Structured light, where complex optical fields are tailored in all their degrees of freedom, has become highly topical of late, advanced by a sophisticated toolkit comprising both linear and nonlinear optics. Removing undesired structure from light is far less developed, leveraging mostly on inverting the distortion, e.g., with adaptive optics or the inverse transmission matrix of a complex channel, both requiring that the distortion be fully characterized through appropriate measurement. We show that distortions in spatially structured light can be corrected through difference-frequency generation in a nonlinear crystal without any need for the distortion to be known. We demonstrate the versatility of our approach using a wide range of aberrations and structured light modes, including higher-order orbital angular momentum (OAM) beams, showing excellent recovery of the original undistorted field. To highlight the efficacy of this process, we deploy the system in a prepare-and-measure communications link with OAM, showing minimal cross talk even when the transmission channel is highly aberrated, and outline how the approach could be extended to alternative experimental modalities and nonlinear processes. Our demonstration of light-correcting light without the need for measurement opens an approach to measurement-free error correction for classical and quantum structured light, with direct applications in imaging, sensing, and communication.

回顾了非线性光学激光合束技术的发展历程，阐述了基于光学相位共轭和基于非线性放大过程的合束思想和基本原理，梳理了重叠耦合、种子注入和布里渊四波混频增强相位锁定激光合束方式的标志性成果，总结了等离子体交叉光束能量转移、金刚石拉曼放大和液体布里渊放大激光合束技术的优势和瓶颈。面向高峰值功率、高平均功率、高重复频率激光输出的实现需求，基于布里渊放大激光合束技术具备系统结构简单、功率负载高且散热效率高的优点，提出了实现单脉冲能量100 J、脉冲宽度10 ns、重复频率10 Hz合束激光输出的可行性方案。