光纤Sagnac干涉仪中单光子干涉及路由控制

Single-photon interference and router-control in an optic fiber Sagnac interferometer

介绍一种光纤中稳定的单光子干涉以及单光子路由控制方式 .使用Sagnac单光子环形干涉仪 ,通过分时相位调制 ,改变其顺时针和逆时针两路光子间的相位差 .在Sagnac单光子环形干涉仪中 ,顺时针和逆时针两路光子走过的是同一段光纤 ,简便有效地补偿了光纤长度随时间缓变带来的相位涨落 ,而且两路光子经历了相同的偏振模色散 ,较好地抑制了偏振态波动对单光子干涉的影响 .在长达 5km的 15 5 0nm单模光纤中 ,获得大于 98%的单光子干涉和大于 90 %单光子路由控制 ;在长度为 2 7和 5 0km光纤环路中 ,分别获得大于 94 %和 84 %单光子干涉 。

A novel scheme to realize stable single-photon interference and router-control is demonstrated in this paper. Phase difference between clockwise and counter-clockwise single-photons is controlled by time-division phase modulation in an optic fiber Sagnac loop. Due to the annular geometric configuration of the Sagnac loop, clockwise and counter-clockwise single-photons travel the same optical path and have the same slowly-varying phase drifts, which are automatically compensated. Furthermore, clockwise and counter-clockwise single-photons encounter the same polarization mode dispersion, which is also automatically compensated at the exit port of the Sagnac interferometer. Long-distance single-mode optic fiber at 1550 nm is used in our experimental realization. Fringe visibility of single-photon interference higher than 98% and fidelity of single-photon router-control higher than 90% have been obtained in a Sagnac fiber loop of 5 km. We also realized a stable single-photon interference in Sagnac fiber loops as long as 27 and 52 km. The corresponding fringe visibilities were higher than 94% and 84%, respectively.