Surface plasmon polaritons(SPPs)on metal surfaces excited by p-polarized light have long been a crucial method for achieving lightmatter interactions due to their small mode-field volumes and strong optical localizati...Surface plasmon polaritons(SPPs)on metal surfaces excited by p-polarized light have long been a crucial method for achieving lightmatter interactions due to their small mode-field volumes and strong optical localization properties.However,the significant losses generated in metals greatly limit the intensity of the SPPs and their potential application scenarios.In this paper,we leverage the high refractive index properties of two-dimensional(2D)transition metal dichalcogenides(TMDCs)to generate transverse-electric(TE)polarized waves excited by s-polarized light on the surface of gold nanofilms by accurately controlling the number of the TMDC layers and the spatial refractive index variations with the structure.Unlike the SPPs excited by p-polarized light,the TE surface waves on the surface of the gold film exhibit low loss and high quality factor(Q factor).Moreover,the difference in refractive index causes the TE surface waves to be electromagnetically separated in space,lifting the electric field component in the excited TE surface waves from the surface of the metal film into the TMDCs,thereby minimizing the ohmic loss in the metal and enabling strong coupling between the TE surface waves and the two-exciton states(A-exciton and B-exciton)in the TMDCs.Experimental results demonstrated the strong coupling of TE waves with double excitons(A-exciton and B-exciton)in multilayer MoS_(2) by exciting the Au/MoS_(2) heterostructure using a KretschmannRaether configuration,showing ultrahigh Rabi splitting up to about 310 meV.Furthermore,the number of MoS_(2) layers can be accurately determined by measuring the redshift of the Rabi splitting peak of the strong coupling spectra in the Au/MoS_(2) heterostructure.Our findings open a new avenue for manipulating strong exciton-photon coupling in 2D materials and offer a novel approach for accurately characterizing the thickness of TMDCs.展开更多
Free electron radiation,particularly Smith-Purcell radiation,provides a versatile platform for exploring lightmatter interactions and generating light sources.A fundamental characteristic of Smith-Purcell radiation is...Free electron radiation,particularly Smith-Purcell radiation,provides a versatile platform for exploring lightmatter interactions and generating light sources.A fundamental characteristic of Smith-Purcell radiation is the monotonic decrease in radiation frequency as the observation angle increases relative to the direction of the free electrons’motion,akin to the Doppler effect.Here,we demonstrate that this fundamental characteristic can be altered in Smith-Purcell radiation generated by photonic crystals with left-handed properties.Specifically,we have achieved,to our knowledge,a novel phenomenon that the lower-frequency components propagate forward,while the higher-frequency components propagate backward,which we define as reverse Smith-Purcell radiation.Additionally,this reverse Smith-Purcell radiation can confine the radiation to a narrow angular range,which provides a way to obtain broadband light sources in a specific observation angle.Furthermore,by precisely adjusting the grating geometry and the kinetic energy of the free electrons,we can control both the radiation direction and the output frequencies.Our results provide a promising platform to study unexplored light-matter interactions and open avenues to obtain tunable,broadband light sources.展开更多
基金Natural Science Foundation of Guangdong Province(2025A1515012259)National Natural Science Foundation of China(12274148,12374347,12174123).
文摘Surface plasmon polaritons(SPPs)on metal surfaces excited by p-polarized light have long been a crucial method for achieving lightmatter interactions due to their small mode-field volumes and strong optical localization properties.However,the significant losses generated in metals greatly limit the intensity of the SPPs and their potential application scenarios.In this paper,we leverage the high refractive index properties of two-dimensional(2D)transition metal dichalcogenides(TMDCs)to generate transverse-electric(TE)polarized waves excited by s-polarized light on the surface of gold nanofilms by accurately controlling the number of the TMDC layers and the spatial refractive index variations with the structure.Unlike the SPPs excited by p-polarized light,the TE surface waves on the surface of the gold film exhibit low loss and high quality factor(Q factor).Moreover,the difference in refractive index causes the TE surface waves to be electromagnetically separated in space,lifting the electric field component in the excited TE surface waves from the surface of the metal film into the TMDCs,thereby minimizing the ohmic loss in the metal and enabling strong coupling between the TE surface waves and the two-exciton states(A-exciton and B-exciton)in the TMDCs.Experimental results demonstrated the strong coupling of TE waves with double excitons(A-exciton and B-exciton)in multilayer MoS_(2) by exciting the Au/MoS_(2) heterostructure using a KretschmannRaether configuration,showing ultrahigh Rabi splitting up to about 310 meV.Furthermore,the number of MoS_(2) layers can be accurately determined by measuring the redshift of the Rabi splitting peak of the strong coupling spectra in the Au/MoS_(2) heterostructure.Our findings open a new avenue for manipulating strong exciton-photon coupling in 2D materials and offer a novel approach for accurately characterizing the thickness of TMDCs.
基金National Natural Science Foundation of China(61988102,62401113)Natural Science Foundation of Sichuan Province(25QNJJ2315)Fund of Key Laboratory of THz Technology,Ministry of Education。
文摘Free electron radiation,particularly Smith-Purcell radiation,provides a versatile platform for exploring lightmatter interactions and generating light sources.A fundamental characteristic of Smith-Purcell radiation is the monotonic decrease in radiation frequency as the observation angle increases relative to the direction of the free electrons’motion,akin to the Doppler effect.Here,we demonstrate that this fundamental characteristic can be altered in Smith-Purcell radiation generated by photonic crystals with left-handed properties.Specifically,we have achieved,to our knowledge,a novel phenomenon that the lower-frequency components propagate forward,while the higher-frequency components propagate backward,which we define as reverse Smith-Purcell radiation.Additionally,this reverse Smith-Purcell radiation can confine the radiation to a narrow angular range,which provides a way to obtain broadband light sources in a specific observation angle.Furthermore,by precisely adjusting the grating geometry and the kinetic energy of the free electrons,we can control both the radiation direction and the output frequencies.Our results provide a promising platform to study unexplored light-matter interactions and open avenues to obtain tunable,broadband light sources.
