title: Wavelength-division multiplexed thin-film filters used in tilted incident angles of light.
abstract: The properties of wavelength-division multiplexed (WDM) narrowband filters used in tilted collimated light are described. The wavelength shift for s polarization in a low-index-spacer filter is larger than that for p polarization when the filter is tilted, but it is smaller in a high-index-spacer filter. Therefore the passbands of the tilted filter can be centered at the same wavelength for two polarization modes by use of high- and low-index materials, as appropriate, as spacers or by selection of a moderate-index material instead of a spacer. With such spacers, WDM filters used for incident angles of 20 degrees or even greater are constructed. Experimental results agree with the computed ones.
authors.affiliation: State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China. gupeifu@zju.edu.cn
authors.forename: Peifu
authors.initials: P
authors.lastname: Gu
authors.forename: Haixing
authors.initials: H
authors.lastname: Chen
authors.forename: Yueguang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Haifeng
authors.initials: H
authors.lastname: Li
authors.forename: Xu
authors.initials: X
authors.lastname: Liu