A joint estimation algorithm of direction of arrival （DOA）, frequency, and polarization, based on fourth-order cumulants and uniform circular array （UCA） of trimmed vector sensors is presented for narrowband non-G...A joint estimation algorithm of direction of arrival （DOA）, frequency, and polarization, based on fourth-order cumulants and uniform circular array （UCA） of trimmed vector sensors is presented for narrowband non-Gaussian signals. The proposed approach, which is suitable for applications in arbitrary Gaussian noise environments, gives a closed-form representation of the estimated parameters, without spectral peak searching. An efficient method is also provided for elimination of cyclic phase ambiguities. Simulations are presented to show the performance of the algorithm.展开更多
Scattering phenomena affect light propagation through any kind of medium from free space to biological tissues.Finding appropriate strategies to increase the robustness to scattering is the common requirement in devel...Scattering phenomena affect light propagation through any kind of medium from free space to biological tissues.Finding appropriate strategies to increase the robustness to scattering is the common requirement in developing both communication protocols and imaging systems.Recently,structured light has attracted attention due to its seeming scattering resistance in terms of transmissivity and spatial behavior.Moreover,correlation between optical polarization and orbital angular momentum(OAM),which characterizes the so-called vector vortex beams(VVBs)states,seems to allow for the preservation of the polarization pattern.We extend the analysis by investigating both the spatial features and the polarization structure of vectorial optical vortexes propagating in scattering media with different concentrations.Among the observed features,we find a sudden swift decrease in contrast ratio for Gaussian,OAM,and VVB modes for concentrations of the adopted scattering media exceeding 0.09%.Our analysis provides a more general and complete study on the propagation of structured light in dispersive and scattering media.展开更多
The problem of statistical description of instantaneous polarization of electromagnetic waves is studied. First, the physical meanings of instantaneous Stokes vectors components are analyzed, which provide a short cut...The problem of statistical description of instantaneous polarization of electromagnetic waves is studied. First, the physical meanings of instantaneous Stokes vectors components are analyzed, which provide a short cut for solving statistical distribution functions of instantaneous Stokes vectors. Second, in the condition of Gaussian hypothesis, the analytical expressions of probability density function (PDF) of instantaneous Stokes vectors are presented. Finally, some computation results are presented in the condition of two independent polarization channels, which show the validity and simplicity of the statistical description method.展开更多
The polarization evolution of vector beams(VBs) generated by q-plates is investigated theoretically and experimentally.An analytical model is developed for the VB created by a general quarter-wave q-plate based on vec...The polarization evolution of vector beams(VBs) generated by q-plates is investigated theoretically and experimentally.An analytical model is developed for the VB created by a general quarter-wave q-plate based on vector diffraction theory.It is found that the polarization distribution of VBs varies with position and the value q.In particular,for the incidence of circular polarization,the exit vector vortex beam has polarization states that cover the whole surface of the Poincarésphere,thereby constituting a full Poincarébeam.For the incidence of linear polarization,the VB is not cylindrical but specularly symmetric,and exhibits an azimuthal spin splitting.These results are in sharp contrast with those derived by the commonly used model,i.e.,regarding the incident light as a plane wave.By implementing q-plates with dielectric metasurfaces,further experiments validate the theoretical results.展开更多
The original vector discrete ordinate radiative transfer(VDISORT)model takes into account Stokes radiance vector but derives its solution assuming azimuthal symmetric surface reflective matrix and atmospheric scatteri...The original vector discrete ordinate radiative transfer(VDISORT)model takes into account Stokes radiance vector but derives its solution assuming azimuthal symmetric surface reflective matrix and atmospheric scattering phase matrix,such as the phase matrix derived from spherical particles or randomly oriented non-spherical particles.In this study,a new VDISORT is developed for general atmospheric scattering and boundary conditions.Stokes vector is decomposed into both sinusoidal and cosinusoidal harmonic modes,and the radiance at arbitrary viewing geometry is solved directly by adding two zero-weighted points in the Gaussian quadrature scheme.The complex eigenvalues in homogeneous solutions are also taken into full consideration.The accuracy of VDISORT model is comprehensively validated by four cases:Rayleigh scattering case,the spherical particle scattering case with the Legendre expansion coefficients of 0th-13th orders of the phase matrix(hereinafter L13),L13 with a polarized source,and the randomoriented oblate particle scattering case with the Legendre expansion coefficients of 0th-11th orders of the phase matrix(hereinafter L11).In all cases,the simulated radiances agree well with the benchmarks,with absolute biases less than 0.0065,0.0006,and 0.0008 for Rayleigh,unpolarized L13,and L11,respectively.Since a polarized bidirectional reflection distribution function(pBRDF)matrix is used as the lower boundary condition,VDISORT is now able to handle fully coupled atmospheric and surface polarimetric radiative transfer processes.展开更多
基金This project was supported by the Graduate Innovation Laboratory of Jilin University(502039)Jilin Science Committee of China(20030519)+1 种基金the National Natural Science Foundation of China (69872012)the Foundation of Nanjing Institute of Technology.
文摘A joint estimation algorithm of direction of arrival （DOA）, frequency, and polarization, based on fourth-order cumulants and uniform circular array （UCA） of trimmed vector sensors is presented for narrowband non-Gaussian signals. The proposed approach, which is suitable for applications in arbitrary Gaussian noise environments, gives a closed-form representation of the estimated parameters, without spectral peak searching. An efficient method is also provided for elimination of cyclic phase ambiguities. Simulations are presented to show the performance of the algorithm.
基金This project received funding from the European Union’s Horizon 2020 research and innovation program(Future and Emerging Technologies)under Grant Agreement No.828978.
文摘Scattering phenomena affect light propagation through any kind of medium from free space to biological tissues.Finding appropriate strategies to increase the robustness to scattering is the common requirement in developing both communication protocols and imaging systems.Recently,structured light has attracted attention due to its seeming scattering resistance in terms of transmissivity and spatial behavior.Moreover,correlation between optical polarization and orbital angular momentum(OAM),which characterizes the so-called vector vortex beams(VVBs)states,seems to allow for the preservation of the polarization pattern.We extend the analysis by investigating both the spatial features and the polarization structure of vectorial optical vortexes propagating in scattering media with different concentrations.Among the observed features,we find a sudden swift decrease in contrast ratio for Gaussian,OAM,and VVB modes for concentrations of the adopted scattering media exceeding 0.09%.Our analysis provides a more general and complete study on the propagation of structured light in dispersive and scattering media.
文摘The problem of statistical description of instantaneous polarization of electromagnetic waves is studied. First, the physical meanings of instantaneous Stokes vectors components are analyzed, which provide a short cut for solving statistical distribution functions of instantaneous Stokes vectors. Second, in the condition of Gaussian hypothesis, the analytical expressions of probability density function (PDF) of instantaneous Stokes vectors are presented. Finally, some computation results are presented in the condition of two independent polarization channels, which show the validity and simplicity of the statistical description method.
基金National Natural Science Foundation of China(NSFC)(10904036)Natural Science Foundation of Hunan Province(2015JJ3036)+2 种基金National High Technology Research and Development Program(2012AA01A301-01)Growth Program for Young Teachers of Hunan UniversityChina Scholarship Council(CSC)([2013]3050)
文摘The polarization evolution of vector beams(VBs) generated by q-plates is investigated theoretically and experimentally.An analytical model is developed for the VB created by a general quarter-wave q-plate based on vector diffraction theory.It is found that the polarization distribution of VBs varies with position and the value q.In particular,for the incidence of circular polarization,the exit vector vortex beam has polarization states that cover the whole surface of the Poincarésphere,thereby constituting a full Poincarébeam.For the incidence of linear polarization,the VB is not cylindrical but specularly symmetric,and exhibits an azimuthal spin splitting.These results are in sharp contrast with those derived by the commonly used model,i.e.,regarding the incident light as a plane wave.By implementing q-plates with dielectric metasurfaces,further experiments validate the theoretical results.
基金Supported by the Natural Science Program of China(U2142212)Natural Science Foundation of Hunan Province(2021JC0009)National Key Research and Development Program of China(2022YFC3004200)。
文摘The original vector discrete ordinate radiative transfer(VDISORT)model takes into account Stokes radiance vector but derives its solution assuming azimuthal symmetric surface reflective matrix and atmospheric scattering phase matrix,such as the phase matrix derived from spherical particles or randomly oriented non-spherical particles.In this study,a new VDISORT is developed for general atmospheric scattering and boundary conditions.Stokes vector is decomposed into both sinusoidal and cosinusoidal harmonic modes,and the radiance at arbitrary viewing geometry is solved directly by adding two zero-weighted points in the Gaussian quadrature scheme.The complex eigenvalues in homogeneous solutions are also taken into full consideration.The accuracy of VDISORT model is comprehensively validated by four cases:Rayleigh scattering case,the spherical particle scattering case with the Legendre expansion coefficients of 0th-13th orders of the phase matrix(hereinafter L13),L13 with a polarized source,and the randomoriented oblate particle scattering case with the Legendre expansion coefficients of 0th-11th orders of the phase matrix(hereinafter L11).In all cases,the simulated radiances agree well with the benchmarks,with absolute biases less than 0.0065,0.0006,and 0.0008 for Rayleigh,unpolarized L13,and L11,respectively.Since a polarized bidirectional reflection distribution function(pBRDF)matrix is used as the lower boundary condition,VDISORT is now able to handle fully coupled atmospheric and surface polarimetric radiative transfer processes.
