Modeling. Simulation, and Optimization of Photoconductive Antennas According to the Gap Size

In the present work, we review and analyze the most widely adopted theoretical models to characterize the radiated terahertz pulse in photoconductive antennas, with a focus on the impact of antenna gap size, small gap, and large gap. Furthermore, based on the reviewed models, we have conducted simulations to investigate the impact of various antenna parameters on the terahertz radiation performance, including semiconductor substrate characteristics, exciting femtosecond laser parameters, and the applied bias voltage. In addition, to provide a structured approach, we have proposed a flowchart outlining the steps for evaluating, and optimizing photoconductive antenna performance. Simulation results permit a well understanding of the contributing parameters' influence on the terahertz radiation. Finally, we have demonstrated the discrepancy arising from inappropriate modeling by comparing experimental measurements of a small gap antenna with simulations based on both small and large gap models. The results showcase a high degree of agreement between the small gap antenna simulations and experimental data, while the large gap model exhibits significant discrepancies. This underscores the importance of employing the appropriate model for accurate antenna performance analysis and optimization which is not satisfied in many recent published papers.