This paper is concerned with the stability of traveling wavefronts for a population dynamics model with time delay. Combining the weighted energy method and the comparison principle, the global exponential stability o...This paper is concerned with the stability of traveling wavefronts for a population dynamics model with time delay. Combining the weighted energy method and the comparison principle, the global exponential stability of noncritical traveling wavefronts （waves with speeds c 〉 c＊, where c=c＊ is the minimal speed） is established, when the initial perturbations around the wavefront decays to zero exponentially in space as x → -∞, but it can be allowed arbitrary large in other locations, which improves the results in[9, 18, 21].展开更多
This note is devoted to the son＇s blowflies equation with diffusion, a critical speed of traveling waves, we give behavior with respect to the mature age study on the traveling wavefronts to the Nicholtime-delayed re...This note is devoted to the son＇s blowflies equation with diffusion, a critical speed of traveling waves, we give behavior with respect to the mature age study on the traveling wavefronts to the Nicholtime-delayed reaction-diffusion equation. For the a detailed analysis on its location and asymptotic展开更多
In this paper, a reaction-diffusion equation with discrete time delay that describes the dynamics of the blood cell production is analyzed. The existence of the traveling wave front solutions is demonstrated using the...In this paper, a reaction-diffusion equation with discrete time delay that describes the dynamics of the blood cell production is analyzed. The existence of the traveling wave front solutions is demonstrated using the technique of upper and lower solutions and the associated monotone iteration.展开更多
The stability of traveling wavefronts for a spatially nonlocal population model with quasi-monotonicity and delay is discussed in this article.It is shown that all monostable wavefronts are exponentially stable for la...The stability of traveling wavefronts for a spatially nonlocal population model with quasi-monotonicity and delay is discussed in this article.It is shown that all monostable wavefronts are exponentially stable for large speed with the help of weightedenergy method and comparison principle.The proper selection of the weighted function is necessary to overcome the difficulty caused by the nonlocal nonlinearity for establishing the energy estimates of solutions.展开更多
We investigate the light propagation by means of simulations of wavefronts and light cones for Kerr spacetimes. Simulations of this kind give us a new insight to better understand the light propagation in presence of ...We investigate the light propagation by means of simulations of wavefronts and light cones for Kerr spacetimes. Simulations of this kind give us a new insight to better understand the light propagation in presence of massive rotating black holes. A relevant result is that wavefronts are backscattered with winding around the black hole. To generate these visualizations, an interactive computer program with a graphical user interface, called JWFront, was written in Java.展开更多
In this paper, traveling wavefront solutions are established for two cooperative systems with time delay and non-local effects. The results are an extension of the existing results for delayed logistic scale equations...In this paper, traveling wavefront solutions are established for two cooperative systems with time delay and non-local effects. The results are an extension of the existing results for delayed logistic scale equations and diffusive Nicholson equations with non-local effects to systems. The approach used is the upper-lower solution technique and Schauder fixed point Theorem developed by Ma（J Differential Equations,2001,171：294-314. ）.展开更多
In this paper, we study the propagation of the pattern for a reaction-diffusionchemotaxis model. By using a weakly nonlinear analysis with multiple temporal and spatial scales, we establish the amplitude equations for...In this paper, we study the propagation of the pattern for a reaction-diffusionchemotaxis model. By using a weakly nonlinear analysis with multiple temporal and spatial scales, we establish the amplitude equations for the patterns, which show that a local perturbation at the constant steady state is spread over the whole domain in the form of a traveling wavefront. The simulations demonstrate that the amplitude equations capture the evolution of the exact patterns obtained by numerically solving the considered system.展开更多
In this paper,we mainly investigate the dynamics of traveling wavefronts for a model describing host tissue degradation by bacteria.We first establish the existence of spreading speed,and show that the spreading speed...In this paper,we mainly investigate the dynamics of traveling wavefronts for a model describing host tissue degradation by bacteria.We first establish the existence of spreading speed,and show that the spreading speed coincides with the minimal wave speed of traveling wavefronts.Moreover,a lower bound estimate of the spreading speed is given.Then,we prove that the traveling wavefronts with large speeds are globally exponentially stable,when the initial perturbation around the traveling wavefronts decays exponentially asχ→-∞,but the initial perturbation can be arbitrarily large in other locations.The adopted methods are the weighted energy and the squeezing technique.展开更多
Adaptive optics （AO） systems greatly improve the resolution of retinal imaging instruments by actively cor- recting ocular aberrations. In this Letter, closed-loop correction as well as ocular aberration compensatio...Adaptive optics （AO） systems greatly improve the resolution of retinal imaging instruments by actively cor- recting ocular aberrations. In this Letter, closed-loop correction as well as ocular aberration compensation of a 62-element silicon unimorph deformable mirror （DM） driven by only positive voltage is performed. The ex- perimental results show that the root-mean square （RMS） wavefront of the initial nlirrof surface is reduced to 0.011 μm in a closed-loop AO system. The DM reproduces Zernike shapes from the third to 35th mode accurately. The simulated compensation of 200 ocular wavefronts shows that the average RMS value after col rection is reduced to 0.017 μm.展开更多
This paper is devoted to the study of traveling wavefronts for a three-component Lotka-Volterra system with nonlocal dispersal.This system arises in the study of three-species competition model in which there is no co...This paper is devoted to the study of traveling wavefronts for a three-component Lotka-Volterra system with nonlocal dispersal.This system arises in the study of three-species competition model in which there is no competition between two of these three species.It has been shown that this system admits a bistable traveling wavefront.In this paper,we further investigate the stability of bistable traveling wavefronts.By constructing suitable super-and sub-solutions and using a dynamical system approach,we obtain the globally asymptotic stability of the bistable traveling wavefronts.展开更多
This paper is concerned with the travelling wavefronts of a nonlocal dispersal cooperation model with harvesting and state-dependent delay,which is assumed to be an increasing function of the population density with l...This paper is concerned with the travelling wavefronts of a nonlocal dispersal cooperation model with harvesting and state-dependent delay,which is assumed to be an increasing function of the population density with lower and upper bound.Especially,state-dependent delay is introduced into a nonlocal reaction-diffusion model.The conditions of Schauder's fixed point theorem are proved by constructing a reasonable set of functionsΓ(see Section 2)and a pair of upper-lower solutions,so the existence of traveling wavefronts is established.The present study is continuation of a previous work that highlights the Laplacian diffusion.展开更多
To realize effective co-phasing adjustment in large-aperture sparse-aperture telescopes,a multichannel stripe tracking approach is employed,allowing simultaneous interferometric measurements of multiple optical paths ...To realize effective co-phasing adjustment in large-aperture sparse-aperture telescopes,a multichannel stripe tracking approach is employed,allowing simultaneous interferometric measurements of multiple optical paths and circumventing the need for pairwise measurements along the mirror boundaries in traditional interferometric methods.This approach enhances detection efficiency and reduces system complexity.Here,the principles of the multibeam interference process and construction of a co-phasing detection module based on direct optical fiber connections were analyzed using wavefront optics theory.Error analysis was conducted on the system surface obtained through multipath interference.Potential applications of the interferometric method were explored.Finally,the principle was verified by experiment,an interferometric fringe contrast better than 0.4 is achieved through flat field calibration and incoherent digital synthesis.The dynamic range of the measurement exceeds 10 times of the center wavelength of the working band(1550 nm).Moreover,a resolution better than one-tenth of the working center wavelength(1550 nm)was achieved.Simultaneous three-beam interference can be achieved,leading to a 50%improvement in detection efficiency.This method can effectively enhance the efficiency of sparse aperture telescope co-phasing,meeting the requirements for observations of 8-10 m telescopes.This study provides a technological foundation for observing distant and faint celestial objects.展开更多
For segmented detectors,surface flatness is critical as it directly influences both energy resolution and image clarity.Additionally,the limited adjustment range of the segmented detectors necessitates precise benchma...For segmented detectors,surface flatness is critical as it directly influences both energy resolution and image clarity.Additionally,the limited adjustment range of the segmented detectors necessitates precise benchmark construction.This paper proposes an architecture for detecting detector flatness based on channel spectral dispersion.By measuring the dispersion fringes for coplanar adjustment,the final adjustment residual is improved to better than 300 nm.This result validates the feasibility of the proposed technology and provides significant technical support for the development of next-generation large-aperture sky survey equipment.展开更多
In this paper, a reaction-diffusion model describing temporal development of tumor tissue, normal tissue and excess H＋ ion concentration is considered. Based on a combi- nation of perturbation methods, the Fredholm t...In this paper, a reaction-diffusion model describing temporal development of tumor tissue, normal tissue and excess H＋ ion concentration is considered. Based on a combi- nation of perturbation methods, the Fredholm theory and Banach fixed point theorem, we theoretically justify the existence of the traveling wave solution for this model.展开更多
Object imaging beyond the direct line of sight is significant for applications in robotic vision,remote sensing,autonomous driving,and many other areas.Reconstruction of a non-line-of-sight(NLOS)screen is a complex in...Object imaging beyond the direct line of sight is significant for applications in robotic vision,remote sensing,autonomous driving,and many other areas.Reconstruction of a non-line-of-sight(NLOS)screen is a complex inverse problem that comes with ultrafast time-resolved imager requirements and substantial computational demands to extract information from the multi-bounce scattered light.Consequently,the echo signal always suffers from serious deterioration in both intensity and shape,leading to limited resolution and image contrast.Here,we propose a concept of vectorial digitelligent optics for high-resolution NLOS imaging to cancel the wall’s scattering and refocus the light onto hidden targets for enhanced echo.In this approach,the polarization and wavefront of the laser spot are intelligently optimized via a feedback algorithm to form a near-perfect focusing pattern through a random scattering wall.By raster scanning the focusing spot across the object’s surface within the optical-memory-effect range of the wall,we obtain nearly diffraction-limited NLOS imaging with an enhanced signal-to-noise ratio.Our experimental results demonstrate a resolution of 0.40 mm at a distance of 0.35 m,reaching the diffraction limit of the system.Furthermore,we demonstrate that the proposed method is feasible for various complex NLOS scenarios.Our methods may open an avenue for active imaging,communication,and laser wireless power transfer.展开更多
The emergence of metalenses has impacted a wide variety of applications such as beam steering,imaging,depth sensing,and display projection.Optical distortion,an important metric among many optical design specification...The emergence of metalenses has impacted a wide variety of applications such as beam steering,imaging,depth sensing,and display projection.Optical distortion,an important metric among many optical design specifications,has however rarely been discussed in the context of meta-optics.Here,we present a generic approach for on-demand distortion engineering using compound metalenses.We show that the extra degrees of freedom afforded by a doublet metasurface architecture allow custom-tailored angle-dependent image height relations and hence distortion control while minimizing other monochromatic aberrations.Using this platform,we experimentally demonstrate a compound fisheye metalens with diffraction-limited performance across a wide field of view of 140°and a low barrel distortion of less than 2%,compared with up to 22%distortion in a reference metalens without compensation.The design strategy and compound metalens architecture presented herein are expected to broadly impact metasurface applications in consumer electronics,automotive and robotic sensing,medical imaging,and machine vision systems.展开更多
This work introduces special states for light in multimode fibers featuring strongly enhanced or reduced correlations be-tween output fields in the presence of environmental temperature fluctuations.Using experimental...This work introduces special states for light in multimode fibers featuring strongly enhanced or reduced correlations be-tween output fields in the presence of environmental temperature fluctuations.Using experimentally measured multi-tem-perature transmission matrix,a set of temperature principal modes that exhibit resilience to disturbances caused by tem-perature fluctuations can be generated.Reversing this concept also allows the construction of temperature anti-principal modes,with output profiles more susceptible to temperature influences than the unmodulated wavefront.Despite changes in the length of the multimode fiber within the temperature-fluctuating region,the proposed approach remains capable of robustly controlling the temperature response within the fiber.To illustrate the practicality of the proposed spe-cial state,a learning-empowered fiber specklegram temperature sensor based on temperature anti-principal mode sensi-tization is proposed.This sensor exhibits outstanding superiority over traditional approaches in terms of resolution and accuracy.These novel states are anticipated to have wide-ranging applications in fiber communication,sensing,imaging,and spectroscopy,and serve as a source of inspiration for the discovery of other novel states.展开更多
Nonlinear wavefront shaping is crucial for advancing optical technologies,enabling applications in optical computation,information processing,and imaging.However,a significant challenge is that once a metasurface is f...Nonlinear wavefront shaping is crucial for advancing optical technologies,enabling applications in optical computation,information processing,and imaging.However,a significant challenge is that once a metasurface is fabricated,the nonlinear wavefront it generates is fixed,offering little flexibility.This limitation often necessitates the fabrication of different metasurfaces for different wavefronts,which is both time-consuming and inefficient.To address this,we combine evolutionary algorithms with spatial light modulators(SLMs)to dynamically control wavefronts using a single metasurface,reducing the need for multiple fabrications and enabling the generation of arbitrary nonlinear wavefront patterns without requiring complicated optical alignment.We demonstrate this approach by introducing a genetic algorithm(GA)to manipulate visible wavefronts converted from near-infrared light via third-harmonic generation(THG)in a silicon metasurface.The Si metasurface supports multipolar Mie resonances that strongly enhance light-matter interactions,thereby significantly boosting THG emission at resonant positions.Additionally,the cubic relationship between THG emission and the infrared input reduces noise in the diffractive patterns produced by the SLM.This allows for precise experimental engineering of the nonlinear emission patterns with fewer alignment constraints.Our approach paves the way for self-optimized nonlinear wavefront shaping,advancing optical computation and information processing techniques.展开更多
The spectral memory effect in scattering media is crucial for applications that employ broadband illumination,as it dictates the available spectral range from independent scattering responses.Previous studies mainly c...The spectral memory effect in scattering media is crucial for applications that employ broadband illumination,as it dictates the available spectral range from independent scattering responses.Previous studies mainly considered a passive result with the average impact of the scattering medium,whereas it is vital to actively enhance or suppress this effect for applications concerned with large spectral range or fine resolution.We construct an analytical model by integrating the concepts of wave-based interference and photon-based propagation,which manifests a potential physical image for active manipulation by utilizing scattering eigenchannels.Our theoretical predictions indicate that the spectral memory effect is enhanced using high-transmission eigenchannels while it is suppressed using low-transmission eigenchannels.These predictions are supported by finite-difference time-domain simulations and experiments,demonstrating that the spectral memory effect’s range can be actively manipulated.Quantitatively,the experiments achieved variations in enhancement and suppression that exceeded threefold(∼3.27).We clarify the underlying principles of the spectral memory effect in scattering media and demonstrate active manipulation of multispectral scattering processes.展开更多
A method for simulating acoustic wavefronts propagating under random sound speed conditions is presented.The approach applies a level set method to solve the Eikonal equation of high frequency acoustics for surfaces o...A method for simulating acoustic wavefronts propagating under random sound speed conditions is presented.The approach applies a level set method to solve the Eikonal equation of high frequency acoustics for surfaces of constant phase,instead of tracing rays.The Lagrangian nature often makes full-field ray solutions difficult to reconstruct.The level set method captures multiple-valued solutions on a fixed grid.It is straightforward to represent other sources of uncertainty in the input data using this model,which has an advantage over Monte Carlo approaches in that it yields an expression for the solution as a function of random variables.展开更多
基金supported by NSF of China(11401478)Gansu Provincial Natural Science Foundation(145RJZA220)
文摘This paper is concerned with the stability of traveling wavefronts for a population dynamics model with time delay. Combining the weighted energy method and the comparison principle, the global exponential stability of noncritical traveling wavefronts （waves with speeds c 〉 c＊, where c=c＊ is the minimal speed） is established, when the initial perturbations around the wavefront decays to zero exponentially in space as x → -∞, but it can be allowed arbitrary large in other locations, which improves the results in[9, 18, 21].
基金supported by Natural Sciences and Engineering Research Council of Canada under the NSERC grant RGPIN 354724-08
文摘This note is devoted to the son＇s blowflies equation with diffusion, a critical speed of traveling waves, we give behavior with respect to the mature age study on the traveling wavefronts to the Nicholtime-delayed reaction-diffusion equation. For the a detailed analysis on its location and asymptotic
文摘In this paper, a reaction-diffusion equation with discrete time delay that describes the dynamics of the blood cell production is analyzed. The existence of the traveling wave front solutions is demonstrated using the technique of upper and lower solutions and the associated monotone iteration.
基金Supported by the NSF of China(Grant No.11761046)Science and Technology Plan Foundation of Gansu Province of China(Grant No.20JR5RA411)Foundation of A Hundred Youth Talents Training Program of Lanzhou Jiaotong University.
文摘The stability of traveling wavefronts for a spatially nonlocal population model with quasi-monotonicity and delay is discussed in this article.It is shown that all monostable wavefronts are exponentially stable for large speed with the help of weightedenergy method and comparison principle.The proper selection of the weighted function is necessary to overcome the difficulty caused by the nonlocal nonlinearity for establishing the energy estimates of solutions.
文摘We investigate the light propagation by means of simulations of wavefronts and light cones for Kerr spacetimes. Simulations of this kind give us a new insight to better understand the light propagation in presence of massive rotating black holes. A relevant result is that wavefronts are backscattered with winding around the black hole. To generate these visualizations, an interactive computer program with a graphical user interface, called JWFront, was written in Java.
文摘In this paper, traveling wavefront solutions are established for two cooperative systems with time delay and non-local effects. The results are an extension of the existing results for delayed logistic scale equations and diffusive Nicholson equations with non-local effects to systems. The approach used is the upper-lower solution technique and Schauder fixed point Theorem developed by Ma（J Differential Equations,2001,171：294-314. ）.
基金partially supported by the National Natural Science Foundation of China(11671359)the Provincial Natural Science Foundation of Zhejiang(LY15A010017,LY16A010009)the Science Foundation of Zhejiang Sci-Tech University 15062173-Y
文摘In this paper, we study the propagation of the pattern for a reaction-diffusionchemotaxis model. By using a weakly nonlinear analysis with multiple temporal and spatial scales, we establish the amplitude equations for the patterns, which show that a local perturbation at the constant steady state is spread over the whole domain in the form of a traveling wavefront. The simulations demonstrate that the amplitude equations capture the evolution of the exact patterns obtained by numerically solving the considered system.
基金supported by NSF of China(11861056)NSF of Gansu Province(21JR7RA121)+1 种基金Department of Education of Gansu Province:Youth Doctoral Fund Project(2021QB-018)Northwest Normal University:Starting Fund for Doctoral Research(202103101204)。
文摘In this paper,we mainly investigate the dynamics of traveling wavefronts for a model describing host tissue degradation by bacteria.We first establish the existence of spreading speed,and show that the spreading speed coincides with the minimal wave speed of traveling wavefronts.Moreover,a lower bound estimate of the spreading speed is given.Then,we prove that the traveling wavefronts with large speeds are globally exponentially stable,when the initial perturbation around the traveling wavefronts decays exponentially asχ→-∞,but the initial perturbation can be arbitrarily large in other locations.The adopted methods are the weighted energy and the squeezing technique.
基金supported by the National Natural Science Foundation of China(11303019)the Zhejiang Provincial Natural Science Foundation of China(LQ13E050016)+2 种基金the Ningbo Natural Science Foundation(2013A610047)the Project of Education Department of Zhejiang Province(Y201326728)the support of the K.C.Wong Magna Fund in Ningbo University
文摘Adaptive optics （AO） systems greatly improve the resolution of retinal imaging instruments by actively cor- recting ocular aberrations. In this Letter, closed-loop correction as well as ocular aberration compensation of a 62-element silicon unimorph deformable mirror （DM） driven by only positive voltage is performed. The ex- perimental results show that the root-mean square （RMS） wavefront of the initial nlirrof surface is reduced to 0.011 μm in a closed-loop AO system. The DM reproduces Zernike shapes from the third to 35th mode accurately. The simulated compensation of 200 ocular wavefronts shows that the average RMS value after col rection is reduced to 0.017 μm.
基金supported by NSF of China (11861056)NSF of Gansu Province (21JR7RA121)Department of Education of Gansu Province:Youth Doctoral Fund Project (2021QB-018).
文摘This paper is devoted to the study of traveling wavefronts for a three-component Lotka-Volterra system with nonlocal dispersal.This system arises in the study of three-species competition model in which there is no competition between two of these three species.It has been shown that this system admits a bistable traveling wavefront.In this paper,we further investigate the stability of bistable traveling wavefronts.By constructing suitable super-and sub-solutions and using a dynamical system approach,we obtain the globally asymptotic stability of the bistable traveling wavefronts.
基金Supported by NSFC(Grant Nos.11771044,11871007)Foundation of Anhui University of Finance and Economics(Grant No.ACKYC19051)Major Research Projects of Natural Science in Colleges and Universities of Anhui Province(Grant No.KJ2017ZD35)
文摘This paper is concerned with the travelling wavefronts of a nonlocal dispersal cooperation model with harvesting and state-dependent delay,which is assumed to be an increasing function of the population density with lower and upper bound.Especially,state-dependent delay is introduced into a nonlocal reaction-diffusion model.The conditions of Schauder's fixed point theorem are proved by constructing a reasonable set of functionsΓ(see Section 2)and a pair of upper-lower solutions,so the existence of traveling wavefronts is established.The present study is continuation of a previous work that highlights the Laplacian diffusion.
文摘To realize effective co-phasing adjustment in large-aperture sparse-aperture telescopes,a multichannel stripe tracking approach is employed,allowing simultaneous interferometric measurements of multiple optical paths and circumventing the need for pairwise measurements along the mirror boundaries in traditional interferometric methods.This approach enhances detection efficiency and reduces system complexity.Here,the principles of the multibeam interference process and construction of a co-phasing detection module based on direct optical fiber connections were analyzed using wavefront optics theory.Error analysis was conducted on the system surface obtained through multipath interference.Potential applications of the interferometric method were explored.Finally,the principle was verified by experiment,an interferometric fringe contrast better than 0.4 is achieved through flat field calibration and incoherent digital synthesis.The dynamic range of the measurement exceeds 10 times of the center wavelength of the working band(1550 nm).Moreover,a resolution better than one-tenth of the working center wavelength(1550 nm)was achieved.Simultaneous three-beam interference can be achieved,leading to a 50%improvement in detection efficiency.This method can effectively enhance the efficiency of sparse aperture telescope co-phasing,meeting the requirements for observations of 8-10 m telescopes.This study provides a technological foundation for observing distant and faint celestial objects.
文摘For segmented detectors,surface flatness is critical as it directly influences both energy resolution and image clarity.Additionally,the limited adjustment range of the segmented detectors necessitates precise benchmark construction.This paper proposes an architecture for detecting detector flatness based on channel spectral dispersion.By measuring the dispersion fringes for coplanar adjustment,the final adjustment residual is improved to better than 300 nm.This result validates the feasibility of the proposed technology and provides significant technical support for the development of next-generation large-aperture sky survey equipment.
文摘In this paper, a reaction-diffusion model describing temporal development of tumor tissue, normal tissue and excess H＋ ion concentration is considered. Based on a combi- nation of perturbation methods, the Fredholm theory and Banach fixed point theorem, we theoretically justify the existence of the traveling wave solution for this model.
基金supported by the National Key Research and Development Program of China(2023YFB2805800 and 2021YFA1401003)the National Natural Science Foundation of China(62222513).
文摘Object imaging beyond the direct line of sight is significant for applications in robotic vision,remote sensing,autonomous driving,and many other areas.Reconstruction of a non-line-of-sight(NLOS)screen is a complex inverse problem that comes with ultrafast time-resolved imager requirements and substantial computational demands to extract information from the multi-bounce scattered light.Consequently,the echo signal always suffers from serious deterioration in both intensity and shape,leading to limited resolution and image contrast.Here,we propose a concept of vectorial digitelligent optics for high-resolution NLOS imaging to cancel the wall’s scattering and refocus the light onto hidden targets for enhanced echo.In this approach,the polarization and wavefront of the laser spot are intelligently optimized via a feedback algorithm to form a near-perfect focusing pattern through a random scattering wall.By raster scanning the focusing spot across the object’s surface within the optical-memory-effect range of the wall,we obtain nearly diffraction-limited NLOS imaging with an enhanced signal-to-noise ratio.Our experimental results demonstrate a resolution of 0.40 mm at a distance of 0.35 m,reaching the diffraction limit of the system.Furthermore,we demonstrate that the proposed method is feasible for various complex NLOS scenarios.Our methods may open an avenue for active imaging,communication,and laser wireless power transfer.
基金funding support provided by the Defense Advanced Research Projects Agency Defense Sciences Office Program: Enhanced Night Vision in Eyeglass Form (ENVision)
文摘The emergence of metalenses has impacted a wide variety of applications such as beam steering,imaging,depth sensing,and display projection.Optical distortion,an important metric among many optical design specifications,has however rarely been discussed in the context of meta-optics.Here,we present a generic approach for on-demand distortion engineering using compound metalenses.We show that the extra degrees of freedom afforded by a doublet metasurface architecture allow custom-tailored angle-dependent image height relations and hence distortion control while minimizing other monochromatic aberrations.Using this platform,we experimentally demonstrate a compound fisheye metalens with diffraction-limited performance across a wide field of view of 140°and a low barrel distortion of less than 2%,compared with up to 22%distortion in a reference metalens without compensation.The design strategy and compound metalens architecture presented herein are expected to broadly impact metasurface applications in consumer electronics,automotive and robotic sensing,medical imaging,and machine vision systems.
基金financial supports from the National Natural Science Foundation of China (62075132 and 92050202)Natural Science Foundation of Shanghai (22ZR1443100)
文摘This work introduces special states for light in multimode fibers featuring strongly enhanced or reduced correlations be-tween output fields in the presence of environmental temperature fluctuations.Using experimentally measured multi-tem-perature transmission matrix,a set of temperature principal modes that exhibit resilience to disturbances caused by tem-perature fluctuations can be generated.Reversing this concept also allows the construction of temperature anti-principal modes,with output profiles more susceptible to temperature influences than the unmodulated wavefront.Despite changes in the length of the multimode fiber within the temperature-fluctuating region,the proposed approach remains capable of robustly controlling the temperature response within the fiber.To illustrate the practicality of the proposed spe-cial state,a learning-empowered fiber specklegram temperature sensor based on temperature anti-principal mode sensi-tization is proposed.This sensor exhibits outstanding superiority over traditional approaches in terms of resolution and accuracy.These novel states are anticipated to have wide-ranging applications in fiber communication,sensing,imaging,and spectroscopy,and serve as a source of inspiration for the discovery of other novel states.
基金support from the Biotechnology and Biological Council Doctoral Training Programme(BBSRC DTP)the support from the Royal Society and Wolfson Foundation(RSWF\FT\191022).
文摘Nonlinear wavefront shaping is crucial for advancing optical technologies,enabling applications in optical computation,information processing,and imaging.However,a significant challenge is that once a metasurface is fabricated,the nonlinear wavefront it generates is fixed,offering little flexibility.This limitation often necessitates the fabrication of different metasurfaces for different wavefronts,which is both time-consuming and inefficient.To address this,we combine evolutionary algorithms with spatial light modulators(SLMs)to dynamically control wavefronts using a single metasurface,reducing the need for multiple fabrications and enabling the generation of arbitrary nonlinear wavefront patterns without requiring complicated optical alignment.We demonstrate this approach by introducing a genetic algorithm(GA)to manipulate visible wavefronts converted from near-infrared light via third-harmonic generation(THG)in a silicon metasurface.The Si metasurface supports multipolar Mie resonances that strongly enhance light-matter interactions,thereby significantly boosting THG emission at resonant positions.Additionally,the cubic relationship between THG emission and the infrared input reduces noise in the diffractive patterns produced by the SLM.This allows for precise experimental engineering of the nonlinear emission patterns with fewer alignment constraints.Our approach paves the way for self-optimized nonlinear wavefront shaping,advancing optical computation and information processing techniques.
基金supported by the National Natural Science Foundation of China(Grant Nos.12325408,92150102,62205302,92150301,12274129,12074121,62105101,62175066,12274139,and 12404380)the Fundamental and Applied Basic Research Project of Guangzhou(Grant No.2024A04J2001)the Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2024B1515020051 and 2023A1515110742).
文摘The spectral memory effect in scattering media is crucial for applications that employ broadband illumination,as it dictates the available spectral range from independent scattering responses.Previous studies mainly considered a passive result with the average impact of the scattering medium,whereas it is vital to actively enhance or suppress this effect for applications concerned with large spectral range or fine resolution.We construct an analytical model by integrating the concepts of wave-based interference and photon-based propagation,which manifests a potential physical image for active manipulation by utilizing scattering eigenchannels.Our theoretical predictions indicate that the spectral memory effect is enhanced using high-transmission eigenchannels while it is suppressed using low-transmission eigenchannels.These predictions are supported by finite-difference time-domain simulations and experiments,demonstrating that the spectral memory effect’s range can be actively manipulated.Quantitatively,the experiments achieved variations in enhancement and suppression that exceeded threefold(∼3.27).We clarify the underlying principles of the spectral memory effect in scattering media and demonstrate active manipulation of multispectral scattering processes.
文摘A method for simulating acoustic wavefronts propagating under random sound speed conditions is presented.The approach applies a level set method to solve the Eikonal equation of high frequency acoustics for surfaces of constant phase,instead of tracing rays.The Lagrangian nature often makes full-field ray solutions difficult to reconstruct.The level set method captures multiple-valued solutions on a fixed grid.It is straightforward to represent other sources of uncertainty in the input data using this model,which has an advantage over Monte Carlo approaches in that it yields an expression for the solution as a function of random variables.
