| 摘要 |
An optical multiplexer/demultiplexer that the passband characteristic of demultiplexed optical signal in a waveguide on the output side can be controlled accurately. Long and narrow guide waveguides, being areas where an effective refractive index is greater than an effective refractive index of a sector slab waveguide on the input side, are formed in the core or in an area adjacent to the core so that the long and narrow guide waveguides will branch at the center of curvature of the sector slab waveguide and so that the long and narrow guide waveguides will extend in an output direction without intersecting with one another. When optical signal is input to the sector slab waveguide, the light is guided more strongly through areas where the guide waveguides are formed. As a result, with the propagation of the optical signal, a peak corresponding to the shape of the guide waveguides will appear in the shape of a mode of the optical signal. Therefore, the shape of a mode of optical signal which propagates can be controlled accurately according to a passband characteristic needed in an optical output waveguide.
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