Yang Hao-Ran, Wu Hai-Jun, Gao Wei, Rosales-Guzmán Carmelo, Zhu Zhi-Han
Opt Lett. 2020 Jun 1;45(11):3034-3037. doi: 10.1364/OL.393146.
The Ince-Gaussian (IG) mode, a recently discovered type of structured Gaussian beam, corresponds to eigenfunctions of the paraxial wave equation in elliptical coordinates. This propagation-invariant mode is of significance in various domains, in particular, its nonlinear transformation; however, there have been few relevant studies to date. In this Letter, we report the parametric upconversion of IG modes and associated full-field selection rule for the first time, to the best of our knowledge. We demonstrate that IG signals can be perfectly upconverted by a flattop-beam pump; in contrast, significant mode distortion occurred when using the most common Gaussian pump. Particular attention was given to the origin of the distortion, i.e., radial-mode degeneration induced by the sum-frequency generation excited by a Gaussian pump. This proof-of-principle demonstration has great significance in relevant areas, such as high-dimensional quantum frequency interfacing and upconversion imaging.
因斯-高斯（IG）模式是最近发现的一种结构化高斯光束，它对应于椭圆坐标下傍轴波动方程的本征函数。这种传播不变模式在各个领域都具有重要意义，特别是其非线性变换；然而，迄今为止相关研究较少。据我们所知，在本信函中，我们首次报道了IG模式的参量上转换及相关的全场选择规则。我们证明，平顶光束泵浦可以使IG信号完美地上转换；相比之下，使用最常见的高斯泵浦时会出现明显的模式畸变。特别关注了畸变的起源，即高斯泵浦激发的和频产生所导致的径向模式简并。这种原理验证演示在高维量子频率接口和上转换成像等相关领域具有重要意义。
