Influence of pulse slippage on the tunable terahertz generation by q-Gaussian laser beats in a rippled magnetized plasma

Abstract

The synergistic combination of q-Gaussian laser beams, an external magnetic field, and a density ripple in a plasma is theoretically explored as an efficient mechanism for generating coherent, tunable terahertz radiation, with a specific focus on the influence of pulse slippage. The scheme leverages the ponderomotive force induced at the beat frequency (ω=ω1−ω2) of the lasers, which drives a nonlinear current. The density ripple provides the essential phase-matching condition, while the q-Gaussian beam offers a tunable parameter to govern the laser’s spatial intensity profile, from a peaked to a flatter-top profile. A self-consistent set of equations for the THz field amplitude is derived, explicitly incorporating the group velocity disparity (slippage) between the laser pulses and the subsequently generated THz radiation. This analysis reveals that this slippage is a critical saturating mechanism that limits the THz energy growth along the propagation path. The analytical solution demonstrates that the normalized THz amplitude is directly proportional to the q-parameter, ripple density, and laser intensities but is governed by a saturation length defined by the slippage. Numerical results indicate that optimizing the q-parameter can enhance the THz field amplitude compared to conventional Gaussian beams, providing a potent mechanism for controlling the output. This work establishes that the synergistic combination of q-Gaussian beam shaping and slippage management is pivotal for developing efficient, high-field, and tunable plasma-based THz sources.