Direct Generation of Polarization-Entangled Photon Pairs in a Poled Fiber

作者：Zhu Eric Y^*; Tang Zhiyuan; Qian Li; Helt Lukas G; Liscidini Marco; Sipe J E; Corbari Costantino; Canagasabey Albert; Ibsen Morten; Kazansky Peter G

来源：Physical Review Letters, 2012, 108(21): 213902.

DOI：10.1103/PhysRevLett.108.213902

We experimentally demonstrate the direct generation of polarization-entangled photon pairs in an optical fiber at room temperature by exploiting type-II phase-matched spontaneous parametric down-conversion. A second-order nonlinearity is artificially induced in the 17-cm-long weakly birefringent step-index fiber through the process of thermal poling, and quasi-phase-matching allows for the generation of entangled photons in the 1.5-micron telecom band when the fiber is pumped at 775 nm. A greater-than 80: 1 coincidence-to-accidental ratio is achieved, limited mainly by multiphoton pair generation. Without the need to subtract accidentals or to compensate for walk-off, the raw two-photon interference visibility is found to be better than 95%, and violation of Bell%26apos;s inequality is observed by more than 18 standard deviations. This makes for a truly alignment-free, plug-and-play source of polarization-entangled photon pairs.

• 出版日期2012-5-21