Strong terahertz radiation generation by beating of extra-ordinary mode lasers in a rippled density magnetized plasma

Abstract

AbstractA scheme of terahertz radiation generation is proposed by beating of two extra-ordinary lasers having frequencies and wave numbers$\lpar {\rm \omega}_1\comma \; \vec k_1 \rpar $and$\lpar {\rm \omega}_2\comma \; \vec k_2 \rpar $, respectively in a magnetized plasma. Terahertz wave is resonantly excited at frequency$\lpar {\rm \omega}_1 - {\rm \omega}_2 \rpar $and wave number (k1 − k2 + q) with a wave number mismatch factorqwhich is introduced by the periodicity of plasma density ripples. In this process, the lasers exert a beat ponderomotive force on plasma electrons and impart them an oscillatory velocity with both transverse and longitudinal components in the presence of transverse static magnetic field. The oscillatory velocity couples with density ripples and produces a nonlinear current that resonantly excites the terahertz radiation. Effects of periodicity of density ripples and applied magnetic field are analyzed for strong THz radiation generation. The terahertz radiation generation efficiency is found to be directly proportional to the square of density ripple amplitude and rises with the magnetic field strength. With the optimization of these parameters, the efficiency ~10−3is achieved in the present scheme. The frequency and power of generated THz radiation can be better tuned with the help of parameters like density ripple amplitude, periodicity and applied magnetic field strength in the present scheme.