaged and fixed on the front surface of the substrate, and the optical terminal and the end surface of the optical wave guide are optically connected.