Evidence for intrinsic Kerr bistability of high-Q microsphere resonators in superfluid helium

Abstract

\n \nQuality factors up to 109 have been obtained in the whispering gallery modes (WGMs) of\n fused silica microspheres immersed in a superfluid helium bath. We have observed a dispersive bistable behaviour of the WGM \nresonances with a threshold power of 10 μW, due to the intrinsic Kerr nonlinearity of silica. These results open\nthe way to the realization of a thresholdless microlaser and other cavity QED projects \nwith microspheres.\n\n\n\n\n