title: Observation of ultrabroadband, beamlike parametric downconversion.
abstract: We report spontaneous parametric downconversion having an unusually wide spectral bandwidth. A collinear type 1 phase-matching configuration is employed with degeneracy near the zero group-velocity dispersion frequency. With a spectral width of 1080 nm and degenerate wavelength of 1885 nm, the source also emits a high flux of 3.4 x 10(11) s(-1)W(-1) photon pairs constrained to a cone of only approximately 2 degrees half-angle. A rigorous theoretical approach is developed that confirms the experimental observations. The source properties are consistent with an ultrashort photon-pair correlation time and, for a narrowband pump, extremely high-dimensional spectral entanglement.
authors.affiliation: División de Física Aplicada, Centro de Investigación Científica yde Educación Superior de Ensenada, Ensenada, Baja California, 22800 Mexico. odonnell@cicese.mx
authors.forename: Kevin A
authors.initials: KA
authors.lastname: O'Donnell
authors.forename: Alfred B
authors.initials: AB
authors.lastname: U'Ren