THz near-field microscopy of semiconductor and metal bowtie antennas

We perform THz near-field measurements on bowtie antennas made of doped Si and gold. The measurements show a similar local field enhancement for the different materials. These measurements constitute the first demonstration of plasmonic near-field enhancement using semiconductors at THz frequencies. Semiconductors offer the possibility of ultrafast optical switching of plasmonic resonances (on a ps time scale), which will enable the active control of sub-wavelength fields. Since this excitation can be implemented in picoseconds time scale, these structures can be used as a tool for ultrafast sub-wavelength THz spectroscopic purposes.