Patent ID: 7386213
Filing Date: 2008-06-10
Classification: G02B

Abstract:
1. A bidirectional communication optical waveguide comprising: a main waveguide core which has a bent portion in a midway in an optical waveguide direction, and which is provided with a main inclined plane forming a constant inclined angle with an optical axis of a pre-bending main waveguide core at the bent portion; and a sub-waveguide core which is provided with a sub-inclined plane in one end portion thereof, the sub-inclined plane being substantially parallel to the main inclined plane, the sub-waveguide core being brought close to the main waveguide core at the bent portion while the sub-inclined plane and the main inclined plane face each other, wherein the main waveguide core has a pre-bending main waveguide core end portion and a post-bending main waveguide core end portion, the pre-bending main waveguide core end portion inputting and outputting a bidirectional light signal from and to an optical fiber, the post-bending main waveguide core end portion being connected to a light receiving device, and the main waveguide core has a structure in which an input light beam from the pre-bending main waveguide core end portion is deflected by total reflection at the main inclined plane and guided to the post-bending main waveguide core end portion, and the sub-waveguide core has a sub-waveguide core end portion on an opposite side to the side on which the sub-waveguide core is brought close to the main waveguide core, the sub-waveguide core end portion being connected to a light emitting device, and the sub-waveguide core has a structure in which a refractive index of the sub-waveguide core is set not more than a refractive index of the main waveguide core and thereby total transmission of an output light beam from the light emitting device is performed through the sub-inclined plane to cause the output light beam to propagate to the main waveguide core, wherein the main waveguide core and the sub-waveguide core are brought close to each other at the bent portion, and the main inclined plane and the sub-inclined plane face each other with a cladding portion therebetween, and the following expressions (1), (2), and (3) are satisfied: