Enhanced Terahertz Emission Bandwidth from Photo-conductive Antenna with Embedded Plasmonic Nano-pillar Array

In this work, we demonstrate a novel photoconductive antenna (PCA) design, capable of emitting Terahertz radiation with enhanced bandwidth. This device consists of Au electrodes on a semi-insulating GaAs substrate. A plasmonic nano-structure array is embedded in the substrate between the two electrodes. The role of this array is two-fold. The plasmonic enhancement of the 800 nm IR light near the nano-structures serves as a rich source of photo-generated charge carriers which are accelerated to generate the THz radiation. Secondly, the nano-structures acts as defect sites which enables fast carrier relaxations, hence, effectively enhancing THz bandwidths. At the same time, the terminal currents are highly reduced implying robustness of the device to high applied bias voltages.