Hong-Ou-Mandel interference experiment of two independent heralded single photon sources in an optical fiber with birefringence

摘要

Single photon sources (SPSs) play important roles in quantum communication and quantum information processing. Spontaneous four wave mixing (SFWM) in optical fibers provides a promising way to realize practical heralded single photon sources (HSPSs), since it is compatible with current techniques of optical communications. In this paper, two independent HSPSs at 1.5μm band are realized in one polarization maintaining dispersion shifted fiber (PM-DSF) utilizing its large birefringence. When pulsed pump light passes through an optical fiber, two kinds of SFWM will take place simultaneously. One is scalar processes, in which two annihilated pump photons and generated photon pair are all polarized along the same fiber polarization axis. The other is vector processes, in which two annihilated pump photons are polarized along different fiber polarization axes, either for the two photons of the generated pair. In the PM-DSF, the large birefringence generates obvious walk-off effect on the two pump polarization components, which leads to an effective suppression of the vector processes. Hence, by proper pump polarization, correlated photon pairs (CPPs) with different polarization directions can be generated independently by the two scalar processes, which can be used to realize two independent HSPSs. The indistinguishability of the heralded photons generated by the two independent sources is demonstrated by an experiment of Hong-Ou-Mandel (HOM) interference. Using a fiber coupler as the beam splitter, a visibility of HOM dip of 76% is achieved, showing their potential on quantum information.