Innovations in structured thin film design and fabrication for optical applications

Abstract

This paper presents the design and fabrication of several versions of structured thin films (STF). One kind of STF is a sculptured thin film, generally deposited with a glancing angle deposition technique. Several optical components were designed and fabricated using this technique. This includes a TiO2 based wave-plate for an operating wavelength of 550 nm, a multilayer based beam splitter with a transmittance of 75.0% for TM light and 38.6% for TE light at 632 nm, and a multilayer based polarization neutral transmission filter for an incidence angle of 45°. Multilayer dielectric gratings (MDG) present another type of STF. To obtain a broad diffraction bandwidth, a novel MDG structure with three materials is proposed. Using multi-parameter optimization, a broadband spectrum with an efficiency >97.5% and a bandwidth >100 nm centered at 800 nm was obtained. For the first time, a new type of two-dimensional (2D) MDG is proposed to obtain higher efficiency (>98%) and broader bandwidth (>110 nm). Finally, the designs of pulse compression gratings and of broadband polarizers, which can be fabricated with a single material, are presented.