Cholesteric liquid crystals（CLCs） have recently sparked an enormous amount of interest in the development of soft matter materials due to their unique ability to self-organize into a helical supra-molecular architec...Cholesteric liquid crystals（CLCs） have recently sparked an enormous amount of interest in the development of soft matter materials due to their unique ability to self-organize into a helical supra-molecular architecture and their excellent selective reflection of light based on the Bragg relationship.Nowadays,by the virtue of building the self-organized nanostructures with pitch gradient or non-uniform pitch distribution,extensive work has already been performed to obtain CLC films with a broad reflection band.Based on authors＇ many years＇ research experience,this critical review systematically summarizes the physical and optical background of the CLCs with broadband reflection characteristics,methods to obtain broadband reflection of CLCs,as well as the application in the field of intelligent optical modulation materials.Combined with the research status and the advantages in the field,the important basic and applied scientific problems in the research direction are also introduced.展开更多
In this article,we review recently achieved Kerr effect progress in novel liquid crystal（LC） material：vertically aligned deformed helix ferroelectric liquid crystal（VADHFLC）.With an increasing applied electric fi...In this article,we review recently achieved Kerr effect progress in novel liquid crystal（LC） material：vertically aligned deformed helix ferroelectric liquid crystal（VADHFLC）.With an increasing applied electric field,the induced inplane birefringence of LCs shows quadratic nonlinearity.The theoretical calculations and experimental details are illustrated.With an enhanced Kerr constant to 130 nm/V2,this VADHFLC cell can achieve a 2π modulation by a small efficient electric field with a fast response around 100 μs and thus can be employed in both display and photonics devices.展开更多
Tin-lead(Sn-Pb)mixed perovskites are extensively investigated in near-infrared(NIR)photodetectors(PDs)owing to their excellent photoelectric performance.However,achieving high-performance Sn-Pb mixed PDs remains chall...Tin-lead(Sn-Pb)mixed perovskites are extensively investigated in near-infrared(NIR)photodetectors(PDs)owing to their excellent photoelectric performance.However,achieving high-performance Sn-Pb mixed PDs remains challenging,primarily because of the rapid crystallization and the susceptibility of Sn^(2+) to oxidation.To ad⁃dress these issues,this study introduces the multifunctional molecules 2,3-difluorobenzenamine(DBM)to modulate the crystallization of Sn-Pb mixed perovskites and retard the oxidation of Sn^(2+),thereby significantly enhancing film quality.Compared with the pristine film,Sn-Pb mixed perovskite films modulated by DBM molecules exhibit a high⁃ly homogeneous morphology,reduced roughness and defect density.The self-powered NIR PDs fabricated with the improved films have a spectral response range from 300 nm to 1100 nm,a peak responsivity of 0.51 A·W^(-1),a spe⁃cific detectivity as high as 2.46×10^(11)Jones within the NIR region(780 nm to 1100 nm),a linear dynamic range ex⁃ceeding 152 dB,and ultrafast rise/fall time of 123/464 ns.Thanks to the outstanding performance of PDs,the fabri⁃cated 5×5 PDs array demonstrates superior imaging ability in the NIR region up to 980 nm.This work advances the development of Sn-Pb mixed perovskites for NIR detection and paves the way for their commercialization.展开更多
Organic-inorganic hybrid perovskite solar cells(PSCs)have garnered significant attention due to their high power conversion efficiency(PCE),low cost,and solution-processability.However,a substantial gap remains in the...Organic-inorganic hybrid perovskite solar cells(PSCs)have garnered significant attention due to their high power conversion efficiency(PCE),low cost,and solution-processability.However,a substantial gap remains in the certified efficiency of single-junction PSCs,primarily due to defects in perovskite films that accelerate nonradiative recombination of carriers.In this study,we designed a multifunctional thiourea derivative,amidinethiourea(ATU),as an additive to modulate the crystallization process of perovskite films and inhibit the formation of organic cations and iodine vacancies.Our work leverages the strong hydrogen-bonding interactions between guanidinium molecules and organic amine components,as well as the robust coordination effects between the C=S bonds in thiourea and Pb^(2+)ions.We demonstrate that ATU treatment significantly enhances the crystallinity of perovskite films,reduces defects,and improves charge transport properties.The ATU-treated PSCs achieved a PCE of 25.32%,with enhanced operational stability and reduced leakage current.Additionally,the ATU-treated perovskite films exhibited superior humidity and light-soaking stability,retaining 85.2%of their initial efficiency after 1500 h of exposure to ambient conditions.展开更多
Sodium ion batteries(SIBs)have been regarded as one of the alternatives to lithium ion batteries owing to their wide availability and significantly low cost of sodium sources.However,they face serious challenges of lo...Sodium ion batteries(SIBs)have been regarded as one of the alternatives to lithium ion batteries owing to their wide availability and significantly low cost of sodium sources.However,they face serious challenges of low energy&power density and short cycling lifespan owing to the heavy mass and large radius of Na^(+).Vanadium-based polyanionic compounds have advantageous characteristic of high operating voltage,high ionic conductivity and robust structural framework,which is conducive to their high energy&power density and long lifespan for SIBs.In this review,we will overview the latest V-based polyanionic compounds,along with the respective characteristic from the intrinsic crystal structure to performance presentation and improvement for SIBs.One of the most important aspect is to discover the essential problems existed in the present V-based polyanionic compounds for high-energy&power applications,and point out most suitable solutions from the crystal structure modulation,interface tailoring and electrode configuration design.Moreover,some scientific issues of V-based polyanionic compounds shall be also proposed and related future direction shall be provided.We believe that this review can serve as a motivation for further development of novel V-based polyanionic compounds and drive them toward high energy&power applications in the near future.展开更多
The liquid crystal spatial light modulator （LC SLM） is very suitable for wavefront correction and optical testing and can produce a wavefront with large phase change and high accuracy. The LC SLM is composed of thou...The liquid crystal spatial light modulator （LC SLM） is very suitable for wavefront correction and optical testing and can produce a wavefront with large phase change and high accuracy. The LC SLM is composed of thousands of pixels and the pixel size and shape have effects on the diffractive characteristics of the LC SLM. This paper investigates the pixel effect on the phase of the wavefront with the scalar diffractive theory. The results show that the maximum optical path difference modulation is 41μm to produce the paraboloid wavefront with the peak to valley accuracy better than λ/10. Effects of the mismatch between the pixel and the period, and black matrix on the diffraction efficiency of the LC SLM are also analysed with the Fresnel phase lens model. The ability of the LC SLM is discussed for optical testing and wavefront correction based on the calculated results. It shows that the LC SLM can be used as a wavefront corrector and a compensator.展开更多
Spatial light modulators,as dynamic flat-panel optical devices,have witnessed rapid development over the past two decades,concomitant with the advancements in micro-and opto-electronic integration technology.In partic...Spatial light modulators,as dynamic flat-panel optical devices,have witnessed rapid development over the past two decades,concomitant with the advancements in micro-and opto-electronic integration technology.In particular,liquid-crystal spatial light modulator(LC-SLM)technologies have been regarded as versatile tools for generating arbitrary optical fields and tailoring all degrees of freedom beyond just phase and amplitude.These devices have gained significant interest in the nascent field of structured light in space and time,facilitated by their ease of use and real-time light manipulation,fueling both fundamental research and practical applications.Here we provide an overview of the key working principles of LC-SLMs and review the significant progress made to date in their deployment for various applications,covering topics as diverse as beam shaping and steering,holography,optical trapping and tweezers,measurement,wavefront coding,optical vortex,and quantum optics.Finally,we conclude with an outlook on the potential opportunities and technical challenges in this rapidly developing field.展开更多
Liquid crystal spatial light modulator （LCSLM） realizing equal-intensity multiple beams often has some features, i.e., phase valley between two adjacent pixels, flybaek region when phase decreases immediately from 2...Liquid crystal spatial light modulator （LCSLM） realizing equal-intensity multiple beams often has some features, i.e., phase valley between two adjacent pixels, flybaek region when phase decreases immediately from 2~r to 0, and inevitable backplane curvature, which are different from those of most conventional diffractive optical elements （DOEs）, such as static DOEs. For optimal intensity uniformity, equal-intensity multi-beam generation must be considered for these artifacts. We present a tunable-grating method in which the intensity uniformity can be improved by considering the LCSLM artifacts. For instance, tuning phase modulation depth of the grating, called isosceles triangle multilevel phase grating （ITMPG）, can be used not only to improve the intensity uniformity, but also to fast steer four beams with narrow beamwidths, determined by the same effective aperture of ITMPG. Improved intensity uniformity and high relative diffraction efficiency are demonstrated through experiments with phase-only LCSLM.展开更多
The primary mirrors of current and future large telescopes always employ a segmented mirror configuration.The small but non-negligible gaps between neighboring segments cause additional diffraction,which restricts the...The primary mirrors of current and future large telescopes always employ a segmented mirror configuration.The small but non-negligible gaps between neighboring segments cause additional diffraction,which restricts the performance of high-contrast coronagraph.To solve this problem,we propose a coronagraph system based on a single liquid crystal spatial light modulator(SLM).This spatial light modulator is used for amplitude apodization,and its feasibility and potential performance are demonstrated using a laboratory setup using the stochastic parallel gradient descent(SPGD)algorithm to control the spatial light modulator,which is based on point spread function(PSF)sensing and evaluation and optimized for maximum contrast in the discovery working area as a merit function.The system delivers a contrast in the order of 10−6,and shows excellent potential to be used in current and future large aperture telescopes,both on the ground and in space.展开更多
We propose a novel light intensity modulator based on magnetic fluid and liquid crystal（LC） filled photonic crystal fibers（PCFs）. The influences of electric and magnetic fields on the transmission intensity are th...We propose a novel light intensity modulator based on magnetic fluid and liquid crystal（LC） filled photonic crystal fibers（PCFs）. The influences of electric and magnetic fields on the transmission intensity are theoretically and experimentally analyzed and investigated. Both the electric and magnetic fields can manipulate the molecular arrangement of LC to array a certain angle without changing the refractive index of the LC. Therefore, light loss in the PCF varies with the electric and magnetic fields whereas the peak wavelengths remain constant. The experimental results show that the transmission intensity decreases with the increase of the electric and magnetic fields. The cut-off electric field is 0.899 V/um at 20 Hz and the cut-off magnetic field is 195 m T. This simple and compacted optical modulator will have a great prospect in sensing applications.展开更多
In this work, the characteristics of the photonic crystal tunneling injection quantum dot vertical cavity surface emitting lasers（Ph C-TIQD-VCSEL） are studied through analyzing a modified modulation transfer functio...In this work, the characteristics of the photonic crystal tunneling injection quantum dot vertical cavity surface emitting lasers（Ph C-TIQD-VCSEL） are studied through analyzing a modified modulation transfer function. The function is based on the rate equations describing the carrier dynamics at different energy levels of dot and injector well. Although the frequency modulation response component associated with carrier dynamics in wetting layer（WL） and at excited state（ES） levels of dots limits the total bandwidth in conventional QD-VCSEL, our study shows that it can be compensated for by electron tunneling from the injector well into the dot in TIQD structure. Carrier back tunneling time is one of the most important parameters, and by increment of that, the bias current dependence of the total bandwidth will be insignificant. It is proved that at high bias current, the limitation of the WL-ES level plays an important role in reducing the total bandwidth and results in rollovers on 3-d B bandwidth-I curves. In such a way, for smaller air hole diameter of photonic crystal, the effect of this reduction is stronger.展开更多
The CsI（T1） crystal modules of the Beijing Spectrometer Ⅲ （BESⅢ） electro-magnetic calorimeter （EMC） were designed and assembled through Monte Carlo simulation and experiments. After the assembly was finished, ...The CsI（T1） crystal modules of the Beijing Spectrometer Ⅲ （BESⅢ） electro-magnetic calorimeter （EMC） were designed and assembled through Monte Carlo simulation and experiments. After the assembly was finished, the performance of each crystal module was tested by cosmic rays. All crystal modules were found to work well before the installation of EMC.展开更多
Additive engineering has been widely employed to address defects-related issues in perovskite solar cells,including Pb^(2+)vacancy defects,halide migration,and FA^(+)lattice mismatch.However,due to the diversity and c...Additive engineering has been widely employed to address defects-related issues in perovskite solar cells,including Pb^(2+)vacancy defects,halide migration,and FA^(+)lattice mismatch.However,due to the diversity and complexity of defect types in perovskites,traditional monofunctional additives are typically limited to passivate specific types of defects and are unable to achieve effective passivation of multiple defects simultaneously.To overcome this limitation,this work proposes a multidentate synergistic coordination strategy using a multifunctional additive,ethyl 4-aminopyrazole-5-carboxylate(EAPC),to achieve coordinated passivation of multiple defects in perovskites.Combined theoretical calculations and experimental investigations reveal that the carbonyl group(C=O)of EAPC forms strong coordination bonds with uncoordinated Pb^(2+),while its amino group(–NH_(2))couples with halide ions,and the pyrazole-ring N sites establish a hydrogen-bonding network with FA^(+)cations,thereby achieving triple-site synergistic passivation of Pb^(2+)-X^(-)-FA^(+)defects.This synergistic effect accelerates the nucleation kinetics of perovskite while retarding its growth rate,thereby reducing the defect density and enhancing the crystallinity of the resulting perovskite films.Based on this strategy,the inverted perovskite solar cells(PSCs)achieved a champion power conversion efficiency(PCE)of 24.40%,maintaining over 90.2%of their initial efficiency after 1000 h of aging in a N_(2)-glovebox environment and retaining 85.1%of the original PCE under ambient conditions.This work pioneers a novel paradigm for synergistic defect passivation in perovskite optoelectronic devices.展开更多
Cesium lead triiodide(CsPbI_(3))perovskite receives tremendous attention for photovoltaic applications,owing to its remarkable thermal stability and optoelectronic properties.However,realizing the CsPbI_(3)perovskite ...Cesium lead triiodide(CsPbI_(3))perovskite receives tremendous attention for photovoltaic applications,owing to its remarkable thermal stability and optoelectronic properties.However,realizing the CsPbI_(3)perovskite with high black-phase stability and optoelectronic properties remains a significant challenge,which largely affects the photovoltaic performance of perovskite solar cells(PSCs).Herein,aromatic ammonium agents are used to modulate the crystallization of the CsPbI_(3)perovskite to improve its black-phase stability and optoelectronic properties for efficient PSCs.Systemically experimental studies and comprehensively theoretical calculations are performed,which reveal that histammonium dihydrochloride(HACl_(2))could strongly couple with the perovskite during its crystallization,leading to faster nucleation and slower perovskite growth,and thus modulating the crystallization dynamics of the perovskites.Moreover,the residual diammonium cations(HA^(2+))distributed at the grain boundaries and on the surface of the perovskites can effectively passivate defects through electrostatic interactions,substantially suppressing trap-assisted nonradiative recombination,and prompting more matched perovskite surface energetics.Consequently,the photovoltaic performance of CsPbI_(3)PSCs is largely improved because of a combination of enhanced crystallinity and optoelectronic properties of the perovskites.This work offers a new avenue to prepare inorganic perovskites with high optoelectronic properties for photovoltaics.展开更多
The phase modulation characteristics of a reflective liquid crystal （LC） spatial light modulator （SLM） under oblique incidence are studied by using our proposed self-interference method. The experimental setup of ...The phase modulation characteristics of a reflective liquid crystal （LC） spatial light modulator （SLM） under oblique incidence are studied by using our proposed self-interference method. The experimental setup of the method is very simple and has good robustness to mechanical vibrations. By changing the gray value of the combined grayscale loaded on the LC-SLM, different sheared fringe patterns, generated by the interference between the constant phase-modulated beam and the ＋1-order diffracted beam of the blazed grating, can be obtained. The amount of phase modulation of the LC-SLM is obtained by subtracting the phase of the two side lobes in the frequency domain. By turning the turntable where the SLM is mounted, the phase modulation characteristics at different incident angles can be measured. The experimental results show that the phase modulation curves do not change significantly with the small angle. When the angle is large （i.e. larger than 10°）, the phase modulation curves become different, especially for the high gray levels. With the increase of the incident angle, the phase modulation depth is reduced. The results indicate that the incident angle plays an important role in the performance of the phase modulation of an LC-SLM.展开更多
A fully automatic fail-safe beam shaping system based on a liquid crystal on a silicon spatial light modulator has been implemented in the high-energy kilowatt-average-power nanosecond laser system Bivoj.The shaping s...A fully automatic fail-safe beam shaping system based on a liquid crystal on a silicon spatial light modulator has been implemented in the high-energy kilowatt-average-power nanosecond laser system Bivoj.The shaping system corrects for gain nonuniformity and wavefront aberrations of the front-end of the system.The beam intensity profile and the wavefront at the output of the front-end were successfully improved by shaping.The beam homogeneity defined by the beam quality parameters was improved two to three times.The root-mean-square value of the wavefront was improved more than 10 times.Consequently,the shaped beam from the second preamplifier led to improvement of the beam profile at the output of the first main cryo-amplifier.The shaping system is also capable of creating nonordinary beam shapes,imprinting cross-references into the beam,or masking certain parts of the beam.展开更多
Due to their excellent advantages such as low toxicity,superior optoelectronic properties,low-temperature fabrication,and costeffectiveness,Sn-based perovskites have become the most promising alternatives for high per...Due to their excellent advantages such as low toxicity,superior optoelectronic properties,low-temperature fabrication,and costeffectiveness,Sn-based perovskites have become the most promising alternatives for high performance lead-free perovskite solar cells.However,the character of Sn ^(2+)is easily oxidized toSn ^(4+),causing unnecessary p-type self-doping and high leakage current.More seriously,trap-induced non-radiative recombination from rapid crystallization causes into large energy loss with a low open circuit voltage.Therefore,the Sn-based solar cells have efficiency far behind the Pb-based solar cells.Herein,the polymer poly(ethylene glycol)diacrylate(PEGDA)is used to control crystal growth and passivate the defects in FA_(0.85)PEA_(0.15)SnI_(3) thin film.This Sn-perovskite layer shows compact crystal with large grain size and reduced defects.Optimized perovskite thin film is further processed to fabricate the inverted solar cell with device structure of ITO(indium tin oxide)/PEDOT:PSS(Poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate))/FA_(0.85)PEA_(0.15)SnI_(3)/ICBA(indene-C60 bisadduct)/BCP(bathocuproine)/Ag,which shows the power conversion efficiency(PCE)of 11.45%with voltage of 0.82 V.Moreover,corresponding perovskite solar cells exhibit an enhanced stability due to PEGDA induced compressive strain in perovskite.This work could shed light on one of successful attempts to improve Sn-based solar cell efficiency for sustainable energy conversion.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51573006,51573003,51203003,51303008,51302006,51402006,51272026,and 51273022)the Major Project of Beijing Science and Technology Program,China(Grant Nos.Z151100003315023 and Z141100003814011)the Fok Ying Tung Education Foundation,China(Grant No.142009)
文摘Cholesteric liquid crystals（CLCs） have recently sparked an enormous amount of interest in the development of soft matter materials due to their unique ability to self-organize into a helical supra-molecular architecture and their excellent selective reflection of light based on the Bragg relationship.Nowadays,by the virtue of building the self-organized nanostructures with pitch gradient or non-uniform pitch distribution,extensive work has already been performed to obtain CLC films with a broad reflection band.Based on authors＇ many years＇ research experience,this critical review systematically summarizes the physical and optical background of the CLCs with broadband reflection characteristics,methods to obtain broadband reflection of CLCs,as well as the application in the field of intelligent optical modulation materials.Combined with the research status and the advantages in the field,the important basic and applied scientific problems in the research direction are also introduced.
基金The funding for the State Key Laboratory on Advanced Displays and Optoelectronics Technologies
文摘In this article,we review recently achieved Kerr effect progress in novel liquid crystal（LC） material：vertically aligned deformed helix ferroelectric liquid crystal（VADHFLC）.With an increasing applied electric field,the induced inplane birefringence of LCs shows quadratic nonlinearity.The theoretical calculations and experimental details are illustrated.With an enhanced Kerr constant to 130 nm/V2,this VADHFLC cell can achieve a 2π modulation by a small efficient electric field with a fast response around 100 μs and thus can be employed in both display and photonics devices.
基金Supported by National Key Research and Development Program of China(2022YFA1404201)National Natural Science Foundation of China(62205187,U23A20380,U22A2091,62222509,62127817,62075120)+3 种基金Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(IRT_17R70)Fundamental Research Program of Shanxi Province(202103021223032,202303021222031)Project Funded by China Postdoctoral Science Foundation(2022M722006)Fund for Shanxi“1331 Project”Key Subjects Construction。
文摘Tin-lead(Sn-Pb)mixed perovskites are extensively investigated in near-infrared(NIR)photodetectors(PDs)owing to their excellent photoelectric performance.However,achieving high-performance Sn-Pb mixed PDs remains challenging,primarily because of the rapid crystallization and the susceptibility of Sn^(2+) to oxidation.To ad⁃dress these issues,this study introduces the multifunctional molecules 2,3-difluorobenzenamine(DBM)to modulate the crystallization of Sn-Pb mixed perovskites and retard the oxidation of Sn^(2+),thereby significantly enhancing film quality.Compared with the pristine film,Sn-Pb mixed perovskite films modulated by DBM molecules exhibit a high⁃ly homogeneous morphology,reduced roughness and defect density.The self-powered NIR PDs fabricated with the improved films have a spectral response range from 300 nm to 1100 nm,a peak responsivity of 0.51 A·W^(-1),a spe⁃cific detectivity as high as 2.46×10^(11)Jones within the NIR region(780 nm to 1100 nm),a linear dynamic range ex⁃ceeding 152 dB,and ultrafast rise/fall time of 123/464 ns.Thanks to the outstanding performance of PDs,the fabri⁃cated 5×5 PDs array demonstrates superior imaging ability in the NIR region up to 980 nm.This work advances the development of Sn-Pb mixed perovskites for NIR detection and paves the way for their commercialization.
基金financial support from various entities,including the National Natural Science Foundation of China[grant number 62405005]the Natural Science Research Project of Anhui Educational Committee[2024AH050314]+1 种基金the Foundation of Anhui Science and Technology University[grant number HCYJ202201]the Anhui Science and Technology University's Student Innovation and Entrepreneurship Training Program[grant numbers S202410879115,S202410879098]。
文摘Organic-inorganic hybrid perovskite solar cells(PSCs)have garnered significant attention due to their high power conversion efficiency(PCE),low cost,and solution-processability.However,a substantial gap remains in the certified efficiency of single-junction PSCs,primarily due to defects in perovskite films that accelerate nonradiative recombination of carriers.In this study,we designed a multifunctional thiourea derivative,amidinethiourea(ATU),as an additive to modulate the crystallization process of perovskite films and inhibit the formation of organic cations and iodine vacancies.Our work leverages the strong hydrogen-bonding interactions between guanidinium molecules and organic amine components,as well as the robust coordination effects between the C=S bonds in thiourea and Pb^(2+)ions.We demonstrate that ATU treatment significantly enhances the crystallinity of perovskite films,reduces defects,and improves charge transport properties.The ATU-treated PSCs achieved a PCE of 25.32%,with enhanced operational stability and reduced leakage current.Additionally,the ATU-treated perovskite films exhibited superior humidity and light-soaking stability,retaining 85.2%of their initial efficiency after 1500 h of exposure to ambient conditions.
基金financial support from the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA21070500)the DNL Cooperation Fund,CAS(DNL201914)。
文摘Sodium ion batteries(SIBs)have been regarded as one of the alternatives to lithium ion batteries owing to their wide availability and significantly low cost of sodium sources.However,they face serious challenges of low energy&power density and short cycling lifespan owing to the heavy mass and large radius of Na^(+).Vanadium-based polyanionic compounds have advantageous characteristic of high operating voltage,high ionic conductivity and robust structural framework,which is conducive to their high energy&power density and long lifespan for SIBs.In this review,we will overview the latest V-based polyanionic compounds,along with the respective characteristic from the intrinsic crystal structure to performance presentation and improvement for SIBs.One of the most important aspect is to discover the essential problems existed in the present V-based polyanionic compounds for high-energy&power applications,and point out most suitable solutions from the crystal structure modulation,interface tailoring and electrode configuration design.Moreover,some scientific issues of V-based polyanionic compounds shall be also proposed and related future direction shall be provided.We believe that this review can serve as a motivation for further development of novel V-based polyanionic compounds and drive them toward high energy&power applications in the near future.
基金Project supported by the National Natural Science Foundation of China （Nos 60578035, 50473040） and the Science Foundation of Jilin Province （Nos 20050520, 20050321-2）.
文摘The liquid crystal spatial light modulator （LC SLM） is very suitable for wavefront correction and optical testing and can produce a wavefront with large phase change and high accuracy. The LC SLM is composed of thousands of pixels and the pixel size and shape have effects on the diffractive characteristics of the LC SLM. This paper investigates the pixel effect on the phase of the wavefront with the scalar diffractive theory. The results show that the maximum optical path difference modulation is 41μm to produce the paraboloid wavefront with the peak to valley accuracy better than λ/10. Effects of the mismatch between the pixel and the period, and black matrix on the diffraction efficiency of the LC SLM are also analysed with the Fresnel phase lens model. The ability of the LC SLM is discussed for optical testing and wavefront correction based on the calculated results. It shows that the LC SLM can be used as a wavefront corrector and a compensator.
基金supports from National Natural Science Foundation of China (No.62235009).
文摘Spatial light modulators,as dynamic flat-panel optical devices,have witnessed rapid development over the past two decades,concomitant with the advancements in micro-and opto-electronic integration technology.In particular,liquid-crystal spatial light modulator(LC-SLM)technologies have been regarded as versatile tools for generating arbitrary optical fields and tailoring all degrees of freedom beyond just phase and amplitude.These devices have gained significant interest in the nascent field of structured light in space and time,facilitated by their ease of use and real-time light manipulation,fueling both fundamental research and practical applications.Here we provide an overview of the key working principles of LC-SLMs and review the significant progress made to date in their deployment for various applications,covering topics as diverse as beam shaping and steering,holography,optical trapping and tweezers,measurement,wavefront coding,optical vortex,and quantum optics.Finally,we conclude with an outlook on the potential opportunities and technical challenges in this rapidly developing field.
基金supported by the National Natural Science Foundation of China (Grant No. 60878048)the China Postdoctoral Science Foundation (Grant No. 20080440898)
文摘Liquid crystal spatial light modulator （LCSLM） realizing equal-intensity multiple beams often has some features, i.e., phase valley between two adjacent pixels, flybaek region when phase decreases immediately from 2~r to 0, and inevitable backplane curvature, which are different from those of most conventional diffractive optical elements （DOEs）, such as static DOEs. For optimal intensity uniformity, equal-intensity multi-beam generation must be considered for these artifacts. We present a tunable-grating method in which the intensity uniformity can be improved by considering the LCSLM artifacts. For instance, tuning phase modulation depth of the grating, called isosceles triangle multilevel phase grating （ITMPG）, can be used not only to improve the intensity uniformity, but also to fast steer four beams with narrow beamwidths, determined by the same effective aperture of ITMPG. Improved intensity uniformity and high relative diffraction efficiency are demonstrated through experiments with phase-only LCSLM.
基金supported by the National Natural Science Foundation of China (U2031210 and 11827804)Science Research from the China Manned Space Project (CMS-CSST-2021-A11 and CMS-CSST-2021-B04).
文摘The primary mirrors of current and future large telescopes always employ a segmented mirror configuration.The small but non-negligible gaps between neighboring segments cause additional diffraction,which restricts the performance of high-contrast coronagraph.To solve this problem,we propose a coronagraph system based on a single liquid crystal spatial light modulator(SLM).This spatial light modulator is used for amplitude apodization,and its feasibility and potential performance are demonstrated using a laboratory setup using the stochastic parallel gradient descent(SPGD)algorithm to control the spatial light modulator,which is based on point spread function(PSF)sensing and evaluation and optimized for maximum contrast in the discovery working area as a merit function.The system delivers a contrast in the order of 10−6,and shows excellent potential to be used in current and future large aperture telescopes,both on the ground and in space.
基金Supported by the Joint Research Fund in Astronomy under Cooperative Agreement between the National Natural Science Foundation of China and Chinese Academy of Sciences under Grant No U1531102the Fundamental Research Funds for the Central Universities under Grant No HEUCF181116the National Natural Science Foundation of China under Grant Nos61107059,61077047 and 11264001
文摘We propose a novel light intensity modulator based on magnetic fluid and liquid crystal（LC） filled photonic crystal fibers（PCFs）. The influences of electric and magnetic fields on the transmission intensity are theoretically and experimentally analyzed and investigated. Both the electric and magnetic fields can manipulate the molecular arrangement of LC to array a certain angle without changing the refractive index of the LC. Therefore, light loss in the PCF varies with the electric and magnetic fields whereas the peak wavelengths remain constant. The experimental results show that the transmission intensity decreases with the increase of the electric and magnetic fields. The cut-off electric field is 0.899 V/um at 20 Hz and the cut-off magnetic field is 195 m T. This simple and compacted optical modulator will have a great prospect in sensing applications.
文摘In this work, the characteristics of the photonic crystal tunneling injection quantum dot vertical cavity surface emitting lasers（Ph C-TIQD-VCSEL） are studied through analyzing a modified modulation transfer function. The function is based on the rate equations describing the carrier dynamics at different energy levels of dot and injector well. Although the frequency modulation response component associated with carrier dynamics in wetting layer（WL） and at excited state（ES） levels of dots limits the total bandwidth in conventional QD-VCSEL, our study shows that it can be compensated for by electron tunneling from the injector well into the dot in TIQD structure. Carrier back tunneling time is one of the most important parameters, and by increment of that, the bias current dependence of the total bandwidth will be insignificant. It is proved that at high bias current, the limitation of the WL-ES level plays an important role in reducing the total bandwidth and results in rollovers on 3-d B bandwidth-I curves. In such a way, for smaller air hole diameter of photonic crystal, the effect of this reduction is stronger.
文摘The CsI（T1） crystal modules of the Beijing Spectrometer Ⅲ （BESⅢ） electro-magnetic calorimeter （EMC） were designed and assembled through Monte Carlo simulation and experiments. After the assembly was finished, the performance of each crystal module was tested by cosmic rays. All crystal modules were found to work well before the installation of EMC.
基金financially supported by the Changzhou Shichuang Energy Co.Ltd of China(Grant no.K81B2038)the National Natural Science Foundation of China(Grant no.50902116)。
文摘Additive engineering has been widely employed to address defects-related issues in perovskite solar cells,including Pb^(2+)vacancy defects,halide migration,and FA^(+)lattice mismatch.However,due to the diversity and complexity of defect types in perovskites,traditional monofunctional additives are typically limited to passivate specific types of defects and are unable to achieve effective passivation of multiple defects simultaneously.To overcome this limitation,this work proposes a multidentate synergistic coordination strategy using a multifunctional additive,ethyl 4-aminopyrazole-5-carboxylate(EAPC),to achieve coordinated passivation of multiple defects in perovskites.Combined theoretical calculations and experimental investigations reveal that the carbonyl group(C=O)of EAPC forms strong coordination bonds with uncoordinated Pb^(2+),while its amino group(–NH_(2))couples with halide ions,and the pyrazole-ring N sites establish a hydrogen-bonding network with FA^(+)cations,thereby achieving triple-site synergistic passivation of Pb^(2+)-X^(-)-FA^(+)defects.This synergistic effect accelerates the nucleation kinetics of perovskite while retarding its growth rate,thereby reducing the defect density and enhancing the crystallinity of the resulting perovskite films.Based on this strategy,the inverted perovskite solar cells(PSCs)achieved a champion power conversion efficiency(PCE)of 24.40%,maintaining over 90.2%of their initial efficiency after 1000 h of aging in a N_(2)-glovebox environment and retaining 85.1%of the original PCE under ambient conditions.This work pioneers a novel paradigm for synergistic defect passivation in perovskite optoelectronic devices.
基金National Key Research and Development Program of China,Grant/Award Number:2022YFB3807200National Natural Science Foundation of China,Grant/Award Numbers:52372169,51872014Recruitment Program of Global Experts,and the“111”project,Grant/Award Number:B17002。
文摘Cesium lead triiodide(CsPbI_(3))perovskite receives tremendous attention for photovoltaic applications,owing to its remarkable thermal stability and optoelectronic properties.However,realizing the CsPbI_(3)perovskite with high black-phase stability and optoelectronic properties remains a significant challenge,which largely affects the photovoltaic performance of perovskite solar cells(PSCs).Herein,aromatic ammonium agents are used to modulate the crystallization of the CsPbI_(3)perovskite to improve its black-phase stability and optoelectronic properties for efficient PSCs.Systemically experimental studies and comprehensively theoretical calculations are performed,which reveal that histammonium dihydrochloride(HACl_(2))could strongly couple with the perovskite during its crystallization,leading to faster nucleation and slower perovskite growth,and thus modulating the crystallization dynamics of the perovskites.Moreover,the residual diammonium cations(HA^(2+))distributed at the grain boundaries and on the surface of the perovskites can effectively passivate defects through electrostatic interactions,substantially suppressing trap-assisted nonradiative recombination,and prompting more matched perovskite surface energetics.Consequently,the photovoltaic performance of CsPbI_(3)PSCs is largely improved because of a combination of enhanced crystallinity and optoelectronic properties of the perovskites.This work offers a new avenue to prepare inorganic perovskites with high optoelectronic properties for photovoltaics.
基金financially supported by the National Natural Science Foundation of China(No.51705404)the China Postdoctoral Science Foundation(No.2016M602806)the Fundamental Research Funds for the Central Universities(No.xjj2017093)
文摘The phase modulation characteristics of a reflective liquid crystal （LC） spatial light modulator （SLM） under oblique incidence are studied by using our proposed self-interference method. The experimental setup of the method is very simple and has good robustness to mechanical vibrations. By changing the gray value of the combined grayscale loaded on the LC-SLM, different sheared fringe patterns, generated by the interference between the constant phase-modulated beam and the ＋1-order diffracted beam of the blazed grating, can be obtained. The amount of phase modulation of the LC-SLM is obtained by subtracting the phase of the two side lobes in the frequency domain. By turning the turntable where the SLM is mounted, the phase modulation characteristics at different incident angles can be measured. The experimental results show that the phase modulation curves do not change significantly with the small angle. When the angle is large （i.e. larger than 10°）, the phase modulation curves become different, especially for the high gray levels. With the increase of the incident angle, the phase modulation depth is reduced. The results indicate that the incident angle plays an important role in the performance of the phase modulation of an LC-SLM.
文摘A fully automatic fail-safe beam shaping system based on a liquid crystal on a silicon spatial light modulator has been implemented in the high-energy kilowatt-average-power nanosecond laser system Bivoj.The shaping system corrects for gain nonuniformity and wavefront aberrations of the front-end of the system.The beam intensity profile and the wavefront at the output of the front-end were successfully improved by shaping.The beam homogeneity defined by the beam quality parameters was improved two to three times.The root-mean-square value of the wavefront was improved more than 10 times.Consequently,the shaped beam from the second preamplifier led to improvement of the beam profile at the output of the first main cryo-amplifier.The shaping system is also capable of creating nonordinary beam shapes,imprinting cross-references into the beam,or masking certain parts of the beam.
基金This work is financially supported by Shenzhen Science and Technology Innovation Committee(No.JCYJ20190809172615277)Guangdong Basic and Applied Basic Research Foundation(No.2020A1515111065)Shenzhen Municipal Development and Reform Commission,New Energy Technology Engineering Laboratory(No.SDRC[2016]172).
文摘Due to their excellent advantages such as low toxicity,superior optoelectronic properties,low-temperature fabrication,and costeffectiveness,Sn-based perovskites have become the most promising alternatives for high performance lead-free perovskite solar cells.However,the character of Sn ^(2+)is easily oxidized toSn ^(4+),causing unnecessary p-type self-doping and high leakage current.More seriously,trap-induced non-radiative recombination from rapid crystallization causes into large energy loss with a low open circuit voltage.Therefore,the Sn-based solar cells have efficiency far behind the Pb-based solar cells.Herein,the polymer poly(ethylene glycol)diacrylate(PEGDA)is used to control crystal growth and passivate the defects in FA_(0.85)PEA_(0.15)SnI_(3) thin film.This Sn-perovskite layer shows compact crystal with large grain size and reduced defects.Optimized perovskite thin film is further processed to fabricate the inverted solar cell with device structure of ITO(indium tin oxide)/PEDOT:PSS(Poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate))/FA_(0.85)PEA_(0.15)SnI_(3)/ICBA(indene-C60 bisadduct)/BCP(bathocuproine)/Ag,which shows the power conversion efficiency(PCE)of 11.45%with voltage of 0.82 V.Moreover,corresponding perovskite solar cells exhibit an enhanced stability due to PEGDA induced compressive strain in perovskite.This work could shed light on one of successful attempts to improve Sn-based solar cell efficiency for sustainable energy conversion.
