近日，中山大学的董建文&何辛涛及其研究小组与上海交通大学的苏翼凯等人合作并取得一项新进展。经过不懈努力，他们成功研制出具有拓扑谷边缘模式的宽带及制造容差3db耦合器。相关研究成果已于2024年7月16日在国际知名学术期刊《光：科学与应用》上发表。

据悉，3db耦合器通常用于片上信息处理、精密测量和量子计算的光子集成电路中，由于其有限的3db带宽和对制造误差的敏感性，在实现鲁棒性能方面面临挑战。

为了解决这个问题，该研究团队将拓扑物理学引入纳米光子学，开发出拓扑3db耦合器的框架。这些耦合器具有宽的工作波长范围和抗制造尺寸误差的鲁棒性。研究人员通过利用谷-霍尔拓扑和镜面对称性，在光子晶体-平板耦合器中实现了理想的3db分裂，其特征是波长不敏感的散射矩阵。容差分析证实了其在48nm宽带宽和20nm尺寸误差下的鲁棒分裂方面的优势。

研究人员进一步提出了一种用于片上距离测量的拓扑干涉仪，它对尺寸误差也具有鲁棒性。将拓扑原理扩展到干涉仪领域，可能为构建鲁棒的波分复用、温度漂移不敏感传感和光学相干层析成像应用开辟新的可能性。

附：英文原文

Title: Broadband and fabrication-tolerant 3-dB couplers with topological valley edge modes

Author: Tang, Guo-Jing, Chen, Xiao-Dong, Sun, Lu, Guo, Chao-Heng, Li, Meng-Yu, Tian, Zhong-Tao, Chen, Hou-Hong, Wang, Hong-Wei, Sun, Qi-Yao, Pan, Ying-Di, He, Xin-Tao, Su, Yi-Kai, Dong, Jian-Wen

Issue&Volume: 2024-07-16

Abstract: 3-dB couplers, which are commonly used in photonic integrated circuits for on-chip information processing, precision measurement, and quantum computing, face challenges in achieving robust performance due to their limited 3-dB bandwidths and sensitivity to fabrication errors. To address this, we introduce topological physics to nanophotonics, developing a framework for topological 3-dB couplers. These couplers exhibit broad working wavelength range and robustness against fabrication dimensional errors. By leveraging valley-Hall topology and mirror symmetry, the photonic-crystal-slab couplers achieve ideal 3-dB splitting characterized by a wavelength-insensitive scattering matrix. Tolerance analysis confirms the superiority on broad bandwidth of 48nm and robust splitting against dimensional errors of 20nm. We further propose a topological interferometer for on-chip distance measurement, which also exhibits robustness against dimensional errors. This extension of topological principles to the fields of interferometers, may open up new possibilities for constructing robust wavelength division multiplexing, temperature-drift-insensitive sensing, and optical coherence tomography applications.

DOI: 10.1038/s41377-024-01512-3

Source: https://www.nature.com/articles/s41377-024-01512-3