Onera, The French Aerospace Lab, BP 80100, 91123 Palaiseau CEDEX, France.
Nat Commun. 2011 Aug 9;2:425. doi: 10.1038/ncomms1423.
For many years twin beams originating from parametric down-converted light beams have aroused great interest and attention in the photonics community. One particular aspect of the twin beams is their peculiar intensity correlation functions, which are related to the coincidence rate of photon pairs. Here we take advantage of the huge bandwidth offered by two-photon absorption in a semiconductor to quantitatively determine correlation functions of twin beams generated by spontaneous parametric down-conversion. Compared with classical incoherent sources, photon extrabunching is unambiguously and precisely measured, originating from exact coincidence between down-converted pairs of photons, travelling in unison. These results strongly establish that two-photon counting in semiconductors is a powerful tool for the absolute measurement of light beam photon correlations at ultrashort timescales.
多年来，源于参量下转换光束的孪生光束在光子学界引起了极大的兴趣和关注。孪生光束的一个特别方面是它们奇特的强度相关函数，这与光子对的符合率有关。在这里，我们利用半导体中双光子吸收提供的巨大带宽，定量地确定自发参量下转换产生的孪生光束的相关函数。与经典的非相干光源相比，光子额外聚集被明确而精确地测量出来，这源于在同一时间传输的下转换光子对之间的精确符合。这些结果强有力地证明了半导体中的双光子计数是在超短时间尺度上对光束光子相关性进行绝对测量的有力工具。
