论文标题
在参数非线性中观察异常轨道角动量保护
Observation of Anomalous Orbital Angular Momentum Conservation in Parametric Nonlinearity
论文作者
论文摘要
轨道角动量（OAM）保护在用非线性光学元件塑造和控制结构光方面起着重要作用。源自三波混合的光束的OAM应该是其他两个输入的总和或差异，因为在参数非线性相互作用中没有光 - 沉淀的OAM交换。在这里，我们报告了参数上转换过程中的异常OAM保护，其中Hermite-Gauss模式信号与能够在晶体中散光转化的特殊工程的泵相互作用，从而导致Laguerre-Gaussian模式总和 - 频率生成（SFG）。这里的异常指的是泵和信号在SFG时没有净绿色的事实。我们表明，丢失的绿色片段具有相反的迹象，该片段在系统中保持OAM保护的含量隐藏在残差泵中。这项意外的OAM选择规则提高了我们对参数非线性系统中的OAM保护的理解，并可能会通过非线性光学器件，尤其是在量子应用中激发了控制OAM状态的新想法。
Orbital angular momentum (OAM) conservation plays an important role in shaping and controlling structured light with nonlinear optics. The OAM of a beam originating from three-wave mixing should be the sum or difference of the other two inputs because no light-matter OAM exchange occurs in parametric nonlinear interactions. Here, we report anomalous OAM conservation during parametric upconversion, in which a Hermite-Gauss mode signal interacts with a specially engineered pump capable of astigmatic transformation in a crystal, resulting in Laguerre-Gaussian mode sum-frequency generation (SFG). The anomaly here refers to the fact that the pump and signal carry no net OAM, while their SFG does. We show that the lost OAM with the opposite sign that maintains OAM conservation in the system is hidden in the residual pump. This unexpected OAM selection rule improves our understanding of OAM conservation in parametric nonlinear systems and may inspire new ideas for controlling OAM states via nonlinear optics, especially in quantum applications.
