Coupling properties of whispering gallery modes

Summary form only given. We investigated the modification of external coupling properties in the presence of modal coupling using high-Q silica microspheres coupled to fiber-tapers. The long photon lifetime of high-Q microresonators makes possible a counter-intuitive effect where minute scattering gives rise to the regime of strong modal coupling. In this regime, scattering into the oppositely oriented mode is the dominant scattering process. We demonstrate that it is possible to experimentally obtain extremely large modal coupling, while maintaining quality factors of 10/sup 8/. Normalized modal splitting ratios as large as 30 were observed.