Codeposition of continuous composition rugate filters

Appl Opt. 1989 Jul 15;28(14):2945-8. doi: 10.1364/AO.28.002945.

Abstract

Rugate filters are optical thin film interference structures with sinusoidal refractive index profiles. Two-wavelength reflection filters have been fabricated by codeposition of SiO(2) and TiO(2). Composition modulation was monitored and controlled using quartz crystal rate controllers. The resulting filters exhibited two well-defined stopbands. Microscopic examination revealed that the structure is glasslike without pronounced thin film microstructure.