Structural and optical properties of different dielectric thin films for planar waveguiding applications

Abstract

Thin films of two different dielectric materials (Yttrium Oxide and Tantalum Pentoxide) were deposited by reactive sputtering and reactive evaporation to determine their suitability as a host for a rare earth doped planar waveguide upconversion laser. The optical properties, structure and crystalline phase of the films were found to be dependent on the deposition method and process parameters. X-ray diffraction (XRD) analysis on several of the 'as-deposited' thin films revealed that the films vary from amorphous to highly crystalline depending on material and process parameters . SEM imaging of the Yttrium Oxide layers revealed a regular column structure confirming their crystalline nature and SEM imaging of the Tantalum Pentoxide layers revealed a smooth amorphous layer confirming their XRD diffractrograms. The dielectric thin film layers which allowed guiding in both the visible and infra-red regions of the spectrum had a more amorphous structure.