The scintillation index（SI） of a Gaussian–Schell model（GSM） beam in a moderate-to-strong anisotropic nonKolmogorov turbulent atmosphere is developed based on the extended Rytov theory. The on-axis SI in a marine ...The scintillation index（SI） of a Gaussian–Schell model（GSM） beam in a moderate-to-strong anisotropic nonKolmogorov turbulent atmosphere is developed based on the extended Rytov theory. The on-axis SI in a marine atmosphere is higher than that in a terrestrial atmosphere, but the off-axis SI exhibits the opposite trend. The on-axis SI first increases and then begins to decrease and saturate as the turbulence strength increases. Turbulence inner and outer scales have different effects on the on-axis SI in different turbulent fluctuation regions. The anisotropy characteristic of atmospheric turbulence leads to the decline in the on-axis SI, and the rise in the off-axis SI. The on-axis SI can be lowered by increasing the anisotropy of turbulence, wavelength, and source partial coherence before entering the saturation attenuation region. The developed model may be useful for evaluating ship-to-ship/shore free-space optical communication system performance.展开更多
Optical metrology is a well-established subject,dating back to early interferometry techniques utilizing light's linear momentum through fringes.In recent years,significant interest has arisen in using vortex ligh...Optical metrology is a well-established subject,dating back to early interferometry techniques utilizing light's linear momentum through fringes.In recent years,significant interest has arisen in using vortex light with orbital angular momentum(OAM),where the phase twists around a singular vortex in space or time.This has expanded metrology's boundaries to encompass highly sensitive chiral interactions between light and matter,three-dimensional motion detection via linear and rotational Doppler effects,and modal approaches surpassing the resolution limit for improved profling and quantification.The intricate structure of vortex light,combined with the integration of artifcial intelligence into optical metrology,unlocks new paradigms for expanding measurement frameworks through additional degrees of freedom,offering the potential for more effcient and accurate sensing and metrological advancements.This review aims to provide a comprehensive overview of recent advances and future trends in optical metrology with structured light,specifically focusing on how utilizing vortex beams has revolutionized metrology and remote sensing,transitioning from classical to quantum approaches.展开更多
Vortex splitting is one of the main causes of instability in orbital angular momentum(OAM) modes transmission. Recent advances in OAM modes free-space propagation have demonstrated that abruptly autofocusing Airy vort...Vortex splitting is one of the main causes of instability in orbital angular momentum(OAM) modes transmission. Recent advances in OAM modes free-space propagation have demonstrated that abruptly autofocusing Airy vortex beams(AAVBs) can potentially mitigate the vortex splitting effect. However, different modes of vortex embedding will affect the intensity gradients of the background beams, leading to changes in the propagation characteristics of vortex beams. This study presents the unification of two common methods of coupling autofocusing Airy beams with vortices by introducing a parameter(m), which also controls the intensity gradients and focusing properties of the AAVBs. We demonstrate that vortex splitting can be effectively reduced by selecting an appropriate value of the parameter(m) according to different turbulence conditions. In this manner,the performance of OAM-based free-space optical systems can be improved.展开更多
We model the effects of weak fluctuations on the probability densities and normalized powers of vortex models for the Bessel–Gauss photon beam with fractional topological charge in the paraxial non-Kolmogorov turbule...We model the effects of weak fluctuations on the probability densities and normalized powers of vortex models for the Bessel–Gauss photon beam with fractional topological charge in the paraxial non-Kolmogorov turbulence channel. We find that probability density of signal vortex models is a function of deviation from the center of the photon beam, and the farther away from the beam center it is, the smaller the probability density is. For fractional topological charge, the average probability densities of signal/crosstalk vortex modes oscillate along the beam radius except the half-integer order. As the beam waist of the photon source grows, the average probability density of signal and crosstalk vortex modes grow together. Moreover, the peak of the average probability density of crosstalk vortex modes shifts outward from the beam center as the beam waist gets larger. The results also show that the smaller index of non-Kolmogorov turbulence and the smaller generalized refractive-index structure parameter may lead to the higher average probability densities of signal vortex modes and lower average probability densities of crosstalk vortex modes. Lower-coherence radius or beam waist can give rise to less reduction of the normalized powers of the signal vortex modes, which is opposite to the normalized powers of crosstalk vortex modes.展开更多
Atmospheric turbulence degrades the performance of free-space optical(FSO)communication and remote sensing systems by introducing phase and intensity distortions.While a majority of research focuses on mitigating thes...Atmospheric turbulence degrades the performance of free-space optical(FSO)communication and remote sensing systems by introducing phase and intensity distortions.While a majority of research focuses on mitigating these effects to ensure robust signal transmission,an underexplored alternative is to leverage the transformation of structured light to characterize the turbulent medium itself.Here,we introduce a deep learning framework that fuses post-propagation intensity speckle patterns and orbital angular momentum(OAM)spectral data for atmospheric turbulence parameter inference.Our architecture,based on a modified InceptionNet backbone,is optimized to extract and integrate multi-scale features from these distinct optical modalities.This multimodal approach achieves validation accuracies exceeding 80%,substantially outperforming conventional single-modality baselines.The framework demonstrates high inference accuracy and enhanced training stability across a broad range of simulated turbulent conditions,quantified by varying Fried parameters(r_(0))and Reynolds numbers(Re).This work presents a scalable and data-efficient method for turbulence characterization,offering a pathway toward robust environmental sensing and the optimization of dynamic FSO systems.展开更多
基金Project supported by the Open Research Fund of State Key Laboratory of Pulsed Power Laser Technology(Grant No.SKL2016KF05)the Key Industrial Innovation Chain Project in Industrial Domain,China(Grant No.2017ZDCXL-GY-06-02)+1 种基金the Huawei Innovation Research Program,China(Grant No.HO2017050001AG)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Grant No.61621005)
文摘The scintillation index（SI） of a Gaussian–Schell model（GSM） beam in a moderate-to-strong anisotropic nonKolmogorov turbulent atmosphere is developed based on the extended Rytov theory. The on-axis SI in a marine atmosphere is higher than that in a terrestrial atmosphere, but the off-axis SI exhibits the opposite trend. The on-axis SI first increases and then begins to decrease and saturate as the turbulence strength increases. Turbulence inner and outer scales have different effects on the on-axis SI in different turbulent fluctuation regions. The anisotropy characteristic of atmospheric turbulence leads to the decline in the on-axis SI, and the rise in the off-axis SI. The on-axis SI can be lowered by increasing the anisotropy of turbulence, wavelength, and source partial coherence before entering the saturation attenuation region. The developed model may be useful for evaluating ship-to-ship/shore free-space optical communication system performance.
基金support from the 111 Project(B17035)National Natural Science Foundation of China(Grant no.U20B2059,62231021,61621005,62201613)+2 种基金Shanghai Aerospace Science and Technology Innovation support from the 111 Project(B17035)National Natural Science Foundation of China(Grant no.U20B2059,62231021,61621005,62201613)Shanghai Aerospace Science and Technology Innovation Foundation(SAST-2022-069)。
文摘Optical metrology is a well-established subject,dating back to early interferometry techniques utilizing light's linear momentum through fringes.In recent years,significant interest has arisen in using vortex light with orbital angular momentum(OAM),where the phase twists around a singular vortex in space or time.This has expanded metrology's boundaries to encompass highly sensitive chiral interactions between light and matter,three-dimensional motion detection via linear and rotational Doppler effects,and modal approaches surpassing the resolution limit for improved profling and quantification.The intricate structure of vortex light,combined with the integration of artifcial intelligence into optical metrology,unlocks new paradigms for expanding measurement frameworks through additional degrees of freedom,offering the potential for more effcient and accurate sensing and metrological advancements.This review aims to provide a comprehensive overview of recent advances and future trends in optical metrology with structured light,specifically focusing on how utilizing vortex beams has revolutionized metrology and remote sensing,transitioning from classical to quantum approaches.
基金supported by the Innovation Fund of Xidian University(No.20108183448)the Key Industrial Innovation Chain Project in Industrial Domain(No.2017ZDCXL–GY–06–02)+2 种基金the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.61621005)the National Natural Science Foundation of China(No.41806210)the Fundamental Research Funds for the Central Universities(No.CJT150502)
文摘Vortex splitting is one of the main causes of instability in orbital angular momentum(OAM) modes transmission. Recent advances in OAM modes free-space propagation have demonstrated that abruptly autofocusing Airy vortex beams(AAVBs) can potentially mitigate the vortex splitting effect. However, different modes of vortex embedding will affect the intensity gradients of the background beams, leading to changes in the propagation characteristics of vortex beams. This study presents the unification of two common methods of coupling autofocusing Airy beams with vortices by introducing a parameter(m), which also controls the intensity gradients and focusing properties of the AAVBs. We demonstrate that vortex splitting can be effectively reduced by selecting an appropriate value of the parameter(m) according to different turbulence conditions. In this manner,the performance of OAM-based free-space optical systems can be improved.
基金supported by the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20140128)the National Natural Science Foundation of Special Theoretical Physics(Grant No.11447174)the Fundamental Research Funds for the Central Universities(JUSRP51517)
文摘We model the effects of weak fluctuations on the probability densities and normalized powers of vortex models for the Bessel–Gauss photon beam with fractional topological charge in the paraxial non-Kolmogorov turbulence channel. We find that probability density of signal vortex models is a function of deviation from the center of the photon beam, and the farther away from the beam center it is, the smaller the probability density is. For fractional topological charge, the average probability densities of signal/crosstalk vortex modes oscillate along the beam radius except the half-integer order. As the beam waist of the photon source grows, the average probability density of signal and crosstalk vortex modes grow together. Moreover, the peak of the average probability density of crosstalk vortex modes shifts outward from the beam center as the beam waist gets larger. The results also show that the smaller index of non-Kolmogorov turbulence and the smaller generalized refractive-index structure parameter may lead to the higher average probability densities of signal vortex modes and lower average probability densities of crosstalk vortex modes. Lower-coherence radius or beam waist can give rise to less reduction of the normalized powers of the signal vortex modes, which is opposite to the normalized powers of crosstalk vortex modes.
基金111 Project(B17035)National Natural Science Foundation of China(U20B2059,62575227,62231021,61621005,62201613)+1 种基金Shanghai Aerospace Science and Technology Innovation Foundation(SAST-2022-069)Fundamental Research Funds for the Central Universities(ZYTS25121).
文摘Atmospheric turbulence degrades the performance of free-space optical(FSO)communication and remote sensing systems by introducing phase and intensity distortions.While a majority of research focuses on mitigating these effects to ensure robust signal transmission,an underexplored alternative is to leverage the transformation of structured light to characterize the turbulent medium itself.Here,we introduce a deep learning framework that fuses post-propagation intensity speckle patterns and orbital angular momentum(OAM)spectral data for atmospheric turbulence parameter inference.Our architecture,based on a modified InceptionNet backbone,is optimized to extract and integrate multi-scale features from these distinct optical modalities.This multimodal approach achieves validation accuracies exceeding 80%,substantially outperforming conventional single-modality baselines.The framework demonstrates high inference accuracy and enhanced training stability across a broad range of simulated turbulent conditions,quantified by varying Fried parameters(r_(0))and Reynolds numbers(Re).This work presents a scalable and data-efficient method for turbulence characterization,offering a pathway toward robust environmental sensing and the optimization of dynamic FSO systems.
