Photoconductive THz emitters with high-aspect-ratio plasmonic gratings

The plasmon-assisted photoconductive antenna-emitter has been developed, optimized, and fabricated on a semi-insulating GaAs photoconductive substrate. Using numerical simulation, we showed that a high aspect-ratio of the antenna plasmonic electrodes h/p = 0.5 (where h and p are height and period of metal grating, respectively) can substantially increase the amplitude of the electric field at the shadow side of the grating leading a robust localization of photocarriers in vicinity to plasmonic electrodes. The plasmonic PCA-emitter exhibits 10 μW of the emitted THz power at optical pump of 10 mW, high thermal (breakdown) stability, and the increased dynamic range, as well.