title: Non-collinear and non-degenerate polarization-entangled photon generation via concurrent type-I parametric downconversion in PPLN.
abstract: A periodically poled lithium niobate (PPLN) crystal has been used as an efficient source of non-collinearly generated polarization-entangled photon pairs at 810 and 1550 nm. The PPLN crystal was endowed with a specially designed poling pattern and the entangled photons were generated via the nonlinear optical process of spontaneous parametric down conversion (SPDC). A novel design based on overlapping two concurrent type-I quasi-phase-matching structures in a single PPLN crystals produced correlated pairs of alternatively polarized photons in largely separated spectral regions. The phase of the resulting two-photon state is directly linked to parameters of the nonlinear grating. Continuous tunability of the generated Bell state, from Phi(+) to Phi(-), has been demonstrated by translating a slightly wedged crystal perpendicular to the pump beam.
authors.forename: Hugues
authors.initials: H
authors.lastname: Guillet de Chatellus
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Sergienko
authors.forename: Bahaa E A
authors.initials: BE
authors.lastname: Saleh
authors.forename: Malvin C
authors.initials: MC
authors.lastname: Teich
authors.forename: Giovanni
authors.initials: G
authors.lastname: Di Giuseppe