Signal and idler photon pairs at about 0.8 and 1.4 μm, respectively, are generated from 1-meter-long photonic crystal fiber. By using pump pulses with different wavelengths, frequency positively correlated and de-correlated photon pairs are obtained.
An actual task of quantum communications over long distances is the creation of a bright source of photon pairs operating at standard wavelengths of fiber optic communication lines. In this work, we experimentally investigated the spectral and correlation characteristics of photon pairs generated on the phenomenon of spontaneous four-wave mixing in a highly nonlinear photonic-crystal fiber with a wavelength of one of the photons near 1.5 μm. The demonstrated source can be used as an efficient single photon generator at a telecommunications wavelength with prediction and tuning over a wide spectral range.
Quantum-correlated photon pairs with tunable wavelength are highly desirable in a number of quantum technologies. In this letter, we demonstrate a wavelength tunable source of the correlated photon pairs based on pulse-pumped spontaneous four-wave mixing in photonic-crystal fiber. The wavelengths of the correlated signal and idler photons can be continuously tuned at room temperature by adjusting the wavelength of pump originating from an ytterbium-doped fiber laser. The tuning range of the idler photons is 757-880 nm and the range of the signal photons is 1310-1610 nm, which covers the 1310- and 1550-nm telecom bands.
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%.