Three-dimensional analysis of THz radiation mechanisms in interaction of arbitrarily polarized multi-color laser pulses and obliquely magnetized plasma

Abstract

Three-dimensional THz radiation generation via wave-mixing and photo-current mechanisms of multi-color femtosecond laser fields in obliquely magnetized plasma for various laser polarization states is considered. The main motive behind present study has been to investigate the development of more efficient and versatile THz radiation generation for a range of applications through a comprehensive mechanism describing the entire THz frequency band. Two and three-color laser waves interactions with plasma electrons results in a transverse nonlinear current density which causes THz radiation generation. Variation of THz electric field under different laser polarizations is examined analytically and numerically. The impacts of the applied oblique magnetic field and the field oblique angle on the THz electric field for both wave mixing and photo-current schemes are studied and result are compared. A method to implement THz radiation for special applications was developed showing that the external magnetic field is crucial in controlling plasma dynamics. The waveforms of THz angular distribution in forward direction are examined and the impact of different harmonics, various polarization states, external magnetic field, oblique angle of the applied external magnetic field, and the length of plasma on generated waveforms is considered. Based on the results of study, laser harmonics and applied external magnetic field increase electrons current density, leading to enhancement of radiation power without change in directionality diagram. These findings are in close agreement with experimental results.