We review recent studies of cavity switching induced by the optical injection of free carriers in micropillar cavities containing quantum dots. Using the quantum dots as a broadband internal light source and a streak camera as detector, we track the resonance frequencies for a large set of modes with picosecond time resolution. We report a record-fast switch-on time constant (1.5 ps) and observe major transient modifications of the modal structure of the micropillar on the 10 ps time scale: mode crossings are induced by a focused symmetric injection of free carriers, while a lifting of several mode degeneracies is observed when off-axis injection breaks the rotational symmetry of the micropillar. We show theoretically and experimentally that cavity switching can be used to tailor the dynamic properties of the coupled QD–cavity system. We report the generation of ultrashort spontaneous emission pulses (as short as 6 ps duration) by a collection of frequency-selected QDs in a switched pillar microcavity. These pulses display a very small coherence length, attractive for ultrafast speckle-free imaging. Moreover, the control of QD-mode coupling on the 10 ps time scale establishes cavity switching as an appealing resource for quantum photonics.

我们回顾了最近对包含量子点的微柱腔中自由载流子的光学注入引起的腔切换的研究。使用量子点作为宽带内部光源和条纹相机作为检测器，我们以皮秒时间分辨率跟踪大量模式的共振频率。我们报告了创纪录的快速开启时间常数 (1.5 ps) 并观察了微柱模态结构在 10 ps 时间尺度上的主要瞬态变化：模式交叉是由自由载流子的聚焦对称注入引起的，而提升当离轴注射破坏微柱的旋转对称性时，观察到几种模式简并。我们从理论上和实验上表明，腔切换可用于定制耦合 QD 腔系统的动态特性。我们报告了通过开关柱微腔中的频率选择 QD 集合产生的超短自发发射脉冲（持续时间短至 6 ps）。这些脉冲显示出非常小的相干长度，对超快无斑点成像很有吸引力。此外，在 10 ps 时间尺度上控制 QD 模式耦合使腔开关成为量子光子学的有吸引力的资源。