小孔径光电导天线产生太赫兹波的辐射特性

The THz Emission Properties of Small-Aperture Photoconductive Antenna

研究了在抽运激光光斑面积不同的情况下,两种小孔径光电导天线各自的辐射特性,并且将它们辐射出的太赫兹(THz)波进行了对比。目的在于找到提高小孔径光电导天线发射效率的方法,为研制高效率的太赫兹波辐射源提供参考依据。利用太赫兹时域光谱(TDS)技术测量了光电导天线辐射的太赫兹脉冲,得到了时域发射光谱,通过快速傅里叶变换得到相应的频域光谱。结果表明,两种光电导天线辐射的太赫兹信号强度都随着抽运激光光斑直径的减小而增强;随偏置电压的增大而增强;随着抽运激光功率的增大出现了先增强后饱和的现象。在偏置电压、抽运激光光斑直径与抽运激光功率相同时,对比两种光电导天线产生的太赫兹信号发现:蝴蝶型光电导天线的太赫兹信号的强度较大并且频域谱的半峰全宽(FWHM)较宽。

The terahertz（THz） emission properties of two kinds of small-aperture photoconductive antennas are studied under the condition of different spot area of pump laser.The characteristic of THz radiation generated by them is compared.Meanwhile,it also provides a reference to investigate and fabricate the high efficient of THz radiation source.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 when the bias voltage is enhanced or the spot area of pump laser becomes smaller,the peak value of THz radiation is increased and saturated with increasing of pump power.Under the same bias voltage,the spot area of pump laser and the pump power,the properties of THz radiation generated by two kinds of photoconductive antennas are compared.The results show that,the full width of half maximum（FWHM） of THz frequency domain spectra which is generated by the small-aperture bow-tie photoconductor antenna is broader and the intensity of THz radiation is larger.