Self-focusing property of a laser beam interacting with a lattice of nanoparticles in the presence of a planar magnetostatic wiggler

Abstract

In this paper, we study the nonlinear interaction of a laser beam with a periodic lattice of nanoparticles in the presence of a planar magnetostatic wiggler. The static magnetic field of the wiggler can couple with the electric field of the laser wave and change the electric field intensity of the pumped wave, leading to the formation of a nonlinear force. In consequence, the nonlinear force enhances plasmonic oscillations of the electronic cloud of each nanoparticle causing electron density modulation, which improves self-focusing property of the laser beam propagating through a periodic lattice of nanoparticles. By manipulating a classical microscopic approach into plasmonic oscillations of electronic clouds of the nanoparticles and the well–known perturbative method, a nonlinear dispersion relation describing the evolution of the laser amplitude propagating through the nanoparticle lattice has been obtained. The effect of the wiggler magnetic strength on the evolution of the laser transverse profile has been discussed. It was found that by increasing the wiggler strength, the transverse profile bandwidth shrinks and laser focusing is enhanced. In addition, further numerical results indicated that by increasing the wiggler field strength, the cut-off frequency of the body waves increases.

Effects of the helical magnetic wiggler on a laser beam interacting with a lattice of metallic nanoparticles: plasmonic and body waves

“…The variations in nonlinear dispersion curves for l = 0.1, 0.03 in the presence of the helical magnetic wiggler with normalized amplitude a = 0.85 in the case of σ = 0 are shown in figure 3. It can be seen that the higher l has the larger cut-off frequency, which is similar to the results of [31] in the absence of the helical magnetic wiggler. In these figures, it is clear that with an increase in l, or in other words, with a decrease in the separation distance of the nanoparticles in the metallic lattice, a body wave occurs at higher frequency and plasmonic waves occur at a lower frequency.…”

“…which is in agreement with the results of [25,31,34]. We introduce the normalized parameters defined by ω = ω/ω p , k = kc/ω p , k w = k w c/ω p and ȳ = yω p /c .…”

“…where B w is the amplitude of the wiggler magnetic field and k w = 2π/λ w denotes the wiggler wave number. The equation describing the relativistic interaction of the laser electromagnetic fields with the electronic cloud of each nanoparticle can be written as [25,[31][32][33] d dt (γv) +…”