ULTIMATE Q OF OPTICAL MICROSPHERE RESONATORS

We demonstrate the quality factor Q = (0.8 +/- 0.1) X 10(10) of whispe ring-gallery modes in fused-silica microspheres at 633 nm, close to th e ultimate level determined by fundamental material attenuation as mea sured in optical fibers. The lifetime of ultimate Q is limited by adso rption of atmospheric water. Monitoring of adsorption kinetics with su bmonolayer sensitivity by Q factors and frequencies of whispering-gall ery modes is demonstrated. The possibility of supermaterial Q's owing to intrinsic suppression of scattering losses in micropheres is discus sed. (C) 1996 Optical Society of America