title: Generation and characterization of ultrafast white-light continuum in condensed media.
abstract: The generation of white-light continuum by femtosecond laser pulses in transparent condensed media is investigated comprehensively with 262-, 393-, and 785-nm pump wavelengths. We find that the ratio of the medium's bandgap energy to the photon energy of the incident wavelength determines the amount of anti-Stokes broadening, independently of the pump wavelength and the medium's bandgap. It is also shown that, although the amount of anti-Stokes broadening is greater for the longer pump wavelength, the shorter pump wavelength is more advantageous for generating shorter-wavelength continua in the UV region. In addition, a self-induced change in polarization of the white-light continuum that is generated is observed in an isotropic material with a cubic crystal structure, such as CaF2 and LiF. After the investigation of polarization, the frequency chirp of the continuum is characterized by the Kerr-gate method with 70-fs temporal and 10-nm wavelength resolution.
authors.affiliation: Laser Technology Laboratory, RIKEN, Hirosawa, Saitama, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Nagura
authors.forename: Akira
authors.initials: A
authors.lastname: Suda
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kawano
authors.forename: Minoru
authors.initials: M
authors.lastname: Obara
authors.forename: Katsumi
authors.initials: K
authors.lastname: Midorikawa