Compact and low-loss on-chip silicon crossing based on subwavelength grating slot waveguides

作     者：Zhu, Jiabao Yu, Qianli Jin, Yuelong Huang, Chongjia Guo, Zhenzhao Hao, Peng Xiao, Jinbiao Wu, Shengbao 

作者机构：Hebei Univ Coll Phys Sci & Technol Photon Informat Innovat Ctr Hebei Prov Ctr Opt Sensing Innovat Baoding 071002 Peoples R China Fuzhou Univ Sch Phys & Informat Engn Inst Micro Nano Devices & Solar Cells Fuzhou 350108 Peoples R China Southeast Univ Sch Elect Sci & Engn Natl Res Ctr Opt Sensing Commun Integrated Network Nanjing 210096 Peoples R China 

出 版 物：《OPTICS EXPRESS》 (Opt. Express)

年 卷 期：2025年第33卷第3期

页      面：4902-4914页

核心收录：

学科分类：070207[理学-光学] 07[理学] 08[工学] 0803[工学-光学工程] 0702[理学-物理学] 

基　　金：National Natural Science Foundation of China [12004092, 62375050] Interdisciplinary Research Program of Natural Science of Hebei University [DXK202204] Natural Science Foundation of Hebei Province [F2024201002] Research Start-up Foundation of Hebei University 

主　　题：Effective refractive index Finite-difference time-domain method Mode division multiplexing Slot waveguides Subwavelength gratings Waveguide gratings 

摘      要：We propose and experimentally demonstrate a compact crossing based on a sub- wavelength grating slot waveguide (SWG-SW), leveraging the anisotropic properties of two orthogonal SWG-SWs to suppress diffraction effects in the crossing region for the input TE polarization mode. The design utilizes the unique mode characteristics of the SWG-SW, enabling low-loss mode transitions through the crossing with a simple and compact hollow structure design at its center. By integrating the above crossing with a well-designed slot-to-SWG-SW mode converter, a crossing for the widely used slot waveguides is achieved, with a footprint of similar to 18x18 mu m2. Simulation results show that the device achieves an insertion loss (IL) of 0.35 dB and a crosstalk (CT) of -40 dB over a bandwidth range of 1500-1600 nm. Experimental results confirm that within the wavelength range of 1500-1580 nm, the IL is approximately 0.4 dB, and CT values are below-28 dB. To further improve the device performance, additional side grating arrays are incorporated into the design. The optimized structure with side gratings achieves IL of 0.13 dB and CT values around-35 dB. Experimental measurements of the device with side gratings demonstrate a stable IL of approximately 0.1 dB and CT values consistently below-35 dB, marking a significant improvement over the original design. To the best of our knowledge, this is the first experimentally verified crossing for slot waveguides. Further analysis indicates that the device exhibits an exceptionally broad bandwidth of approximately 576 nm (1257 nm to 1833nm) with IL 1 dB and CT -30 dB. (c) 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement