A combination of stepwise graded refractive-index profiles and a cavity structure is used for designing narrow-bandpass filters of TiO<sub>2</sub>/SiO<sub>2</sub> multilayer films upon BK7 glass substrates. Symmetrical profiles of stepwise graded refractive indices result in high transmittance of passbands for the designed filters. The bandwidth of the narrow-bandpass filter is controlled by adjustment of parameters such as the thickness and the number of layers in the multilayer stack. This design is proposed as a new and simple method for coating synthesis of optical filters.
© 2001 Optical Society of America
(230.0230) Optical devices : Optical devices
(240.0310) Optics at surfaces : Thin films
(310.6860) Thin films : Thin films, optical properties
(350.2460) Other areas of optics : Filters, interference
Xinrong Wang, Hiroshi Masumoto, Yoshihiro Someno, Lidong Chen, and Toshio Hirai, "Stepwise graded refractive-index profiles for design of a narrow-bandpass filter," Appl. Opt. 40, 3746-3752 (2001)