A novel non-situ film thickness control method based on reflection spectrum analysis is proposed for anti-reflection(AR) coating,which is especially suitable for optoelectronic devices with small facet area.The refractive index of the coating film in 300-1 700 nm wavelength range is evaluated by spectroscopic ellipsometery,and the optimum deposition conditions for AR coating film are determined at a specified wavelength(e.g.1 550 nm).The reflection spectrum of AR coating with optimum film thickness and its ...