Great enhancement of strong-field ionization in femtosecond-laser subwavelength-structured fused silica

TL;DR

This study demonstrates significant enhancement of strong-field ionization and nonlinear optical effects in femtosecond-laser subwavelength-structured fused silica, highlighting the role of local field enhancement in dielectric ablation.

Contribution

It provides direct experimental evidence of local field enhancement effects in subwavelength structures during femtosecond-laser ionization, advancing understanding of laser-matter interactions.

Findings

Enhanced strong-field ionization in subwavelength structures

Significant increase in third-order nonlinear effects

Contribution to understanding the incubation effect

Abstract

A wavelength-degenerate pump-probe spectroscopy is used to study the ultrafast dynamics of strong-field ionization in femtosecond-laser subwavelength-structured fused silica. The comparative spectra demonstrate that femtosecond-laser subwavelength structuring always give rise to great enhancement for strong-field ionization as well as third-order nonlinear optical effects, which is the direct evidence of great local field enhancement in subwavelength apertures of fs-laser highly-excited surface. In short, the study shows the prominent subwavelength spatial effect of strong-field ionization in femtosecond-laser ablation of dielectrics, which greatly contributes to the well-known "incubation effect".