Authors:
Anna Bogatskaya
1
;
2
;
Ekaterina A. Volkova
3
and
Alexander Popov
1
;
2
Affiliations:
1
Department of Physics, Lomonosov Moscow State University, 1199991, Moscow, Russia
;
2
Lebedev Physical Institute, Russian Academy of Sciences, 119991, Moscow Russia
;
3
Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 1199991, 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 work, a numerical study of the formation of plasma periodic subwavelength nanogratings in fused silica along the propagation of a focused laser pulse is carried out. It is shown that the tightly focused beam creates a supercritical plasma in the focal plane, which provides an effective reflection of the parts of incident and reflected laser pulse. As a result, standing wave of ionization occurs which generates a plasma lattice with a period equal to the period of the standing wave in the medium. The results of modelling allow us to determine the optimal laser parameters in the regime of linear (geometrical) focusing when the contrast nanogratings can emerge. Analysis of energy release processes with subsequent melting of the fused silica sample confirms the previously proposed mechanism of laser modification.