用飞秒激光触发GaAs光电导体产生THz电磁波的研究

Investigation on Terahertz Generation with GaAs Photoconductor Triggered by Femo-Second Laser Pulse

报道了用半绝缘 Ga As材料研制的光电导偶极天线在飞秒激光脉冲触发下辐射 THz电磁波的实验结果 .Ga As光电导偶极芯片的两个欧姆接触电极间隙为 3m m,采用 Si3N4 薄膜绝缘保护 ,在 5 4 0 V直流偏置下被波长80 0 nm,脉宽 14 fs,重复频率 75 MHz,平均功率 130 m W的飞秒激光脉冲触发时产生 THz电磁波 .用电光取样测量得到了 THz电磁脉冲的时域波形和频谱分布 .THz电磁波的辐射峰值位于 0 .5 THz左右 ,频谱宽度大于 2 THz,脉冲宽度约为 1ps.

Experiments of terahertz generation with semi-insulating GaAs photoconductive dipole antenna triggered by femto-second laser pulses are reported.The switch is insulated by Si 3N 4 film and the gap of two electrodes is 3mm.When it is triggered by Ti-sapphire femo-second laser pulses with 130mW of average power,14fs of pulse duration,82 of MHz repetition rate and operated at 540V of biased electric voltage,both terahertz waveform and about 1ps width of the THz electric pulse is observed from the test of electro-optic sampling.The frequency spectrum of the terahertz radiation ranges about 2THz,and its amplitude peaks are at roughly 0.5THz.