title: Optical detection of tunneling ionization.
abstract: We have experimentally detected optical harmonics that are generated due to a tunneling-ionization-induced modulation of the electron density. The optical signature of electron tunneling can be isolated from concomitant optical responses by using a noncollinear pump-probe setup. Whereas previously demonstrated tools for attosecond metrology of gases, plasmas, and surfaces rely on direct detection of charged particles, detection of the background-free time-resolved optical signal, which uniquely originates from electron tunneling, offers an interesting alternative that is especially suited for systems in which free electrons cannot be directly measured.
authors.affiliation: Photonics Institute, Vienna University of Technology, Gusshausstrasse 27-29/387, A-1040, Vienna, Austria.
authors.forename: Aart J
authors.initials: AJ
authors.lastname: Verhoef
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Mitrofanov
authors.forename: Evgenii E
authors.initials: EE
authors.lastname: Serebryannikov
authors.forename: Daniil V
authors.initials: DV
authors.lastname: Kartashov
authors.forename: Aleksei M
authors.initials: AM
authors.lastname: Zheltikov
authors.forename: Andrius
authors.initials: A
authors.lastname: Baltuska