| 摘要 |
PURPOSE: To output a signal according to the reception intensity of incidence light from a photodetector by making the relation among a refractive index n of N/ a core layer, a refractive index n' of an adhesive layer, and a refractive index n" of the light reception part of the photodetector to n<=n'<=n". CONSTITUTION: Light advancing inside a core layer 31 is refracted by an end face 30a of a light pipe 30 and enters an adhesive layer 40. At this time, n'.sinθ"' is equal to n.sinθ", where a refraction angle is θ". θ"'<θ" is always true due to n<n'. Therefore, entire light reaching the end face 30a of a light pipe 30 enters the adhesive layer 40 without totally reflected on the end face 30a. The same occurs on the junction surface between the adhesive layer 40 and a photodetector 20 and total light reaching the end face 30a of the light pipe 30 reaches a light reception part 20a of the photodetector 20. In this manner, incidence light can be focused at the light reception part of the photodetector with an extremely small light loss. Also, light spot image can be extremely made small since light is focused using a waveguide. |
