| 摘要 |
The present invention relates to an optical plane waveguide capable of reducing the coupling loss with respect to an optical fiber and achieving downsizing and higher integration. The optical plane waveguide according to the present invention comprises a core region provided in a substrate, and one or more side core regions provided along the tip portion of the core region. The core region and the side core regions have a higher refractive index than the substrate. Moreover, end faces of the core region and the side core regions coincide with the end face of the substrate and function as a light input/output port for signal light. In particular, since the side core regions are provided along the core region and positioned at a peripheral portion of the substrate where the end face of the substrate is included. According to the configuration, the mode field diameter of signal light can be enlarged at least in a direction parallel to a surface of the substrate with a single mode condition satisfied, whereby the coupling loss with respect to the optical fiber can be reduced.
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