Photoconductive microprobe based near-field scanning of Terahertz resonances of a single high-index TiO 2 microsphere

We present experimental results revealing new details of the resonant electromagnetic behavior of a single TiO 2 microsphere in the THz frequency range. In order to reduce background signal contributions and to increase the excitation efficiency, measurements are done using aperture-less photoconductive near-field microprobes in parallel and crossed alignment to the polarization of a free-space radiation pulse or a guided pulse on a coplanar stripline — both applied alternatively for sample excitation.