Optical waveguide device

Abstract

An optical waveguide device comprises an optical waveguide for guiding an optical wave therethrough, and a grating coupler located on a surface of the optical waveguide in order to radiate the guided optical wave, which travels in the optical waveguide, out of the optical waveguide. The grating coupler is provided with a plurality of bars, the heights h of which increase approximately linearly and little by little in the direction along which the guided optical wave travels. The inclination b of the variation of the bar heights h satisfies the condition ##EQU1## where a represents a coefficient which determines a radiation loss coefficient .alpha. (.alpha.=ah.sup.m, where 2<m), and L represents the length of the grating coupler, which length is taken in the direction along which the guided optical wave travels. The guided optical wave is radiated very efficiently as an approximately Gaussian beam out of the optical waveguide, or an external optical wave, which takes on the form of a Gaussian beam, is introduced very efficiently into the optical waveguide.

Dependencies are inferred from the claim text.