title: Nearly degenerate wavelength-multiplexed polarization entanglement by cascaded optical nonlinearities in a PPLN ridge waveguide device.
abstract: In this paper we report the generation of wavelength-multiplexed polarization-entangled photon pairs in the 1.5-μm communication wavelength band by using cascaded optical second nonlinearities (sum-frequency generation and subsequent spontaneous parametric down-conversion, c-SFG/SPDC) in a periodically poled LiNbO(3) ridge waveguide device. The c-SFG/SPDC method makes it possible to fully use the broad spectral bandwidth of SPDC in nearly frequency-degenerate conditions, and can provide more than 50 pairs of wavelength channels for the entangled photon pairs in the 1.5-μm wavelength band, using only standard optical resources in the telecom field. Visibilities higher than 98% were clearly observed in two-photon interference fringes for all the wavelength channels under investigation (eight pairs). We further performed a detailed experimental investigation of the cross-talk characteristics and the impact of detuning the pump wavelengths.
authors.affiliation: Corporate Research & Development Center, Oki Electric Industry Co., Ltd., 1-16-8 Chuou, Warabi-shi, Saitama 335-8510, Japan. arahira335@oki.com
authors.forename: Shin
authors.initials: S
authors.lastname: Arahira
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Murai
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D007834:Lasers; D009556:Niobium / Q000737:chemistry*; D017711:Nonlinear Dynamics; D010087:Oxides / Q000737:chemistry*; D012031:Refractometry / Q000295:instrumentation*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*
chemical_list: D010087:Oxides; D009556:Niobium; C091692:lithium niobate