title: Nonlinear X-shaped waves by second-harmonic generation with collimated femtosecond pulses.
abstract: Nonlinear X-shaped angle-wavelength spectrum of the generated second-harmonic wave is observed for a collimated femtosecond pulse of a large beam waist, where the spatiotemporal balance is originated from mutual coupling of the effective nonlinear Kerr effects, pulse frequency chirp, and negative phase shift from cascaded quadratic processes with appropriate phase mismatch.
authors.affiliation: State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China.
authors.forename: Wenqi
authors.initials: W
authors.lastname: Lei
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
authors.forename: Hua
authors.initials: H
authors.lastname: Cai
authors.forename: Heping
authors.initials: H
authors.lastname: Zeng