Peřina Jan, Haderka Ondřej, Allevi Alessia, Bondani Maria
RCPTM, Joint Laboratory of Optics of Palacký University and Inst. Phys. CAS, 17. listopadu 12, 77146 Olomouc, Czech Republic.
Institute of Physics CAS, Joint Laboratory of Optics, 17. listopadu 50a, 77146 Olomouc, Czech Republic.
Sci Rep. 2016 Feb 29;6:22320. doi: 10.1038/srep22320.
The dynamics of intense twin beams in pump-depleted parametric down-conversion is studied. A generalized parametric approximation is suggested to solve the quantum model. Its comparison with a semiclassical model valid for larger twin-beam intensities confirms its applicability. The experimentally observed maxima in the spectral and spatial intensity auto- and cross- correlation functions depending on pump power are explained in terms of different speeds of the (back-) flow of energy between the individual down-converted modes and the corresponding pump modes. This effect is also responsible for the gradual replacement of the initial exponential growth of the down-converted fields by the linear one. Furthermore, it forms a minimum in the curve giving the effective number of twin-beam modes. These effects manifest a tight relation between the twin-beam coherence and its internal structure, as clearly visible in the model. Multiple maxima in the intensity correlation functions originating in the oscillations of energy flow between the pump and down-converted modes are theoretically predicted.
研究了泵浦耗尽型参量下转换中强孪生光束的动力学。提出了一种广义参量近似来求解量子模型。将其与适用于更大孪生光束强度的半经典模型进行比较，证实了其适用性。根据能量在各个下转换模式与相应泵浦模式之间（反向）流动的不同速度，解释了实验观测到的光谱和空间强度自相关及互相关函数中依赖于泵浦功率的最大值。这种效应还导致下转换场的初始指数增长逐渐被线性增长所取代。此外，它在给出孪生光束模式有效数量的曲线上形成一个最小值。这些效应表明孪生光束的相干性与其内部结构之间存在紧密关系，这在模型中清晰可见。理论上预测了由泵浦模式与下转换模式之间能量流振荡引起的强度相关函数中的多个最大值。
