title: Dramatic enhancement of supercontinuum generation in elliptically-polarized laser filaments.
abstract: Broadband laser sources based on supercontinuum generation in femtosecond laser filamentation have enabled applications from stand-off sensing and spectroscopy to the generation and self-compression of high-energy few-cycle pulses. Filamentation relies on the dynamic balance between self-focusing and plasma defocusing - mediated by the Kerr nonlinearity and multiphoton or tunnel ionization, respectively. The filament properties, including the supercontinuum generation, are therefore highly sensitive to the properties of both the laser source and the propagation medium. Here, we report the anomalous spectral broadening of the supercontinuum for filamentation in molecular gases, which is observed for specific elliptical polarization states of the input laser pulse. The resulting spectrum is accompanied by a modification of the supercontinuum polarization state and a lengthening of the filament plasma column. Our experimental results and accompanying simulations suggest that rotational dynamics of diatomic molecules play an essential role in filamentation-induced supercontinuum generation, which can be controlled with polarization ellipticity.
authors: Center for High Tech Materials, University of New Mexico, Albuquerque NM 87106, USA.
authors: Shermineh
authors: S
authors: Rostami
authors: Townes Laser Institute, CREOL - The College of Optics and Photonics, University of Central Florida, Orlando FL 32816, USA.|Department of Physics, University of Central Florida, Orlando FL 32816, USA.
authors: Michael
authors: M
authors: Chini
authors: Townes Laser Institute, CREOL - The College of Optics and Photonics, University of Central Florida, Orlando FL 32816, USA.
authors: Khan
authors: K
authors: Lim
authors: Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375-5346, USA.
authors: John P
authors: JP
authors: Palastro
authors: Townes Laser Institute, CREOL - The College of Optics and Photonics, University of Central Florida, Orlando FL 32816, USA.
authors: Magali
authors: M
authors: Durand
authors: Center for High Tech Materials, University of New Mexico, Albuquerque NM 87106, USA.
authors: Jean-Claude
authors: JC
authors: Diels
authors: Center for High Tech Materials, University of New Mexico, Albuquerque NM 87106, USA.
authors: Ladan
authors: L
authors: Arissian
authors: Townes Laser Institute, CREOL - The College of Optics and Photonics, University of Central Florida, Orlando FL 32816, USA.|National Center for Forensic Science, University of Central Florida, Orlando FL 32816, USA.|Department of Chemistry, University of Central Florida,Orlando FL 32816, USA.
authors: Matthieu
authors: M
authors: Baudelet
authors: Townes Laser Institute, CREOL - The College of Optics and Photonics, University of Central Florida, Orlando FL 32816, USA.
authors: Martin
authors: M
authors: Richardson