Modifications of filament spectra by shaped octave-spanning laser pulses

TL;DR

This study investigates how shaped octave-spanning laser pulses influence filament spectra in argon gas, demonstrating control over spectral properties through pulse shaping techniques like parametric chirp and genetic algorithms.

Contribution

It introduces the use of complex, parametrically shaped white light pulses to control filament spectra, a novel approach in filament spectroscopy.

Findings

Pulse spectrum can be shifted to higher or lower wavelengths using parametric chirp.

Genetic algorithms optimize pulse shapes for desired spectral modifications.

Spectral and temporal properties are significantly affected by plasma and self-phase modulation.

Abstract

In this paper we examine the spectral changes in a white light laser filament due to different pulse shapes generated by a pulse shaping setup. We particularly explore how the properties of the filament spectra can be controlled by parametrically tailored white light pulses. The experiments are carried out in a gas cell with up to 9 bar of argon. Plasma generation and self-phase modulation strongly affect the pulse in the spectral and temporal domain. By exploiting these effects we show that the pulse spectrum can be modified in a desired way by either using second order parametric chirp functions to shift the filament spectrum to higher or lower wavelengths, or by optimizing pulse shapes with a genetic algorithm to generate more complex filament spectra. This paper is one of the first examples of the application of complex, parametrically shaped white light pulses.