Blazed subwavelength grating coupler

作     者：RONGXIANG GUO SHUJIAO ZHANG HAORAN GAO GANAPATHY SENTHIL MURUGAN TIEGEN LIU ZHENZHOU CHENG 

作者机构：School of Precision Instruments and Optoelectronics EngineeringTianjin UniversityTianjin 300072China Key Laboratory of Optoelectronics Information TechnologyMinistry of EducationTianjin 300072China Optoelectronics Research CentreUniversity of SouthamptonSouthampton SO171BJUK Georgia Tech-Shenzhen InstituteTianjin UniversityShenzhen 518055China Department of ChemistryThe University of TokyoTokyo 113-0033Japan 

出 版 物：《Photonics Research》 (光子学研究（英文版）)

年 卷 期：2023年第11卷第2期

页      面：189-195页

核心收录：

学科分类：080903[工学-微电子学与固体电子学] 0809[工学-电子科学与技术（可授工学、理学学位）] 08[工学] 0803[工学-光学工程] 

基　　金：National Natural Science Foundation of China(62161160335,62175179) Natural Science Foundation of Guangdong Province(2022B1515130002) 

主　　题：coupling directional grating 

摘      要：Short-wavelength mid-infrared(2–2.5 μm wave band) silicon photonics has been a growing area to boost the applications of integrated optoelectronics in free-space optical communications, laser ranging, and biochemical sensing. In this spectral region, multi-project wafer foundry services developed for the telecommunication band are easily adaptable with the low intrinsic optical absorption from silicon and silicon dioxide materials. However,light coupling techniques at 2–2.5 μm wavelengths, namely, grating couplers, still suffer from low efficiencies,mainly due to the moderated directionality and poor diffraction-field tailoring capability. Here, we demonstrate a foundry-processed blazed subwavelength coupler for high-efficiency, wide-bandwidth, and large-tolerance light coupling. We subtly design multi-step-etched hybrid subwavelength grating structures to significantly improve directionality, as well as an apodized structure to tailor the coupling strength for improving the optical mode overlap and backreflection. Experimental results show that the grating coupler has a recorded coupling efficiency of-4.53 dB at a wavelength of 2336 nm with a 3-dB bandwidth of ~107 nm. The study opens an avenue to developing state-of-the-art light coupling techniques for short-wavelength mid-infrared silicon photonics.