OPTICAL FILTER DEVICE AND WAVELENGTH SELECTING PHOTODETECTOR

摘要

PROBLEM TO BE SOLVED: To obtain a simple filter which can be produced at a low cost by using a thin silicon layer of a silicon-on-insulator substrate as the core of a waveguide of an asymmetric directional coupler filter. SOLUTION: An SOI water consisting of a silicon substrate 100, embedded silicon dioxide layer 102, and a waveguide 104 comprising an active silicon layer has a silicon dioxide coating layer 106 formed by oxidation. Further a dielectric material having low refractive index is applied on the structural body to form an upper waveguide 108. This layer consists of a glass or polymer doped with Ge:SiO2 or silicon oxide nitride (SiON), and the structural body forms an asymmetric directional coupler filter. When light of plural wavelengths 110-112 is coupled with the upper waveguide 108, the light of specified wavelength 111 can be coupled with the core of the lower waveguide 104 being a silicon layer.