Bound states in the continuum(BICs)have gained considerable attention for their ability to strengthen light-matter interactions,enabling applications in lasing,sensing,and imaging.These properties also show great prom...Bound states in the continuum(BICs)have gained considerable attention for their ability to strengthen light-matter interactions,enabling applications in lasing,sensing,and imaging.These properties also show great promise for intensifying free-electron radiation.Recently,researchers realized momentum-mismatch-driven quasi-BICs in compound grating waveguides.This category of quasi-BICs exhibits high Q factors over a broad frequency spectrum.In this paper,we explore the possibility of achieving multi-frequency terahertz Smith-Purcell radiation empowered by momentum-mismatch-driven quasi-BICs in silicon compound grating waveguides.By leveraging the low-loss properties of silicon in the terahertz range,quasi-BICs are achieved through guided-mode resonance,delivering exceptionally high Q factors over a broad frequency spectrum.The broadband nature of these quasi-BICs enables efficient energy extraction from electron beams across varying voltages,while their multimode characteristics support simultaneous interactions with multiple modes,further boosting radiation intensity.The findings demonstrate significant enhancement of free-electron radiation at multiple frequencies,addressing the limitations of narrowband methods and high-loss metallic systems.By integrating broadband performance with the advantages of low-loss dielectric platforms,this work advances the development of compact,tunable terahertz free-electron radiation sources and provides valuable insights into optimizing quasi-BIC systems for practical applications.展开更多
Surface-Enhanced Raman Scattering(SERS)integrated with optical waveguide sensing offers a transformative approach to overcoming the limitations of conventional SERS techniques,such as complex alignment requirements an...Surface-Enhanced Raman Scattering(SERS)integrated with optical waveguide sensing offers a transformative approach to overcoming the limitations of conventional SERS techniques,such as complex alignment requirements and limited signal collection efficiency.By leveraging the unique properties of optical waveguides,this integration significantly enhances detection sensitivity,simplifies sensor design,and enables the analysis of ultra-low concentration analytes in trace-volume samples.This review explores the latest advancements in combining diverse optical waveguide architectures with SERS technology,focusing on strategies to optimize the sensing interface and SERS substrate design for maximal Raman signal enhancement.By enabling efficient analyte excitation and enhanced scattered signal collection through waveguide-mediated light-matter interactions,this approach unlocks new possibilities for high-sensitivity Raman detection.Furthermore,we discuss the potential of this integration to drive breakthroughs in fields such as biomedical diagnostics,environmental monitoring,and chemical sensing,paving the way for next-generation,portable and ultra-sensitive sensing platforms.展开更多
基金National Natural Science Foundation of China(62271011,U21A20458)National Key R&D Program of China(2021YFA1600302)Beijing Science Foundation for Distinguished Young Scholars(JQ21011)。
文摘Bound states in the continuum(BICs)have gained considerable attention for their ability to strengthen light-matter interactions,enabling applications in lasing,sensing,and imaging.These properties also show great promise for intensifying free-electron radiation.Recently,researchers realized momentum-mismatch-driven quasi-BICs in compound grating waveguides.This category of quasi-BICs exhibits high Q factors over a broad frequency spectrum.In this paper,we explore the possibility of achieving multi-frequency terahertz Smith-Purcell radiation empowered by momentum-mismatch-driven quasi-BICs in silicon compound grating waveguides.By leveraging the low-loss properties of silicon in the terahertz range,quasi-BICs are achieved through guided-mode resonance,delivering exceptionally high Q factors over a broad frequency spectrum.The broadband nature of these quasi-BICs enables efficient energy extraction from electron beams across varying voltages,while their multimode characteristics support simultaneous interactions with multiple modes,further boosting radiation intensity.The findings demonstrate significant enhancement of free-electron radiation at multiple frequencies,addressing the limitations of narrowband methods and high-loss metallic systems.By integrating broadband performance with the advantages of low-loss dielectric platforms,this work advances the development of compact,tunable terahertz free-electron radiation sources and provides valuable insights into optimizing quasi-BIC systems for practical applications.
基金National Natural Science Foundation of China(42406182)the China Postdoctoral Science Foundation Funded Project(GZC20232979)+3 种基金Jilin Postdoctoral Merit Funding Programthe China Postdoctoral Science Foundation Funded Project(2023TQ0369)the National Natural Science Foundation of China(42327805)the National Natural Science Foundation of China(62205091).
文摘Surface-Enhanced Raman Scattering(SERS)integrated with optical waveguide sensing offers a transformative approach to overcoming the limitations of conventional SERS techniques,such as complex alignment requirements and limited signal collection efficiency.By leveraging the unique properties of optical waveguides,this integration significantly enhances detection sensitivity,simplifies sensor design,and enables the analysis of ultra-low concentration analytes in trace-volume samples.This review explores the latest advancements in combining diverse optical waveguide architectures with SERS technology,focusing on strategies to optimize the sensing interface and SERS substrate design for maximal Raman signal enhancement.By enabling efficient analyte excitation and enhanced scattered signal collection through waveguide-mediated light-matter interactions,this approach unlocks new possibilities for high-sensitivity Raman detection.Furthermore,we discuss the potential of this integration to drive breakthroughs in fields such as biomedical diagnostics,environmental monitoring,and chemical sensing,paving the way for next-generation,portable and ultra-sensitive sensing platforms.
