This work presents the characterization of the optical and mechanical properties of thin films based on ( T a 2 O 5 ) 1 − x ( S i O 2 ) x mixed oxides deposited by microwave plasma assisted co-sputtering, including post-annealing treatments. The deposition of low mechanical loss materials ( 3 × 10 − 5 ) with a high refractive index (1.93) while maintaining low processing costs was achieved and the following trends were demonstrated: The energy band gap increased as the S i O 2 concentration was increased in the mixture, and the disorder constant decreased when the annealing temperatures increased. Annealing of the mixtures also showed positive effects to reduce the mechanical losses and the optical absorption. This demonstrates their potential as an alternative high-index material for optical coatings in gravitational wave detectors using a low-cost process.

A patterned dual colour filter has been deposited by microwave plasma assisted pulsed DC sputtering (MPAS) and photolithography. Compatibility between MPAS and photolithography for fabrication of patterned optical filters has been demonstrated.

This work presents the characterisation of optical and mechanical properties of thin films based on (Ta2O5)1-x(SiO2)x mixed oxides deposited by microwave plasma assisted co-sputtering to demonstrate their potential as optical coatings in gravitational wave detectors.

An automated measurement system was developed to characterize the spatial gradient, linearity of the spatial gradient, bandwidth and transverse uniformity of a linear variable filter (LVF). To demonstrate this, the LVF fabricated in our group has been measured and analyzed. Simulations for beam spot size effects on measurements were performed for various LVF spectral peak profiles with results indicting significant averaging effect due to beam spot size and this is consistent with experiment results. Moreover, to fit the peak profile more accurately, a modified Pearson VII function was proposed and demonstrated high capability to express complex shapes of peaks mathematically. This provides a methodology for deconvoluting the original LVF peak profile from a measured averaged peak profile and has been verified using actual measured data.