title: Raman-resonance-enhanced composite nonlinearity of air-guided modes in hollow photonic-crystal fibers.
abstract: Coherent anti-Stokes Raman scattering (CARS) is used to measure relations between the resonant (Raman) and nonresonant (Kerr-type) optical nonlinearities of air-guided modes in a hollow-core photonic-crystal fiber (PCF). We demonstrate that, due to its interference nature, CARS provides a convenient tool for measuring the contribution of the fiber cladding to the total nonlinearity sensed by air-guided modes in hollow PCFs. On a Raman resonance with molecular vibrations in the gas that fills the fiber core, a two-color laser field is shown to induce optical nonlinearities that are several orders of magnitude higher than the nonresonant Kerr-type nonlinearities typical of air-guided PCF modes.
authors.affiliation: Physics Department, International Laser Center, M. V. Lomonosov Moscow State University, Vorob'evy gory, Moscow, Russia.
authors.forename: Il'ya V
authors.initials: IV
authors.lastname: Fedotov
authors.forename: Andrei B
authors.initials: AB
authors.lastname: Fedotov
authors.forename: Aleksei M
authors.initials: AM
authors.lastname: Zheltikov