Plasmonic Metasurfaces for Controlling the Spectrum of Photoconductive THz Emitters

Abstract—Plasmonic metasurfaces for photoconductive antennas (PCAs) based on InAlAs/InGaAs superlattice heterostructures are proposed and fabricated. It is found by the measurements of the PCAs in a terahertz pulsed spectrometer that the maximum detected integrated terahertz power is 5.3 μW (the optical-to-THz conversion efficiency is 0.19%) under laser pumping at an average power of 2.8 mW and a bias voltage of 8.6 V. The signal increment caused by the excitation of plasmonic modes makes it possible to obtain a high signal-to-noise ratio (~80 dB). The experiments show that the emitted power density increases with the metasurface metallization height (thickness). With the parameters obtained, the developed antennas can open a path towards the development of THz spectroscopic and imaging systems in Russia.