An efficient on-chip platform for generating customizable vectorial optical fields is crucial and highly-pursued.While on-chip metasurfaces have opened up avenues for multi-functional coupling from on-chip surface wav...An efficient on-chip platform for generating customizable vectorial optical fields is crucial and highly-pursued.While on-chip metasurfaces have opened up avenues for multi-functional coupling from on-chip surface wave to free-space propagating wave,they typically encounter the trade-off between extraction efficiency and wavefront accuracy.Recently,Prof.Lei Zhou’s group pioneered a strategy employing geometric metal meta-atoms with low polarization conversion ratio to overcome this bottleneck and experimentally demonstrated generation of pre-designed terahertz vector beams with efficiency exceeding 90%.This approach establishes a generic,high-performance framework for advanced on-chip meta-devices.展开更多
An optically levitated nanoparticle in a vacuum provides an ideal platform for ultra-precision measurements and fundamental physics studies because of the exceptionally high-quality factor and rich motion modes,which ...An optically levitated nanoparticle in a vacuum provides an ideal platform for ultra-precision measurements and fundamental physics studies because of the exceptionally high-quality factor and rich motion modes,which can be engineered by manipulating the optical field and the geometry of the nanoparticle.Nanofabrication technology with the ability to create arbitrary nanostructure arrays offers a precise way of engineering the optical field and the geometry of the nanoparticle.Here,for the first time,we optically levitate and rotate a nanofabricated nanorod via a nanofabricated a-Si metalens which strongly focuses a 1550 nm laser beam with a numerical aperture of 0.953.By manipulating the laser beam’s polarization,the levitated nanorod’s translation frequencies can be tuned,and the spin rotation mode can be switched on and off.Then,we showed the control of rotational frequency by changing the laser beam’s intensity and polarization as well as the air pressure.Finally,a MHz spin rotation frequency of the nanorod is achieved in the experiment.This is the first demonstration of controlled optical spin in a metalens-based compact optical levitation system.Our research holds promise for realizing scalable on-chip integrated optical levitation systems.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
Micromachining based on femtosecond lasers usually requires accurate control of the sample movement,which may be very complex and costly.Therefore,the exploration of micromachining without sample movement is valuable....Micromachining based on femtosecond lasers usually requires accurate control of the sample movement,which may be very complex and costly.Therefore,the exploration of micromachining without sample movement is valuable.Herein,we have illustrated the manipulation of optical fields by controlling the polarization or phase to vary periodically and then realized certain focal traces by real-time loading of the computer-generated holograms(CGHs) on the spatial light modulator.The focal trace is composed of many discrete focal spots,which are generated experimentally by using the real-time dynamically controlled CGHs.With the designed focal traces,various microstructures such as an ellipse,a Chinese character "Nan",and an irregular quadrilateral grid structure are fabricated in the z-cut LiNbO_(3) wafers,showing good qualities in terms of continuity and homogeneity.Our method proposes a movement free solution for micromachining samples and completely abandons the high precision stage and complex movement control,making microstructure fabrication more flexible,stable,and cheaper.展开更多
We proposed an approach for the generation of interference-pattern helico-conical beams(HCBs)both theoretically and experimentally.The HCBs exhibiting intricate fringe structures are obtained by exploiting amplitude m...We proposed an approach for the generation of interference-pattern helico-conical beams(HCBs)both theoretically and experimentally.The HCBs exhibiting intricate fringe structures are obtained by exploiting amplitude modulation and interference techniques.To precisely control the optical field distributions,we manipulate the azimuthal term within the helicoconical phase expression,presenting several illustrative cases that highlight the versatility of our approach.Through further combinations,more sophisticated comprehensive HCB patterns are investigated.This study deepens our knowledge about spiral-like optical patterns and paves a new avenue for potential applications,especially in the fields of particle manipulation,nanostructure fabrication,and optical metrology.展开更多
基金support by the National Natural Science Foundation of China(Grant Nos.62325504,92250304,and 12174186)Dengfeng Project B of Nanjing University.
文摘An efficient on-chip platform for generating customizable vectorial optical fields is crucial and highly-pursued.While on-chip metasurfaces have opened up avenues for multi-functional coupling from on-chip surface wave to free-space propagating wave,they typically encounter the trade-off between extraction efficiency and wavefront accuracy.Recently,Prof.Lei Zhou’s group pioneered a strategy employing geometric metal meta-atoms with low polarization conversion ratio to overcome this bottleneck and experimentally demonstrated generation of pre-designed terahertz vector beams with efficiency exceeding 90%.This approach establishes a generic,high-performance framework for advanced on-chip meta-devices.
文摘An optically levitated nanoparticle in a vacuum provides an ideal platform for ultra-precision measurements and fundamental physics studies because of the exceptionally high-quality factor and rich motion modes,which can be engineered by manipulating the optical field and the geometry of the nanoparticle.Nanofabrication technology with the ability to create arbitrary nanostructure arrays offers a precise way of engineering the optical field and the geometry of the nanoparticle.Here,for the first time,we optically levitate and rotate a nanofabricated nanorod via a nanofabricated a-Si metalens which strongly focuses a 1550 nm laser beam with a numerical aperture of 0.953.By manipulating the laser beam’s polarization,the levitated nanorod’s translation frequencies can be tuned,and the spin rotation mode can be switched on and off.Then,we showed the control of rotational frequency by changing the laser beam’s intensity and polarization as well as the air pressure.Finally,a MHz spin rotation frequency of the nanorod is achieved in the experiment.This is the first demonstration of controlled optical spin in a metalens-based compact optical levitation system.Our research holds promise for realizing scalable on-chip integrated optical levitation systems.
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supported by the National Key R&D Program of China (Nos. 2017YFA0303800 and 2017YFA0303700)National Natural Science Foundation of China (Nos. 11534006, 11774183, 12074196, and 11904152)
文摘Micromachining based on femtosecond lasers usually requires accurate control of the sample movement,which may be very complex and costly.Therefore,the exploration of micromachining without sample movement is valuable.Herein,we have illustrated the manipulation of optical fields by controlling the polarization or phase to vary periodically and then realized certain focal traces by real-time loading of the computer-generated holograms(CGHs) on the spatial light modulator.The focal trace is composed of many discrete focal spots,which are generated experimentally by using the real-time dynamically controlled CGHs.With the designed focal traces,various microstructures such as an ellipse,a Chinese character "Nan",and an irregular quadrilateral grid structure are fabricated in the z-cut LiNbO_(3) wafers,showing good qualities in terms of continuity and homogeneity.Our method proposes a movement free solution for micromachining samples and completely abandons the high precision stage and complex movement control,making microstructure fabrication more flexible,stable,and cheaper.
基金supported by the National Natural Science Foundation of China(Nos.62231005,62275131,62105164,12374353,and 62305176)the Natural Science Foundation of Tianjin(No.22JCQNJC01540)the Tianjin Development Program for Innovation and Entrepreneurship,and the Fundamental Research Funds for the Central Universities,Nankai University(Nos.63241446,63241330,and 63241331).
文摘We proposed an approach for the generation of interference-pattern helico-conical beams(HCBs)both theoretically and experimentally.The HCBs exhibiting intricate fringe structures are obtained by exploiting amplitude modulation and interference techniques.To precisely control the optical field distributions,we manipulate the azimuthal term within the helicoconical phase expression,presenting several illustrative cases that highlight the versatility of our approach.Through further combinations,more sophisticated comprehensive HCB patterns are investigated.This study deepens our knowledge about spiral-like optical patterns and paves a new avenue for potential applications,especially in the fields of particle manipulation,nanostructure fabrication,and optical metrology.
