Microspectroscopy with an optically-manipulated lasing particle

Spectroscopic and spatial characteristics of microspherical laser oscillation were investigated by use of a simultaneous optical trapping and lasing spectroscopy system. Laser oscillation within a micrometer-sized spherical particle was greatly suppressed by a transient absorber that quenched lasing emission when excited by light. Transient absorbance of the particle was amplified with the intracavity effect, as compared with absorption loss caused by a single path through the microsphere. With approaching a lasing microsphere to a nonlasing particle or to a glass plate, emission spectra were drastically changed by photon tunneling loss. The intensity ratio between resonant peaks exhibited exponential dependencies on the sphere-object distance, whose decay constant agreed with the penetration depth of an evanescent field just outside of the microsphere. Applications of microspherical lasing to high-sensitive transient absorption measurement of a single particle and to near-field scanning optical microscopy are also discussed