Development of functional nanoprobes for optical near-field characterization

Subwavelength optical imaging can be accomplished by scanning a nanoscale aperture or a nanoprobe containing a locally defined nanoscale optical source. Currently, most such methods, including various implementations of near-field scanning optical microscopy (NSOM), form near-field images by measuring the intensity of optical signals generated by optical transmission, scattering or fluorescence. Here we report the development of a nanoprobe that can extend NSOM functionalities by focusing on the dynamical aspects of light emission (such as fluorescence lifetime measurement) and nonlinear optical processes (such as second harmonic generation). Our nanoprobes consist of a silica fiber taper, a single nanowire or a nanotube, and appropriate functional nano-optical structures. The fabrication, characterization and potential applications of such nanoprobes are discussed. (Some figures in this article are in colour only in the electronic version)