title: Stimulated Raman scattering in hydrogen-filled hollow-core photonic crystal fiber.
abstract: We report on stimulated Raman scattering in an approximately 1-meter-long hollow-core photonic crystal fiber filled with hydrogen gas under pressure. Light was guided and confined in the 15-micrometer-diameter hollow core by a two-dimensional photonic bandgap. Using a pulsed laser source (pulse duration, 6 nanoseconds; wavelength, 532 nanometers), the threshold for Stokes (longer wavelength) generation was observed at pulse energies as low as 800 +/- 200 nanojoules, followed by a coherent anti-Stokes (shorter wavelength) generation threshold at 3.4 +/- 0.7 microjoules. The pump-to-Stokes conversion efficiency was 30 +/- 3% at a pulse energy of only 4.5 microjoules. These energies are almost two orders of magnitude lower than any other reported energy, moving gas-based nonlinear optics to previously inaccessible parameter regimes of high intensity and long interaction length.
authors.affiliation: Optoelectronics Group, Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UK. pysab@bath.ac.uk
authors.forename: F
authors.initials: F
authors.lastname: Benabid
authors.forename: J C
authors.initials: JC
authors.lastname: Knight
authors.forename: G
authors.initials: G
authors.lastname: Antonopoulos
authors.forename: P St J
authors.initials: PS
authors.lastname: Russell