This study is to report a ZnSe quantum dot with a large two-photon absorption cross section and good biocompatibility,which can be used in bioimaging.Fluorescence emission at 410 nm is observed in the quantum dot unde...This study is to report a ZnSe quantum dot with a large two-photon absorption cross section and good biocompatibility,which can be used in bioimaging.Fluorescence emission at 410 nm is observed in the quantum dot under 760-nm laser excitation.These biocompatible quantum dots exhibit a two-photon cross-section of 9.1×105 GM(1 GM=10-50 cm4·s/photon).Two-photon excited laser scanning microscopic images show that cells co-cultured with ZnSe quantum dots are found in the blue channel at a fluorescence intensity that is 14.5 times that of control cells not cocultured with quantum dots.After incubating zebrafish larvae with ZnSe quantum dots for 24 h,the fluorescence intensity of the yolk sac stimulated by ultraviolet light is 2.9 times that of the control group.The proposed material shows a great potential application in biological imaging.展开更多
High-index dielectric nanoparticles supporting strong Mie resonances,such as silicon(Si)nanoparticles,provide a platform for manipulating optical fields at the subwavelength scale.However,in general,the quality factor...High-index dielectric nanoparticles supporting strong Mie resonances,such as silicon(Si)nanoparticles,provide a platform for manipulating optical fields at the subwavelength scale.However,in general,the quality factors of Mie resonances supported by an isolated nanoparticle are not sufficient for realizing strong light-matter interaction.Here,we propose the use of dielectric-metal hybrid nanocavities composed of Si nanoparticles and silicon nitride/silver(Si_(3)N_(4)∕Ag)heterostructures to improve light-matter interaction.First,we demonstrate that the nonlinear optical absorption of the Si nanoparticle in a Si∕Si_(3)N_(4)∕Ag hybrid nanocavity can be greatly enhanced at the magnetic dipole resonance.The Si∕Si_(3)N_(4)∕Ag nanocavity exhibits luminescence burst at substantially lower excitation energy(~20.5 pJ)compared to a Si nanoparticle placed on a silica substrate(~51.3 pJ).The luminescence intensity is also enhanced by an order of magnitude.Second,we show that strong exciton-photon coupling can be realized when a tungsten disulfide(WS2)monolayer is inserted into a Si∕Si_(3)N_(4)∕Ag nanocavity.When such a system is excited by using s-polarized light,the optical resonance supported by the nanocavity can be continuously tuned to sweep across the two exciton resonances of the WS_(2)monolayer by simply varying the incident angle.As a result,Rabi splitting energies as large as~146.4 meV and~110 meV are observed at the A-and B-exciton resonances of the WS_(2)monolayer,satisfying the criterion for strong exciton-photon coupling.The proposed nanocavities provide,to our knowledge,a new platform for enhancing light-matter interaction in multiple scenarios and imply potential applications in constructing nanoscale photonic devices.展开更多
The possibility to achieve unprecedented multiplexing of light-matter interaction in nanoscale is of virtue importance from both fundamental science and practical application points of view. Cylindrical vector beams(C...The possibility to achieve unprecedented multiplexing of light-matter interaction in nanoscale is of virtue importance from both fundamental science and practical application points of view. Cylindrical vector beams(CVBs) manifested as polarization vortices represent a robust and emerging degree of freedom for information multiplexing with increased capacities. Here, we propose and demonstrate massivelyencoded optical data storage(ODS) by harnessing spatially variant electric fields mediated by segmented CVBs. By tight focusing polychromatic segmented CVBs to plasmonic nanoparticle aggregates, recordhigh multiplexing channels of ODS through different combinations of polarization states and wavelengths have been experimentally demonstrated with a low error rate. Our result not only casts new perceptions for tailoring light-matter interactions utilizing structured light but also enables a new prospective for ultra-high capacity optical memory with minimalist system complexity by combining CVB’s compatibility with fiber optics.展开更多
Nanoparticles made of different materials usually support optical resonances in the visible to near infrared spectral range,such as the localized surface plasmons observed in metallic nanoparticles and the Mie resonan...Nanoparticles made of different materials usually support optical resonances in the visible to near infrared spectral range,such as the localized surface plasmons observed in metallic nanoparticles and the Mie resonances observed in dielectric ones.Such optical resonances,which are important for practical applications,depend strongly on the morphologies of nanoparticles.Laser irradiation is a simple but effective way to modify such optical resonances through the change in the morphology of a nanoparticle.Although laser-induced shaping of metallic nanoparticles has been successfully demonstrated,it remains a big challenge for dielectric nanoparticles due to their larger Young’s modulus and smaller thermal conductivities.Here,we proposed and demonstrated a strategy for realizing controllable shaping of high-index dielectric nanoparticles by exploiting the giant optical force induced by femtosecond laser pulses.It was found that both Si and Ge nanoparticles can be lit up by resonantly exciting the optical resonances with femtosecond laser pulses,leading to the luminescence burst when the laser power exceeds a threshold.In addition,the morphologies of Si and Ge nanoparticles can be modified by utilizing the giant absorption force exerted on them and the reduced Young’s modulus at high temperatures.The shape transformation from sphere to ellipsoid can be realized by laser irradiation,leading to the blueshifts of the optical resonances.It was found that Si and Ge nanoparticles were generally elongated along the direction parallel to the polarization of the laser light.Controllable shaping of Si and Ge can be achieved by deliberately adjusting the excitation wavelength and the laser power.Our findings are helpful for understanding the giant absorption force of femtosecond laser light and are useful for designing nanoscale photonic devices based on shaped highindex nanoparticles.展开更多
Optical pulling provides a new degree of freedom in optical manipulation.It is generally believed that long-range optical pulling forces cannot be generated by the gradient of the incident field.Here,we theoretically ...Optical pulling provides a new degree of freedom in optical manipulation.It is generally believed that long-range optical pulling forces cannot be generated by the gradient of the incident field.Here,we theoretically propose and numerically demonstrate the realization of a long-range optical pulling force stemming from a self-induced gradient field in the manipulated object.In analogy to potential barriers in quantum tunnelling,we use a photonic band gap design in order to obtain the intensity gradients inside a manipulated object placed in a photonic crystal waveguide,thereby achieving a pulling force.Unlike the usual scattering-type optical pulling forces,the proposed gradient-field approach does not require precise elimination of the reflection from the manipulated objects.In particular,the Einstein-Laub formalism is applied to design this unconventional gradient force.The magnitude of the force can be enhanced by a factor of up to 50 at the optical resonance of the manipulated object in the waveguide,making it insensitive to absorption.The developed approach helps to break the limitation of scattering forces to obtain longrange optical pulling for manipulation and sorting of nanoparticles and other nano-objects.The developed principle of using the band gap to obtain a pulling force may also be applied to other types of waves,such as acoustic or water waves,which are important for numerous applications.展开更多
Single photonic crystal defects based on an air-bridge structure were fabricated. We obtained sharp defect modes with quality factors higher than 600 and observed their response to ultrashort optical pulses by utilizi...Single photonic crystal defects based on an air-bridge structure were fabricated. We obtained sharp defect modes with quality factors higher than 600 and observed their response to ultrashort optical pulses by utilizing two-photon absorption.展开更多
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
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61774062 and U20A20206)the Science and Techology Program of Guangzhou City,China(Grant No.2019050001)the Natural Science Foundation of Guangdong Province,China(Grant Nos.2018A030313854 and2016A030308010)。
文摘This study is to report a ZnSe quantum dot with a large two-photon absorption cross section and good biocompatibility,which can be used in bioimaging.Fluorescence emission at 410 nm is observed in the quantum dot under 760-nm laser excitation.These biocompatible quantum dots exhibit a two-photon cross-section of 9.1×105 GM(1 GM=10-50 cm4·s/photon).Two-photon excited laser scanning microscopic images show that cells co-cultured with ZnSe quantum dots are found in the blue channel at a fluorescence intensity that is 14.5 times that of control cells not cocultured with quantum dots.After incubating zebrafish larvae with ZnSe quantum dots for 24 h,the fluorescence intensity of the yolk sac stimulated by ultraviolet light is 2.9 times that of the control group.The proposed material shows a great potential application in biological imaging.
基金National Natural Science Foundation of China(12174123,12374347)Basic and Applied Basic Research Foundation of Guangdong Province(2022A1515010747)。
文摘High-index dielectric nanoparticles supporting strong Mie resonances,such as silicon(Si)nanoparticles,provide a platform for manipulating optical fields at the subwavelength scale.However,in general,the quality factors of Mie resonances supported by an isolated nanoparticle are not sufficient for realizing strong light-matter interaction.Here,we propose the use of dielectric-metal hybrid nanocavities composed of Si nanoparticles and silicon nitride/silver(Si_(3)N_(4)∕Ag)heterostructures to improve light-matter interaction.First,we demonstrate that the nonlinear optical absorption of the Si nanoparticle in a Si∕Si_(3)N_(4)∕Ag hybrid nanocavity can be greatly enhanced at the magnetic dipole resonance.The Si∕Si_(3)N_(4)∕Ag nanocavity exhibits luminescence burst at substantially lower excitation energy(~20.5 pJ)compared to a Si nanoparticle placed on a silica substrate(~51.3 pJ).The luminescence intensity is also enhanced by an order of magnitude.Second,we show that strong exciton-photon coupling can be realized when a tungsten disulfide(WS2)monolayer is inserted into a Si∕Si_(3)N_(4)∕Ag nanocavity.When such a system is excited by using s-polarized light,the optical resonance supported by the nanocavity can be continuously tuned to sweep across the two exciton resonances of the WS_(2)monolayer by simply varying the incident angle.As a result,Rabi splitting energies as large as~146.4 meV and~110 meV are observed at the A-and B-exciton resonances of the WS_(2)monolayer,satisfying the criterion for strong exciton-photon coupling.The proposed nanocavities provide,to our knowledge,a new platform for enhancing light-matter interaction in multiple scenarios and imply potential applications in constructing nanoscale photonic devices.
基金the financial support from the National Key R&D Program of China (2018YFB1107200)the National Natural Science Foundation of China (91750110, 11674130, 61605061, 11674110 and 11874020)+2 种基金the Guangdong Provincial Innovation and Entrepreneurship Project (2016ZT06D081)the Natural Science Foundation of Guangdong Province (2016A030306016, 2016TQ03X981 and 2016A030308010)Pearl River S and T Nova Program of Guangzhou (201806010040)。
文摘The possibility to achieve unprecedented multiplexing of light-matter interaction in nanoscale is of virtue importance from both fundamental science and practical application points of view. Cylindrical vector beams(CVBs) manifested as polarization vortices represent a robust and emerging degree of freedom for information multiplexing with increased capacities. Here, we propose and demonstrate massivelyencoded optical data storage(ODS) by harnessing spatially variant electric fields mediated by segmented CVBs. By tight focusing polychromatic segmented CVBs to plasmonic nanoparticle aggregates, recordhigh multiplexing channels of ODS through different combinations of polarization states and wavelengths have been experimentally demonstrated with a low error rate. Our result not only casts new perceptions for tailoring light-matter interactions utilizing structured light but also enables a new prospective for ultra-high capacity optical memory with minimalist system complexity by combining CVB’s compatibility with fiber optics.
基金National Natural Science Foundation of China(12174123)。
文摘Nanoparticles made of different materials usually support optical resonances in the visible to near infrared spectral range,such as the localized surface plasmons observed in metallic nanoparticles and the Mie resonances observed in dielectric ones.Such optical resonances,which are important for practical applications,depend strongly on the morphologies of nanoparticles.Laser irradiation is a simple but effective way to modify such optical resonances through the change in the morphology of a nanoparticle.Although laser-induced shaping of metallic nanoparticles has been successfully demonstrated,it remains a big challenge for dielectric nanoparticles due to their larger Young’s modulus and smaller thermal conductivities.Here,we proposed and demonstrated a strategy for realizing controllable shaping of high-index dielectric nanoparticles by exploiting the giant optical force induced by femtosecond laser pulses.It was found that both Si and Ge nanoparticles can be lit up by resonantly exciting the optical resonances with femtosecond laser pulses,leading to the luminescence burst when the laser power exceeds a threshold.In addition,the morphologies of Si and Ge nanoparticles can be modified by utilizing the giant absorption force exerted on them and the reduced Young’s modulus at high temperatures.The shape transformation from sphere to ellipsoid can be realized by laser irradiation,leading to the blueshifts of the optical resonances.It was found that Si and Ge nanoparticles were generally elongated along the direction parallel to the polarization of the laser light.Controllable shaping of Si and Ge can be achieved by deliberately adjusting the excitation wavelength and the laser power.Our findings are helpful for understanding the giant absorption force of femtosecond laser light and are useful for designing nanoscale photonic devices based on shaped highindex nanoparticles.
基金Q.D.thanks for the financial support from the Natural Science Foundation of Guangdong Province,China(2019A1515011578)Department of Science and Technology of Guangdong Province,China(2020B1212060067)A.K.and A.Z.work was supported by the ERC iCOMM project(789340).
文摘Optical pulling provides a new degree of freedom in optical manipulation.It is generally believed that long-range optical pulling forces cannot be generated by the gradient of the incident field.Here,we theoretically propose and numerically demonstrate the realization of a long-range optical pulling force stemming from a self-induced gradient field in the manipulated object.In analogy to potential barriers in quantum tunnelling,we use a photonic band gap design in order to obtain the intensity gradients inside a manipulated object placed in a photonic crystal waveguide,thereby achieving a pulling force.Unlike the usual scattering-type optical pulling forces,the proposed gradient-field approach does not require precise elimination of the reflection from the manipulated objects.In particular,the Einstein-Laub formalism is applied to design this unconventional gradient force.The magnitude of the force can be enhanced by a factor of up to 50 at the optical resonance of the manipulated object in the waveguide,making it insensitive to absorption.The developed approach helps to break the limitation of scattering forces to obtain longrange optical pulling for manipulation and sorting of nanoparticles and other nano-objects.The developed principle of using the band gap to obtain a pulling force may also be applied to other types of waves,such as acoustic or water waves,which are important for numerous applications.
文摘Single photonic crystal defects based on an air-bridge structure were fabricated. We obtained sharp defect modes with quality factors higher than 600 and observed their response to ultrashort optical pulses by utilizing two-photon absorption.
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.
