| 摘要 |
PURPOSE:To enable the formation of an optical waveguide having a small propagation loss, by providing an optical propagation layer which has a refractive index larger than the refractive index of a transparent substrate and of which the width is decreased monotonously from an input optical path to an output optical path. CONSTITUTION:The light wave beam which is made incident to an optical propagation layer 33 from an input optical path 331 repeats total reflection on the side surface 333 of said layer and is propagated to an output optical path 332. The light wave beam is condensed during the course of propagation in the layer 33 and when, for example, the width of the layer 33 attains <=50mum near the path 332, the propagation mode of a rectangular type from the propagation mode of a slab type of the light wave beam can no longer be disregarded and the light wave beam is propagated in the layer 33 by having a certain phase constant. If the angle theta of intersection is made increasingly smaller toward the path 332 until the propagation layer is connected to the path 332, an optical focusing device by which the light wave beam is propagated to the path 332 is obtained. Here, 1mum< the width of the output optical path <50mum, 0.02mm.< the width of the input optical path <5mm.. |
