High refractive index difference and low loss optical waveguide fabricated by low temperature processes

A singlemode optical waveguide has been developed with a high refractive index difference Delta of 2% and low loss of 0.12 dB/cm at 1.3 mu m wavelength. This waveguide consists of buffer layer, core ridge, and cladding layer of SiO_xN_yH_z formed by the plasma CVD method at a low temperature of 270 degrees C. The absorption loss which is affected by the OH ion content at 1.39 mu m wavelength can be decreased by annealing at 500 degrees C under N₂ atmosphere. The low temperature fabrication process is effectively used for the monolithic integration of photonic/electronic circuits.