Enhanced absorption and plasmon excitation in the bulk of fused silica with femtosecond Bessel beams

FEMTO-ST Institute, UMR 6174 CNRS University of Bourgogne Franche-Comte, 15 B, rue des Montboucons, F-25030 Besancon, France 2 Centre de Physique Theorique, CNRS, Ecole polytechnique Universite Paris-Saclay, F-91128 Palaiseau, France We image femtosecond Bessel beam propagation in fused silica under ablation conditions, and observe unexpectedly high absorption. We identify plasmon excitation and plasma channel field enhancement as the likely mechanism for this increased absorption.