We report on ultrafast all-optical switching experiments performed on pillar microcavities containing a collection of quantum dots (QDs). Using QDs as a broadband internal light source and a detection setup based on a streak camera, we track in parallel the frequencies of a large set (>10) of resonant modes of an isolated micropillar during the entire duration of switching events and with a 2 ps temporal resolution. Being much faster and more convenient than standard approaches based on pump–probe spectroscopy, this method is very well suited for in-depth studies of cavity switching, noticeably in view of applications in the field of quantum photonics. We report as a first demonstrative example an investigation of the switch-on time constant τ_on dependence as a function of the pump power and the observation of a remarkably low value of τ_on(≈1.5 ps) for optimized pumping conditions. As a second illustration, we report the observation of a transient lifting of the degeneracy of a polarization-degenerate cavity mode, induced by a non-centrosymmetric injection of free carriers.

中文翻译：

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使用量子点作为宽带内部荧光源，在皮秒时间尺度上探测微腔切换事件

我们报告了在包含量子点（QD）集合的支柱微腔上执行的超快全光切换实验。使用QD作为宽带内部光源和基于条纹相机的检测设置，我们在开关事件的整个过程中并行跟踪孤立微柱的一大组（> 10）共振模式的频率，并使用2 ps时间分辨率。这种方法比基于泵浦-探针光谱的标准方法要快得多，也更方便，非常适合于腔体转换的深入研究，尤其是在量子光子学领域的应用方面。作为第一个说明性示例，我们报告了接通时间常数τon的调查_。依赖性泵浦功率的函数的和显着低的值的观测τ_上（≈1.5PS）优化泵送的条件。作为第二个说明，我们报告了由自由载流子的非中心对称注入引起的极化简并腔模简并性的短暂提升的观察结果。