近日，意大利布雷西亚大学Domenico de Ceglia团队研究了平面光学非线性总角动量相加的光结构。相关论文于2025年11月12日发表在《光：科学与应用》杂志上。

用平面光学器件塑造光的结构已经推动了人们对光和光物质相互作用的基本理解的重大进步，并实现了广泛的应用，从图像处理和显微镜到光通信，量子信息处理和微粒操纵。然而，超越线性光学体制的结构光的边界仍然是一个开放的挑战。非线性光学相互作用，如非线性平面光学中的波混频，提供了一个强大的平台来解锁新的自由度和功能，以产生和检测结构光。

在这项研究中，研究组通过实验证明了三次谐波光的非平凡结构是通过在非线性、各向同性的平面光学元件中添加总角动量投影而实现的，即一个非晶硅薄膜。研究组认为总角动量投影和螺旋度是分析实验结果最关键的性质。他们提出的理论方法，在数值模拟的支持下，提供了在各种泵浦条件下，包括矢量和非旁轴泵浦光下，通过非线性波混频光结构的定量预测。值得注意的是，研究组发现三次谐波光的形状对泵浦的偏振状态高度敏感。他们的发现表明，在非线性波混合中利用总角动量投影可以成为产生和检测精确控制的结构光的有力策略。

附：英文原文

Title: Light structuring via nonlinear total angular momentum addition with flat optics

Author: Menshikov, Evgenii, Franceschini, Paolo, Frizyuk, Kristina, Fernandez-Corbaton, Ivan, Tognazzi, Andrea, Cino, Alfonso Carmelo, Garoli, Denis, Petrov, Mihail, de Ceglia, Domenico, De Angelis, Costantino

Issue&Volume: 2025-11-12

Abstract: Shaping the structure of light with flat optical devices has driven significant advancements in our fundamental understanding of light and light-matter interactions, and enabled a broad range of applications, from image processing and microscopy to optical communication, quantum information processing, and the manipulation of microparticles. Yet, pushing the boundaries of structured light beyond the linear optical regime remains an open challenge. Nonlinear optical interactions, such as wave mixing in nonlinear flat optics, offer a powerful platform to unlock new degrees of freedom and functionalities for generating and detecting structured light. In this study, we experimentally demonstrate the non-trivial structuring of third-harmonic light enabled by the addition of total angular momentum projection in a nonlinear, isotropic flat optics element—a single thin film of amorphous silicon. We identify the total angular momentum projection and helicity as the most critical properties for analyzing the experimental results. The theoretical approach we propose, supported by numerical simulations, offers quantitative predictions for light structuring through nonlinear wave mixing under various pumping conditions, including vectorial and non-paraxial pump light. Notably, we reveal that the shape of third-harmonic light is highly sensitive to the polarization state of the pump. Our findings demonstrate that harnessing the addition of total angular momentum projection in nonlinear wave mixing can be a powerful strategy for generating and detecting precisely controlled structured light.

DOI: 10.1038/s41377-025-02004-8

Source: https://www.nature.com/articles/s41377-025-02004-8