Broadband polarization measurement plays a crucial role in numerous fields,spanning from fundamental physics to a wide range of practical applications.However,traditional approaches typically rely on combinations of v...Broadband polarization measurement plays a crucial role in numerous fields,spanning from fundamental physics to a wide range of practical applications.However,traditional approaches typically rely on combinations of various dispersive optical elements,requiring bulky systems and complicated time-consuming multiple procedures.Here we have achieved broadband spectropolarimetry based on single-shot images for spatial intensity distributions of polychromatic vector beams.A custom-designed diffractive optical element and a vortex retarder convert the incident polychromatic waves into structured vector beams:the former diffracts light of different wavelengths into concentric circles of different radii,while the latter codes their polarization information into intensity distributions along the azimuthal direction.The validation experiments verify our exceptional measurement accuracy(RMS errors<1%)for each Stokes component in the visible light range(400-700 nm),with good spectral(<0.8 nm)and temporal(an output rate of 100 Hz)resolutions.We have further employed our broadband polarimeter to study the mutarotation of glucose,making direct observations of temporal evolutions of chemical reactions accessible.Our work has significantly broadened the toolboxes of spectropolarimetry,which can potentially incubate various disruptive applications that depend on broadband polarization measurements.展开更多
While conventional photodetectors can only measure light intensity,the vectorial light field contains much richer information,including polarization and spectrum,that are essential for numerous applications ranging fr...While conventional photodetectors can only measure light intensity,the vectorial light field contains much richer information,including polarization and spectrum,that are essential for numerous applications ranging from imaging to telecommunication.However,the simultaneous measurement of multi-dimensional light field information typically requires the multiplexing of dispersive or polarization-selective elements,leading to excessive system complexity.Here,we demonstrate a near-infrared spectropolarimeter based on an electrically-tunable liquid crystal metasurface.The tunable metasurface,which acts as an encoder of the vectorial light field,is tailored to support high-quality-factor guided-mode resonances with diverse and anisotropic spectral features,thus allowing the full Stokes parameters and the spectrum of the incident light to be computationally reconstructed with high fidelity.The concept of using a tunable metasurface for multi-dimensional light field encoding may open up new horizons for developing vectorial light field sensors with minimized size,weight,cost,and complexity.展开更多
Compressive full-Stokes spectropolarimetric imaging(SPI),integrating passive polarization modulator(PM)into general imaging spectrometer,is powerful enough to capture high-dimensional information via incomplete measur...Compressive full-Stokes spectropolarimetric imaging(SPI),integrating passive polarization modulator(PM)into general imaging spectrometer,is powerful enough to capture high-dimensional information via incomplete measurement;a reconstruction algorithm is needed to recover 3D data cube(x,y,andλ)for each Stokes parameter.However,existing PMs usually consist of complex elements and enslave to accurate polarization calibration,current algorithms suffer from poor imaging quality and are subject to noise perturbation.In this work,we present a single multiple-order retarder followed a polarizer to implement passive spectropolarimetric modulation.After building a unified forward imaging model for SPI,we propose a deep image prior plus sparsity prior algorithm for high-quality reconstruction.The method based on untrained network does not need training data or accurate polarization calibration and can simultaneously reconstruct the 3D data cube and achieve self-calibration.Furthermore,we integrate the simplest PM into our miniature snapshot imaging spectrometer to form a single-shot SPI prototype.Both simulations and experiments verify the feasibility and outperformance of our SPI scheme.It provides a paradigm that allows general spectral imaging systems to become passive full-Stokes SPI systems by integrating the simplest PM without changing their intrinsic mechanism.展开更多
N -Butyl chitosan(NBCS) derivatives were prepared by introducing butyl groups into the amine groups of chitosan via Schiff base intermediates. The quaternization of NBCS was carried out by using ethyl iodide to pr...N -Butyl chitosan(NBCS) derivatives were prepared by introducing butyl groups into the amine groups of chitosan via Schiff base intermediates. The quaternization of NBCS was carried out by using ethyl iodide to produce water-soluble cationic polyelectrolytes. The degree of the substitution of the products was measured by means of the electron spectroscopy for a successful chemical analysis. The quaternary ammonium chitosan salt(QACS) was proved to be a novel cholesteric liquid crystalline chitin, by means of the polarized optical microscopy and the circular dichroism spectropolarimetry. The critical mass fraction of the QACS/formic acid solution forming a lyotropic liquid crystal phase was 50%, which was almost the same as that of the NBCS/formic acid solution, but much higher than that of the chitosan in the same solvent.展开更多
Shared-aperture technology for multifunctional planar systems,performing several simultaneous tasks,was first introduced in the field of radar antennas.In photonics,effective control of the electromagnetic response ca...Shared-aperture technology for multifunctional planar systems,performing several simultaneous tasks,was first introduced in the field of radar antennas.In photonics,effective control of the electromagnetic response can be achieved by a geometric-phase mechanism implemented within a metasurface,enabling spin-controlled phase modulation.The synthesis of the shared-aperture and geometric-phase concepts facilitates the generation of multifunctional metasurfaces.Here shared-aperture geometric-phase metasurfaces were realized via the interleaving of sparse antenna sub-arrays,forming Si-based devices consisting of multiplexed geometric-phase profiles.We study the performance limitations of interleaved nanoantenna arrays by means of a Wigner phasespace distribution to establish the ultimate information capacity of a metasurface-based photonic system.Within these limitations,we present multifunctional spin-dependent dielectric metasurfaces,and demonstrate multiple-beam technology for optical rotation sensing.We also demonstrate the possibility of achieving complete real-time control and measurement of the fundamental,intrinsic properties of light,including frequency,polarization and orbital angular momentum.展开更多
The mysteries of sunspot penumbrae have been under an intense scrutiny for the past 10 years. During this time, some models have been proposed and refuted, while the surviving ones had to be modified, adapted and evol...The mysteries of sunspot penumbrae have been under an intense scrutiny for the past 10 years. During this time, some models have been proposed and refuted, while the surviving ones had to be modified, adapted and evolved to explain the ever-increasing array of observational constraints. In this contribution I will review two of the present models, emphasizing their contributions to this field, but also pinpointing some of their inadequacies to explain a number of recent observations at very high spatial resolution (0.32 ). To help explaining these new observations I propose some modifications to each of those models. These modifications bring those two seemingly opposite models closer together into a general picture that agrees well with recent 3D magneto-hydrodynamic simulations.展开更多
基金National Natural Science Foundation of China(62475285,61975235)Natural Science Foundation of Hunan Province(2019JJ40342)。
文摘Broadband polarization measurement plays a crucial role in numerous fields,spanning from fundamental physics to a wide range of practical applications.However,traditional approaches typically rely on combinations of various dispersive optical elements,requiring bulky systems and complicated time-consuming multiple procedures.Here we have achieved broadband spectropolarimetry based on single-shot images for spatial intensity distributions of polychromatic vector beams.A custom-designed diffractive optical element and a vortex retarder convert the incident polychromatic waves into structured vector beams:the former diffracts light of different wavelengths into concentric circles of different radii,while the latter codes their polarization information into intensity distributions along the azimuthal direction.The validation experiments verify our exceptional measurement accuracy(RMS errors<1%)for each Stokes component in the visible light range(400-700 nm),with good spectral(<0.8 nm)and temporal(an output rate of 100 Hz)resolutions.We have further employed our broadband polarimeter to study the mutarotation of glucose,making direct observations of temporal evolutions of chemical reactions accessible.Our work has significantly broadened the toolboxes of spectropolarimetry,which can potentially incubate various disruptive applications that depend on broadband polarization measurements.
基金National Natural Science Foundation of China(61975251,62135008)Guoqiang Institute,Tsinghua University。
文摘While conventional photodetectors can only measure light intensity,the vectorial light field contains much richer information,including polarization and spectrum,that are essential for numerous applications ranging from imaging to telecommunication.However,the simultaneous measurement of multi-dimensional light field information typically requires the multiplexing of dispersive or polarization-selective elements,leading to excessive system complexity.Here,we demonstrate a near-infrared spectropolarimeter based on an electrically-tunable liquid crystal metasurface.The tunable metasurface,which acts as an encoder of the vectorial light field,is tailored to support high-quality-factor guided-mode resonances with diverse and anisotropic spectral features,thus allowing the full Stokes parameters and the spectrum of the incident light to be computationally reconstructed with high fidelity.The concept of using a tunable metasurface for multi-dimensional light field encoding may open up new horizons for developing vectorial light field sensors with minimized size,weight,cost,and complexity.
基金supported by the National Natural Science Foundation of China(Grant No.62175196)the Shaanxi Fundamental Science Research Project for Mathematics and Physics(Grant No.22JSY020)the Shaanxi Province Key Research and Development Program of China(Grant No.2021GXLH-Z-058).
文摘Compressive full-Stokes spectropolarimetric imaging(SPI),integrating passive polarization modulator(PM)into general imaging spectrometer,is powerful enough to capture high-dimensional information via incomplete measurement;a reconstruction algorithm is needed to recover 3D data cube(x,y,andλ)for each Stokes parameter.However,existing PMs usually consist of complex elements and enslave to accurate polarization calibration,current algorithms suffer from poor imaging quality and are subject to noise perturbation.In this work,we present a single multiple-order retarder followed a polarizer to implement passive spectropolarimetric modulation.After building a unified forward imaging model for SPI,we propose a deep image prior plus sparsity prior algorithm for high-quality reconstruction.The method based on untrained network does not need training data or accurate polarization calibration and can simultaneously reconstruct the 3D data cube and achieve self-calibration.Furthermore,we integrate the simplest PM into our miniature snapshot imaging spectrometer to form a single-shot SPI prototype.Both simulations and experiments verify the feasibility and outperformance of our SPI scheme.It provides a paradigm that allows general spectral imaging systems to become passive full-Stokes SPI systems by integrating the simplest PM without changing their intrinsic mechanism.
基金Supported by the National Natural Science Foundation of China( No. 2 9974 0 2 3)
文摘N -Butyl chitosan(NBCS) derivatives were prepared by introducing butyl groups into the amine groups of chitosan via Schiff base intermediates. The quaternization of NBCS was carried out by using ethyl iodide to produce water-soluble cationic polyelectrolytes. The degree of the substitution of the products was measured by means of the electron spectroscopy for a successful chemical analysis. The quaternary ammonium chitosan salt(QACS) was proved to be a novel cholesteric liquid crystalline chitin, by means of the polarized optical microscopy and the circular dichroism spectropolarimetry. The critical mass fraction of the QACS/formic acid solution forming a lyotropic liquid crystal phase was 50%, which was almost the same as that of the NBCS/formic acid solution, but much higher than that of the chitosan in the same solvent.
基金supported by the Israel Science Foundation(ISF)the United States—Israel Binational Science Foundation(BSF)the Israel Ministry of Science,Technology and Space,and KLA-Tencor.
文摘Shared-aperture technology for multifunctional planar systems,performing several simultaneous tasks,was first introduced in the field of radar antennas.In photonics,effective control of the electromagnetic response can be achieved by a geometric-phase mechanism implemented within a metasurface,enabling spin-controlled phase modulation.The synthesis of the shared-aperture and geometric-phase concepts facilitates the generation of multifunctional metasurfaces.Here shared-aperture geometric-phase metasurfaces were realized via the interleaving of sparse antenna sub-arrays,forming Si-based devices consisting of multiplexed geometric-phase profiles.We study the performance limitations of interleaved nanoantenna arrays by means of a Wigner phasespace distribution to establish the ultimate information capacity of a metasurface-based photonic system.Within these limitations,we present multifunctional spin-dependent dielectric metasurfaces,and demonstrate multiple-beam technology for optical rotation sensing.We also demonstrate the possibility of achieving complete real-time control and measurement of the fundamental,intrinsic properties of light,including frequency,polarization and orbital angular momentum.
文摘The mysteries of sunspot penumbrae have been under an intense scrutiny for the past 10 years. During this time, some models have been proposed and refuted, while the surviving ones had to be modified, adapted and evolved to explain the ever-increasing array of observational constraints. In this contribution I will review two of the present models, emphasizing their contributions to this field, but also pinpointing some of their inadequacies to explain a number of recent observations at very high spatial resolution (0.32 ). To help explaining these new observations I propose some modifications to each of those models. These modifications bring those two seemingly opposite models closer together into a general picture that agrees well with recent 3D magneto-hydrodynamic simulations.
