A frequency-nondegenerate entanglement source using periodically-poled lithium niobate

We demonstrate efficient generation of highly nondegenerate photon pairs with a type-I phase-matched, periodically-poled lithium niobate parametric downconverter. The signal photons at 800nm and the idler photons at 1600nm were generated in a collinear-propagation configuration with an inferred pair generation rate of 1.4x10(7)/s/mW of pump power. Detection of a signal photon triggered a thermoelectrically cooled, 20%-efficient InGaAs avalanche photodiode for the detection of the 1600-nm conjugate idler photon. Using single-mode fibers as spatial mode filters, the signal-conditioned idler-detection probability was similar to3.1%.