Enhancement of Terahertz Photoconductive Antennas and Photomixers Operation by Optical Nanoantennas

TL;DR

This paper reviews how integrating optical nanoantennas with terahertz photoconductive antennas and photomixers enhances their efficiency in generating terahertz radiation, addressing low energy conversion issues.

Contribution

It systematically compiles recent research on using optical nanoantennas to improve terahertz antenna performance, highlighting novel nanophotonics applications.

Findings

Nanoantennas increase pump laser absorption efficiency.

Reduced carrier lifetime improves thermal efficiency.

Enhanced terahertz radiation output demonstrated.

Abstract

Photoconductive antennas and photomixers are very promising sources of terahertz radiation that is widely used for spectroscopy, characterisation and imaging of biological objects, deep space studies, scanning of surfaces and detection of potentially hazardous substances. These antennas are compact and allow generation of both ultrabroadband pulse and tunable continuous wave terahertz signal at room temperatures, without a need of high-power optical sources. However, such antennas have relatively low energy conversion efficiency of femtosecond laser pulses or two close pump wavelengths (photomixer) into the pulsed and continuous terahertz radiation, correspondingly. Recently, an approach to solving this problem has been proposed, that involves known methods of nanophotonics applied to terahertz photoconductive antennas and photomixers. This approach comprises the use of optical nanoantennas for enhancing the efficiency of pump laser radiation absorption in the antenna gap, reducing the lifetime of photoexcited carriers, and improving antenna thermal efficiency. This Review is intended to systematise all the results obtained by researchers in this promising field of hybrid optical-to-terahertz photoconductive antennas and photomixers.