title: Spatiotemporal focusing dynamics of intense supercontinuum THz pulses.
abstract: High-field terahertz (THz) single-cycle pulses with 1.5 MV/cm are generated by optical rectification in the stilbazolium salt crystal 4-N,N-dimethylamino-4'-N'-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate. We show experimentally that the generated THz transient carrying 5 octaves (0.15 to 5.5 THz) undergoes a complex time-frequency evolution when tightly focused, and we present a model based on three independent oscillating dipoles capable to describe this anomalous field evolution. Finally, we present a method to control the absolute phase of such supercontinuum THz pulses as an essential tool for future field-sensitive investigations.
authors.affiliation: Paul Scherrer Institute, SwissFEL, 5232 Villigen PSI, Switzerland.
authors.forename: Clemens
authors.initials: C
authors.lastname: Ruchert
authors.affiliation: Paul Scherrer Institute, SwissFEL, 5232 Villigen PSI, Switzerland.
authors.forename: Carlo
authors.initials: C
authors.lastname: Vicario
authors.affiliation: Paul Scherrer Institute, SwissFEL, 5232 Villigen PSI, Switzerland and Ecole Polytechnique Federale de Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Christoph P
authors.initials: CP
authors.lastname: Hauri