近日，美国耶鲁大学Cao, Hui团队研究了基于时空对称映射的耗散非线性多模放大器输出控制。这一研究成果发表在2025年4月1日出版的《自然—物理学》杂志上。

在许多线性和非线性系统中，时间反演对称性使得通过适当地整形输入波来控制输出波成为可能。然而，在具有能量耗散的系统中，时间反转对称性被打破，因此需要采用不同的方法来关联输入和输出场。

研究组从理论上考虑了一种饱和多模光纤放大器，其中光产生热流并遭受热光非线性，从而破坏了时间反演对称性。他们识别出一种时空对称性，将目标输出映射回输入字段。这种时空对称映射应用相位共轭、增益和吸收替代，但不应用时间反转，并且它在稳态和缓慢变化的输入下保持不变。该方法能够实现非线性耗散系统的相干波前控制。

附：英文原文

Title: Output control of dissipative nonlinear multimode amplifiers using spacetime symmetry mapping

Author: Chen, Chun-Wei, Wisal, Kabish, Fink, Mathias, Stone, A. Douglas, Cao, Hui

Issue&Volume: 2025-04-01

Abstract: In many linear and nonlinear systems, time-reversal symmetry makes it possible to control the output waves by appropriately shaping the input waves. However, time-reversal symmetry is broken in systems with energy dissipation, necessitating a different approach for relating the input and output fields. We theoretically consider a saturated multimode fibre amplifier in which light generates a heat flow and suffers thermo-optical nonlinearity, thus breaking time-reversal symmetry. We identify a spacetime symmetry that maps the target output back to an input field. This spacetime symmetry mapping applies phase conjugation, gain and absorption substitution but not time reversal, and it holds in a steady state and for slowly varying inputs. Our approach enables coherent wavefront control of nonlinear dissipative systems.

DOI: 10.1038/s41567-025-02853-5

Source: https://www.nature.com/articles/s41567-025-02853-5