Resonant terahertz generation by cross-focusing of Gaussian laser beams in the array of vertically aligned anharmonic and magnetized CNTs

Abstract

In this novel scheme of terahertz (THz) generation, the effect of cross-focusing of Gaussian laser beams in the array of vertically aligned anharmonic carbon nanotubes (CNTs) has been studied. The static magnetic field is applied transverse to the axis of CNTs to magnetize the CNTs. The nonlinearity in the system arises due to the ponderomotive force exerted by the laser beams on the electrons of CNTs. The plasma in the CNTs rearranges itself due to this ponderomotive nonlinearity, which gives rise to the cross-focusing of both laser beams. The nonlinear current at THz frequency appears in the array of CNTs on account of the ponderomotive nonlinearity and anharmonicity of the system. The anharmonicity plays a pivotal role in the enhancement of THz generation. The normalized amplitude of THz radiation shows a notable enhancement with the increase of the externally applied static magnetic field 90kG to330kG, dimensions of CNTs, and inter-tube separation. The cross-focusing of two laser beams in the magnetized collisional plasma makes a significant enhancement in the THz generation with the help of anharmonicity.