Surface roughness of thermally evaporated ZnS optical waveguides

In this study, the propagation loss and the surfaces of ZnS thin films on silicon substrates have been investigated. ZnS thin films have been prepared by thermal evaporation at two different substrate temperatures, which were at ambient temperature and at °50°C. The propagation losses were measured with scanning detection technique attached to a prism coupling and the thin film surfaces were characterized with an atomic force microscope. The waveguide propagation loss of ambient deposited film is 131.50 dB/cm whereas the loss of cold deposited film is 20.41 dB/cm. The surface roughness of the waveguide is enhanced for cold evaporated ZnS film.