# Femtosecond Self-Reconfiguration of Laser-Induced Plasma Patterns in Dielectrics

## TL;DR

This paper presents a numerical model demonstrating that femtosecond laser pulses can cause ultrafast, self-reconfiguring plasma patterns in dielectrics, explaining nanograting formation and orientation changes.

## Contribution

It introduces a self-consistent dynamic approach to model plasma-light interactions, revealing how plasma patterns reconfigure rapidly and grow into the material bulk, aligning with experimental observations.

## Key findings

- Plasma patterns reconfigure within a field-cycle time scale.
- Pattern orientation depends on laser energy density threshold.
- Self-organization leads to volume nanogratings with half-wavelength periodicity.

## Abstract

Laser-induced modification of transparent solids by intense femtosecond laser pulses allows fast integration of nanophotonic and nanofluidic devices with controlled optical properties. So far, the local and dynamic nature of the interactions between plasma and light needed to correctly explain nanograting fabrication on dielectric surfaces has been missing in the theoretical models. With our numerical approach, we show that a self-consistent dynamic treatment of the plasma formation and its interaction with light triggers an ultrafast reconfiguration of the periodic plasma patterns on a field-cycle time scale. Within this framework, a simple stability analysis of the local interactions explains how the laser-induced plasma patterns change their orientation with respect to the incident light polarization, when a certain energy density threshold is reached. Moreover, the reconfigured sub-wavelength plasma structures grow into the bulk of the sample and agree with the experimental findings of self-organized volume nanogratings. Mode coupling of the incident and transversally scattered light with the periodic plasma structures is sufficient to initiate the growth and the self-organization of the characteristic pattern with a periodicity of a half-wavelength in the medium.