Excitation of terahertz radiation by parametric coupling of a laser beam and its frequency shifted second harmonic in a corrugated magnetized plasma

摘要

An analytical scheme is developed for the excitation of terahertz radiation (THz) by parametric coupling of a linearly polarized fundamental laser beam (omega(1), (k) over right arrow (1)) and its frequency shifted second harmonic laser (omega(2), (k) over right arrow (2)) in corrugated magnetized plasma. The laser exerts nonlinear ponderomotive force on plasma electrons at frequencies 2 omega(1) and omega(1)-omega(2) consequently density perturbations at these frequencies arise. These density perturbations couple with plasma corrugations of suitable wave number q and produces density oscillations at (2 omega(1), 2k(1)-q(z)) and (omega(1)-omega(2), k(1)-k(2)-q(z)). Density oscillations beat with oscillatory velocities of electrons at col and cot (due to lasers) and resonantly excite terahertz radiation at phase matching conditions of frequency omega = 2 omega(1)-omega(2) and wave number k = 2k(1)-k(2)-q. Perturbation technique is used to obtain the electric field of terahertz radiation. The terahertz electric field amplitude 8.04 x 10(6)V/m is achieved for the lasers intensity of similar to 10(15) W/cm(2) in a 10% corrugated under dense plasma at applied magnetic field similar to 175 kG.