Abstract

Titanium dioxide (TiO₂) is a material often used for thin films in optical interference coatings because of its high index of refraction. However, conventional physical vapor deposition (PVD) results commonly in thin films with pronounced columnar microstructure. This causes light scattering to an extent that PVD thin films of a thickness suitable to guide one or more modes become too lossy to guide lightwaves at all. Reactive low voltage ion plating (RLVIP) produces very dense, amorphous (i.e. vitreous) thin films¹ with surfaces significantly smoother than those of conventional PVD thin films.² Thus, RLVIP thin films appear to be potentially useful as high-index optical waveguides, similar to those produced from organometallic solutions (sol-gel coatings).³ Vice versa, we show that waveguide characterization of the refractive index and optical losses is a useful aid for optimizing the RLVIP process toward low-loss optical coatings, for example for laser applications.⁴ In addition, the waveguide measurements of a few select samples were compared to variable angle spectroscopic ellipsometer (VASE)⁵ measurements.

© 1992 Optical Society of America