Tantalum pentoxide micro-resonators for frequency comb generation

We present the design, fabrication, simulation and initial characterisation of tantalum pentoxide (Ta2O5) optical waveguides and micro-ring resonators for the purpose of supercontinuum and frequency comb generation. Spectral broadening results are presented for linear Ta2O5 waveguides for a range of central pump wavelengths between 900 nm and 1500 nm. These results are used as the basis for the dispersion engineering and development of Ta2O5 micro-ring resonators. The losses for sputtered and TEOS PECVD deposited SiO2 top cladded waveguides are characterised using a Fabry-Pérot loss measurement set-up. A solver based on the Lugiato-Lefever equation is presented and used to simulate the expected emission from the Ta2O5 micro-ring resonators. Promising initial experimental results show critical coupling and a Q-factor of 3.7×104.