Optical terahertz emission from a magnetized plasma strip driven by counter laser pulses

We investigate the generation of intense terahertz (THz) radiation from a magnetized plasma driven by two counter-propagating laser pulses with a frequency detuning Δ ω ∼2 ω p , where ω p is the electron plasma frequency. For laser pulse durations satisfying τ L ≫ ω p −1 , the overlapping region of the pulses produces a beat-frequency ponderomotive force, which excites nonlinear plasma currents oscillating at Δ ω . These currents radiate coherently in the THz range. The presence of an external magnetic field introduces electron cyclotron resonance, significantly enhancing the current amplitude and the resulting THz field. Our results show that a magnetic field of B =2.5T yields a peak THz electric field of 4.8GV/m and a conversion efficiency of ∼10 −5 . The proposed mechanism offers a tunable and broadband THz source with potential applications in ultrafast spectroscopy, imaging, and nonlinear THz science.