Femtosecond laser pulse train interaction with dielectric materials

TL;DR

This paper models and experimentally investigates how trains of femtosecond laser pulses interact with dielectric materials, revealing energy accumulation effects that lead to permanent modifications even at low pulse energies.

Contribution

It presents a multi-scale theoretical model validated by experiments, showing how pulse repetition rate influences energy buildup and material modification in dielectrics.

Findings

Energy can accumulate in the absorption region due to low heat conductivity.

High temperatures and permanent modifications occur at certain pulse repetition rates.

The model accurately predicts zones of permanent material change.

Abstract

We investigate the interaction of trains of femtosecond microjoule laser pulses with dielectric materials by means of a multi-scale model. Our theoretical predictions are directly confronted with experimental observations in soda-lime glass. We show that due to the low heat conductivity, a significant fraction of the laser energy can be accumulated in the absorption region. Depending on the pulse repetition rate, the material can be heated to high temperatures even though the single pulse energy is too low to induce a significant material modification. Regions heated above the glass transition temperature in our simulations correspond very well to zones of permanent material modifications observed in the experiments.