Thermal stabilisation of a high-Q sapphire microwave resonator using a thermosensitive Quartz sensor

The authors demonstrate the use of a thermosensitive quartz resonator oscillator as a thermal sensor to measure and control the temperature of a sapphire whispering gallery mode resonator. The high sensitivity of the quartz sensor allows an efficient thermal regulation of the sapphire resonator at ambient temperature as well as at 77K. At 300K, the measured frequency stability of the 9.4 GHz sapphire resonator oscillator is better than 10-9 for integration times up to 1000s.