近日，美国宾夕法尼亚大学的Liang Feng及其研究团队取得一项新进展。经过不懈努力，他们实现非厄米混合硅光子切换。相关研究成果已于2025年1月2日在国际知名学术期刊《自然—光子学》上发表。
本文通过III-V族/硅混合集成技术，在双层集成光子芯片上实现了一个可扩展的非厄米切换网络。该平台采用混合结构，底层为硅层，顶层为提供光学增益的InGaAsP层。通过调节顶层的增益水平，垂直耦合波导在异常点上下工作，实现光在两层之间以及不同输入输出端口之间的切换。
对于单个切换单元，切换动力学是超快的，时间在100皮秒量级。在大型切换网络中，单波长和波长选择切换均实现了无阻塞和其他多种连接，且具有高消光比。这一方法将可扩展的非厄米切换添加到光子设计工具包中，同时将切换时间和带宽密度提升到前沿水平，从而为下一代光学信息网络中实现紧凑、超快的单片集成硅光子学铺平了道路。
据悉，非厄米光子学利用复介电常数的全空间，从根本上改变了具有复杂光学势的波传播特性，并催生了一系列新的光子学应用。通过宇称-时间对称性及其破缺（即增益与损耗之间的微妙相互作用），即便仅是两个实体之间的相互作用也变得反直觉且有趣。
附：英文原文
Title: Non-Hermitian hybrid silicon photonic switching
Author: Feng, Xilin, Wu, Tianwei, Gao, Zihe, Zhao, Haoqi, Wu, Shuang, Zhang, Yichi, Ge, Li, Feng, Liang
Issue&Volume: 2025-01-02
Abstract: Leveraging the entire space of complex dielectric permittivity, non-Hermitian photonics has fundamentally altered wave propagation with complex optical potentials and has ushered in a host of new photonic applications. Through parity–time symmetry and its breaking—a delicate interplay between gain and loss—even the interaction between just two entities becomes counter-intuitive and intriguing. Here we realize, through hybrid III–V/Si integration, a scalable non-Hermitian switching network on a two-layer integrated photonic chip. Our platform is a hybrid, with a bottom silicon layer and a top InGaAsP layer that provides optical gain. By tuning the gain level in the top layer, vertically coupled waveguides operate below or above the exceptional point, where light is switched across two layers, among different input–output ports. For a single switching unit, the switching dynamics are ultrafast, on the order of 100ps. In a large switching network, non-blocking and other diverse connectivities are established in single-wavelength and wavelength-selective switching, with high extinction ratios. Our approach adds scalable non-Hermitian switching to photonic design toolkits to simultaneously boost the switching time and bandwidth density to cutting-edge levels, therefore paving the way for compact and ultrafast monolithic integrated silicon photonics in next-generation optical information networks.
DOI: 10.1038/s41566-024-01579-9
Source: https://www.nature.com/articles/s41566-024-01579-9