Photon tunneling from an optically manipulated microsphere to a surface by lasing spectral analysis

Photon tunneling of lasing emission from a dye-doped microspherical particle to an object was investigated by use of a microspectroscopy system combined with a laser manipulation technique. An emission spectrum drastically changed with approaching the lasing microsphere to a glass plate. The intensity ratio between resonant peaks exhibited exponential dependence on the sphere-object distance, whose decay constant agreed with the penetration depth of an evanescent field just outside of the microsphere. The variation in the spectral profile can be explained with the Mie scattering theory. Applicability of the lasing microsphere as a probe of a near-field scanning optical microscope is discussed.