title: Generation and bistability of a waveguide nanoplasma observed by enhanced extreme-ultraviolet fluorescence.
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.
authors.affiliation: IV. Physical Institute, University of Göttingen, 37077 Göttingen, Germany.
authors.forename: Murat
authors.initials: M
authors.lastname: Sivis
authors.forename: Claus
authors.initials: C
authors.lastname: Ropers