近日，德国慕尼黑大学的Stefan A.Maier及其研究小组与澳大利亚莫纳什大学的Haoran Ren等人合作并取得一项新进展。经过不懈努力，他们通过亚线性色散实现声子极化子轨道角动量的倍增。相关研究成果已于2024年4月2日在国际知名学术期刊《自然—光子学》上发表。

据悉，光涡旋(OVs)有望通过轨道角动量复用极大地提高光信息容量。对轨道角动量技术片上集成的需求，促进了对亚波长受限极化子光涡旋的研究。然而，用于从自由空间光束转导到表面极化的结构所印迹的拓扑序，在制造后本质上是固定的。

该研究团队通过色散驱动的拓扑电荷倍增克服了这一限制。研究人员利用低损耗表面声子极化子在碳化硅膜上的强亚线性色散，在小频率范围内(约3%)切换OV拓扑电荷。研究人员应用惠更斯原理，定量评价了近场成像检测到的实验光涡旋的拓扑序。他们进一步探索了氘核效应，该效应预测了高阶极化子OVs中多重拓扑电荷的共存。这项研究工作展示了一种可行的方法来操纵极化OVs的拓扑电荷，为探索中红外频率下新的轨道角动量光物质相互作用铺平了道路。

附：英文原文

Title: Multiplication of the orbital angular momentum of phonon polaritons via sublinear dispersion

Author: Mancini, Andrea, Nan, Lin, Bert, Rodrigo, Corts, Emiliano, Ren, Haoran, Maier, Stefan A.

Issue&Volume: 2024-04-02

Abstract: Optical vortices (OVs) promise to greatly enhance optical information capacity via orbital angular momentum multiplexing. The need for the on-chip integration of orbital angular momentum technologies has prompted research into subwavelength-confined polaritonic OVs. However, the topological order imprinted by the structure used for transduction from free-space beams to surface polaritons is inherently fixed after fabrication. Here we overcome this limitation via dispersion-driven topological charge multiplication. We switch the OV topological charge within a small frequency range (~3%) by leveraging the strong sublinear dispersion of low-loss surface phonon polaritons on silicon carbide membranes. Applying the Huygens principle, we quantitatively evaluate the topological order of experimental OVs detected by near-field imaging. We further explore the deuterogenic effect, which predicts the coexistence of multiple topological charges in higher-order polaritonic OVs. Our work demonstrates a viable method to manipulate the topological charge of polaritonic OVs, paving the way for the exploration of novel orbital-angular-momentum-enabled light–matter interactions at mid-infrared frequencies.

DOI: 10.1038/s41566-024-01410-5

Source: https://www.nature.com/articles/s41566-024-01410-5