title: Second-harmonic generation in silicon waveguides strained by silicon nitride.
abstract: Silicon photonics meets the electronics requirement of increased speed and bandwidth with on-chip optical networks. All-optical data management requires nonlinear silicon photonics. In silicon only third-order optical nonlinearities are present owing to its crystalline inversion symmetry. Introducing a second-order nonlinearity into silicon photonics by proper material engineering would be highly desirable. It would enable devices for wideband wavelength conversion operating at relatively low optical powers. Here we show that a sizeable second-order nonlinearity at optical wavelengths is induced in a silicon waveguide by using a stressing silicon nitride overlayer. We carried out second-harmonic-generation experiments and first-principle calculations, which both yield large values of strain-induced bulk second-order nonlinear susceptibility, up to 40 pm V(-1) at 2,300 nm. We envisage that nonlinear strained silicon could provide a competing platform for a new class of integrated light sources spanning the near- to mid-infrared spectrum from 1.2 to 10 μm.
authors.affiliation: Nanoscience Laboratory, Department of Physics, University of Trento, via Sommarive 14, 38123 Povo, Trento, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Cazzanelli
authors.forename: F
authors.initials: F
authors.lastname: Bianco
authors.forename: E
authors.initials: E
authors.lastname: Borga
authors.forename: G
authors.initials: G
authors.lastname: Pucker
authors.forename: M
authors.initials: M
authors.lastname: Ghulinyan
authors.forename: E
authors.initials: E
authors.lastname: Degoli
authors.forename: E
authors.initials: E
authors.lastname: Luppi
authors.forename: V
authors.initials: V
authors.lastname: Véniard
authors.forename: S
authors.initials: S
authors.lastname: Ossicini
authors.forename: D
authors.initials: D
authors.lastname: Modotto
authors.forename: S
authors.initials: S
authors.lastname: Wabnitz
authors.forename: R
authors.initials: R
authors.lastname: Pierobon
authors.forename: L
authors.initials: L
authors.lastname: Pavesi