title: Observation of a gradient catastrophe generating solitons.
abstract: We investigate the propagation of a dark beam in a defocusing medium in the strong nonlinear regime. We observe for the first time a shock fan filled with noninteracting one-dimensional gray solitons that emanates from a gradient catastrophe developing around a null of the optical intensity. This scenario turns out to be very robust, persisting also when the material nonlocal response averages the nonlinearity over dimensions much larger than the emerging soliton filaments.
authors.affiliation: Research Center SOFT INFM-CNR, Università di Roma La Sapienza, P. A. Moro 2, 00185 Roma, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Conti
authors.forename: Andrea
authors.initials: A
authors.lastname: Fratalocchi
authors.forename: Marco
authors.initials: M
authors.lastname: Peccianti
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Ruocco
authors.forename: Stefano
authors.initials: S
authors.lastname: Trillo