Terahertz Nano-Spectroscopy With Resonant Scattering Probes

We propose and demonstrate tunable resonant scattering probes for terahertz (THz) near-field microscopy, using sharp indium tips fabricated to the tine of a quartz tuning fork. We find the antenna resonance of the indium tips can be tuned by altering the tip length, which we support with numerical models. We also demonstrate the indium tips can provide nanoscale field confinement at the tip apex, with spatial resolution better than 100 nm.