Realization of Directional-Coupler-Based Optical Waveguide Devices by Ultraviolet-Imprinting Technique Using Sol-Gel Derived Inorganic GeO2 : SiO2 Films

An efficient fabrication scheme of directional coupler (DC) optical waveguide devices is demonstrated using a direct ultraviolet imprinting (DUI) technique in sol-gel derived inorganic 0.2GeO₂:0.8SiO₂ slab waveguide. The slab waveguide has a ~3-mum-thick photosensitive inorganic 0.2GeO₂:0.8SiO₂ film which is prepared by the sol-gel spin-coating technique on (10 mum) SiO₂-Si substrate. This inorganic thick film of slab waveguide has the ability to induce a high refractive index change of ~5times10^-3 under ultraviolet irradiations, which is suitable for the fabrication of waveguiding channel of photonic devices by a DUI technique. DC geometries were theoretically evaluated by the beam propagation method for various optical power splitting ratios and experimental performances of DCs 3-dB light splitter and complete power exchange from one waveguide to another were demonstrated and found to be in good agreement with the simulation.