title: Spectral broadening of mid-infrared femtosecond pulses in GaAs.
abstract: We achieved efficient spectral broadening for mid-IR pulses of few-microjoule energy. The spectral bandwidth of the femtosecond pulses at the center wavelength of 5000 nm increased from 540 nm to 2060 nm (from 220 to 910 cm(-1) in frequency) by nonlinear propagation in a gallium arsenide single crystal. The spectral broadening was accompanied by nonlinear absorption loss of 25%. The demonstrated scheme should be available at any operation wavelength within the material transparency range and provides a useful tool in nonlinear vibrational spectroscopy.
authors.affiliation: Department of Applied Physics, Tokyo University of Agriculture and Technology,2-24-16 Nakacho, Koganei, Tokyo 184-8588 Japan. ashihara@cc.tuat.ac.jp
authors.forename: S
authors.initials: S
authors.lastname: Ashihara
authors.forename: Y
authors.initials: Y
authors.lastname: Kawahara