Surface plasma wave aided Laguerre–Gaussian laser beam second harmonic generation in arrays of vertically aligned carbon nanotube over metal surface

In this paper, we have proposed a scheme of second harmonic generation by a high power Laguerre–Gaussian laser beam excited surface plasma wave at a metal-air interface embedded with a cylindrical carbon nanotube over the metal surface by beating of the density ripple. The electrons absorb the laser energy and attenuate the surface plasma wave. The excited surface plasma waves elongate over the entire interacting region, and the laser field only interacts with its region of spot size. Due to the association of the surface plasma wave, the laser beam beats and exerts a nonlinear ponderomotive force on the conduction electron. The second harmonic nonlinear ponderomotive force beats with the surface ripple and efficiently produces a nonlinear second harmonic current density. The resonant second harmonic field is observed at a frequency 1/2 times of the electron plasma frequency. The amplitude of the second harmonic field depends on various laser associated parameters (beam width, radial index, azimuthal index, and transverse propagation distance) and interacting medium parameters (density of electrons, size, and shape of a carbon nanotube). This resonant enhanced second harmonic field can be applicable in optoelectronic devices, upconversion of frequency, and other plasmonic devices.