Wiersig J, Gies C, Jahnke F, Assmann M, Berstermann T, Bayer M, Kistner C, Reitzenstein S, Schneider C, Höfling S, Forchel A, Kruse C, Kalden J, Hommel D
Physics Department, University of Bremen, 28334 Bremen, Germany.
Nature. 2009 Jul 9;460(7252):245-9. doi: 10.1038/nature08126.
Lasers are recognized for coherent light emission, the onset of which is reflected in a change in the photon statistics. For many years, attempts have been made to directly measure correlations in the individual photon emission events of semiconductor lasers. Previously, the temporal decay of these correlations below or at the lasing threshold was considerably faster than could be measured with the time resolution provided by the Hanbury Brown/Twiss measurement set-up used. Here we demonstrate a measurement technique using a streak camera that overcomes this limitation and provides a record of the arrival times of individual photons. This allows us to investigate the dynamical evolution of correlations between the individual photon emission events. We apply our studies to micropillar lasers with semiconductor quantum dots as the active material, operating in the regime of cavity quantum electrodynamics. For laser resonators with a low cavity quality factor, Q, a smooth transition from photon bunching to uncorrelated emission with increasing pumping is observed; for high-Q resonators, we see a non-monotonic dependence around the threshold where quantum light emission can occur. We identify regimes of dynamical anti-bunching of photons in agreement with the predictions of a microscopic theory that includes semiconductor-specific effects.
激光以其相干光发射而闻名，其产生反映在光子统计特性的变化上。多年来，人们一直试图直接测量半导体激光器单个光子发射事件中的相关性。此前，这些相关性在低于或处于激光阈值时的时间衰减速度比使用汉伯里·布朗/特威斯测量装置所能提供的时间分辨率要快得多。在此，我们展示了一种使用条纹相机的测量技术，该技术克服了这一限制，并记录了单个光子的到达时间。这使我们能够研究单个光子发射事件之间相关性的动态演化。我们将研究应用于以半导体量子点作为有源材料的微柱激光器，其工作在腔量子电动力学 regime 下。对于腔品质因数 Q 较低的激光谐振器，观察到随着泵浦增加，从光子聚束到不相关发射的平滑转变；对于高 Q 谐振器，我们在量子光发射可能发生的阈值附近看到非单调依赖性。我们确定了光子动态反聚束的 regime，这与包含半导体特定效应的微观理论预测一致。
