Optical manipulation of a lasing microparticle and its application to near-field microspectroscopy

A novel probe of a near-field scanning optical microscope (NSOM) is proposed. The probe is composed of a micrometer-sized spherical particle doped with laser dye, that acts as an optical cavity for lasing, and of a nanometer-sized particle attached to the microsphere. The high-intensity evanescent field is generated just outside of the lasing microsphere and scattered with the nm particle, which forms a minute light source for NSOM. Three-dimensional positioning control of the probe is performed with the accuracy of <10 nm by a laser manipulation technique. Photon tunneling from the lasing microsphere to an object was demonstrated as a drastic change of an emission spectrum depending on the microsphere-object distance. The lasing microspherical probe has the advantage of high sensitivity due to intracavity enhancement of the tunneling loss.