Generation of high-purity telecom-band entangled photon pairs in dispersion-shifted fiber
Kim Fook Lee, Jun shuo Chen, Chuang Liang, Xiaoying Li, Paul L. Voss, Prem Kumar · Optics Letters · 2006
We study the purity of correlated photon pairs generated in a dispersion-shifted fiber at various temperatures. The ratio of coincidence to accidental-coincidence counts greater than 100 can be obtained as the fiber is cooled to liquid-nitrogen temperature (77 K). We then generate polarization-entangled photon pairs by using a compact counterpropagating scheme. Two-photon interference with visibility >98% and Bell's inequality violation by >8 standard deviations of measurement uncertainty are observed at 77 K, without subtracting the accidental-coincidence counts due to background Raman photons.