Low-phase noise temperature-compensated cryogenic whispering gallery mode resonator operated at 63K in a closed-cycle cooler

We report further progress on whispering gallery (WG) modes in a miniature temperature compensated composite dielectric sapphire and rutile resonator operating in a closed cycle cooler which can exhibit loaded Q(L) values abo ve 10(7) at similar to 10 GHz. The geometrical size of the dielectric pucks has been increased so that a compact loop-oscillator system is realized at a frequency close to the Cs atomic clock hyperfine frequency and an operat ing temperature of 63.5K. Excellent long term temperature control (stabilit y is better than 100 muK) has been achieved, The high Q of the dielectric r esonators can be used to produce low phase noise oscillators limited only b y the performance of amplifiers and mixers. Effective mechanical vibration isolation is also demonstrated in a Giffard-McMahon cooler.