低温生长砷化镓光电导天线产生太赫兹波的辐射特性

Terahertz Radiation Properties of Low-Temperature-Grown GaAs Photoconductive Antenna

研究了低温生长砷化镓光电导天线(LT-GaAs PCA)产生太赫兹(THz)波的辐射特性。利用太赫兹时域光谱(TDS)技术测量了光电导发射极在飞秒激光作用下辐射的太赫兹脉冲,得到了时域发射光谱,并通过快速傅里叶变换(FFT)得到相应的频域光谱。结果表明,低温砷化镓光电导天线产生的太赫兹波信号比飞秒激光激发半导体表面产生的太赫兹波信号具有更高的强度和信噪比;太赫兹波信号与光电导天线的偏置电压成线性关系;随着抽运激光功率的增强,太赫兹波信号增大并出现饱和。

The terahertz （THz） radiation properties of low temperature-grown GaAs photoconductive antenna （LT- GaAs PCA） are studied in order to improve the THz radiation efficiency. The emission spectra of the photoconductive antenna are obtained by THz time domain spectroscopy （TDS） technology. The corresponding frequency domain spectra are obtained by fast Fourier transform （FFT）. The results show that the THz signal generated by LT-GaAs PCA is more efficient than that generated by femtosecond electromagnetic pulse from semiconductor surface. The peak of THz electric field increases linearly as bias voltage increasing, and tends to saturation as pump power increasing.