Patent ID: 8285092
Filing Date: 2012-10-09
Classification: G02B

Abstract:
1. An optical waveguide including a substrate in the shape of a flat plate, lower clad that is disposed on the substrate, and a core that is disposed on the lower clad and transmits light, the optical waveguide comprising: a first optical waveguide that includes a first core on the lower clad as the core, and is disposed so as to extend along a direction in which the light travels to a first position of the optical waveguide; and a second optical waveguide that includes a second core on the lower clad as the core, is disposed so as to extend along a second direction in which the light travels to a second position of the optical waveguide, and has a lower refractive index difference than the first optical waveguide does, wherein: the first optical waveguide and the second optical waveguide form, between the first position and the second position, a layer structure where the first core and the second core are disposed such that the first core is positioned a predetermined distance away from the second core in a third direction perpendicular to the substrate; and at least either the first optical waveguide or the second optical waveguide includes: a mode coupling section that includes a directional coupler to conduct the mode coupling of the first core and the second core between the first position and the second position; and a mode conversion section that is connected to the mode coupling section, and has a tapered core structure to adjust the mode diameter of the first core to the mode diameter of the second core, wherein the second optical waveguide is sandwiched between an optical fiber and the first optical waveguide, such that the first optical waveguide is not positioned on an end face of the optical device.