华中科技大学张金伟团队近日实现了锁模准频率简并激光产生飞秒多边形光学涡流。2025年6月23日出版的《光：科学与应用》杂志发表了这项成果。

多边形光学涡旋是光学涡旋的一个新子集，由于提供了新的自由度和可定制的光强结构，它独特地实现了众多应用。到目前为止，它们的产生只被报道为连续波。研究组演示了第一个飞秒多边形光学涡旋脉冲，这也是第一个对这种涡旋进行脉冲演示。 

从锁模Yb:KGW激光振荡器中，产生了准频率简并态的飞秒厄米-高斯脉冲，随后通过像散模式转换将其转换为飞秒多边形光学涡旋。它们具有方形、五边形和六边形的光强分布，并携带轨道角动量。在所有这些变化中，平均功率和脉冲持续时间分别大于1瓦，小于500 fs。这些结果为飞秒光镊和三维微结构制造领域的新应用开辟了道路。

附：英文原文

Title: Generation of femtosecond polygonal optical vortices from a mode-locked quasi-frequency-degenerate laser

Author: Liu, Hongyu, Yan, Lisong, Wang, Liang, Li, Dongfang, Zhang, Shenao, Liu, Xin, Liu, Heyan, Dai, Kunjian, Wang, Qing, Zhang, Jinwei

Issue&Volume: 2025-06-23

Abstract: Polygonal optical vortices—a new subset of optical vortices—uniquely enable numerous applications due to the new degrees of freedom offered and their customizable light intensity structure. So far, their generation has only been reported for continuous wave. Here, we demonstrate the first femtosecond polygonal optical vortex pulses, which is also the first pulsed demonstration of such vortices in general. From a mode-locked Yb:KGW laser oscillator, femtosecond Hermit-Gaussian pulses at the quasi-frequency-degenerate state were generated and subsequently converted by astigmatic mode conversion to femtosecond polygonal optical vortices. They have light intensity distributions of square, pentagonal, and hexagonal shapes and carry orbital angular momentums. In all these variations, the average power and pulse duration are greater than one watt and less than 500fs. These results open the way to new applications in the fields of femtosecond optical tweezer and three-dimensional microstructure fabrication.

DOI: 10.1038/s41377-025-01902-1

Source: https://www.nature.com/articles/s41377-025-01902-1