All-fiber Quantum-Correlated Photon-pair Source

Quantum correlated photon-pair source has a broad application prospect in quantum information. Commercial dispersion shifted fiber (DSF) not only has a low price, but also can produce quantum-correlated photon pairs based on spontaneous four-wave mixing (SFWM) in fiber effectively. Optical fiber elements are rich in variety, mature in technology, small in size, and flexible in structure. Especially, optical fiber elements in communication band have a significant price advantage. So all-fiber structure can realize the low cost and miniaturization of quantum correlated photon-pair source easily.However, the disadvantage of preparing photo pairs in communication band with DSF is that DSF can produce Raman photos. In order to reduce Raman photons and get high purity photon-pair source, the advantage of pulse pumping compared with CW pumping has been studied. Other parameters for the purity of the photon-pair source, which is the wavelength detuning between the correlated photons, the temperature of fiber, the peak power and spectrum width of pump pulse, and self-phase modulation, have also been reported. In order to optimize the photon-pair source comprehensively and let Raman noise lower, this thesis displays the further research on the influence of pump chirp on the purity of correlated photon pairs. Then, realizing the practicability of the photon-pair source, we select optimal parameters on a more comprehensive theoretical basis, set up a desk-top all-fiber quantum correlated photon-pair source, and test analysis it.So, the main content of this thesis includes two major parts:1. The effect of pump chirp on the purity of photon-pairs source is analyzed in theory and experiment. Base on the quantum theory of four-wave mixing in fiber pumping with Gaussian pulse with linear chirp, the theoretical formula of number of SFWM photons in signal (idler) channel and the purity of photon-pairs source are deduced. In experiment,1.2km SMF is added before pump filtering for inducing greater chirp. Theoretically and experimentally, it is demonstrated that the purity of quantum-correlated photon-pairs source decreases because of the decline of proportion of SFWM photons with increasing pump chirp. 2. Integrating theory and optimizing parameters comprehensively, we set up a practical desk-top all-fiber quantum correlated photon-pair source in communication band. Photon pairs (1529.55nm and1537.4nm) in communication band are prepared by using pump pulse,1nm in spectrum width and1533.47nm in wavelength, pumping800m DSF with zero-dispersion wavelength at1532nm. The CAR>10can be achieved at the single channel production rate less than0.013photons/pulse, which shows that the source is useful for realizing quantum communication.