Basic Research On Sn-SiO₂ Optical Waveguide Material By Sol-Gel

Optic waveguides is important for integrated optics. SiO₂ waveguides can be widely used in integrated optics. For fabricating AWG used for WDM, we carried out the study of growing SiO₂waveguide material on Si by sol-gel. Based on our good experimental conditions in the field of uv-written planar waveguides, we propose a method to fabricate AWG in Sn-SiO₂ material by 248nm excimer laser writing. Sol-gel is widely used to -synthesize many kinds of oxide compositions. It has the advantage of good chemical homogeneity, low processing temperature, low cost. Sol is a liquid with dispersed colloidal particles. Gel is a rigid network with great volumes of pores, filled with liquids. We use TEOS to synthesize S1O2waveguide cladding material. TEOS is mixed with water, ethanol and HC1 (catalyst). After hydrolysis and polycondensation, clear SiO₂sol is formed. Aged for 24 hours, SiO₂ sol is spun on (100) Si substrate. It is annealed at high temperature to eliminate water and other organic materials. We use IR, Raman spectrum to analyze the impact of heat treatment on SiO₂ structure. During annealing, SiO₂ structure is formed and densified. 1000 °C heat treatment is necessary for eliminate water molecule in SiO₂. SEM indicates our SiO₂ film is very flat without cracking. SiO₂ spheres are about 10-20nm. And there are only a littel number of pores in our films. They do not affect light transfer. Sn-SiO₂ waveguide material is also synthesized. We use SnCU as the source of Sn. It is added before TEOS hydrolysis. Sn-SiC>2 waveguide material is irradiated with 248 nm excimer laser. Its refractive index is positively changed. The refractive index of 1% Sn doped Sn-SiO₂ is enhanced 1.02% at 155Onm irradiated for 30min...