Numerical simulation of terahertz radiation in photoconductive antenna

The terahertz radiation in photoconductive antenna involves the multiple physical processes. It is a challenge to simulate the terahertz radiation in photoconductive antenna. A numerical simulation tool for the photoconductive antenna is very necessary to effectively design and optimize the terahertz radiation source. In this paper, by introducing the auxiliary equations describing the dynamic behaviors of carriers in the semiconductor into the Maxwell's equations, we use the three-dimensional finite-difference time-domain method to solve these equations and obtain the time-domain solutions in the nearfield of antenna. A near-to-far-field transformation in the layered medium is adopted in order to obtain the wave pattern of terahertz radiation in the far field. Assisted by the developed simulation tool, the terahertz time-domain waveforms and other terahertz radiation characteristics for the photoconductive antenna can be presented. By comparing with the experimental results reported in the references, the validity and reliability of these physical models and the developed simulation tool are demonstrated. More importantly, the results given in this paper will be of great significance to design and optimize the radiation performance of photoconductive antenna with different structures.