Origin of anomalous nanostructures formation under linear polarized femtosecond laser irradiation of condensed matter

Analysis of the results obtained in experiments on formation of spatial nanogratings with anomalous orientation at boundary between different condensed media (metals, semiconductors and dielectrics) is presented. The analysis is made in the context of a universal polariton model of the laser-induced damage of the condensed media. To explain the wide set of findings of nanostructure formation with anomalous orientation a physical model based on phenomena of excitation of wedge (channel) surface plasmon polaritons with mutually antithetical directions of propagation and their interference at spatial overlapping is proposed. To explain formation of nanogratings with a spatial period dramatically less than a wavelength of the actuating laser radiation the previously suggested non-linear mathematical model of laser-induced formation of nanograting spatial periods is used.