Investigation of the terahertz emission characteristics from low-temperature grown gallium arsenide dipole and bowtie photoconductive antennas via finite element analysis

Abstract

In this study, we numerically investigated the effects of the photoconducting gap width and laser beam spot radius on the terahertz (THz) emission characteristics of low-temperature grown gallium arsenide (LT-GaAs) dipole and bowtie photoconductive antennas (PCAs). Using finite element analysis (FEA), the emission spectra of the PCAs were calculated. Simulation results show that bowtie design generally had a higher emission intensity compared to the dipole design. Moreover, both designs with a larger beam radius of 2.0 microns resulted in an emission spectra that peaks at a lower frequency compared to a 1.5 micron beam radius. Meanwhile, a comparison of photoconducting gaps shows that the larger gap width of 5 microns resulted in spectra that peaks at a higher frequency compared to a smaller gap of 3 microns. This suggests that (1) the antenna's design geometry, gap width, and beam size can be modified to obtain the desired emission characteristics and (2) and simulations, such as FEA, can be effective tools in investigating and optimizing such devices prior to actual device fabrication. Further research into a wider range of gap widths is essential to optimize these antennas for various frequency-dependent applications, including 6G and future networks.