| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to keep the incident coupling efficiency at a constant level or higher while achieving a high speed scanning ability by using a specific waveguide type switch and setting an angle formed between converged light and a grating vector to be within a specified range. SOLUTION: The waveguide type optical switch 1 is composed of a substrate 10, an optical waveguide layer 20 formed on this substrate 10, a gratings 21, 22 for optically coupling the outside to the optical waveguide layer 20, and a deflection means for deflecting the guided light. When it is incident light on the grating in such a composition, an angleγformed by the convergent light and the grating vector is set so that the angleγis in the range of 0<γ<=ΔγMAX and a maximum variationΔγMAX of the angleγand a variationΔθf of a guided light propagation angleθf satisfy the formulae. In the formulae, (nc ) expresses the refractive index of the medium on the optical waveguide layer, (nf ) expresses the refractive index of the optical waveguide layer,λis the wave length of incident light,θis an incident angle of incident light,Λis a cycle of the grating, and (q) is a diffraction degree, respectively. Thus, it is possible to maintain at least a necessary incident coupling efficiency in practical use. |
