Authors:
Anna Bogatskaya
1
;
2
;
Ekaterina A. Volkova
3
and
Alexander Popov
1
;
2
Affiliations:
1
Department of Physics, Lomonosov Moscow State University, 119991, Moscow, Russia
;
2
Lebedev Physical Institute, Russian Academy of Sciences, 119991, Moscow, Russia
;
3
Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991, Moscow, Russia
Keyword(s):
Laser Microstructuring in Dielectrics, Birefringent Nanolattices, Fused Silica, Multiphoton Ionization of Dielectrics, Plasma Formation, Numerical Modelling, Wave Equation.
Abstract:
In this study we perform 3D self-consistent numerical simulations of a focused laser pulse exposure in the bulk of fused silica. The model combines the second-order wave equation in cylindrical coordinates with a rate equation for the density of charge carriers in the conduction band. Our results indicate that a dense plasma formation near the focal plane effectively scatters and reflects the laser pulse. The coherent interference between the incident and scattered laser waves creates regions of intense field ionization, resulting in periodic plasma nanostructures along both the ρ- and z-axes. We also examine the impact of nonlinear refractive index effects, which lead to pulse self-focusing. We should note that similar subwavelength, divergent structures in material modification regions have been observed in recent experiments conducted under comparable laser focusing conditions.