Elongated plasmonic nanoparticles have been extensively explored over the past two decades.However,in comparison with the dipolar plasmon mode that has attracted the most interest,much less attention has been paid to ...Elongated plasmonic nanoparticles have been extensively explored over the past two decades.However,in comparison with the dipolar plasmon mode that has attracted the most interest,much less attention has been paid to multipolar plasmon modes because they are usually thought to be“dark modes”,which are unable to interact with farfield light efficiently.Herein,we report on an intriguing far-field scattering phenomenon,colour routing,based on longitudinal multipolar plasmon modes supported by high-aspect-ratio single Ag nanorods.Taking advantage of the distinct far-field behaviours of the odd and even multipolar plasmon modes,we demonstrate two types of colour routing,where the incident white light can be scattered into several beams with different colours as well as different propagation directions.Because of the narrow linewidths of the longitudinal multipolar plasmon modes,there is little spectral overlap between the adjacent peaks,giving rise to outstanding colour selectivity.Our experimental results and theoretical model provide a simple yet effective picture for understanding the far-field behaviour of the longitudinal multipolar plasmon modes and the resultant colour routing phenomenon.Moreover,the outstanding colour routing capability of the high-aspect-ratio Ag nanorods enables nanoscale optical components with simple geometries for controlling the propagation of light below the diffraction limit of light.展开更多
基金financial support from the Hong Kong Research Grants Council(General Research Fund,14306817)a joint grant between the Chinese Academy of Engineering Physics and the National Natural Science Foundation of China(NSAF,U1530401)the National Natural Science Foundation of China(91630313).
文摘Elongated plasmonic nanoparticles have been extensively explored over the past two decades.However,in comparison with the dipolar plasmon mode that has attracted the most interest,much less attention has been paid to multipolar plasmon modes because they are usually thought to be“dark modes”,which are unable to interact with farfield light efficiently.Herein,we report on an intriguing far-field scattering phenomenon,colour routing,based on longitudinal multipolar plasmon modes supported by high-aspect-ratio single Ag nanorods.Taking advantage of the distinct far-field behaviours of the odd and even multipolar plasmon modes,we demonstrate two types of colour routing,where the incident white light can be scattered into several beams with different colours as well as different propagation directions.Because of the narrow linewidths of the longitudinal multipolar plasmon modes,there is little spectral overlap between the adjacent peaks,giving rise to outstanding colour selectivity.Our experimental results and theoretical model provide a simple yet effective picture for understanding the far-field behaviour of the longitudinal multipolar plasmon modes and the resultant colour routing phenomenon.Moreover,the outstanding colour routing capability of the high-aspect-ratio Ag nanorods enables nanoscale optical components with simple geometries for controlling the propagation of light below the diffraction limit of light.
