Highly efficient photon-pair source using periodically poled lithium niobate waveguide

A new kind of correlated photon-pair source based on a waveguide integrated on a periodically poled Lithium niobate substrate is reported. Using a pum p laser of a few muW at 657nm, photon-pairs are generated/degenerated at 13 14nm. Detecting similar to 1500 coincidences per second, a conversion rate of 10(-6) pairs per pump photon can be inferred, which is four orders of ma gnitude higher than that obtained with previous bulk sources. These results are very promising for the realisation of sources for quantum communicatio n and quantum metrology experiments requiring a high signal-to-noise ratio or working with more than one photon-pair at a time.