Opt Lett. 2018 Dec 15;43(24):6101-6104. doi: 10.1364/OL.43.006101.
We propose and demonstrate a simple and easy-to-implement projective-measurement protocol to determine the radial index p of a Laguerre-Gaussian (LGpl) mode. Our method entails converting any specified high-order LGp0 mode into a near-Gaussian distribution that matches the fundamental mode of a single-mode fiber (SMF) through the use of two phase screens (unitary transforms) obtained by applying a phase-retrieval algorithm. The unitary transforms preserve the orthogonality of modes before the SMF and guarantee that our protocol can, in principle, be free of crosstalk. We measure the coupling efficiency of the transformed radial modes to the SMF for different pairs of phase screens. Because of the universality of phase-retrieval methods, we believe that our protocol provides an efficient way of fully characterizing the radial spatial profile of an optical field.
我们提出并演示了一种简单易行的投影测量协议，用于确定拉盖尔-高斯（LGpl）模式的径向指数 p。我们的方法包括通过使用通过应用相位检索算法获得的两个相位屏（幺正变换），将任何指定的高阶 LGp0 模式转换为接近高斯分布的模式，该模式与单模光纤（SMF）的基本模式匹配。幺正变换在进入 SMF 之前保持模式的正交性，并保证我们的协议原则上可以没有串扰。我们测量了不同相位屏对变换后的径向模式与 SMF 的耦合效率。由于相位检索方法的普遍性，我们相信我们的协议提供了一种有效方法来完全描述光场的径向空间分布。
