title: Non-instantaneous optical nonlinearity of an a-Si:H nanowire waveguide.
abstract: We use pump-probe spectroscopy and continuous wave cross-phase and cross-amplitude modulation measurements to study the optical nonlinearity of a hydrogenated amorphous silicon (a-Si:H) nanowire waveguide, and we compare the results to those of a crystalline silicon waveguide of similar dimensions. The a-Si:H nanowire shows essentially zero instantaneous two-photon absorption, but it displays a strong, long-lived non-instantaneous nonlinearity that is both absorptive and refractive. Power scaling measurements show that this non-instantaneous nonlinearity in a-Si:H scales as a third-order nonlinearity, and the refractive component possesses the opposite sign to that expected for free-carrier dispersion.
authors.forename: Jeremiah J
authors.initials: JJ
authors.lastname: Wathen
authors.forename: Vincent R
authors.initials: VR
authors.lastname: Pagán
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Suess
authors.forename: Ke-Yao
authors.initials: KY
authors.lastname: Wang
authors.forename: Amy C
authors.initials: AC
authors.lastname: Foster
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Murphy
mesh_terms: D004867:Equipment Design; D008027:Light; D053770:Nanowires; D017711:Nonlinear Dynamics; D012031:Refractometry / Q000295:instrumentation*; D012542:Scattering, Radiation; D012825:Silicon / Q000737:chemistry*
chemical_list: D012825:Silicon