Emission efficiency of terahertz antennas with conventional topology and metal metasurface: a comparative analysis

Characteristics of photoconductive antennas (PCAs)–radiation sources with conventional topology and a metal metasurface in the shape of a plasmonic grating made on the basis of InGaAs/InAlAs superlattice heterostructures–have been studied experimentally. The photocurrents and THz power spectra of samples of PCAs have been measured, the energy characteristics of terahertz (THz) radiation, and the optical-to-THz conversion efficiency at different bias voltages and average laser excitation power have been determined. For PCAs with a metasurface, the integrated THz radiation power of 10 $\mu$W and a conversion efficiency of up to 0.2%, unattainable for antennas with conventional topology due to their thermal breakdown, have been demonstrated experimentally. Therefore, it can be stated that PCAs with a metasurface are efficient sources of THz radiation and can become an element base for constructing THz spectroscopy systems associated with solving medical diagnostic problems.