Terahertz emission improvement of gallium-arsenide-based bowtie photoconductive antenna by AAO-patterned gold nanoparticles integration on the photoconducting gap

We report on the terahertz emission improvement in GaAs-based photoconductive antennas (PCA) with gold (Au) nanoparticles (NPs) on the PCA gap, patterned using anodic aluminum oxide template. Two PCA devices were fabricated with Au NPs having average diameters of 200 nm and 20 nm. The THz peak-to-peak intensity increased ∼2-fold for the 200-nm PCA, and increased ∼1.5-fold in peak-to-peak intensity for the 20-nm PCA. Finite-difference time-domain (FDTD) simulations revealed that surface plasmon resonance enhancement effects were more pronounced for the 200-nm diameter Au NP PCA with a ∼1.9-fold increase in photoabsorption as compared to the ∼1.8-fold enhancement in the 20-nm Au NP. The results demonstrate a cost-effective method of utilizing nanostructures to improve PCA performance.