Observation of whispering-gallery mode splitting in spherical resonator

Abstract:

We report the observation of the splitting of whispering-gallery mode in the silica spherical resonator. To characterize the fused-silica spherical resonator, an evanescent fiber taper coupling technique is employed. The coupling system consists of a fiber taper with a diameter of about 2.8 microns and a fused-silica spherical resonator with a diameter of about 143 microns. By injecting the laser power into the fiber taper, a number of narrow absorption peaks with equal peak spacing of 3.7 nm are observed in a wide spectral range. After replacing the resonator by the other one with the shape being slightly modified, whispering-gallery mode splitting in the spherical resonator is observed. The wavelength spacing between adjacent peaks is 0.32 nm, much smaller than that of the previous one.