| 摘要 |
PURPOSE:To obtain high opposite-directional interruption efficiency by providing a circular curved waveguide part in an optical waveguide and deviating an output waveguide at its intermediate place outward in a curvature radial direction. CONSTITUTION:Curved paths 21 and 23 which have the radius R of curvature about a point O as a center are provided in a single mode optical waveguide 20 formed on a substrate 10 to a constant angle theta (90 deg.), and the output-side curved path 21 is deviated by a constant gap (d) outward in the curvature radial direction about an offset part 22 as a boundary. As light is propagated in the waveguide 20 in the forward direction 1 to travel in the curved path 23, a mode distribution 30 moves outward gradually in the curvature radius direction. When the curved path 23 having the same curvature further follows, luminous flux at the outer peripheral part of the distribution of the light becomes higher in light velocity than in the medium at the part to generate radiation loss. The curved path 21, however, is deviated outward after a middle place 22, so the light is propagated in the output-side waveguide 24 nearly without accompanying any loss. Return light, on the other hand, is interrupted by the offsetting pat 22. |
