Direct measurement of the electron density of extended femtosecond laser pulse-induced filaments

TL;DR

This paper reports direct measurements of electron density in femtosecond laser-induced plasma filaments, revealing that molecular rotation is the main nonlinearity causing extended atmospheric filaments.

Contribution

It provides the first direct time- and space-resolved electron density measurements in femtosecond laser filaments, identifying molecular rotation as the key nonlinearity.

Findings

Electron density measured directly in filaments.

Molecular rotation is the dominant nonlinearity.

Filament extension is primarily due to molecular rotation.

Abstract

We present direct time- and space- resolved measurements of the electron density of femtosecond laser pulse-induced plasma filaments. The dominant nonlinearity responsible for extended atmospheric filaments is shown to be field-induced rotation of air molecules.