Coherent Detection of Multiband Terahertz Radiation Using a Surface Plasmon-Polariton Based Photoconductive Antenna

We characterize a dipole antenna structure that allows for coherent detection of narrowband terahertz radiation with enhanced sensitivity at the resonant frequency. The antenna incorporates a corrugated metal structure that surrounds the dipole. Each periodically spaced groove in the corrugation couples an approximate replica of the incident THz pulse to a surface plasmon-polariton pulse, which then propagates towards and is detected by the dipole. We use numerical simulations to validate the experimental data. Based on these results, we describe a multiband dipole antenna detector that allows for enhanced sensitivity at multiple frequencies. This device can also be used as an emitter.