We experimentally detect high-refractive-index media (n > 1.5) using a surface plasmon resonance (SPR) sensor with a diffraction grating. While SPR sensors are generally based on the attenuated total reflection met...We experimentally detect high-refractive-index media (n > 1.5) using a surface plasmon resonance (SPR) sensor with a diffraction grating. While SPR sensors are generally based on the attenuated total reflection method using metal films, here, we focus on a method using a diffraction grating, which can detect relatively higher refractive-index media and is suitable for device miniaturization. In this study, we used the rigorous coupled-wave analysis method to simulate the dependence of the reflectance on an incident angle for media with refractive index values up to 1.700. In the experiment, a medium (n = 1.660 - 1.700) was successfully detected using this grating. Under the conditions of the grating (period: 600 nm, Au thickness: 40 nm) using a red laser (λ: 635 nm), a sharp decline in the reflectance and a rise in the transmittance at certain angles were confirmed, demonstrating the extraordinary transmission enabled by SPR. Because excitation angles changed with changes in the refractive index, we concluded that this method can be applied to sensors that detect high-refractive-index media.展开更多
We present a technique for fabricating a fluorescence enhancement device composed of metal nanoparticles(NPs) and porous silicon(PSi) diffraction grating.The fluorescence emission enhancement properties of the PSi and...We present a technique for fabricating a fluorescence enhancement device composed of metal nanoparticles(NPs) and porous silicon(PSi) diffraction grating.The fluorescence emission enhancement properties of the PSi and the fluorescence enhancement of the probe molecules are studied on PSi gratings.The fluorescence enhancement of the probe molecules on a fluorescence enhancement device is further improved through the deposition of metal NPs onto the PSi grating.In comparison to metal NP/PSi devices,metal NP periodic distributions can produce a stronger fluorescence enhancement that couples with the PSi grating fluorescence enhancement to achieve an overall three-fold enhancement of the fluorescence intensity.展开更多
Chirped-pitch nanoscale circular surface-relief diffraction gratings were photoinscribed on thin films of a Disperse Red 1 functionalized material using a holographic technique. A truncated conical mirror splits and r...Chirped-pitch nanoscale circular surface-relief diffraction gratings were photoinscribed on thin films of a Disperse Red 1 functionalized material using a holographic technique. A truncated conical mirror splits and redirects a converging or diverging laser beam, resulting in an interference pattern of concentric circles with a chirped pitch that can be controlled by varying the wavefront curvature. The resulting circular gratings have a diameter of 12 mm and have the advantage of being produced in a fast, single-step procedure with no requirement for a master grating,photomask, or milling equipment.展开更多
For numerical simulation of one-dimensional diffraction gratings both in TE and TM polarization,an enhanced adaptive finite element method is proposed in this paper.A modified perfectly matched layer(PML)formulation i...For numerical simulation of one-dimensional diffraction gratings both in TE and TM polarization,an enhanced adaptive finite element method is proposed in this paper.A modified perfectly matched layer(PML)formulation is proposed for the truncation of the unbounded domain,which results in a homogeneous Dirichlet boundary condition and the corresponding error estimate is greatly simplified.The a posteriori error estimates for the adaptive finite element method are provided.Moreover,a lower bound is obtained to demonstrate that the error estimates obtained are sharp.展开更多
The integral equation method for the simulation of the diffraction by optical gratings is an efficient numerical tool if profile gratings determined by simple crosssection curves are considered.This method in its rece...The integral equation method for the simulation of the diffraction by optical gratings is an efficient numerical tool if profile gratings determined by simple crosssection curves are considered.This method in its recent version is capable to tackle profile curves with corners,gratings with thin coated layers,and diffraction scenarios with unfavorably large ratio period over wavelength.We discuss special implementational issues including the efficient evaluation of the quasi-periodic Green kernels,the quadrature algorithm,and the iterative solution of the arising systems of linear equations.Finally,as an example we present the simulation of echelle gratings which demonstrates the efficency of our approach.展开更多
We present preparation of asymmetric grating with higher diffraction efficiency in quantum dot molecules by combining the tunneling effect and parity-time antisymmetry.In the presence of tunneling between two quantum ...We present preparation of asymmetric grating with higher diffraction efficiency in quantum dot molecules by combining the tunneling effect and parity-time antisymmetry.In the presence of tunneling between two quantum dots,the system exhibits the striking PT antisymmetry via spatially modulating the driving field and the detuning with respect to the driven transition.For this reason,the asymmetric grating could be achieved.The results show that the diffraction efficiency can be adjustable via changing the driving intensity,detuning,tunneling strength,and interaction length,and then the high-order diffraction can be reached.The scheme provides a feasible way to obtain the direction-controlled diffraction grating,which can be helpful for optical information processing and realization of controllable optical self-image.展开更多
In this work,we compare different methods for implementing a triplicator,a phase grating that generates three equiintense diffraction orders.The design with optimal efficiency features a continuous phase profile,which...In this work,we compare different methods for implementing a triplicator,a phase grating that generates three equiintense diffraction orders.The design with optimal efficiency features a continuous phase profile,which cannot be easily reproduced,and is typically affected by quantization.We compare its performance with binary and sinusoidal phase profiles.We also analyze the effect of quantizing the phase levels.Finally,a random approach is adopted to eliminate the additional harmonic orders.In all cases,a liquid-crystal-on-silicon spatial light modulator is employed to experimentally verify and compare the different approaches.展开更多
In this paper, a novel method of a subwavelength binary simple periodic rectangular structure is presented to realize even beam splitting by combining the rigorous couple-wave analysis with the genetic algorithm. Seve...In this paper, a novel method of a subwavelength binary simple periodic rectangular structure is presented to realize even beam splitting by combining the rigorous couple-wave analysis with the genetic algorithm. Several even splitters in the terahertz region were designed and one of the silicon-based beam splitters designed to separate one incident beam into four emergent beams has total efficiency up to 92.23 %. Zero-order diffraction efficiency was reduced to less than 0.192 % and the error of uniformity decreased to 6.51 9 10-6. These results break the limitation of even beam splitting based on the traditional scalar theory. In addition, the effects of the incident angle, wavelength, as well as the polarizing angle on the diffraction efficiency and uniformity were also investigated.展开更多
Optical surface scattering analyses based on diffractive optics (DO) are typically applied to one surface;however, there is a need for simulating surface scattering losses for devices having many surface interactions ...Optical surface scattering analyses based on diffractive optics (DO) are typically applied to one surface;however, there is a need for simulating surface scattering losses for devices having many surface interactions such as light pipes. Light pipes are often simulated with geometric optics (GO) using ray tracing, where surface scattering is driven by the surface slope distribution. In the DO case, surface scattering analyses depend on the spatial frequency distribution and amplitude as well as wavelength, with the sinusoidal grating as a fundamental basis. A better understanding of the link, or transition, between DO and GO scattering domains would be helpful for efficiently incorporating scattering loss analyses into ray trace simulations. A formula for the root-mean-square (rms) scattered angle width of a sinusoidal reflection grating that depends only on the surface rms slope is derived from the nonparaxial scalar diffraction theory, thereby linking it to GO. The scatter angle’s mean and rms width are evaluated over a range of grating amplitudes and periods using scalar theory and full vector simulations from the COMSOL® wave optic module for a sinusoidal reflection grating. The conditions under which the diffraction-based solution closely approximates the GO solution, as predicted by the rms slope, are identified. Close agreement is shown between the DO and GO solutions for the same surface rms slope scattering loss due to angular filtering near the critical angle of a total internal reflection (TIR) glass-to-air interface.展开更多
A single-order diffraction transmission grating named spectroscopic photon sieve(SPS)for soft x-ray region is proposed and demonstrated in this paper.The SPS consists of many circular pinholes located randomly,and can...A single-order diffraction transmission grating named spectroscopic photon sieve(SPS)for soft x-ray region is proposed and demonstrated in this paper.The SPS consists of many circular pinholes located randomly,and can realize both free-standing diffractions and the suppression of higher-order differations.In this paper,the basic concept,numerical simulations,and calibration results of a 1000-lines/mm SPS for soft x-ray synchrotron radiation are presented.As predicted by theoretical calculations,the calibration results of a 1000-lines/mm SPS verify that the higher-order diffractions can be significantly suppressed along the symmetry axis.With the current nanofabrication technique,the SPS can potentially have a higher line density,and can be widely used in synchrotron radiation,laser-induced plasma diagnostics,and astrophysics.展开更多
Holographic recording analysis was performed on the films that were sensitized with ammonium dichromate with albumin of hen and quail (Gallus gallus and Callipepla cali) as abiopolymeric photosensitive matrix. The sam...Holographic recording analysis was performed on the films that were sensitized with ammonium dichromate with albumin of hen and quail (Gallus gallus and Callipepla cali) as abiopolymeric photosensitive matrix. The samples were exposed to an He-Cd laser, λ = 442 nm, at various concentrations, and diffraction efficiencies were measured as a function to the energy, thickness, protein density, aging time, and spatial frequencies. The photosensitivity was measured as a function of storage time, and the gratings were recorded in real time. The photochemical processes involved in the formation of holographic image are described. The results indicate the behavior of colloidal systems based on albumin bird build holographic recording materials.展开更多
We propose a wavelength selective diffraction using reflectors placed on three-dimensional grid cross points. Different wavelengths are separated into spots distributed in two-dimensional plane. Compact device with hi...We propose a wavelength selective diffraction using reflectors placed on three-dimensional grid cross points. Different wavelengths are separated into spots distributed in two-dimensional plane. Compact device with high port counts is attainable.展开更多
An improved self-mixing grating interferometer based on the Littrow structure has been proposed in this Letter to measure displacement.The grating is integrated inside the interferometer to reduce the impact on the vi...An improved self-mixing grating interferometer based on the Littrow structure has been proposed in this Letter to measure displacement.The grating is integrated inside the interferometer to reduce the impact on the vibration parameters of the object caused by the grating attached to the vibrating object.The+1 st diffracted light returns to the laser cavity after being reflected by the target object,and self-mixing interference occurs.The displacement can be reconstructed by processing the self-mixing signals.The feasibility of the proposed interferometer is demonstrated by experimental measurements,and results show that it can achieve micro displacement measurement with the maximum absolute errors of less than 50 nm.展开更多
Consider the inverse diffraction problem to determine a two-dimensional periodic structure from scattered elastic waves measured above the structure.We formulate the inverse problem as a least squares optimization pro...Consider the inverse diffraction problem to determine a two-dimensional periodic structure from scattered elastic waves measured above the structure.We formulate the inverse problem as a least squares optimization problem,following the two-step algorithm by G.Bruckner and J.Elschner[Inverse Probl.,19(2003),315–329]for electromagnetic diffraction gratings.Such a method is based on the Kirsch-Kress optimization scheme and consists of two parts:a linear severely ill-posed problem and a nonlinear well-posed one.We apply this method to both smooth(C2)and piecewise linear gratings for the Dirichlet boundary value problem of the Navier equation.Numerical reconstructions from exact and noisy data illustrate the feasibility of the method.展开更多
Single-camera stereo-digital image correlation(stereo-DIC) techniques have gained increasing attentions and demonstrated excellent prospects in the experimental mechanics community owing to their prominent advantages ...Single-camera stereo-digital image correlation(stereo-DIC) techniques have gained increasing attentions and demonstrated excellent prospects in the experimental mechanics community owing to their prominent advantages of cost-effectiveness,compactness, and the avoidance of the complicated camera synchronization. Using additional optical devices, e.g. a diffraction grating, a bi-prism or a set of planar mirrors, pseudo stereo images of a test sample surface can be recorded with a single camera.By correlating these stereo images using DIC, full-field three-dimensional(3 D) shape and deformation can be retrieved. This review comprehensively summarizes the historical development, methodologies, strengths and weaknesses of the diffraction grating-based, prism-based, four-mirror-adaptor-based single-camera stereo-DIC techniques, and the recently proposed novel full-frame single color camera-based stereo-DIC technique for full-field 3 D shape and deformation measurement. The optical arrangements, principles and calibration procedures of these single-camera stereo-DIC techniques are described in detail. Since high-speed deformation measurement is efficiently achieved by combining the single-camera stereo-DIC with one high-speed camera, single-camera stereo-DIC techniques show great potential in impact engineering, vibration and other dynamic tests.展开更多
Lab-on-a-Chip(LoC)devices are extremely promising in that they enable diagnostic functions at the point-of-care.Within this scope,an important goal is to design imaging schemes that can be used out of the laboratory.I...Lab-on-a-Chip(LoC)devices are extremely promising in that they enable diagnostic functions at the point-of-care.Within this scope,an important goal is to design imaging schemes that can be used out of the laboratory.In this paper,we introduce and test a pocket holographic slide that allows digital holography microscopy to be performed without an interferometer setup.Instead,a commercial off-the-shelf plastic chip is engineered and functionalized with this aim.The microfluidic chip is endowed with micro-optics,that is,a diffraction grating and polymeric lenses,to build an interferometer directly on the chip,avoiding the need for a reference arm and external bulky optical components.Thanks to the single-beam scheme,the system is completely integrated and robust against vibrations,sharing the useful features of any common path interferometer.Hence,it becomes possible to bring holographic functionalities out of the lab,moving complexity from the external optical apparatus to the chip itself.Label-free imaging and quantitative phase contrast mapping of live samples are demonstrated,along with flexible refocusing capabilities.Thus,a liquid volume can be analyzed in one single shot with no need for mechanical scanning systems.展开更多
The 256×1 linear array of multiple quantum wells infrared photodetector (QWIP) is designed and fabricated for the peak response wavelength at λP=14.6 μm. The response spectral width is bigger than 2.2 μm. The ...The 256×1 linear array of multiple quantum wells infrared photodetector (QWIP) is designed and fabricated for the peak response wavelength at λP=14.6 μm. The response spectral width is bigger than 2.2 μm. The two-dimensional (2D) diffractive coupling grating has been formed on the top QWIP photosensitive pixel for coupling the infrared radiation to the infrared detective layers. The performance of the device at VB=3 V and T=45 K has the responsibility 4.28×10-2 (A/W), the blackbody detectivity Db*=5.14×109 (cm·Hz1/2/W), and the peak detectivity Dλ*=4.24× 1010 (cm·Hz1/2/W). The sensor pixels are connected with CMOS read out circuit (ROC) hybridization by indium bumps. When integral time is 100 μs, the linear array has the effective pixel of QWIP FPA Nef of 99.2%, the average responsibility (V/W) of 3.48×106 (V/W), the average peak detectivity Dλ* of 8.29×109 (cm·Hz1/2/W), and the non-uniformity UR of 5.83%. This device is ready for the thermal image application.展开更多
The behavior of a negative refraction photonic crystal slab irradiated with out-of-plane incident beam is an unexplored subject.In such an experimental configuration,guided mode resonance appears in the reflection spe...The behavior of a negative refraction photonic crystal slab irradiated with out-of-plane incident beam is an unexplored subject.In such an experimental configuration,guided mode resonance appears in the reflection spectrum.We show that,in this case,the light coupled inside the photonic crystal is backpropagating.A relationship with the negative index properties is established using a new approach in which the guided resonance is recovered by modeling the photonic crystal layer with a simple Lorentz resonator using the Fresnel reflection formula.展开更多
In this work,we present the first experimental evidence of negative dielectric susceptibility in a two-dimensional silicon photonic crystal(PhC)with negative refractive index behavior.In the frequency range in which t...In this work,we present the first experimental evidence of negative dielectric susceptibility in a two-dimensional silicon photonic crystal(PhC)with negative refractive index behavior.In the frequency range in which the effective refractive index neff is equal to 21,the incident light couples efficiently to the guided modes in the top surface layer of the PhC metamaterial.These modes resemble surface plasmon polariton resonances.This finding was confirmed by ellipsometric measurements,demonstrating the isotropy of the PhC resonances.Such negative index PhC materials may be of use in biosensing applications.展开更多
We experimentally demonstrated an approach to generate arbitrary total angular momentum(TAM) states by using two liquid crystal devices. Photons’ TAM, the sum of spin and orbital angular momenta(SAM and OAM)under par...We experimentally demonstrated an approach to generate arbitrary total angular momentum(TAM) states by using two liquid crystal devices. Photons’ TAM, the sum of spin and orbital angular momenta(SAM and OAM)under paraxial approximation, has found many applications in optics and attracted increasing attention in recent years. Our approach is based on the orthogonality of two eigen SAM components, that arbitrary TAM states will be produced through encoding different holograms in one system. The comparison with theoretical predications yields an excellent agreement, including both the separable state and the non-separable state. The proposed scheme takes a step forward for generating complex structured fields and broadens its application to various fields like laser processing and large capacity data transmission.展开更多
文摘We experimentally detect high-refractive-index media (n > 1.5) using a surface plasmon resonance (SPR) sensor with a diffraction grating. While SPR sensors are generally based on the attenuated total reflection method using metal films, here, we focus on a method using a diffraction grating, which can detect relatively higher refractive-index media and is suitable for device miniaturization. In this study, we used the rigorous coupled-wave analysis method to simulate the dependence of the reflectance on an incident angle for media with refractive index values up to 1.700. In the experiment, a medium (n = 1.660 - 1.700) was successfully detected using this grating. Under the conditions of the grating (period: 600 nm, Au thickness: 40 nm) using a red laser (λ: 635 nm), a sharp decline in the reflectance and a rise in the transmittance at certain angles were confirmed, demonstrating the extraordinary transmission enabled by SPR. Because excitation angles changed with changes in the refractive index, we concluded that this method can be applied to sensors that detect high-refractive-index media.
基金supported by the National Natural Science Foundation of China under Grant Nos.61575168 and 61665012
文摘We present a technique for fabricating a fluorescence enhancement device composed of metal nanoparticles(NPs) and porous silicon(PSi) diffraction grating.The fluorescence emission enhancement properties of the PSi and the fluorescence enhancement of the probe molecules are studied on PSi gratings.The fluorescence enhancement of the probe molecules on a fluorescence enhancement device is further improved through the deposition of metal NPs onto the PSi grating.In comparison to metal NP/PSi devices,metal NP periodic distributions can produce a stronger fluorescence enhancement that couples with the PSi grating fluorescence enhancement to achieve an overall three-fold enhancement of the fluorescence intensity.
文摘Chirped-pitch nanoscale circular surface-relief diffraction gratings were photoinscribed on thin films of a Disperse Red 1 functionalized material using a holographic technique. A truncated conical mirror splits and redirects a converging or diverging laser beam, resulting in an interference pattern of concentric circles with a chirped pitch that can be controlled by varying the wavefront curvature. The resulting circular gratings have a diameter of 12 mm and have the advantage of being produced in a fast, single-step procedure with no requirement for a master grating,photomask, or milling equipment.
基金The work is partially supported by the NTU start-up grant M58110011.
文摘For numerical simulation of one-dimensional diffraction gratings both in TE and TM polarization,an enhanced adaptive finite element method is proposed in this paper.A modified perfectly matched layer(PML)formulation is proposed for the truncation of the unbounded domain,which results in a homogeneous Dirichlet boundary condition and the corresponding error estimate is greatly simplified.The a posteriori error estimates for the adaptive finite element method are provided.Moreover,a lower bound is obtained to demonstrate that the error estimates obtained are sharp.
基金the German Federal Ministry of Education and Research under Grant number 13N8478.
文摘The integral equation method for the simulation of the diffraction by optical gratings is an efficient numerical tool if profile gratings determined by simple crosssection curves are considered.This method in its recent version is capable to tackle profile curves with corners,gratings with thin coated layers,and diffraction scenarios with unfavorably large ratio period over wavelength.We discuss special implementational issues including the efficient evaluation of the quasi-periodic Green kernels,the quadrature algorithm,and the iterative solution of the arising systems of linear equations.Finally,as an example we present the simulation of echelle gratings which demonstrates the efficency of our approach.
基金the National Natural Science Foundation of China(Grant Nos.11905064,11775190 and 11565013)the Scientific Research Foundation of Jiangxi Provincial Education Department,China(Grant No.GJJ200624).
文摘We present preparation of asymmetric grating with higher diffraction efficiency in quantum dot molecules by combining the tunneling effect and parity-time antisymmetry.In the presence of tunneling between two quantum dots,the system exhibits the striking PT antisymmetry via spatially modulating the driving field and the detuning with respect to the driven transition.For this reason,the asymmetric grating could be achieved.The results show that the diffraction efficiency can be adjustable via changing the driving intensity,detuning,tunneling strength,and interaction length,and then the high-order diffraction can be reached.The scheme provides a feasible way to obtain the direction-controlled diffraction grating,which can be helpful for optical information processing and realization of controllable optical self-image.
基金supported by the Ministerio de Ciencia e Innovación,Spain(PID2021-126509OB-C22)Generalitat Valenciana(CIAICO/2021/276)。
文摘In this work,we compare different methods for implementing a triplicator,a phase grating that generates three equiintense diffraction orders.The design with optimal efficiency features a continuous phase profile,which cannot be easily reproduced,and is typically affected by quantization.We compare its performance with binary and sinusoidal phase profiles.We also analyze the effect of quantizing the phase levels.Finally,a random approach is adopted to eliminate the additional harmonic orders.In all cases,a liquid-crystal-on-silicon spatial light modulator is employed to experimentally verify and compare the different approaches.
基金supported by grants from the Natural Science Foundation of China(Nos.61275167,60878036and 60178023)the Basic Research Project of Shenzhen(Nos.JCYJ20130329103020637,JCYJ20120613112628842,JCYJ20140418095735591 and JC201005280533A)
文摘In this paper, a novel method of a subwavelength binary simple periodic rectangular structure is presented to realize even beam splitting by combining the rigorous couple-wave analysis with the genetic algorithm. Several even splitters in the terahertz region were designed and one of the silicon-based beam splitters designed to separate one incident beam into four emergent beams has total efficiency up to 92.23 %. Zero-order diffraction efficiency was reduced to less than 0.192 % and the error of uniformity decreased to 6.51 9 10-6. These results break the limitation of even beam splitting based on the traditional scalar theory. In addition, the effects of the incident angle, wavelength, as well as the polarizing angle on the diffraction efficiency and uniformity were also investigated.
文摘Optical surface scattering analyses based on diffractive optics (DO) are typically applied to one surface;however, there is a need for simulating surface scattering losses for devices having many surface interactions such as light pipes. Light pipes are often simulated with geometric optics (GO) using ray tracing, where surface scattering is driven by the surface slope distribution. In the DO case, surface scattering analyses depend on the spatial frequency distribution and amplitude as well as wavelength, with the sinusoidal grating as a fundamental basis. A better understanding of the link, or transition, between DO and GO scattering domains would be helpful for efficiently incorporating scattering loss analyses into ray trace simulations. A formula for the root-mean-square (rms) scattered angle width of a sinusoidal reflection grating that depends only on the surface rms slope is derived from the nonparaxial scalar diffraction theory, thereby linking it to GO. The scatter angle’s mean and rms width are evaluated over a range of grating amplitudes and periods using scalar theory and full vector simulations from the COMSOL® wave optic module for a sinusoidal reflection grating. The conditions under which the diffraction-based solution closely approximates the GO solution, as predicted by the rms slope, are identified. Close agreement is shown between the DO and GO solutions for the same surface rms slope scattering loss due to angular filtering near the critical angle of a total internal reflection (TIR) glass-to-air interface.
基金Project supported by the National Natural Science Foundation for Young Scientists of China(Grant No.11805179).
文摘A single-order diffraction transmission grating named spectroscopic photon sieve(SPS)for soft x-ray region is proposed and demonstrated in this paper.The SPS consists of many circular pinholes located randomly,and can realize both free-standing diffractions and the suppression of higher-order differations.In this paper,the basic concept,numerical simulations,and calibration results of a 1000-lines/mm SPS for soft x-ray synchrotron radiation are presented.As predicted by theoretical calculations,the calibration results of a 1000-lines/mm SPS verify that the higher-order diffractions can be significantly suppressed along the symmetry axis.With the current nanofabrication technique,the SPS can potentially have a higher line density,and can be widely used in synchrotron radiation,laser-induced plasma diagnostics,and astrophysics.
基金Thanks are due to The Instituto Nacional de Astrofisica Optica y Electronica(INAOE)for the infrastructure and economic support received.
文摘Holographic recording analysis was performed on the films that were sensitized with ammonium dichromate with albumin of hen and quail (Gallus gallus and Callipepla cali) as abiopolymeric photosensitive matrix. The samples were exposed to an He-Cd laser, λ = 442 nm, at various concentrations, and diffraction efficiencies were measured as a function to the energy, thickness, protein density, aging time, and spatial frequencies. The photosensitivity was measured as a function of storage time, and the gratings were recorded in real time. The photochemical processes involved in the formation of holographic image are described. The results indicate the behavior of colloidal systems based on albumin bird build holographic recording materials.
文摘We propose a wavelength selective diffraction using reflectors placed on three-dimensional grid cross points. Different wavelengths are separated into spots distributed in two-dimensional plane. Compact device with high port counts is attainable.
基金supported by the Northeast Petroleum University Youth Science Foundation(No.2020QNL-13)。
文摘An improved self-mixing grating interferometer based on the Littrow structure has been proposed in this Letter to measure displacement.The grating is integrated inside the interferometer to reduce the impact on the vibration parameters of the object caused by the grating attached to the vibrating object.The+1 st diffracted light returns to the laser cavity after being reflected by the target object,and self-mixing interference occurs.The displacement can be reconstructed by processing the self-mixing signals.The feasibility of the proposed interferometer is demonstrated by experimental measurements,and results show that it can achieve micro displacement measurement with the maximum absolute errors of less than 50 nm.
基金the support by the German Research Foundation(DFG)under Grant No.EL 584/1-2.
文摘Consider the inverse diffraction problem to determine a two-dimensional periodic structure from scattered elastic waves measured above the structure.We formulate the inverse problem as a least squares optimization problem,following the two-step algorithm by G.Bruckner and J.Elschner[Inverse Probl.,19(2003),315–329]for electromagnetic diffraction gratings.Such a method is based on the Kirsch-Kress optimization scheme and consists of two parts:a linear severely ill-posed problem and a nonlinear well-posed one.We apply this method to both smooth(C2)and piecewise linear gratings for the Dirichlet boundary value problem of the Navier equation.Numerical reconstructions from exact and noisy data illustrate the feasibility of the method.
基金supported by the National Natural Science Foundation of China(Grant Nos.11272032,11322220,11427802&11632010)the Aeronautical Science Foundation of China(Grant No.2016ZD51034)the Academic Excellence Foundation of BUAA for PhD Students
文摘Single-camera stereo-digital image correlation(stereo-DIC) techniques have gained increasing attentions and demonstrated excellent prospects in the experimental mechanics community owing to their prominent advantages of cost-effectiveness,compactness, and the avoidance of the complicated camera synchronization. Using additional optical devices, e.g. a diffraction grating, a bi-prism or a set of planar mirrors, pseudo stereo images of a test sample surface can be recorded with a single camera.By correlating these stereo images using DIC, full-field three-dimensional(3 D) shape and deformation can be retrieved. This review comprehensively summarizes the historical development, methodologies, strengths and weaknesses of the diffraction grating-based, prism-based, four-mirror-adaptor-based single-camera stereo-DIC techniques, and the recently proposed novel full-frame single color camera-based stereo-DIC technique for full-field 3 D shape and deformation measurement. The optical arrangements, principles and calibration procedures of these single-camera stereo-DIC techniques are described in detail. Since high-speed deformation measurement is efficiently achieved by combining the single-camera stereo-DIC with one high-speed camera, single-camera stereo-DIC techniques show great potential in impact engineering, vibration and other dynamic tests.
基金supported by IC+project:Imaging Citometry in PLastic Ultramobile Systems in the framework of Progetto Bandiera‘La Fabbrica del Futuro Piattaforma Manifatturiera Nazionale.’。
文摘Lab-on-a-Chip(LoC)devices are extremely promising in that they enable diagnostic functions at the point-of-care.Within this scope,an important goal is to design imaging schemes that can be used out of the laboratory.In this paper,we introduce and test a pocket holographic slide that allows digital holography microscopy to be performed without an interferometer setup.Instead,a commercial off-the-shelf plastic chip is engineered and functionalized with this aim.The microfluidic chip is endowed with micro-optics,that is,a diffraction grating and polymeric lenses,to build an interferometer directly on the chip,avoiding the need for a reference arm and external bulky optical components.Thanks to the single-beam scheme,the system is completely integrated and robust against vibrations,sharing the useful features of any common path interferometer.Hence,it becomes possible to bring holographic functionalities out of the lab,moving complexity from the external optical apparatus to the chip itself.Label-free imaging and quantitative phase contrast mapping of live samples are demonstrated,along with flexible refocusing capabilities.Thus,a liquid volume can be analyzed in one single shot with no need for mechanical scanning systems.
基金the National Natural Science Foundation of China(Grant No.10374095)
文摘The 256×1 linear array of multiple quantum wells infrared photodetector (QWIP) is designed and fabricated for the peak response wavelength at λP=14.6 μm. The response spectral width is bigger than 2.2 μm. The two-dimensional (2D) diffractive coupling grating has been formed on the top QWIP photosensitive pixel for coupling the infrared radiation to the infrared detective layers. The performance of the device at VB=3 V and T=45 K has the responsibility 4.28×10-2 (A/W), the blackbody detectivity Db*=5.14×109 (cm·Hz1/2/W), and the peak detectivity Dλ*=4.24× 1010 (cm·Hz1/2/W). The sensor pixels are connected with CMOS read out circuit (ROC) hybridization by indium bumps. When integral time is 100 μs, the linear array has the effective pixel of QWIP FPA Nef of 99.2%, the average responsibility (V/W) of 3.48×106 (V/W), the average peak detectivity Dλ* of 8.29×109 (cm·Hz1/2/W), and the non-uniformity UR of 5.83%. This device is ready for the thermal image application.
基金Portions of this work were performed at the Molecular Foundry,Lawrence Berkeley National Laboratory,which is supported by the Office of Science,Office of Basic Energy Sciences,of the US Department of Energy under contract no.DE-AC02-05CH11231This work was partially supported by the Italian Ministry of University and Research under grants PON PANDION 01_00375.
文摘The behavior of a negative refraction photonic crystal slab irradiated with out-of-plane incident beam is an unexplored subject.In such an experimental configuration,guided mode resonance appears in the reflection spectrum.We show that,in this case,the light coupled inside the photonic crystal is backpropagating.A relationship with the negative index properties is established using a new approach in which the guided resonance is recovered by modeling the photonic crystal layer with a simple Lorentz resonator using the Fresnel reflection formula.
基金Portions of this work were completed as part of a user project at the Molecular Foundry,Lawrence Berkeley National Laboratory,which is supported by the US Department of Energy under contract DE-AC02-05CH11231We gratefully acknowledge Aleksandr Polyakov for his suggestions in critically revising the manuscript.This work was partially supported by Italian National Operative Programs PON01_02782,PON01_01525 and PON01_00375.
文摘In this work,we present the first experimental evidence of negative dielectric susceptibility in a two-dimensional silicon photonic crystal(PhC)with negative refractive index behavior.In the frequency range in which the effective refractive index neff is equal to 21,the incident light couples efficiently to the guided modes in the top surface layer of the PhC metamaterial.These modes resemble surface plasmon polariton resonances.This finding was confirmed by ellipsometric measurements,demonstrating the isotropy of the PhC resonances.Such negative index PhC materials may be of use in biosensing applications.
基金supported by the National Natural Science Foundation of China (NSFC)(Nos. 11834001 and61905012)the National Postdoctoral Program for Innovative Talents of China (No. BX20190036)+1 种基金the China Postdoctoral Science Foundation (No. 2019M650015)the Beijing Institute of Technology Research Fund Program for Young Scholars。
文摘We experimentally demonstrated an approach to generate arbitrary total angular momentum(TAM) states by using two liquid crystal devices. Photons’ TAM, the sum of spin and orbital angular momenta(SAM and OAM)under paraxial approximation, has found many applications in optics and attracted increasing attention in recent years. Our approach is based on the orthogonality of two eigen SAM components, that arbitrary TAM states will be produced through encoding different holograms in one system. The comparison with theoretical predications yields an excellent agreement, including both the separable state and the non-separable state. The proposed scheme takes a step forward for generating complex structured fields and broadens its application to various fields like laser processing and large capacity data transmission.
