Theoretical Modeling of a Photoconductive Antenna in a Terahertz Pulsed System

The most common device for terahertz (THz) wave generation and detection is a THz photoconductive antenna. This paper examines the factors which affect the radiated power and optical-to-THz power conversion efficiency of the antenna. A novel equivalent circuit model using lumped elements is developed for analyzing the performance of these antennas. In this model, whilst keeping the simplicity of the lumped element approach, the underlying physical behavior of the device is taken into account when calculating the circuit elements. Based on the model, the influence of various parameters on the optical-to-THz power conversion efficiency and radiated power is then investigated. The simulated results agree well with published measured results. The model predicts that an increase in the laser power and/or bias voltage, and a reduction in reflections from the air-substrate can improve the optical-to-THz power conversion efficiency of the device. This novel model is very useful for both designing a THz antenna and tuning a THz system to achieve maximized optical-to-THz power conversion efficiency and THz radiated power.