| 摘要 |
<p>PROBLEM TO BE SOLVED: To actualize low connection loss and high operation efficiency by making small the waveguide sectional area of a light control part as part of an optical waveguide and making relatively large the spot size of guided light at the light control part. SOLUTION: A light input part 22, the light control part 24, and a light output part 26 respectively satisfy single-mode conditions in terms of size and the widths W1, W2, and W3 of the light input part 22, light control part 24, and light output part 26 are specified such that W2<W1 and W2<W3. Or the thicknesses T1, T2, and T3 of the light input part 22, light control part 24, and light output part 26 are specified such that T2<T1 and T2<R3.</p> |
