title: Direct measurement of the electron density of extended femtosecond laser pulse-induced filaments.
abstract: We present direct time- and space-resolved measurements of the electron density of femtosecond laser pulse-induced plasma filaments. The dominant nonlinearity responsible for extended atmospheric filaments is shown to be field-induced rotation of air molecules.
authors.affiliation: Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Y-H
authors.initials: YH
authors.lastname: Chen
authors.forename: S
authors.initials: S
authors.lastname: Varma
authors.forename: T M
authors.initials: TM
authors.lastname: Antonsen
authors.forename: H M
authors.initials: HM
authors.lastname: Milchberg