title: Phase-resolved two-dimensional terahertz spectroscopy including off-resonant interactions beyond the χ((3)) limit.
abstract: We present the first two-dimensional (2D) terahertz (THz) experiment with three phase-locked THz pulses and a fully phase-resolved detection of the nonlinearly emitted field by electrooptic sampling. In a prototype experiment we study the ultrafast dynamics of nonlinear two-phonon and two-photon interband coherences in the narrow-gap semiconductor InSb. Due to the extraordinarily large optical interband dipole of InSb the experiments were performed in the strongly nonperturbative regime of light-matter interaction allowing for impulsive off-resonant excitation of both two-phonon coherences and two-photon interband coherences, the ultrafast dynamics of which is experimentally observed as a function of the waiting time in the three-pulse 2D experiment. Our novel three-pulse 2D THz spectroscopy paves the way for the detailed investigation of nonlinear quantum coherences in solids and holds potential for an extension to other systems.
authors.affiliation: Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany.
authors.forename: Carmine
authors.initials: C
authors.lastname: Somma
authors.affiliation: Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany.
authors.forename: Giulia
authors.initials: G
authors.lastname: Folpini
authors.affiliation: Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Reimann
authors.affiliation: Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Woerner
authors.affiliation: Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Elsaesser