High power terahertz radiation generation by optical rectification of a shaped pulse laser in axially magnetized plasma

• Published in: Physics of plasmas 2017-10, Vol.24 (10)
• Main Authors: Singh, Ram Kishor, Singh, Monika, Rajouria, Satish Kumar, Sharma, R. P.
• Format: Article
• Language: English
• ISSN: 1070-664X; 1089-7674
• DOI: 10.1063/1.4994296

An analytical expression has been derived for terahertz (THz) emission by optical rectification of a laser pulse having a Gaussian as well as hyperbolic-secant shape in axially magnetised ripple density plasma. The interaction between short laser pulses of sub picoseconds duration and plasma leads to the radiation of a wave having frequency in THz regime. The non-uniform intensity profile, say supper-Gaussian, of laser beam exerts a quasi-static ponderomotive force to the electron. The electron acquired a nonlinear transverse drift velocity component. Hence, a strong transient current density having a frequency component in the THz regime produces due to coupling of this velocity component with ripple density plasma and derives a strong THz wave. The generated THz field amplitude is directly proportional to the amplitude of the density ripple and field amplitude of the laser beam. In this generation mechanism, the ripple wave number plays a critical role. The THz field amplitude is maximized when cyclotron frequency approaches to the THz frequency and higher value of profile index. For typical laser plasma parameter, the emitted normalised amplitude of THz field is on the order of 10−2.