Abstract-Enhanced terahertz radiation by an intense femtosecond laser field assisted with sub-cycle pulses

Xiao-Fang Shu, Cheng-Xin Yu, and Jie Liu

Fig. 1 (a) The profiles of the driving, the proposed sub-cycle and the synthesized pulses, and the calculated ionization probability is given in black solid line.; (b) The photocurrents JE and JC are presented in the arbitrary unit (arb.u.).

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-5-7751

In this work, we theoretically investigate the enhanced Terahertz (THz) radiation by an intense laser pulse assisted with sub-cycle pulses (SCP) in the framework of quantum theory. By numerically solving the Schrödinger equation, the production and the dynamics of ionized electrons are analyzed. The simulations show that the SCP plays different roles for different time delays in the generation of THz radiation, such as increasing the production of the ionized electrons and manipulating their trajectories. The time-frequency analysis of the THz radiation is also carried out, which indicates that the THz radiation mainly occurs where the SCP is launched, and the THz radiation mainly comes from the formation of the asymmetric electric current. Finally, the scheme of dual sub-cycle pulses is studied, and we find that the THz radiations can constructively or destructively interfere, which leads to the formation of the streaky structures of radiation spectra.

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Enhanced THz radiation from beating of two Cosh–Gaussian laser beams in a wiggler-assisted collisional magnetized plasma

Mehdi Abedi-Varaki and Saed Jafari

https://www.osapublishing.org/josab/abstract.cfm?uri=josab-35-5-1165&origin=search

In this paper, the terahertz (THz) radiation generated by mixing two Cosh–Gaussian laser beams (decentered Gaussian beams) in collisional magnetized plasma has been studied in the presence of a helical magnetostatic wiggler. Equations governing the THz radiation generation of laser beams and the efficiency of emitted radiation for both left- and right-hand circular polarizations have been derived. The effects of the wiggler strengths and the decentered parameter on the THz field amplitude and laser electric field magnitude have been investigated. Numerical results indicate that the amplitude of THz electric field radiation increases when the wiggler frequency increases, and consequently the THz radiation becomes stronger. Moreover, it is seen that normalized laser efficiency has a decreasing trend with increasing normalized collision frequency for different wiggler magnetic field strengths. Furthermore, it is found that the efficiency increases with an increase in the values of the wiggler frequencies. Finally, by adjusting the decentered parameter and wiggler magnetic field strength, the peak intensity of lasers can be shifted and a significant change is found in the THz field amplitude and its conversion efficiency.

© 2018 Optical Society of America