Investigation of Terahertz Peak Frequencies from GaAs Photoconductive Antennas
To theoretically predict the peak frequencies of terahertz (THz) electromagnetic radiation generated by photoconductive antennas, we have calculated the peak frequency of THz waves from laser-induced plasma. The peak frequency is the frequency with the greatest generation probability from different volume elements in a laser pulse period. Using the methods of probability and statistics, the plasma density distribution function Fn(n) is solved. Then, the probability density function φN (n) is calculated. Finally, the maximum of probability density is calculated, which is the factor that is vital to calculating the peak frequency. The peak frequencies calculated theoretically are verified by experiment. The theoretical model serves as the basis for the design of a GaAs photoconductive antenna with a specific peak frequency.