Radiation characteristics of terahertz GaAs photoconductive antenna arrays

Abstract

A GaAs photoconductive antenna is one of the important radiation sources of terahertz electromagnetic waves. Antenna arrays can increase the radiation intensity of terahertz waves. Therefore, photoconductive antennas and arrays have attracted much attention for a long time. In this study, CST Microwave Studio is used to conduct a simulation calculation of the characteristics of a photoconductive antenna array radiating terahertz electromagnetic waves. Using the current transient model, the pulsed photocurrents generated when the laser is incident on the GaAs photoconductive antenna are calculated. With the pulsed photocurrents serving as an excitation source, a simulation calculation of the radiation performance of photoconductive antenna is conducted, and the effects of antenna structure and substrate material on the radiation of terahertz waves are analyzed. Based on this, the far-field radiation of terahertz wave radiated by the GaAs photoconductive antenna array is calculated. The simulation results show that the photoconductive antenna array radiates terahertz waves with stronger directivity. The width of main lobe is reduced, and its far-field radiation conforms to the multiple relationships of electric field superposition. A 1 × 2 GaAs photoconductive antenna array is developed, and the experimental results are consistent with the simulation conclusions, thereby laying a theoretical and experimental basis for fabricating the multielement terahertz photoconductive antenna arrays.