Two-color laser wavelength effect on intense terahertz generation in air

• 来源期刊: 中国物理B（英文版）
• 关键词: THz generation two-color scheme laser-plasma interaction near-IR laser simulation
• 年，卷（期）: 2017,（11）
• 页码范围: 225-231
• 页数: 7页
• 语种: 英文
• DOI: 10.1088/1674-1056/26/11/114206

摘要

Near-IR femtosecond lasers have been proposed to produce high-field terahertz radiation in the air via the laser-plasma interaction,but the physical mechanism still needs to be further explored.In this work,we theoretically investigate the effect of the two-color laser wavelength on the terahertz generation in the air based on a transient photocurrent model.We show that the long wavelength laser excitation can greatly enhance the terahertz amplitude for a given total laser intensity.Furthermore,we utilize a local current model to illustrate the enhancement mechanism.Our analysis shows that the terahertz amplitude is determined by the superposition of contributions from individual ionization events,and for the long wavelength laser excitation,the electron production concentrates in a few ionization events and acquires the larger drift velocities,which results in the stronger terahertz radiation generation.These results will be very helpful for understanding the terahertz generation process and optimizing the terahertz output.