title: Highly efficient THG in TiO2 nanolayers for third-order pulse characterization.
abstract: Third harmonic generation (THG) of femtosecond laser pulses in sputtered nanocrystalline TiO2 thin films is investigated. Using layers of graded thickness, the dependence of THG on the film parameters is studied. The maximum THG signal is observed at a thickness of 180 nm. The corresponding conversion efficiency is 26 times larger compared to THG at the air-glass interface. For a demonstration of the capabilities of such a highly nonlinear material for pulse characterization, third-order autocorrelation and interferometric frequency-resolved optical gating (IFROG) traces are recorded with unamplified nanojoule pulses directly from a broadband femtosecond laser oscillator.
authors.affiliation: Max Born Institute for Nonlinear Optics and Short-Pulse Spectroscopy, Berlin, Germany.
authors.forename: Susanta Kumar
authors.initials: SK
authors.lastname: Das
authors.forename: Christoph
authors.initials: C
authors.lastname: Schwanke
authors.forename: Andreas
authors.initials: A
authors.lastname: Pfuch
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Seeber
authors.forename: Martin
authors.initials: M
authors.lastname: Bock
authors.forename: Günter
authors.initials: G
authors.lastname: Steinmeyer
authors.forename: Thomas
authors.initials: T
authors.lastname: Elsaesser
authors.forename: Ruediger
authors.initials: R
authors.lastname: Grunwald