Terahertz wave generation from air plasma induced by special laser beam

In the past few decades, terahertz waves generation from the interaction between femtosecond laser pulses and gas plasma have attracted widespread attention due to their advantages of ultra-broad frequency band and high electric field. In order to excite stronger terahertz radiation from laser induced air plasma, various methods such as changing laser parameters and gas medium are used. This article reviews the technology of using special laser beams instead of Gaussian beam to generate terahertz waves in air plasma, and explores the enhancement effects of special beams such as abruptly autofocusing beams, quasi-square Airy beams, and off-axis vortex beams on terahertz wave generation performed under different experimental conditions. Analyzing the physical process of terahertz wave generation from air plasma induced by special laser beam can provide new approaches for obtaining higher quality terahertz wave sources.