Temperature compensated sapphire-rutile microwavewhispering gallery mode resonator

Abstract

A 2 µm-thick film of rutile (TiO2) was deposited on a sapphire disk using a sol-gel method to realise a temperature compensated microwave resonator operating in whispering gallery mode configuration. The resonator, though not yet completely optimised, shows turnover temperatures ranging from 40 to 60 K depending on the mode azimutal number. For the WGH7,0,0 mode at 9.4 GHz, the Q-factor is of the order of 1.5 × 106 at 46 K. The technique appears easy to implement and can be used for the design of high-frequency stability microwave source.