Dielectric metasurfaces can achieve strong light-matter interaction based on several types of collective(nonlocal)resonances,such as surface lattice resonances(SLRs)and quasi-bound states in the continuum(quasi-BICs)....Dielectric metasurfaces can achieve strong light-matter interaction based on several types of collective(nonlocal)resonances,such as surface lattice resonances(SLRs)and quasi-bound states in the continuum(quasi-BICs).Spectral selectivity,field enhancement,and high and controllable Q-factors make these resonances appealing for technological applications in lasing,sensing,nonlinear optics,and quantum photon sources.An emerging challenge focuses on tailoring light-matter interaction via mode coupling and hybridisation between the fundamental resonances of a metasurface.While strong coupling phenomena have been demonstrated between various resonant modes,the interplay between collective resonances of different natures has not been observed to date.Here,we theoretically,numerically,and experimentally demonstrate the onset of coupling and hybridisation between symmetry-protected quasi-BICs and SLRs in a dielectric metasurface.We show the emergence of anticrossing(or Rabi splitting)in the strong coupling regime with suppression of reflection,observed under TE-polarised excitation,and the manifestation of an accidental BIC under TM-polarised illumination as a result of energy exchange between the participating collective resonances in the weak coupling regime.The first effect is accompanied by hybridised near fields of the modes.The observed coupling mechanisms can be controlled by modifying the angle of incidence,polarisation,and the surrounding environment.This foundational study on the coupling and hybridisation of collective resonances offers insights that can be leveraged for the design of metasurfaces with targeted quasi-aBIC and collective hybridised resonances.It could also open new possibilities to control the near fields associated with such resonances,with promising applications in tunable nanophotonics and light manipulation.展开更多
Light absorption near a surface of conductive materials and nanostructures leads to the excitation of nonequilibrium,high-energy charge carriers:electrons above the Fermi level or holes below it.When remaining inside ...Light absorption near a surface of conductive materials and nanostructures leads to the excitation of nonequilibrium,high-energy charge carriers:electrons above the Fermi level or holes below it.When remaining inside a material,these so-called hot carriers result in nonlinear,Kerr-type,optical effects important for controlling light with light.They can also transfer into the surroundings of the nanostructures,resulting in photocurrent,or they can interact with adjacent molecules and media,inducing photochemical transformations.Understanding the dynamics of hot carriers and related effects in plasmonic nanostructures is important for the development of ultrafast detectors and nonlinear optical components,broadband photocatalysis,enhanced nanoscale optoelectronic devices,nanoscale and ultrafast temperature control,and other technologies of tomorrow.In this review,we will discuss the fundamentals of plasmonically-engendered hot electrons,focusing on the overlooked aspects,theoretical descriptions and experimental methods to study them,and describe prototypical processes and examples of most promising applications of hotelectron processes at the metal interfaces.展开更多
基金supported by Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany’s Excellence Strategy within the Cluster of Excellence PhoenixD(EXC 2122,Project ID 390833453)the Alexander von Humboldt Foundation,the ERC iCOMM project(789340)the UK EPSRC project EP/Y015673/1.Open Access funding enabled and organized by Projekt DEAL.
文摘Dielectric metasurfaces can achieve strong light-matter interaction based on several types of collective(nonlocal)resonances,such as surface lattice resonances(SLRs)and quasi-bound states in the continuum(quasi-BICs).Spectral selectivity,field enhancement,and high and controllable Q-factors make these resonances appealing for technological applications in lasing,sensing,nonlinear optics,and quantum photon sources.An emerging challenge focuses on tailoring light-matter interaction via mode coupling and hybridisation between the fundamental resonances of a metasurface.While strong coupling phenomena have been demonstrated between various resonant modes,the interplay between collective resonances of different natures has not been observed to date.Here,we theoretically,numerically,and experimentally demonstrate the onset of coupling and hybridisation between symmetry-protected quasi-BICs and SLRs in a dielectric metasurface.We show the emergence of anticrossing(or Rabi splitting)in the strong coupling regime with suppression of reflection,observed under TE-polarised excitation,and the manifestation of an accidental BIC under TM-polarised illumination as a result of energy exchange between the participating collective resonances in the weak coupling regime.The first effect is accompanied by hybridised near fields of the modes.The observed coupling mechanisms can be controlled by modifying the angle of incidence,polarisation,and the surrounding environment.This foundational study on the coupling and hybridisation of collective resonances offers insights that can be leveraged for the design of metasurfaces with targeted quasi-aBIC and collective hybridised resonances.It could also open new possibilities to control the near fields associated with such resonances,with promising applications in tunable nanophotonics and light manipulation.
基金UKRI EPSRC projects EP/W017075/1 and EP/Y015673/1.
文摘Light absorption near a surface of conductive materials and nanostructures leads to the excitation of nonequilibrium,high-energy charge carriers:electrons above the Fermi level or holes below it.When remaining inside a material,these so-called hot carriers result in nonlinear,Kerr-type,optical effects important for controlling light with light.They can also transfer into the surroundings of the nanostructures,resulting in photocurrent,or they can interact with adjacent molecules and media,inducing photochemical transformations.Understanding the dynamics of hot carriers and related effects in plasmonic nanostructures is important for the development of ultrafast detectors and nonlinear optical components,broadband photocatalysis,enhanced nanoscale optoelectronic devices,nanoscale and ultrafast temperature control,and other technologies of tomorrow.In this review,we will discuss the fundamentals of plasmonically-engendered hot electrons,focusing on the overlooked aspects,theoretical descriptions and experimental methods to study them,and describe prototypical processes and examples of most promising applications of hotelectron processes at the metal interfaces.
