JPS57195210A - Optical coupler - Google Patents

Abstract

PURPOSE:To elevate optical coupling efficiency, by slantingly forming a dielectric layer whose refractive index is larger than that of an optical waveguide, on the tip of the optical waveguide such as an optical fiber, etc., and making its layer gradually thicker in order toward the incident direction of light. CONSTITUTION:In a coupling part where light from a light emitting element 6 is made incident to an optical fiber 10, clad layers 3, 4 of an optical dielectric are doubled in the outside circumference of a clad layer 2, and also its circumferential surface is formed so that its layer becomes gradually thicker in a tapered state. Among light which have been made incident to the optical fiber 10 from the light emitting element 6, a light B1 satisfying a total reflecting condition is propagated in a core 1, and a part of light B2 travels into the cladlayer 2, but it is totally reflected by the boundary surface of the clad layers 2, 3, travels through the clad layer 2, is refracted again, and is returned into the core 1, therefore, the light which can be transferred in the core 1 is increased. In case of the boundary surface of the clad layers 3, 4, too, the light is returned toward the inside of the core 1 in the same way.