Femtosecond Laser-Induced Damage and Filamentary Propagation in Fused Silica

TLDR

The study investigates bulk damage induced by femtosecond infrared laser pulses in fused silica experimentally and numerically, and examines the relative contributions of avalanche and photoionization. Experimental and numerical approaches are used to analyze the damage mechanisms, focusing on avalanche and photoionization contributions. Strong focusing produces an initial damage zone followed by a submicron filamentary track whose size matches electron densities near 10²⁰ cm⁻³, and the plasma density in the wake saturates at 2–4 × 10²⁰ cm⁻³.

Abstract

Bulk damage induced by fs IR laser pulses in silica is investigated both experimentally and numerically. In a strong focusing geometry, a first damage zone is followed by a narrow track with submicron width, indicating a filamentary propagation. The shape and size of the damage tracks are shown to correspond to the zone where the electron density created by optical field ionization and avalanche is close to 10(20) cm(-3). The relative role of avalanche and photoionization is studied. The plasma density produced in the wake of the pulse is shown to saturate around 2-4x10(20) cm(-3).