Generation and Bistability of a Waveguide Nanoplasma Observed by Enhanced Extreme-Ultraviolet Fluorescence

TL;DR

This study investigates how intense laser pulses induce nanoplasma formation in noble gases within tapered waveguides, leading to extreme-ultraviolet fluorescence with bistable behavior, but without high-order harmonic generation.

Contribution

It demonstrates the generation of a nanoplasma and bistable fluorescence in noble gases using waveguide-enhanced fields, revealing new nonlinear optical phenomena.

Findings

Observation of extreme-ultraviolet fluorescence from noble gases

Detection of intensity hysteresis indicating bistability

Absence of high-order harmonic generation despite high intensities

Abstract

We present a study of the highly nonlinear optical excitation of noble gases in tapered hollow waveguides using few-femtosecond laser pulses. The local plasmonic field enhancement induces the generation of a nanometric plasma, resulting in incoherent extreme-ultraviolet fluorescence from optical transitions of neutral and ionized xenon, argon, and neon. Despite sufficient intensity in the waveguide, high-order harmonic generation is not observed. The fluorescent emission exhibits a strong bistability manifest as an intensity hysteresis, giving strong indications for multistep collisional excitations.