Fiber coupling of DFB laser to micro spherical cavities-a novel approach for frequency control and linewidth quenching utilizing morphology dependent resonances

This paper describes a novel scheme for coupling semiconductor lasers to a new type of miniature optical resonator that has a small dissipation, and as a result, very high Q-a microsphere (μ-sphere). We report, for the first time, to our knowledge, the lateral coupling of light into whispering-gallery-modes of a μ-sphere using a side-polished single-mode optical fiber. We observed well defined high-Q morphology dependent resonances in the scattered field along with associated dips in the transmission spectrum of the optical fiber. The Q-factor of the combined fiber-sphere system is 5×10⁶. The intensity and location of the various resonance orders is understood by the localization principle and the recently developed Generalized Lorentz-Mie Theory