基于超快激光技术的THz波产生和探测

主要介绍利用超快激光技术产生和探测THz波辐射。THz波探测方法包括电光取样和空气探测。电光取样利用光学电光效应，采用探测激光偏振态的改变得到THz电场时域波形，广泛应用在TDS系统中。空气探测方法利用激光在空气中的三阶非线性效应，可以测得THz时域波形，并且该方法没有晶体的限制，因此可以探测频谱较宽的THz脉冲。产生THz的方法主要包括光电导天线、光学Dember效应、光整流和激光等离子体。其中前三者受到材料本征声子的影响，产生的THz谱宽有一定限制。倾斜激光脉冲波前入射非线性晶体光整流可以产生很强的THz波。双色飞秒激光脉冲与空气等离子体作用，可以产生较强的宽谱THz辐射，并且其谱宽与激光脉冲宽度密切相关。

Terahertz wave generation and detection based upon ultrafast laser technology

Terahertz (THz) waves generation and detection methods based upon ultrafast laser technology are introduced. The detection methods include free-space electro-optic sampling (EO) and air-biased-coherent-detection (ABCD). EO is based upon the electro-optic effect and it can detect THz time waveform by measuring the change of the probe laser polarization. ABCD is an three-order nonlinear optics effect and there is no frequency limitation for ABCD so it can detect broad bandwidth THz pulses. THz generation from photoconductor antenna, optical Dember effect, optical rectification and laser air-plasma interaction are introduced. And the properties of THz generation from them are discussed. Optics rectification with tilted pump laser pulses front excitation can generate strong THz emission. The THz pulses bandwidths are limited in the former three methods while it is broader from laser air-plasma interaction.