OPTICAL COUPLING DEVICE AND OPTICAL FUNCTION DEVICE

摘要

PURPOSE: To provide an optical coupling device which converts a spot size with low loss, lessens the coupling loss by a difference in a light wave field distribution and is less sever in manufacturing accuracy and an optical function device. CONSTITUTION: This optical coupling device is provided with a core layer 101 of an optical waveguide on an (n) type semiconductor substrate 102 constituting a clad region and is coated with a semiconductor layer 103 as a clad layer. The shape of a core layer is changed to a taper shape in a light propagation direction. The semiconductor layer 103 is so set in the surface shape near the part right above the core layer, shape and thickness so as to meet the shape of the spot size of the optical waveguide device near the end face of the optical waveguide device having the large spot size. For example, the semiconductor layer is provided with a projecting part 103a. The incident light 109 is made into exit light 108 converted in the spot size by the tapered core layer.