Dielectric Thin-Film Structures

Optical interference filters are constructed from thin layers of optical materials of different indices of refraction deposited on a substrate. The performance of the filter is determined by the choice of material used for the thin layers and how the layers are organized. The simplest interference filter designs use quarter-wavelength optical thicknesses of high– and low–index-ofrefraction materials. Varying the sequence of the layers creates different filter types. In this way, reflection, bandpass, antireflection, or high-transmission filters with varying transmission and reflection profiles are all possible.