Research On Radiation Characteristics Of THz Photoconductive Antenna

Terahertz electromagnetic radiation source is one of the key parts in terahertz technology. With thedevelopment of high-power femtosecond laser technology, the new opportunities have been brought tothe research of terahertz source based on PCSS in recent years.Currently, many researchers focus on generation of terahertz radiation while little attention is paid onemission performance of the PCSS antenna, such as radiation pattern and spectrum (bandwidth). Sincea single photoconductive antenna output power is limited as it will be saturated in the case of large lightintensity, the spatial power combination using array antenna is an effective method to obtain enoughterahertz power. This requires a precise control of the radiation characteristics of antenna arrayelements, especially a reasonable prior knowledge about the radiation characteristics in the design. Asthe relationship between carriers and current in the semiconductor photoconductive antenna isrelatively complex, analytical methods are difficult in actual application. The numerical method isapplied in this paper to calculate the terahertz radiation characteristics of photoconductive antennas.The main works are as follows:1. According to semiconductor theory, changes of carrier density in semiconductor under laser pulseexcitation is analyzed.2. The mutual influence between external bias electric field, carrier movement and current density insemiconductor is considered, and the electric and magnetic fields equation is deduced.3. Based on theoretical models of PCSS radiation system, THz photoconductive antenna radiationcharacteristics are simulated with three-dimensional full-wave finite-difference time-domain method.