Generation of frequency de-correlated photon pairs by using photonic crystal fiber

Based on the dispersion property of a given photonic crystal fiber (PCF), we study how to directly generate frequency de-correlated photon pairs via pulse pumped spontaneous four wave mixing from both the theoretical and experimental aspects. The numerical investigation shows that to generated the frequency de-correlated photon pairs, the experimental parameters should be properly optimized by balancing the influences of the high order dispersion and the intrinsic sinc oscillation of phase matching function, apart from the satisfaction of specified phase matching condition and the usage of transform limited pump pulses. We also conduct experiment to verify the numerical simulations, and the experimental results qualitatively agree with the calculations. For the filter free case, the experimentally obtained maximum g(2) of the individual signal photons is 1.76 +/- 0.02. When this kind of photon pairs is used to realize the heralded single photons, the heralding efficiency can reach 86%.