Study of the dipole characteristic of terahertz wave emitted from photoconductor switches
光电导开关产生太赫兹电磁波双极特性分析

In this paper,different methods are used to simulate the dipole characteristic of terahertz(THz)wave emitted from low-temperature grown GaAs(LT-GaAs)and Semi-insulting GaAs(SI-GaAs)photoconductive semiconductor switches.The results indicate that the main cause of the dipole characteristic of THz wave emitted from LT-GaAs is the lifetime of optical-generated carriers being shorted than the generation time.For SI-GaAs photoconductive semiconductor switches with lifetime of optical-generated carriers longer than 100ps,the dipole characteristic of THz waveforms is mainly caused by intra-valley scattering and space charge field screening under different experimental conditions(different bias field and different optical pulse energy).