Liquid crystal Pacharatnam-Berry phase optical elements(PBOEs)have found promising applications in augmented reality and virtual reality because of their slim formfactor,lightweight,and high optical efficiency.However...Liquid crystal Pacharatnam-Berry phase optical elements(PBOEs)have found promising applications in augmented reality and virtual reality because of their slim formfactor,lightweight,and high optical efficiency.However,chromatic aberration remains a serious longstanding problem for diffractive optics,hindering their broader adoption.To overcome the chromatic aberrations for red,green and blue(RGB)light sources,in this paper,we propose a counterintuitive multi-twist structure to achieve narrowband PBOEs without crosstalk,which plays a vital role to eliminate the chromatic aberration.The performance of our designed and fabricated narrowband Pacharatnam-Berry lenses(PBLs)aligns well with our simulation results.Furthermore,in a feasibility demonstration experiment using a laser projector,our proposed PBL system indeed exhibits a diminished chromatic aberration as compared to a broadband PBL.Additionally,polarization raytracing is implemented to demonstrate the versatility of the multi-twist structure for designing any RGB wavelengths with high contrast ratios.This analysis explores the feasibility of using RGB laser lines and quantum dot light-emitting diodes.Overall,our approach enables high optical efficiency,low fabrication complexity,and high degree of design freedom to accommodate any liquid crystal material and RGB light sources,holding immense potential for widespread applications of achromatic PBOEs.展开更多
In the Fresnel transform domain, an effective improvement to the conventional iterative algorithm for designing the diffractive optical elements (DOEs) used for spatial beam shaping has been proposed. The algorithm ca...In the Fresnel transform domain, an effective improvement to the conventional iterative algorithm for designing the diffractive optical elements (DOEs) used for spatial beam shaping has been proposed. The algorithm can successfully achieve to design DOEs for beam shaping. Compared with conventional algorithm, this algorithm can provide faster convergence, more powerful ability to overcome local minimum problem and better shaping quality. By computer simulation, the result has shown that the DOEs designed by this algorithm has snch advantages as high uniformity at the main lobe, low profile error and steep edge.展开更多
1 Introduction 1.1 Advantages of DOE 1)High diffraction efficiency; 2)Dispersive; 3)More selectivity of designing parameters; 4)More selectivity of primary materials; 5)Can make components miniature,forming array and ...1 Introduction 1.1 Advantages of DOE 1)High diffraction efficiency; 2)Dispersive; 3)More selectivity of designing parameters; 4)More selectivity of primary materials; 5)Can make components miniature,forming array and integration. 1.2 1.3 megapixel triplet plastic mobile展开更多
Diffractive optical elements（DOEs） with spectrum separation and beam concentration（SSBC） functions have important applications in solar cell systems. With the SSBC DOEs, the sunlight radiation is divided into seve...Diffractive optical elements（DOEs） with spectrum separation and beam concentration（SSBC） functions have important applications in solar cell systems. With the SSBC DOEs, the sunlight radiation is divided into several wave bands so as to be effectively absorbed by photovoltaic materials with different band gaps. A new method is proposed for designing high-efficiency SSBC DOEs, which is physically simple, numerically fast, and universally applicable. The SSBC DOEs are designed by the new design method, and their performances are analyzed by the Fresnel diffraction integral method.The new design method takes two advantages over the previous design method. Firstly, the optical focusing efficiency is heightened by up to 10%. Secondly, focal positions of all the designed wavelengths can be designated arbitrarily and independently. It is believed that the designed SSBC DOEs should have practical applications to solar cell systems.展开更多
We propose a promising method to develop flexible,compact,and tunable light-activated film diffractive optical elements(FDOEs)with exceptional diffraction efficiency,by integrating liquid crystal(LC)geometric phase-ba...We propose a promising method to develop flexible,compact,and tunable light-activated film diffractive optical elements(FDOEs)with exceptional diffraction efficiency,by integrating liquid crystal(LC)geometric phase-based diffractive optical elements(DOEs)with a specifically designed light-activated LC polymer(LCP)film.Arbitrary film bending induced by UV/Vis irradiation is realized through precise mesogens arrangement within the LCP film,enabling 1D and 2D beam steering,as well as dynamic and reversible switching between structured and Gaussian lights after cooperating with the DOE design.Furthermore,remarkable fatigue resistance,solvent resistance,and thermal stability are demonstrated,providing a solid material platform for advanced optical applications.展开更多
Diffractive optical elements(DOEs)are intricately designed devices with the purpose of manipulating light fields by precisely modifying their wavefronts.The concept of DOEs has its origins dating back to 1948 when D.G...Diffractive optical elements(DOEs)are intricately designed devices with the purpose of manipulating light fields by precisely modifying their wavefronts.The concept of DOEs has its origins dating back to 1948 when D.Gabor first introduced holography.Subsequently,researchers introduced binary optical elements(BOEs),including computer-generated holograms(CGHs),as a distinct category within the realm of DOEs.This was the first revolution in optical devices.The next major breakthrough in light field manipulation occurred during the early 21st century,marked by the advent of metamaterials and metasurfaces.Metasurfaces are particularly appealing due to their ultra-thin,ultra-compact properties and their capacity to exert precise control over virtually every aspect of light fields,including amplitude,phase,polarization,wavelength/frequency,angular momentum,etc.The advancement of light field manipulation with micro/nano-structures has also enabled various applications in fields such as information acquisition,transmission,storage,processing,and display.In this review,we cover the fundamental science,cutting-edge technologies,and wide-ranging applications associated with micro/nano-scale optical devices for regulating light fields.We also delve into the prevailing challenges in the pursuit of developing viable technology for real-world applications.Furthermore,we offer insights into potential future research trends and directions within the realm of light field manipulation.展开更多
Diffractive optical elements such as the complementary Dammann gratings are incorporated for dynamic optical fiber splitting and combining. Experimental results of 1×8 dynamic optical couplings are presented.
Peculiarities of propagation of femtosecond pulses through a focusing diffractive optical element (DOE) are considered. It is shown that the time delay between the pulse and phase wavefronts can be decreased by fabric...Peculiarities of propagation of femtosecond pulses through a focusing diffractive optical element (DOE) are considered. It is shown that the time delay between the pulse and phase wavefronts can be decreased by fabricating the DOE on the optimal curvilinear surface.展开更多
In this paper,a novel method is proposed and employed to design a single diffractive optical element（DOE） for implementing spectrum-splitting and beam-concentration（SSBC） functions simultaneously.We develop an opt...In this paper,a novel method is proposed and employed to design a single diffractive optical element（DOE） for implementing spectrum-splitting and beam-concentration（SSBC） functions simultaneously.We develop an optimization algorithm,through which the SSBC DOE can be optimized within an arbitrary thickness range according to the limitations of modern photolithography technology.Theoretical simulation results reveal that the designed SSBC DOE has a high optical focusing efficiency.It is expected that the designed SSBC DOE should have practical applications in high-efficiency solar cell systems.展开更多
Based on the facts that multijunction solar cells can increase the efficiency and concentration can reduce the cost dramatically, a special design of parallel multijunction solar cells was presented. The design employ...Based on the facts that multijunction solar cells can increase the efficiency and concentration can reduce the cost dramatically, a special design of parallel multijunction solar cells was presented. The design employed a diffractive optical element （DOE） to split and concentrate the sunlight. A rainbow region and a zero-order diffraction region were generated on the output plane where solar cells with corresponding band gaps were placed. An analytical expression of the light intensity distribution on the output plane of the special DOE was deduced, and the limiting photovoltaic efficiency of such parallel multijunction solar ceils was obtained based on Shockley-Queisser＇s theory. An efficiency exceeding the Shockley--Queisser limit （33%） can be expected using multijunction solar cells consisting of separately fabricated subcells. The results provide an important alternative approach to realize high photovoltaic efficiency without the need for expensive epitaxial technology widely used in tandem solar cells, thus stimulating the research and application of high efficiency and low cost solar cells.展开更多
Two improved algorithms are proposed to extend a diffractive optical element （DOE） to work under the broad spec- trum of sunlight. An optimum design has been found for the DOE, with a weighted average optical effici...Two improved algorithms are proposed to extend a diffractive optical element （DOE） to work under the broad spec- trum of sunlight. An optimum design has been found for the DOE, with a weighted average optical efficiency of about 6.8% better than that of the previous design. The optimization of designing high optical efficiency DOEs will pave the way for future designs of high-efficiency, low-cost lateral multijunction solar cells based on such a DOE.展开更多
Diffractive optics is an important technique for beam shaping with high light efficiency and strong diffraction pattern flexibility. Since the diffraction angle is limited by the unit size of the diffractive optical e...Diffractive optics is an important technique for beam shaping with high light efficiency and strong diffraction pattern flexibility. Since the diffraction angle is limited by the unit size of the diffractive optical element （DOE）, the size of the required diffraction pattern is always rather small. In this Letter, refractive/diffractive hybrid optical elements （RDHOEs） consisting of a DOE and a lens are used to realize beam shaping for a large diffraction pattern. The lens, as the component of the RDHOEs, can not only be concave but also convex, and the double sampling Fresnel diffraction algorithm is developed for the design of these two types of RDHOEs. The simulation and experimental results provide solid evidence to demonstrate the proposed method with the pure phase spatial light modulator.展开更多
We propose a design method for a diffractive neural network(DNN)for imaging through scattering media,offering robustness against the spatial coherence of illumination,scattering strength,and scattering dynamics.Most t...We propose a design method for a diffractive neural network(DNN)for imaging through scattering media,offering robustness against the spatial coherence of illumination,scattering strength,and scattering dynamics.Most techniques for imaging through scattering media are time-consuming and/or tailored to specific optical conditions.The DNN,composed of layers of diffractive optical elements(DOEs),optically reproduces the intensity distributions of objects behind scattering media without any computational processing.Datasets with randomized optical parameters are provided during the training process to achieve this robustness.We demonstrate the proposed method through numerical calculations and show its promising capability for DOE design.Our study paves the way for unifying and generalizing techniques for imaging through scattering media,which are currently fragmented by specific scenarios,enabling highly flexible imaging independent of optical conditions.展开更多
One of the challenges in the field of multi-photon 3D laser printing lies in further increasing the print speed in terms of voxels/s.Here,we present a setup based on a 7×7 focus array(rather than 3×3 in our ...One of the challenges in the field of multi-photon 3D laser printing lies in further increasing the print speed in terms of voxels/s.Here,we present a setup based on a 7×7 focus array(rather than 3×3 in our previous work)and using a focus velocity of about 1 m/s(rather than 0.5 m/s in our previous work)at the diffraction limit(40×/NA1.4 microscope objective lens).Combined,this advance leads to a ten times increased print speed of about 108 voxels/s.We demonstrate polymer printing of a chiral metamaterial containing more than 1.7×10^(12) voxels as well as millions of printed microparticles for potential pharmaceutical applications.The critical high-quality micro-optical components of the setup,namely a diffractive optical element generating the 7×7 beamlets and a 7×7 lens array,are manufactured by using a commercial two-photon grayscale 3D laser printer.展开更多
In this paper,we present the electric field controllable diffractive optical elements in strontium-barium niobate single crystals with stable tailored spiral-shaped domain structure and demonstrate the generation of o...In this paper,we present the electric field controllable diffractive optical elements in strontium-barium niobate single crystals with stable tailored spiral-shaped domain structure and demonstrate the generation of optical beam with orbital angular momentum.The required domain pattern was created in the sample with initial domain structure by electric field application using the photolithographically defined liquid electrode.A series of bipolar triangular electric field pulses were applied to the sample for determination of the optimal parameters for complete polarization switching under the electrode.The stable tailored domain pattern of the spiral shape was created by the application of the unipolar pulse of a special shape.The complete switching under the electrode and partial switching under the photoresist layer have been revealed.The imaging by Cherenkov-type second harmonic generation microscopy confirmed that the created domain structure reaches the opposite polar surface.The imaging of the diffraction pattern of the laser beam passing through a voltage-biased DOE confirmed the formation of the beam with orbital angular momentum.The half-wave voltages of 237V and 302 V for wavelength 632.8 nm and 532 nm,respectively,for 2-mmthick sample were measured.The obtained knowledge can be used for the development of domain engineering methods in strontium-barium niobate single crystals for the creation of tailored domain structures for manufacturing of electric field controllablediffractiveoptical elements.展开更多
Annular-focused beams have attracted attention because of their novel properties and applications in optical trapping, high resolution microscopy, and laser-induced periodic surface structuring. Generation of this bea...Annular-focused beams have attracted attention because of their novel properties and applications in optical trapping, high resolution microscopy, and laser-induced periodic surface structuring. Generation of this beam is very important and necessary. In this article, a novel design of zone plate for forming the annular-focused beams is proposed. The design principle is introduced, and the characteristics of zone plate are analyzed by numerical simulation. The result shows that the zone plate can form a monochromatic ring-shaped intensity distribution in the focal plane. And the design method is also generally suitable for designing the other optical elements to generate the annular-focused beams.展开更多
We propose an efficient method of generating a vortex beam with multi-foci by using a fractal spiral zone plate(FSZP), which is designed by combining fractal structure with a spiral zone plate(SZP) in the squared radi...We propose an efficient method of generating a vortex beam with multi-foci by using a fractal spiral zone plate(FSZP), which is designed by combining fractal structure with a spiral zone plate(SZP) in the squared radial coordinate.The theoretical analysis reveals that the number of foci that embed vortices is significantly increased as compared with that obtained by using a conventional SZP. Furthermore, the influence of topological charge on the intensity distribution in focal plane is also discussed in detail. For experimental investigation, an FSZP with topological charge p = 1 and 6.4 mm diameter is fabricated by using a photo-etching technique. The calibration indicates that the focusing performances of such a kind of zone plane(ZP) accord well with simulations, thereby providing its potential applications in multi-dimensional optical manipulation and optical imaging technology.展开更多
Optical imaging techniques provide low-cost,non-radiative images with high spatiotemporal resolution,making them advantageous for long-term dynamic observation of blood perfusion in stroke research and other brain stu...Optical imaging techniques provide low-cost,non-radiative images with high spatiotemporal resolution,making them advantageous for long-term dynamic observation of blood perfusion in stroke research and other brain studies compared to non-optical methods.However,high-resolution imaging in optical microscopy fundamentally requires a tight optical focus,and thus a limited depth of field(DOF).Consequently,large-scale,non-stitched,high-resolution images of curved surfaces,like brains,are difficult to acquire without z-axis scanning.To overcome this limitation,we developed a needle-shaped beam optical coherence tomography angiography(NB-OCTA)system,and for the first time,achieved a volumetric resolution of less than 8μm in a non-stitched volume space of 6.4 mm×4 mm×620μm in vivo.This system captures the distribution of blood vessels at 3.4-times larger depths than normal OCTA equipped with a Gaussian beam(GB-OCTA).We then employed NB-OCTA to perform long-term observation of cortical blood perfusion after stroke in vivo,and quantitatively analyzed the vessel area density(VAD)and the diameters of representative vessels in different regions over 10 days,revealing different spatiotemporal dynamics in the acute,sub-acute and chronic phase of post-ischemic revascularization.Benefiting from our NB-OCTA,we revealed that the recovery process is not only the result of spontaneous reperfusion,but also the formation of new vessels.This study provides visual and mechanistic insights into strokes and helps to deepen our understanding of the spontaneous response of brain after stroke.展开更多
The matrix eigenvalue method is used to analyze a laser resonator composed of diffraction optical elements. The results show that this type of resonator can separate fundamental mode and high order modes effectively. ...The matrix eigenvalue method is used to analyze a laser resonator composed of diffraction optical elements. The results show that this type of resonator can separate fundamental mode and high order modes effectively. The output beams can be designed for different requests.展开更多
In the integral imaging light field display, the introduction of a diffractive optical element (DOE) can solve the problem of limited depth of field of the traditional lens. However, the strong aberration of the DOE s...In the integral imaging light field display, the introduction of a diffractive optical element (DOE) can solve the problem of limited depth of field of the traditional lens. However, the strong aberration of the DOE significantly reduces the final display quality. Thus, herein, an end-to-end joint optimization method for optimizing DOE and aberration correction is proposed. The DOE model is established using thickness as the variable, and a deep learning network is built to preprocess the composite image loaded on the display panel. The simulation results show that the peak signal to noise ratio value of the optimized image increases by 8 dB, which confirms that the end-to-end joint optimization method can effectively reduce the aberration problem.展开更多
基金supports from the National Key Research and Development Program of China(2023YFB2806803)the National Natural Science Foundation of China(62075127).
文摘Liquid crystal Pacharatnam-Berry phase optical elements(PBOEs)have found promising applications in augmented reality and virtual reality because of their slim formfactor,lightweight,and high optical efficiency.However,chromatic aberration remains a serious longstanding problem for diffractive optics,hindering their broader adoption.To overcome the chromatic aberrations for red,green and blue(RGB)light sources,in this paper,we propose a counterintuitive multi-twist structure to achieve narrowband PBOEs without crosstalk,which plays a vital role to eliminate the chromatic aberration.The performance of our designed and fabricated narrowband Pacharatnam-Berry lenses(PBLs)aligns well with our simulation results.Furthermore,in a feasibility demonstration experiment using a laser projector,our proposed PBL system indeed exhibits a diminished chromatic aberration as compared to a broadband PBL.Additionally,polarization raytracing is implemented to demonstrate the versatility of the multi-twist structure for designing any RGB wavelengths with high contrast ratios.This analysis explores the feasibility of using RGB laser lines and quantum dot light-emitting diodes.Overall,our approach enables high optical efficiency,low fabrication complexity,and high degree of design freedom to accommodate any liquid crystal material and RGB light sources,holding immense potential for widespread applications of achromatic PBOEs.
文摘In the Fresnel transform domain, an effective improvement to the conventional iterative algorithm for designing the diffractive optical elements (DOEs) used for spatial beam shaping has been proposed. The algorithm can successfully achieve to design DOEs for beam shaping. Compared with conventional algorithm, this algorithm can provide faster convergence, more powerful ability to overcome local minimum problem and better shaping quality. By computer simulation, the result has shown that the DOEs designed by this algorithm has snch advantages as high uniformity at the main lobe, low profile error and steep edge.
文摘1 Introduction 1.1 Advantages of DOE 1)High diffraction efficiency; 2)Dispersive; 3)More selectivity of designing parameters; 4)More selectivity of primary materials; 5)Can make components miniature,forming array and integration. 1.2 1.3 megapixel triplet plastic mobile
基金Project supported by the National Basic Research Program of China(Grant No.2013CBA01702)the National Natural Science Foundation of China(Grant Nos.11474206,91233202,11374216,and 11404224)+1 种基金the Scientific Research Project of Beijing Education Commission,China(Grant No.KM201310028005)the Scientific Research Base Development Program of the Beijing Municipal Commission of Education and the Beijing Youth Top-Notch Talent Training Plan,China(Grant No.CIT&TCD201504080)
文摘Diffractive optical elements（DOEs） with spectrum separation and beam concentration（SSBC） functions have important applications in solar cell systems. With the SSBC DOEs, the sunlight radiation is divided into several wave bands so as to be effectively absorbed by photovoltaic materials with different band gaps. A new method is proposed for designing high-efficiency SSBC DOEs, which is physically simple, numerically fast, and universally applicable. The SSBC DOEs are designed by the new design method, and their performances are analyzed by the Fresnel diffraction integral method.The new design method takes two advantages over the previous design method. Firstly, the optical focusing efficiency is heightened by up to 10%. Secondly, focal positions of all the designed wavelengths can be designated arbitrarily and independently. It is believed that the designed SSBC DOEs should have practical applications to solar cell systems.
基金the National Key Research and Development Program of China(No.2022YFA1203700)the National Natural Science Foundation of China(Nos.62275081,62035008,and 22305079)+4 种基金the Innovation Program of Shanghai Municipal Education Commission,Scientific Committee of Shanghai(No.2021-01-07-00-02-E00107)the“Shuguang Program”of Shanghai Education Development Foundation,the Shanghai Municipal Education Commission(No.21SG29)the Shanghai Sailing Program(No.23YF1409000)the Fellowship of China National Postdoctoral Program for Innovative Talents(No.BX20230125)the Postdoctoral Fellowship Program of CPSF(No.GZB20240218)。
文摘We propose a promising method to develop flexible,compact,and tunable light-activated film diffractive optical elements(FDOEs)with exceptional diffraction efficiency,by integrating liquid crystal(LC)geometric phase-based diffractive optical elements(DOEs)with a specifically designed light-activated LC polymer(LCP)film.Arbitrary film bending induced by UV/Vis irradiation is realized through precise mesogens arrangement within the LCP film,enabling 1D and 2D beam steering,as well as dynamic and reversible switching between structured and Gaussian lights after cooperating with the DOE design.Furthermore,remarkable fatigue resistance,solvent resistance,and thermal stability are demonstrated,providing a solid material platform for advanced optical applications.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030009)the National Natural Science Foundation of China(Nos.62235009,62035003,62205173,61935013,62375181,61975133,and 12104318)+1 种基金the Science and Technology Innovation Commission of Shenzhen(Nos.KQTD20170330110444030 and JCYJ20200109114018750)the Scientific Instrument Developing Project of Shenzhen University(No.2023YQ001).
文摘Diffractive optical elements(DOEs)are intricately designed devices with the purpose of manipulating light fields by precisely modifying their wavefronts.The concept of DOEs has its origins dating back to 1948 when D.Gabor first introduced holography.Subsequently,researchers introduced binary optical elements(BOEs),including computer-generated holograms(CGHs),as a distinct category within the realm of DOEs.This was the first revolution in optical devices.The next major breakthrough in light field manipulation occurred during the early 21st century,marked by the advent of metamaterials and metasurfaces.Metasurfaces are particularly appealing due to their ultra-thin,ultra-compact properties and their capacity to exert precise control over virtually every aspect of light fields,including amplitude,phase,polarization,wavelength/frequency,angular momentum,etc.The advancement of light field manipulation with micro/nano-structures has also enabled various applications in fields such as information acquisition,transmission,storage,processing,and display.In this review,we cover the fundamental science,cutting-edge technologies,and wide-ranging applications associated with micro/nano-scale optical devices for regulating light fields.We also delve into the prevailing challenges in the pursuit of developing viable technology for real-world applications.Furthermore,we offer insights into potential future research trends and directions within the realm of light field manipulation.
基金The authors acknowledge the support from National Natural Science Foundation of China (60125512, 60177016)
文摘Diffractive optical elements such as the complementary Dammann gratings are incorporated for dynamic optical fiber splitting and combining. Experimental results of 1×8 dynamic optical couplings are presented.
文摘Peculiarities of propagation of femtosecond pulses through a focusing diffractive optical element (DOE) are considered. It is shown that the time delay between the pulse and phase wavefronts can be decreased by fabricating the DOE on the optimal curvilinear surface.
基金Project supported by the National Basic Research Program of China (Grant No. 2011CB301801)the National Natural Science Foundation of China (GrantNos. 91233202,10904099,11204188,61205097,and 11174211)
文摘In this paper,a novel method is proposed and employed to design a single diffractive optical element（DOE） for implementing spectrum-splitting and beam-concentration（SSBC） functions simultaneously.We develop an optimization algorithm,through which the SSBC DOE can be optimized within an arbitrary thickness range according to the limitations of modern photolithography technology.Theoretical simulation results reveal that the designed SSBC DOE has a high optical focusing efficiency.It is expected that the designed SSBC DOE should have practical applications in high-efficiency solar cell systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.91233202,21173260,and 51072221)the National Basic Research Program of China(Grant No.2012CB932903)
文摘Based on the facts that multijunction solar cells can increase the efficiency and concentration can reduce the cost dramatically, a special design of parallel multijunction solar cells was presented. The design employed a diffractive optical element （DOE） to split and concentrate the sunlight. A rainbow region and a zero-order diffraction region were generated on the output plane where solar cells with corresponding band gaps were placed. An analytical expression of the light intensity distribution on the output plane of the special DOE was deduced, and the limiting photovoltaic efficiency of such parallel multijunction solar ceils was obtained based on Shockley-Queisser＇s theory. An efficiency exceeding the Shockley--Queisser limit （33%） can be expected using multijunction solar cells consisting of separately fabricated subcells. The results provide an important alternative approach to realize high photovoltaic efficiency without the need for expensive epitaxial technology widely used in tandem solar cells, thus stimulating the research and application of high efficiency and low cost solar cells.
基金Project supported by the National Natural Science Foundation of China(Grants Nos.91233202,21173260,and 51072221)the National Basic Research Program of China(Grant No.2012CB932903
文摘Two improved algorithms are proposed to extend a diffractive optical element （DOE） to work under the broad spec- trum of sunlight. An optimum design has been found for the DOE, with a weighted average optical efficiency of about 6.8% better than that of the previous design. The optimization of designing high optical efficiency DOEs will pave the way for future designs of high-efficiency, low-cost lateral multijunction solar cells based on such a DOE.
基金partially supported by the National Key Basic Research Program of China(No.2013CB329202)the National Scientific Equipment Development SpecialFoundation of China(No.2011YQ03013401)+1 种基金the National Natural Science Foundation of China(No.61475021)the Beijing Natural Science Foundation(No.4152015)
文摘Diffractive optics is an important technique for beam shaping with high light efficiency and strong diffraction pattern flexibility. Since the diffraction angle is limited by the unit size of the diffractive optical element （DOE）, the size of the required diffraction pattern is always rather small. In this Letter, refractive/diffractive hybrid optical elements （RDHOEs） consisting of a DOE and a lens are used to realize beam shaping for a large diffraction pattern. The lens, as the component of the RDHOEs, can not only be concave but also convex, and the double sampling Fresnel diffraction algorithm is developed for the design of these two types of RDHOEs. The simulation and experimental results provide solid evidence to demonstrate the proposed method with the pure phase spatial light modulator.
基金Japan Society for the Promotion of Science(JP20H05890,JP22H05197,JP23H05444,JP23K26567)。
文摘We propose a design method for a diffractive neural network(DNN)for imaging through scattering media,offering robustness against the spatial coherence of illumination,scattering strength,and scattering dynamics.Most techniques for imaging through scattering media are time-consuming and/or tailored to specific optical conditions.The DNN,composed of layers of diffractive optical elements(DOEs),optically reproduces the intensity distributions of objects behind scattering media without any computational processing.Datasets with randomized optical parameters are provided during the training process to achieve this robustness.We demonstrate the proposed method through numerical calculations and show its promising capability for DOE design.Our study paves the way for unifying and generalizing techniques for imaging through scattering media,which are currently fragmented by specific scenarios,enabling highly flexible imaging independent of optical conditions.
基金funding by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany’s Excellence Strategy for the Excellence Cluster“3D Matter Made to Order”(2082/1-390761711)by the Carl Zeiss Foundation,and by the Helmholtz program Materials Systems Engineering.
文摘One of the challenges in the field of multi-photon 3D laser printing lies in further increasing the print speed in terms of voxels/s.Here,we present a setup based on a 7×7 focus array(rather than 3×3 in our previous work)and using a focus velocity of about 1 m/s(rather than 0.5 m/s in our previous work)at the diffraction limit(40×/NA1.4 microscope objective lens).Combined,this advance leads to a ten times increased print speed of about 108 voxels/s.We demonstrate polymer printing of a chiral metamaterial containing more than 1.7×10^(12) voxels as well as millions of printed microparticles for potential pharmaceutical applications.The critical high-quality micro-optical components of the setup,namely a diffractive optical element generating the 7×7 beamlets and a 7×7 lens array,are manufactured by using a commercial two-photon grayscale 3D laser printer.
基金support of the Ministry of Science and Higher Education of the Russian Federation(state task FEUZ-2023-0017)The equipment of the Ural Center for Shared Use“"Modern nanotechnology"Ural Federal University(Reg.No 2968)was used.
文摘In this paper,we present the electric field controllable diffractive optical elements in strontium-barium niobate single crystals with stable tailored spiral-shaped domain structure and demonstrate the generation of optical beam with orbital angular momentum.The required domain pattern was created in the sample with initial domain structure by electric field application using the photolithographically defined liquid electrode.A series of bipolar triangular electric field pulses were applied to the sample for determination of the optimal parameters for complete polarization switching under the electrode.The stable tailored domain pattern of the spiral shape was created by the application of the unipolar pulse of a special shape.The complete switching under the electrode and partial switching under the photoresist layer have been revealed.The imaging by Cherenkov-type second harmonic generation microscopy confirmed that the created domain structure reaches the opposite polar surface.The imaging of the diffraction pattern of the laser beam passing through a voltage-biased DOE confirmed the formation of the beam with orbital angular momentum.The half-wave voltages of 237V and 302 V for wavelength 632.8 nm and 532 nm,respectively,for 2-mmthick sample were measured.The obtained knowledge can be used for the development of domain engineering methods in strontium-barium niobate single crystals for the creation of tailored domain structures for manufacturing of electric field controllablediffractiveoptical elements.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0206004)the National Natural Science Foundation of China(Grant No.11375160)the Science and Technology Fund from the Plasma Physics Laboratory,China(Grant No.ZY2018-01)。
文摘Annular-focused beams have attracted attention because of their novel properties and applications in optical trapping, high resolution microscopy, and laser-induced periodic surface structuring. Generation of this beam is very important and necessary. In this article, a novel design of zone plate for forming the annular-focused beams is proposed. The design principle is introduced, and the characteristics of zone plate are analyzed by numerical simulation. The result shows that the zone plate can form a monochromatic ring-shaped intensity distribution in the focal plane. And the design method is also generally suitable for designing the other optical elements to generate the annular-focused beams.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11404290 and 61505178)the Major National Scientific Instruments Developing Special Project(Grant No.2012YQ130125)+2 种基金the Postdoctoral Science Foundation of Henan Province,China(Grant No.2013008)the Program for Science&Technology Innovation Talents in Universities of Henan Province,China(Grant No.172102210481)the Key Scientific Research Projects in Universities of Henan Province,China(Grant No.19B140005)
文摘We propose an efficient method of generating a vortex beam with multi-foci by using a fractal spiral zone plate(FSZP), which is designed by combining fractal structure with a spiral zone plate(SZP) in the squared radial coordinate.The theoretical analysis reveals that the number of foci that embed vortices is significantly increased as compared with that obtained by using a conventional SZP. Furthermore, the influence of topological charge on the intensity distribution in focal plane is also discussed in detail. For experimental investigation, an FSZP with topological charge p = 1 and 6.4 mm diameter is fabricated by using a photo-etching technique. The calibration indicates that the focusing performances of such a kind of zone plane(ZP) accord well with simulations, thereby providing its potential applications in multi-dimensional optical manipulation and optical imaging technology.
基金supported by the National Key R&D Program of China(No.2022YFB4702902)National Natural Science Foundation of China(Nos.61831014,62275023,and 32021002)+2 种基金Beijing Municipal Natural Science Foundation(No.4232077)Overseas Expertise Introduction Project for Discipline Innovation(No.B18005)STI2030-Major Projects(No.2022ZD0212000).
文摘Optical imaging techniques provide low-cost,non-radiative images with high spatiotemporal resolution,making them advantageous for long-term dynamic observation of blood perfusion in stroke research and other brain studies compared to non-optical methods.However,high-resolution imaging in optical microscopy fundamentally requires a tight optical focus,and thus a limited depth of field(DOF).Consequently,large-scale,non-stitched,high-resolution images of curved surfaces,like brains,are difficult to acquire without z-axis scanning.To overcome this limitation,we developed a needle-shaped beam optical coherence tomography angiography(NB-OCTA)system,and for the first time,achieved a volumetric resolution of less than 8μm in a non-stitched volume space of 6.4 mm×4 mm×620μm in vivo.This system captures the distribution of blood vessels at 3.4-times larger depths than normal OCTA equipped with a Gaussian beam(GB-OCTA).We then employed NB-OCTA to perform long-term observation of cortical blood perfusion after stroke in vivo,and quantitatively analyzed the vessel area density(VAD)and the diameters of representative vessels in different regions over 10 days,revealing different spatiotemporal dynamics in the acute,sub-acute and chronic phase of post-ischemic revascularization.Benefiting from our NB-OCTA,we revealed that the recovery process is not only the result of spontaneous reperfusion,but also the formation of new vessels.This study provides visual and mechanistic insights into strokes and helps to deepen our understanding of the spontaneous response of brain after stroke.
基金This project is supported by the National Natural Science Foundation of China under the Grant No. 19970438.
文摘The matrix eigenvalue method is used to analyze a laser resonator composed of diffraction optical elements. The results show that this type of resonator can separate fundamental mode and high order modes effectively. The output beams can be designed for different requests.
基金supported by the National Natural Science Foundation of China(Nos.62175015,61905019,and 62075016)Fundamental Research Funds for the Central Universities(No.2021RC13)。
文摘In the integral imaging light field display, the introduction of a diffractive optical element (DOE) can solve the problem of limited depth of field of the traditional lens. However, the strong aberration of the DOE significantly reduces the final display quality. Thus, herein, an end-to-end joint optimization method for optimizing DOE and aberration correction is proposed. The DOE model is established using thickness as the variable, and a deep learning network is built to preprocess the composite image loaded on the display panel. The simulation results show that the peak signal to noise ratio value of the optimized image increases by 8 dB, which confirms that the end-to-end joint optimization method can effectively reduce the aberration problem.
