Coupling light from a high-Q microsphere resonator using a UV-induced surface grating

Summary form only given. High-Q microspheres with whispering-gallery modes have very narrow resonances that can be used for fiber-optic filters, ultra-compact narrow-linewidth lasers and optical/microwave oscillators. In this report we demonstrate, for the first time to our knowledge, far-field coupling of light from a microsphere resonator via a refractive-index grating written onto the sphere's surface. The grating is written by shining a pattern of UV light onto the surface doped with germanium to increase its photosensitivity.