Metasurfaces and metagratings offer new platforms for electromagnetic wave control with significant responses.However,metasurfaces based on abrupt phase change and resonant structures suffer from the drawback of high ...Metasurfaces and metagratings offer new platforms for electromagnetic wave control with significant responses.However,metasurfaces based on abrupt phase change and resonant structures suffer from the drawback of high loss and face challenges when applied in water waves.Therefore,the application of metasurfaces in water wave control is not ideal due to the limitations associated with high loss and other challenges.We have discovered that non-resonant metagratings exhibit promising effects in water wave control.Leveraging the similarity between bridges and metagratings,we have successfully developed a water wave metagrating model inspired by the ancient Luoyang Bridge in China.We conduct theoretical calculations and simulations on the metagrating and derive the equivalent anisotropic model of the metagrating.This model provides evidence that the metagrating has the capability to control water waves and achieve unidirectional surface water wave.The accuracy of our theory is strongly supported by the clear observation of the unidirectional propagation phenomenon during simulation and experiments conducted using a reduced version of the metagrating.It is the first time that the unidirectional propagation of water waves has been seen in water wave metagrating experiment.Above all,we realize the water wave metagrating experiment for the first time.By combining complex gratings with real bridges,we explore the physics embedded in the ancient building—Luoyang Bridge,which are of great significance for the water wave metagrating design and provide a new method for analyzing the effects of water waves on bridges.At the same time,this discovery also provides a new idea for ocean cargo transportation,ocean garbage cleaning,and the development and protection of ancient bridges.展开更多
Cherenkov radiation(CR)is available for a wide variety of terahertz(THz)radiation sources,but its efficiency is deeply affected by intrinsic losses.We find that if the tilted angle(α)of anisotropic material and radia...Cherenkov radiation(CR)is available for a wide variety of terahertz(THz)radiation sources,but its efficiency is deeply affected by intrinsic losses.We find that if the tilted angle(α)of anisotropic material and radiation angle(θ)meet the condition ofθ+α=π/2,the intensity of radiation fields for the charged particle bunch(CPB)moving from left to right cannot be influenced by intrinsic losses,which means long-distance radiation can be achieved.Furthermore,we observe an asymmetric CR when the CPB moves from the opposite direction.In addition,we select natural van der Waals(vd W)materialα-MoO3as an example,further confirming that the radiation field can reach the far field and the asymmetric CR radiation can also be observed.These wonderful properties with long-distance radiation will extend the application of CR to a certain extent for future design and fabrication.展开更多
基金Shenzhen Science and Technology Program(Grant No.JCYJ20230807091300001)the National Natural Science Foundation of China(Grant Nos.12374410 and 92050102)+1 种基金the National Key Research and Development Program of China(Grant Nos.2023YFA1407100 and 2020YFA0710100)the Fundamental Research Funds for the Central Universities(Grant No.20720220033).
文摘Metasurfaces and metagratings offer new platforms for electromagnetic wave control with significant responses.However,metasurfaces based on abrupt phase change and resonant structures suffer from the drawback of high loss and face challenges when applied in water waves.Therefore,the application of metasurfaces in water wave control is not ideal due to the limitations associated with high loss and other challenges.We have discovered that non-resonant metagratings exhibit promising effects in water wave control.Leveraging the similarity between bridges and metagratings,we have successfully developed a water wave metagrating model inspired by the ancient Luoyang Bridge in China.We conduct theoretical calculations and simulations on the metagrating and derive the equivalent anisotropic model of the metagrating.This model provides evidence that the metagrating has the capability to control water waves and achieve unidirectional surface water wave.The accuracy of our theory is strongly supported by the clear observation of the unidirectional propagation phenomenon during simulation and experiments conducted using a reduced version of the metagrating.It is the first time that the unidirectional propagation of water waves has been seen in water wave metagrating experiment.Above all,we realize the water wave metagrating experiment for the first time.By combining complex gratings with real bridges,we explore the physics embedded in the ancient building—Luoyang Bridge,which are of great significance for the water wave metagrating design and provide a new method for analyzing the effects of water waves on bridges.At the same time,this discovery also provides a new idea for ocean cargo transportation,ocean garbage cleaning,and the development and protection of ancient bridges.
基金supported by the National Key Research and Development Program of China(Grant Nos.2023YFA1407100,and 2020YFA0710100)the National Natural Science Foundation of China(Grant Nos.92050102,12374410)+3 种基金the Jiangxi Provincial Natural Science Foundation(Grant No.20224ACB201005)the Fundamental Research Funds for the Central Universities(Grant Nos.20720230102,and 20720220033)the 111 project(Grant No.B16029)the China Scholarship Council(Grant No.202206310008)。
文摘Cherenkov radiation(CR)is available for a wide variety of terahertz(THz)radiation sources,but its efficiency is deeply affected by intrinsic losses.We find that if the tilted angle(α)of anisotropic material and radiation angle(θ)meet the condition ofθ+α=π/2,the intensity of radiation fields for the charged particle bunch(CPB)moving from left to right cannot be influenced by intrinsic losses,which means long-distance radiation can be achieved.Furthermore,we observe an asymmetric CR when the CPB moves from the opposite direction.In addition,we select natural van der Waals(vd W)materialα-MoO3as an example,further confirming that the radiation field can reach the far field and the asymmetric CR radiation can also be observed.These wonderful properties with long-distance radiation will extend the application of CR to a certain extent for future design and fabrication.
