Circularly Polarized Light-Enabled Chiral Nanomaterials:From Fabrication to Application

For decades,chiral nanomaterials have been extensively studied because of their extraordinary properties.Chiral nanostructures have attracted a lot of interest because of their potential applications including biosensing,asymmetric catalysis,optical devices,and negative index materials.Circularly polarized light(CPL)is the most attractive source for chirality owing to its high availability,and now it has been used as a chiral source for the preparation of chiral matter.In this review,the recent progress in the field of CPL-enabled chiral nanomaterials is summarized.Firstly,the recent advancements in the fabrication of chiral materials using circularly polarized light are described,focusing on the unique strategies.Secondly,an overview of the potential applications of chiral nanomaterials driven by CPL is provided,with a particular emphasis on biosensing,catalysis,and phototherapy.Finally,a perspective on the challenges in the field of CPL-enabled chiral nanomaterials is given.

Light-modulated graphene-based φ_(0) Josephson junction and -φ_(0) to φ_(0) transition

We investigate the chiral edge states-induced Josephson current–phase relation in a graphene-based Josephson junction modulated by the off-resonant circularly polarized light and the staggered sublattice potential.By solving the Bogoliubov–de Gennes equation,a φ_(0) Josephson junction is induced in the coaction of the off-resonant circularly polarized light and the staggered sublattice potential,which arises from the fact that the center of-mass wave vector of Cooper pair becomes finite and the opposite center of-mass wave vector to compensate is lacking in the nonsuperconducting region.Interestingly,when the direction of polarization of light is changed,-φ_(0) to φ_(0) transition generates,which generalizes the concept of traditional 0–πtransition.Our findings provide a purely optical way to manipulate a phase-controllable Josephson device and guidelines for future experiments to confirm the presence of graphene-based φ_(0)Josephson junction.

Self-powered circularly polarized light detector based on asymmetric chiral metamaterials

Circularly polarized light(CPL)has been given great attention because of its extensive application.While several devices for CPL detection have been studied,their performance is affected by the magnitude of photocurrent.In this paper,a self-powered photodetector based on hot electrons in chiral metamaterials is proposed and optimized.CPL can be distinguished by the direction of photocurrent without external bias owing to the interdigital electrodes with asymmetric chiral metamaterials.Distinguished by the direction of photocurrent,the device can easily detect the rotation direction of the CPL electric field,even if it only has a very weak responsivity.The responsivity of the proposed detector is near 1.9 mA/W at the wavelength of 1322 nm,which is enough to distinguish CPL.The detector we proposed has the potential for application in optical communication.

Detecting Spin Bias with Circularly Polarized Light

We theoretically study the spin transport through a two-terminal quantum dot device under the influence of a symmetric spin bias and circularly polarized light. It is found that the combination of the circularly polarized light and the applied spin bias can result in a net charge current. The resultant charge current is large enough to be measured when properly choosing the system parameters. The resultant charge current can be used to deduce the spin bias due to the fact that there exists a simple linear relation between them. When the external circuit is open, a charge bias instead of a charge current can be induced, which is also measurable by present technologies. These findings indicate a new approach to detect the spin bias by using circularly polarized light.

MONTE CARLO SIMULATION OF POLARIZED LIGHT SCATTERING IN TISSUES

We investigate the propagation of polarized light in fibrous tissues such as muscle and skin.The myofibrils and collagen fibers are approximated as long cylinders and the tissue phantom is composed of spherical and cylindrical structures.We apply Monte Carlo method based on this phantom to simulate and analyze polarization imaging process of muscle.The good agreement between the simulation results and the experimental results validate the assumption of the phantom composition.This paper also presents how to describe the fiber orientation distribution and tissue anisotropy according to three parameters derived from the polarization imaging.

Relationship between Colored Microstructure under Polarized Light and Shape Recovery Characteristics on the Thermomechanical Cycled CuAlNi Single Crystals

The paper studied the relationship between microstructure and shape recovery characteristics by using colored microstructure analysis under polarized light on the thermomechanical cycled CuAlNi single crystals. The two-way shape memory effect in quenched thin bar resulted from the preferential formation/extinction of martensite variant due to the internal quench stress, and the variant was formed at an angle of about 45 deg. with the tension direction ([001] of the βphase). Initial thermomechanical cycling under relatively low stress single variant stress-induced martensite was formed at an angle of 45 deg. with the tension and its morphology was a lath of parallel twins. More than one group of variants were formed after several training cycles and such variants also caused tilting of some thermally formed accommodated martensite. By overheating the trained sample containing stabilized multi-variants of stress-induced martensite, very coarse martensite structure with a strong asymmetry was produced, which caused the reverse two-way shape memory effect.

Advancing respirable coal mine dust source apportionment:a preliminary laboratory exploration of optical microscopy as a novel monitoring tool

Exposure to respirable coal mine dust(RCMD)can cause chronic and debilitating lung diseases.Real-time monitoring capabilities are sought which can enable a better understanding of dust components and sources.In many underground mines,RCMD includes three primary components which can be loosely associated with three major dust sources:coal dust from the coal seam itself,silicates from the surrounding rock strata,and carbonates from the inert‘rock dust’products that are applied to mitigate explosion hazards.A monitor which can reliably partition RCMD between these three components could thus allow source apportionment.And tracking silicates,specifically,could be valuable since the most serious health risks are typically associated with this component-particularly if abundant in crystalline silica.Envisioning a monitoring concept based on field microscopy,and following up on prior research using polarized light,the aim of the current study was to build and test a model to classify respirable-sized particles as either coal,silicates,or carbonates.For model development,composite dust samples were generated in the laboratory by successively depositing dust from high-purity materials onto a sticky transparent substrate,and imaging after each deposition event such that the identity of each particle was known a priori.Model testing followed a similar approach,except that real geologic materials were used as the source for each dust component.Results showed that the model had an overall accuracy of 86.5%,indicating that a field-microscopy based moni-tor could support RCMD source apportionment and silicates tracking in some coal mines.

Polarized imaging dynamic light scattering for simultaneous measurement of nanoparticle size and morphology

The performance of nanoparticles is often affected by particle size and morphology.Currently,electron microscopy or atomic force microscopy is typically utilized to determine the size and morphology of nanoparticles.However,there are issues such as difficult sample preparation,long processing times,and challenges in quantitative characterization.Therefore,it is of great significance to develop a fast,accu-rate,and statistical method to measure the size and morphology of nanoparticles.In this study,a new method,called polarized imaging dynamic light scattering(PIDLS),is proposed.The nanoparticles are irradiated with a vertical linearly polarized laser beam,and a polarization camera collected the dynamic light scattering images of particles at four different polarization directions(0°,45°,90°,and 135°)at a scattering angle of 90°.The average particle size and distribution are obtained using the imaging dy-namic light scattering method at 0°polarization direction,and the morphology of the particles is ob-tained based on the depolarization patterns of the scattered light.The optical sphericityΦis defined based on the degree of linear polarization(DoLP).It is also implemented for the quantitative evaluation of the sphericity of the nanoparticles,including spherical,octahedral,nanoplate,nanorod,and linear ones.Together with the Poincarésphere parameterψ,the morphology of the nanoparticles can be roughly identified.In addition,PIDLS enables the measurement of particle size and morphology distributions simultaneously for evaluating the uniformity of particles.The effectiveness of PIDLS is verified by the measurement of five kinds of industrial titanium dioxide as well.

Circularly polarized light emission and detection by chiral inorganic semiconductors

Chiral inorganic semiconductors with high dissymmetric factor are highly desirable,but it is generally difficult to induce chiral structure in inorganic semiconductors because of their structure rigidity and symmetry.In this study,we introduced chiral ZnO film as hard template to transfer chirality to CsPbBr_(3) film and PbS quantum dots(QDs)for circularly polarized light(CPL)emission and detection,respectively.The prepared CsPbBr_(3)/ZnO thin film exhibited CPL emission at 520 nm and the PbS QDs/ZnO film realized CPL detection at 780 nm,featuring high dissymmetric factor up to around 0.4.The electron transition based mechanism is responsible for chirality transfer.

Peculiar influence of linearly polarized spectrum illumination patterns on the sensitivity characteristics of locust response to polarized light

This study investigated the influence of different linearly polarized spectrum lights on locusts polartactic response characteristics linearly polarized vector sensitivity mode and polartactic response by using linearly polarized spectrum vector light module and experimental device.The objective was to clarify the vector sensitivity characteristics and functional effect of linearly polarized light spectrum intensity on locusts polartactic response,determine the influence specificity of linearly polarized spectrum illumination properties on locusts polarization-related behavior.When spectrum and illumination were constant,locusts polartactic response,presenting the response feature of sine and cosine function change specificity,was related to spectrum attribute.The visual acuity effect stimulated by violet spectrum was the best,whereas the optical distance modulation effect induced by orange spectrum was the strongest.When illumination was enhanced,locusts vector sensitivity mode shifted to present the specific sensitivity prompted by light intensity at long distance and inhibited by light intensity at short distance.Moreover,the regulating function of violet spectrum was the strongest,and the regulatory mutation effect of orange spectrum was the least significant.Simultaneously,locusts polartactic sensitivity to 300°vector at 100 lx,whereas to 240°vector at 1000 lx of linearly polarized violet light was the strongest.Locusts polartactic aggregation and visual tendency sensitivity to 90°vector at 100 lx,whereas to 270°vector at 1000 lx of linearly polarized violet light was the strongest.The heterogeneous regulation function of different linearly polarized spectrum couplings with light intensity led to significant variations in locusts vector sensitivity mode.This was derived from the antagonistic and specific tuning characteristics of locusts polartactic vision,reflecting the integrated output effect of locusts vector dependence regulated by linearly polarized spectrum intensity attribute.The findings were significant for the construction of pest polarization induction light sources and the investigation of the sensitive physiology pathway of locusts polarization vision.

Delayed Fluorescence and Amplified Chirality via Modified Substitution Position for Deep-red Circularly Polarized Organic Light Emitting-diodes

Developing easily accessible deep-red/near-infrared circularly polarized emitters for practical organic light-emitting diodes remains a significant challenge.Here,a practical strategy has been proposed for developing deep-red circularly polarized delayed fluorescent emitters based on a novel chiral acceptor platform.By changing triphenylamine(TPA)substitution position from para to meta,R/S-M-TBBTCN demonstrated thermally activated delayed fluorescence(TADF)properties with a delayed lifetime of 6.6µs that R/S-P-TBBTCN doesn’t have.Furthermore,R/S-M-TBBTCN showed a 65 nm red-shift in emission and a 10-fold enhancement in asymmetry factor(glum),compared with R/S-P-TBBTCN.The solution-processed nondoped circularly polarized organic light-emitting diodes(CP-OLEDs)based on R-M-TBBTCN display deep-red emission and 2.2%external quantum efficiency.

Light-modulated electron retroreflection and Klein tunneling in a graphene-based n-p-n junction

We investigate the electron retroreflection and the Klein tunneling across a graphene-based n-p-n junction irradiated by linearly polarized off-resonant light with the polarization along the x direction.The linearly polarized off-resonant light modifies the band structure of graphene,which leads to the anisotropy of band structure.By adjusting the linearly polarized light and the direction of n-p-n junction simultaneously,the electron retroreflection appears and the anomalous Klein tunneling,the perfect transmission at a nonzero incident angle regardless of the width and height of potential barrier,happens,which arises from the fact that the light-induced anisotropic band structure changes the relation of wavevector and velocity of electron.Our finding provides an alternative and flexible method to modulate electron retroreflection and Klein tunneling.

E®ect of light polariztion on pattern illumination super-resolution imaging

Far-¯eld°uorescence microscopy has made great progress in the spatial resolution,limited by light diffraction,since the super-resolution imaging technology appeared.And stimulated emission depletion(STED)microscopy and structured illumination microscopy(SIM)can be grouped into one class of the super-resolution imaging technology,which use pattern illumination strategy to circumvent the di®raction limit.We simulated the images of the beads of SIM imaging,the intensity distribution of STED excitation light and depletion light in order to observe effects of the polarized light on imaging quality.Compared to¯xed linear polarization,circularly polarized light is more suitable for SIM on reconstructed image.And right-handed circular polarization(CP)light is more appropriate for both the excitation and depletion light in STED system.Therefore the right-handed CP light would be the best candidate when the SIM and STED are combined into one microscope.Good understanding of the polarization will provide a reference for the patterned illumination experiment to achieve better resolution and better image quality.

Polarized Electronic Spectra of Organic/Inorganic Hybrid Materials of Chiral Schiff Base Ni（ll） or Cu（ll） Complexes and Disperse Red 1 or Azobenzene in PMMA Films

We have prepared new chiral Schiff base complexes, and copper（Ⅱ） （2） to investigate steric effect of ligands for 1 and bis（N-R-l-phenylethyl-5- methoxysalicydenaminato） nickel（Ⅱ） （1） 2 and known bis（N-R-l-phenylethyl-3,5-dichlorosalicydenaminato） nickel（Ⅱ） （3） and copper（Ⅱ） （4）. By using two kinds of photochromic dyes, disperse red 1 （DRI） and azobenzene （AZ）, we investigated the efficiency of increasing optical anisotropy of organic/inorganic hybrid materials of 1 through 4＋AZ or DRI＋PMMA in polymethylmethacrylate （PMMA） cast films by Weigert effect （and compared with cis-trans isomerization by alternate UV and visible light for 3 and 4 to previous study）. Gradual increase of optical anisotropy was observed for all the hybrid materials regardless of flexibility of Schiff base complexes, and the degree of dichroism and weak intermolecular interactions were discussed based on polarized absorption electronic spectra.

Static Laser Light Scattering Studies from Red Blood Cells

A homemade Static Light scattering studies has been used to determine angle resolved scattered intensity for different polarization states of the incident laser light. Classical light scattering set ups are being used to study morphological aspects of scatterers using simple set ups using low power lasers. Red blood cells form rather interesting as well as a challenging system for scattering experiments. The scattering spectrometer consists of a scattering arm, a scattering turn table and collimating arm. Along with polarizers integrated in the collimating arm as well as scattering arms ensures collection of scattered flux with the required polarization state. This technique is being developed for its in vitro studies using fresh red blood cells. A brief review of the theoretical models used for scattering from Red Blood Cells (RBC) has been discussed in the paper. Scattering pattern (scattering plots) as well as polar plots of scattered flux have been determined for different polarization state of the incident light. Insight into the orientation of major axis of particles can be inferred from the polar plots.

Influences of DRA and non-DRA vision on the visual responses of locusts stimulated by linearly polarized and unpolarized lights

Locust and grasshopper plagues pose a serious threat to crop production in many areas worldwide.However,there is a lack of effective,quick-acting methods to control such outbreaks.Methods exploiting the phototactic response of these insects are receiving increasing attention.The current study investigated the effect of linearly polarized and unpolarized light on locust phototactic and polarotactic responses,in particular the function of their dorsal rim area(DRA)and non-DRA visual fields.The results showed that the polarotactic function weight of DRA vision was stimulated by linearly polarized ultraviolet(UV)and violet light,the phototactic function weight was induced by blue,green,and orange light,and under linearly polarized light,the functional effect of DRA vision was strongest in response to linearly polarized violet light.Moreover,the locust visual response effect was related to spectral light attributes,with the linear polarization effect intensifying in response to the short-range vision sensitivity of non-DRA visual fields,whereas DRA vision regulated the short-range sensitivity of compound eye vision.When illumination increased,the synergistic enhancement effects of linearly polarized ultraviolet and violet light were significant,whereas the visual sensitivity was restricted significantly by linearly polarized blue,green,or orange light.Thus,non-DRA vision determined,while DRA vision enhanced,the phototactic response sensitivity,whereas,in linearly polarized UV or violet light,non-DRA vision determined,while DRA vision enhanced,the visual trend and polarotaxic aggregation sensitivity,with opposite effects in linearly polarized blue,green,or orange light.When illumination increased,there was a driving effect caused by linearly polarized violet light on non-DRA vision,whereas at short-wave lengths,the control effect induced by linearly polarized orange light was optimal;however,the photo-induced effect of linearly polarized violet light and the visual distance control effect of linearly polarized orange light were optimal.These results provide theoretical support for the photo-induced mechanism of the locust visual response effect and for the development of linearly polarized light sources for the environmentally friendly prevention and control of locust populations.

Absolute asymmetric synthesis driven by circularly polarized light

Circularly polarized light(CPL)is an inherently chiral entity and is regarded as one of the possible deterministic signals that led to the evolution of homochirality in earth.Thus,CPL as an external physical field has been widely used in a technique known as absolute asymmetric synthesis,because a product enriched in one enantiomer is formed from racemic precursor molecules without the intervention of a chiral catalyst.In this review,we retrospect the historical research of CPL-induced absolute asymmetric synthesis,including chiral organic molecules,helical polymers,supramolecular assemblies,noble metal nanostructures.However,based on these results,we concluded that the chiral photon-matter interaction is very faint due to the arrangement of molecular bonds giving rise to chiral features,is over a smaller distance than the helical pitch of CPL,leading extremely small enantiomeric excess for product.Therefore,we highlight the recently emerged technology called superchiral field,in which the superchiral far-field and near-field could enhance the dissymmetry of optical field and near-field,respectively.In sum,we hope this review could bring some enlightenment to researchers and further improve the enantioselectivity of CPL-induced absolute asymmetric synthesis.

Application of polarized light microscopy on microstructural characterization of semisolid slurry

In this paper,two ways of micro structural characterization,optical microscopy(OM) and polarized light microscopy(PLM),were both employed to describe the micro structure of semisolid slurry prepared by swirling enthalpy equilibration device(SEED).The results show that PLM is more reliable and accurate than OM to describe the special morphology feature of semisolid slurry made by SEED process.Meanwhile,the effects of pouring temperature and mass of molten liquid on the primary α-Al particle size and morphology were also investigated using PLM.The quantitative metallographic results measured from PLM demonstrate that the grain size and morphology and their distribution are significantly affected by both pouring temperature and the mass of molten liquid.The grain size poured with 2.7 kg liquid decreases from 659 to186 μm,and grain morphology transforms from dendrite to globular structure with pouring temperature reducing from690 to 630℃.The decreasing pouring temperature also promotes the distribution of spherical structure on the cross section.Meanwhile,the mass of molten liquid decreasing from 2.7 to 2.3 kg can decrease the grain size by maximum of 44% at high pouring temperature.

Discrimination and quantification of scar tissue by Mueller matrix imaging with machine learning

Scarring is one of the biggest areas of unmet need in the long-term success of glaucoma filtration surgery.Quantitative evaluation of the scar tissue and the post-operative structure with micron scale resolution facilitates development of anti-fibrosis techniques.However,the distinguishment of conjunctiva,sclera and the scar tissue in the surgical area still relies on pathologists'experience.Since polarized light imaging is sensitive to anisotropic properties of the media,it is ideal for discrimination of scar in the subconjunctival and episcleral area by characterizing small differences between proportion,organization and the orientation of the fibers.In this paper,we defined the conjunctiva,sclera,and the scar tissue as three target tissues after glaucoma filtration surgery and obtained their polarization characteristics from the tissue sections by a Mueller matrix microscope.Discrimination score based on parameters derived from Mueller matrix and machine learning was calculated and tested as a diagnostic index.As a result,the discrimination score of three target tissues showed significant difference between each other(p<0.001).The visualization of the discrimination results showed significant contrast between target tissues.This study proved that Mueller matrix imaging is effective in ocular scar discrimination and paves the way for its application on other forms of ocular fibrosis as a substitute or supplementary for clinical practice.

Bioinspired Polarized Skylight Orientation Determination Artificial Neural Network

This paper proposes an artificial neural network to determine orientation using polarized skylight. This neural network has specific dilated convolution, which can extract light intensity information of different polarization directions. Then, the degree of polarization (DOP) and angle of polarization (AOP) are directly extracted in the network. In addition, the exponential function encoding of orientation is designed as the network output, which can better reflect the insect’s encoding of polarization information and improve the accuracy of orientation determination. Finally, training and testing were conducted on a public polarized skylight navigation dataset, and the experimental results proved the stability and effectiveness of the network.