Towards a novel microsphere laser

Summary form only given. In our novel experimental set-up, an active nanoparticle is attached to the end of a fiber tip. In order to achieve coupling, the tapered fiber tip is placed close to the surface of a microsphere resonator using the shear-force mechanism. In this way, light emitted from the nanoparticle couples to the cavity, when the particle is optically pumped via the fiber. In a first experiment, a stabilized diode laser was frequency-tuned across a single whispering-gallery mode. The light scattered into a bare fiber tip was recorded while scanning 10 /spl mu/m perpendicular to the equator of the sphere with a constant tip-sphere separation of approx. 10 nm. In another experiment, we placed a larger tapered and cleaved fiber tip (front diameter 13.5 /spl mu/m) in an intensity maximum of a particular high-Q whispering-gallery mode.