Study of filamentation with a high power high repetition rate ps laser at 1.03 µm.

A Houard,M Schultze,A Mysyrowicz,S Klingebiel,Y-B André,K Michel,T Metzger,V Jukna,G Point

doi:10.1364/oe.24.007437

Abstract

We study the propagation of intense, high repetition rate laser pulses of picosecond duration at 1.03 µm central wavelength through air. Evidence of filamentation is obtained from measurements of the beam profile as a function of distance, from photoemission imaging and from spatially resolved sonometric recordings. Good agreement is found with numerical simulations. Simulations reveal an important self shortening of the pulse duration, suggesting that laser pulses with few optical cycles could be obtained via double filamentation. An important lowering of the voltage required to induce guided electric discharges between charged electrodes is measured at high laser pulse repetition rate.

Highlights

Thanks to the development of diode pumping, laser systems operating at a wavelength close to 1 μm with picosecond pulse duration, peak powers on the order of 1011 W and kHz repetition rate are available [1,2,3]
We have characterized the propagation in air of laser pulses of 100 GW peak power and ps pulse duration
Good overall agreement between experiments and simulations was found. This shows that the classical filamentation model is applicable to laser pulses around 1 μm

Summary

Introduction

Thanks to the development of diode pumping, laser systems operating at a wavelength close to 1 μm with picosecond pulse duration, peak powers on the order of 1011 W and kHz repetition rate are available [1,2,3]. Pulses of femtosecond duration undergo filamentation, a process during which a dynamic competition between diffraction, self-focusing, plasma defocusing, and other nonlinear effects lead to the emergence of a beam with narrow diameter and high peak intensity (1013-14 W/cm2) that is maintained over long distances [5,6,7,8,9]. Most experiments on propagation of short laser pulses in gases have been performed at a wavelength of 800 nm (where reliable fs laser sources based on Ti:Sapphire technology are available) They are well explained by the classical filamentation model where reabsorption of laser energy by the plasma plays a minor role because of the short pulse duration. The good agreement between experimental results and simulations allows extracting other filament parameters, such as peak intensity, pulse time profile, plasma density and beam diameter as a function of distance. We draw conclusions on the merit of such a laser for applications such as laser lightning rod or virtual plasma antenna

Description of the laser

Experimental evidence for filamentation

Simulations

Comparison with experimental results and discussion

Findings

Conclusions