Terahertz bound states in the continuum with incident angle robustness induced by a dual period metagrating

作     者：Wenqiao Shi Jianqiang Gu Xingyuan Zhang Quan Xu Jiaguang Han Quanlong Yang Longqing Cong Weili Zhang WENQIAO SHI;JIANQIANG GU;XINGYUAN ZHANG;QUAN XU;JIAGUANG HAN;QUANLONG YANG;LONGQING CONG;WEILI ZHANG

作者机构：Center for Terahertz Waves and College of Precision Instrument and Optoelectronics EngineeringTianjin Universityand Key Laboratory of Optoelectronics Information and TechnologyMinistry of EducationTianjin 300072China Nonlinear Physics CentreAustralian National UniversityCanberraACT 2601Australia Department of Electrical and Electronic EngineeringSouthern University of Science and TechnologyShenzhen 518055China School of Electrical and Computer EngineeringOklahoma State UniversityStillwaterOklahoma 74078USA 

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

年 卷 期：2022年第10卷第3期

页      面：810-819页

核心收录：

学科分类：0809[工学-电子科学与技术（可授工学、理学学位）] 08[工学] 0702[理学-物理学] 

基　　金：National Science Foundation(ECCS-1232081) China Postdoctoral Science Foundation(2020TQ0224) National Natural Science Foundation of China(61975143,62005193,62027820). 

主　　题：incident dielectric continuum 

摘      要：Metasurface-empowered bound state in the continuum(BIC)provides a unique route for fascinating functional devices with infinitely high quality factors.This method is particularly attractive to the terahertz community because it may essentially solve the deficiencies in terahertz filters,sensors,lasers,and nonlinear sources.However,most BIC metasurfaces are limited to specified incident angles that seriously dim their application prospects.Here,we propose that a dual-period dielectric metagrating can support multiple families of BICs that originate from guided mode resonances in the dielectric grating and exhibit infinite quality factors at arbitrarily tilted incidence.This robustness was analyzed based on the Bloch theory and verified at tilted incident angles.We also demonstrate that inducing geometric asymmetry is an efficient way to manipulate the leakage and coupling of these BICs,which can mimic the electromagnetically induced transparency(EIT)effect in our dual-period metagrating.In this demonstration,a slow-light effect with a measured group delay of 117 ps was achieved.The incidence-insensitive BICs proposed here may greatly extend the application scenarios of the BIC effect.The high Q factor and outstanding slow-light effect in the metagrating show exciting prospects in realizing high-performance filters,sensors,and modulators for prompting terahertz applications.