Abstract-Spectral interference of terahertz pulses from two laser filaments in air

Yanping Chen^1,2,a), Zhelin Zhang^1,2, Zhen Zhang^1,2, Xiaohui Yuan^1,2, Feng Liu^1,2, Min Chen^1,2, Jianqiu Xu^1,2, Jin Yu^1,3, Zhengming Sheng^1,2,4,b) and Jie Zhang^1,2
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a) Electronic mail: yanping.chen@sjtu.edu.cn
b) Electronic mail: zmsheng@sjtu.edu.cn
Appl. Phys. Lett. 106, 221105 (2015); http://dx.doi.org/10.1063/1.4922143

Spectral interference is experimentally demonstrated by two terahertz pulses emitting from filaments induced by two successive femtosecond laser pulses in air. Here, a leading pulse is set to be weaker than a trailing pulse and their temporal separation is larger than the pulse duration of the terahertz pulses. When the leading pulse is stronger than the trailing pulse, thefrequency modulation within the whole terahertz envelope is greatly deteriorated due tononlinear effects applying on the trailing pulse through the plasmas generated by the leading pulses. Such unique terahertz spectrum may find applications in terahertz spectroscopy.