We present a new method for the spectral characterization of pulsed twin-beam sources in the high-gain regime, using cascaded stimulated emission. We show an implementation of this method for a periodically poled potassium titanyl phosphate spontaneous parametric down-conversion source generating up to 60 photon pairs per pulse, and we demonstrate excellent agreement between our experiments and our theory. This work enables the complete and accurate experimental characterization of high-gain effects in parametric down-conversion, including self- and cross-phase modulation. Moreover, our theory allows the exploration of designs with the goal of improving the specifications of twin-beam sources for application in quantum information, computation, sampling, and metrology.

中文翻译：

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使用级联受激发射来了解高增益双光束源

我们提出了一种新方法，用于级联受激发射，在高增益状态下脉冲双光束源的光谱表征。我们展示了这种方法对周期性极化的钛氧基磷酸氧钛钾自发参量下转换源的实现，每个脉冲产生多达60个光子对，并且证明了我们的实验与理论之间的出色一致性。这项工作可以对参数下变频中的高增益效应进行完整而准确的实验表征，包括自相位和交叉相位调制。此外，我们的理论允许探索设计，目的是提高双束光源的规格，以用于量子信息，计算，采样和计量。