Tunable plasmonic properties and absorption enhancement in terahertz photoconductive antenna based on optimized plasmonic nanostructures

Abstract

Herein, we numerically investigate terahertz photoconductive antennas (PCAs) based on optimized plasmonic nanostructures and absorption enhancement in nanocylinders. Plasmonic behavior in the visible to near-infrared light spectrum is achievable due to the metallic nanostructure employment. Herein, we study the absorption enhancement of silver and transparent-conducting oxides (TCO) nanocylinders with different diameters by means of effective medium approximation. This study also reports on the stronger enhancement in the case of TCO nanocylinders. The results show that resonant absorption amplitude and wavelength are dramatically affected by the thickness of the nanostructure as well as by the distances between nanocylinders. The outputs reported here provide a fertile ground for precise control of the nanowire structures for sensing and other enhanced optical applications. It is worthwhile noting that in case of TCO nanocylinders, absorption enhancement for NIR wavelengths, being relevant for present terahertz generation setup, reaches up to fivefold leading to 25-fold increase in terahertz radiation.