Fabrication and optical properties of sol-gel derived interference coating for high power laser applications

摘要

A single layer sol-gel derived TiO_2 thin films and 6 periods SiO_2/TiO_2 multilayer coating were designed and prepared on GaAs substrates as anti-reflection coating or near-infrared-reflective coating for high power semiconductor laser applications. Crack free TiO_2 thin films having thickness of 80-150 nm, and refractive indices of 1.8～2.1 have been obtained by simply sol-gel method upon heating at different temperatures. The obtained TiO_2 thin films on GaAs substrates have shown reflectance of ≤1% in the wavelength of about 808 nm. Thin films of TiO-2 and SiO_2 were also used to fabricate near infrared reflector on GaAs substrates. The reflector consisted of 6 SiO_2/Tio_2 bi-layers, designed with a high-reflective band in the wavelength of 1064 nm. A minimum transmittance of ≤2% in the wavelength range between 950 and 1100 nm has been obtained in the present multiplayer SiO_2/TiO_2 coating.