OPTICAL WAVEGUIDE AND CONDENSER

摘要

PROBLEM TO BE SOLVED: To obtain an optical waveguide capable of efficiently exciting wave- guided light in all bearings and forming a condensed light spot at a high light condensing property with the uniform amplitude and polarization direction of radiation light without depending on bearings by adopting phase matching of TE/TM and a condenser. SOLUTION: A waveguide layer 4 is composed of three layers; transparent layers 4A, 4B and 4C and the refractive index of the intermediate layer 4 is set highest, by which the equiv. refractive index of the TE mode is equaled to the equiv. refractive index of the TM mode. Grating couplers 5 and 6 by a concentric rugged structure are formed on a transparent substrate 1 and the axis L orthogonal with the waveguide layer is formed as the central axis of both grating shapes. The incident light 7 on the grating coupler 5 efficiently excites the wave-guided light 8 and the wave-guided light 8 propagated toward the outer periphery from the center is radiated by the grating coupler 6. Since the equiv. refractive indices of the TE and TM are equal, the amplitude and polarization direction of the radiation light are made uniform without depending on bearings. The condensed light spot having the high light condensing property is obtd. at the condensing light point.