Abstract

Earlier research indicated that optical thin films deposited by molecular beam deposition (MBD) techniques exhibit refractive indices approaching bulk material values and have densities higher than those of conventional thermally deposited films.¹ These superior characteristics provide very stable films with an increased laser damage threshold. A new MBD machine was recently purchased from VG Semicon and modified by OCLI to provide commercially available MBD optical coatings. The new system, a V90H, was developed for the semiconductor industry to produce high quality epitaxial GaAs films in production quantities. Investigations are proceeding on numerous materials used in diverse optical applications. Single layer studies of various chalcogenides and fluorides, including ZnSe, ZnS, BaF₂, and PbF₂, on typical optical substrates (glass, quartz, sapphire, and silicon) confirm that improved film properties are consistently achieved. The V90H provides a thickness uniformity of ~±0.2% over a 4-in. diam substrate which is a significant improvement from previous MBD systems. The highly stable MBD process combined with automated control allows the deposition of innovative multilayer optical designs with a precisely varying index of refraction throughout the thickness of the film.

© 1989 Optical Society of America