This PDF file contains the front matter associated with SPIE Proceedings Volume 12072, including the Title Page, Copyright information, and Table of Contents.

Benefit from its subwavelength scale, metasurface has been widely used at the area of holograms. However, the existing researches about meta-hologram are mostly based on the illumination of propagating wave. In this condition, the ability of information coding of the evanescent wave is wasted. Thus, we demonstrated a complex structure which consists of prism and metasurface. This structure realizes the evanescent wave illumination, and extracted the image information from the evanescent wave region successfully. This scheme shows large potential in the area of information storage and information encryption.

Over the past decade, major progress in emerging mid-infrared (IR) sources and detectors leads to increased interests for various IR-based applications, such as trace-gas detection, biological and medical sensing, and environmental monitoring. However, a limiting factor in the middle and long wave IR range is the lack of suitable materials that are transparent, low cost, lightweight and easy to fabricate. Here, we numerically demonstrate the artificially constructed Huygens meta-surface with versatile mid-IR wavefront control, by hybridizing the dielectric meta-atoms of high-permittivity chalcogenide on fluoride substrates. Based on the double-elements Huygens meta-atom design for linear phase tuning, transmission is enhanced substantially with high-efficiency (85%) by concentrating beam propagation into the first diffraction order similar as traditional blazed grating but with ultra-thin thickness (λ/8). Further, based on centrosymmetric deflection to produce a local and highly focused propagation mode, a Bessel beam generator is demonstrated (λ=5.22 μm, NA = 0.5) by coding a well-defined phase map into dielectric meta-atoms. As a result, the proposed dielectric metasurface with nanometer level thickness shows great prospects in the field of integrated photonics.

In this study, surgical operation for the myocardial ischemia of rat was used to simulate the model of critically ill patients. Speckle variance optical coherence tomography was applied to study the effects of myocardial ischemia on blood microcirculation. The main method is to simulate the severe condition through the heart ligation operation in rats, and then the OCT system is used to image the ear of rats. First of all, the variance operation is performed on the same position of the structure map through speckle variance algorithm, so as to obtain the blood flow intensity information. Finally, the vascular morphological structure can be roughly seen through the basic vascular enhancement algorithm. A comparison of vascular images before and after heart ligation surgery revealed that surgery had a significant effect on the circulation of microvessels, and many microvessels were lost intermittently after surgery. Accurate in vivo study model is very important to obtain OCT images and accurate analysis, and it is of great value to promote the development of microangiography4 and its clinical application.

Hitherto, methods to generate optical vortex beams have been widely researched, ranging from mode conversion to diffractive optical elements. However, bulky-sized traditional methods are unsuitable for nanophotonic systems, metasurface has become an alternative option for generating optical vortices. In this paper, a metasurface combining dynamic and geometric phases is proposed. Under the incidence of circular polarized light, optical vortices with different topological charges can be generated simultaneously by a single metasurface. The dynamic phase makes the topological charge of the vortex light vary with distance. The intensity distribution and relative distance of the focused vortices can be manipulated with different focal length of the metasurface. This method provides a new design to generate different vortices in a single device and has potential applications in particle capture and integrated optical systems.

Optical beam carrying orbital angular momentum(OAM) exhibits profound potential in optical communications, micromanipulation and other related fields due to its helical wavefront. However, complex configuration of manipulating optical vortices have hindered the realization of nanophotonic systems. Recently, owing to the ultrathin structure, plasmonic metasurfaces based on abrupt phase shift have aroused appreciable interest. In this paper, we introduce a multifunctional device that integrates a focusing apparatus and an orbital angular momentum generator by the use of the plasmonic metasurfaces. This metasurface combining Archimedean spirals and spatially variant nanoslits achieves plasmonic focusing and an optical needle in the near- and far-field, respectively. Moreover, generation of optical vortex beams is shown in the far- and near-field simultaneously, where light field can be arbitrarily manipulated. We expect this work to have further applications in integrated photonic systems.

Enantioseparation is a fundamental problem in pharmaceutics and agrochemicals. Yet, the prevailing chemical techniques are not effective. In this paper, we proposed an achiral metasurface, which consists of a disk-double split ring (DDSR) resonator sustaining dipole-octupole (DO) Fano resonance (FR). We have proved that such a resonance can significantly enlarge the chiral gradient force of the enantiomers by numerical simulation. We find that the resonator has a large chirality density gradient near the DO-FR, which strengthens the chiral gradient force that can discriminate the sub-10 nm chiral nanoparticles. Therefore, the enantioselective optical potential can trap or push different enantiomers. We propose a method to enhance the chiral gradient force by using an achiral metasurface consisting of a disk and an asymmetric double split-ring resonator, which can promote the development of enantiomer purification and separation technology, and bring new prospects for the latest all-optical enantiomer synthesis technology.

Multispectral imaging technology plays an important role in lots of domains, but traditional systems are limited by large volumes and complex constructions. Here, we propose a high-efficiency multispectral integrated imaging system based on metasurfaces, with its spectral range covering two important infrared windows of 3-5 μm and 8-12 μm. This system is composed of the microlens, metasurface, and filter array, hence its volume, weight, and complexity can be greatly decreased. The average efficiencies of the aforementioned two bands are over 96.47% and 97.43%, respectively. The bandwidth of each spectral channel can be tuned flexibly according to realistic requirements, which makes the system more applicable to various circumstances. The proposed design method is universally applicable and has potential applications in many aspects, such as remote sensing, epidemic monitoring, and archeology.

In this paper, we propose an ultra-thin metasurface to achieve simultaneous thermal infrared camouflage and 1.06 μm laser scattering with thermal management. First, the metasurface has an average absorptivity/emissivity of 0.04 in the band of 8~14 μm and a emission peak at 5.62 μm with nearly 100% emissivity. Therefore, camouflage against thermal infrared detectors and effective thermal management can be achieved. Second, the chessboard-like square patches on the top of the meatsurface make it possible to reduce the specular reflection at the laser wavelength of 1.06 μm to less than 2% by redirecting the reflected light to non-normal angles. These excellent simulated results indicate that our proposed metasurface has promising applications in the fields of multi-band infrared camouflage.

The functionality of simultaneous dichroism and wavefront manipulation of orthogonally polarized electromagnetic waves has attracted considerable attention in the fields of polarization imaging, polarization sensing, vector generation, and optical communication. However, the conventional methodology requires the combination of many optical components, which limits the integration and reduces the efficiency of optical systems. Although multilayer metasurfaces have been proposed to increase efficiency, complicated fabrication hinders its practical applications. Herein, we employ the monolithic all-dielectric metasurface to simultaneously implement linear dichroism and wavefront manipulation based on the principle of local polarization-selective constructive or destructive interference. The average transmittance exceeding 87.88% and polarization extinction ratio up to 23 dB are achieved by the all-dielectric metasurface at the central wavelength of 532 nm. It is believed that this high-performance metasurface may provide a novel scheme for the complex optical field manipulation and replace the bulk optical elements in polarization imaging or other optical domains.

For cosmic microwave background (CMB) telescopes, high-density polyethylene (HDPE) is widely used as reimaging lens material on account of its extremely low loss and excellent mechanical properties. The impedance mismatch between free space and lens can cause non-negligible reflection loss and low image quality. An anti-reflection (AR) coating is essential to reduce such effect. Single or multiple layers porous polytetrafluoroethylene (PTFE) membranes are glued to the HDPE lens surface as AR coatings in many previous CMB experiments. However, it is difficult to get a uniform bonding across a curvature surface for a large-aperture CMB telescope. Due to the mismatch of the thermal expansion of the lens and AR coating materials, the AR coatings have delamination or separation problem during cryogenic cycling. Simulated dielectric AR (SDAR) coatings based on the theory of meta-surface are suitable for low frequency and large aperture CMB telescopes. The effective refractive index of SDAR coating is tunable by cutting holes or grooves into the lens material to form sub-wavelength structure. The SDAR coating is made directly from lens bulk material, which can naturally solve the thermal expansion mismatch problem. In this paper, we present the SDAR coating prototype machined on a 30 mm thick HDPE plate. The measurement results show that the SDAR coating can effectively eliminate standing waves with the performance improvement about -10 dB to -20 dB. And the transmittance exceeds 98% in the 30 GHz to 50 GHz band, which is about 10% higher than that without AR coating.

We designed a broadband achromatic multilevel diffractive lens which is using the nanoparticle composite. Nanoparticle composite is a new artificial material, which has both pattern-transfer capability and high refractive index requirements. The device has good achromatic performance and good focusing performance at the focal plane in the visible band. The simulated average focusing efficiency is over 85% at the visible frequency.

Super-oscillation phenomenon provides an effective solution for realizing far-field non-invasive super-resolution imaging. However, most super-oscillatory lenses are challenging to balance the working bandwidth and working efficiency, which greatly limits the practical applications of super-oscillation lenses in optical systems. In this work, a broadband high-efficiency super-oscillatory metalens for sub-diffraction focusing about 0.75 times the diffraction limit based on the reflective metasurface is proposed for super-resolution imaging in the visible ranging from 400 nm to 700 nm. Moreover, another metalens with a sub-diffraction focusing spot equal to 0.6 times of the diffraction limit is also designed to prove the universal applicability of the proposed method. The proposed method provides an effective pathway for the development of microscopy, holography, and machine vision.

In this work, we propose a loaded diode frequency reconfigurable ultra-thin metasurface for beam switching. Different bias voltages are applied to the ultra-thin reconfigurable unit to achieve different phase gradients between adjacent units in the x-axis direction. Different voltage configurations are used to achieve stable phase gradient in different working frequencies which ensures the stability of beam scanning and expands the operating bandwidth of the antenna. The characteristics of frequency reconfigurable metasurface have been verified over the frequency band 9.1-10.1 GHz. This study paves a novel strategy of bandwidth expansion with the advantages of reconfigurable frequency and lightweight.

We design a simple catenary metasurface with high efficiency, which could obtain both the degree of circular polarization and the wavelength of incident polarized light by measuring the diffraction intensity and the deflection angle. The catenary decomposes the incidence into left and right circularly polarized light and diffracts them to different predesigned directions with different deflection angles that present the wavelength information. The diffraction efficiency of the designed catenary exceeds 94%, the average diffraction efficiency is up to 97.6% at the wavelength of 8-14μm, and angular dispersion is 0.078°/nm. Moreover, the degree of circular polarization for various incident polarization states can be characterized by diffraction intensities. This work may provide extensive applications for biosensing, DNA structural analysis, stereochemistry, etc.

We report a lightweight metasurface with wide field of view (FOV), which can calculate incident angle by the focus of the sun for navigation. The solar altitude angle and solar azimuth angle for navigation can be resolved with converting the coordinate system to connect the sun with the focus. The designed metasurface overcomes bulky devices and bad weather owing to the fact that the metasurface operates at short-wavelength infrared band (SWIR) that penetrates smoke and fog.

Ultraviolet surface plasmon polaritons (UV SPPs) have important and extensive potential applications in SPPs nanolithography, SERS, LEDs, solar cells, photocatalysis, and so on. Recently, more and more attention has been paid to extend plasmonic properties from the visible and near-IR band into the ultraviolet range. However, the low efficiency to generate UV plasma is an enormous challenge and unidirectional excitation of SPPs is considered as a reliable way to solve the problem. Here we theoretically propose a structure with an asymmetric nano-slit cavity that serves as an efficient unidirectional coupler for deep UV plasmons, especially for the wavelength of 248nm, which is a typical light source used in the SPPs nanolithography. The theoretical results based on FDTD algorithm show that by optimally designing the asymmetric nano-slit cavity the extinction ratio can reach 16.8 dB and can be further increased to 28.0 dB when assisted by a nano grating. Additionally the direction of the proposed unidirectional excitation is controllable by adjusting the length of nano-slit cavity.

Terahertz (THz) absorbers have drawn great attention due to their potential applications in high-resolution imaging systems, sensing, and imaging. In particular, metasurface-based THz absorbers have exhibited the exotic advantage in high efficiency and broad bandwidth benefitted from the excellent abilities of metasurface in flexible modulating electromagnetic (EM) waves. However, the interactions between metasurface and EM waves are complex, and the metasurface-based absorbers have many structural parameters to optimize for high performance. Therefore, the absorbers are constrained by the manual design process with limited geometry complexity and tedious parameters sweeping. In this paper, the genetic algorithm (GA) is employed to the design of THz metasurface absorber. The EM responses of metasurface device is calculated by a simple yet powerful analytic method derived from catenary field. The employment of GA can achieve the automatic design process and demand-oriented reverse design for high performance and decreasing time consumption. As a proof-of-concept, the broadband and monolayer metasurface terahertz absorber with absorbance exceeding 80% in the frequency range from 1 to 4 THz is designed by the proposed strategy based on five typical types of metasurface. The investigations of this article present important guidance and a promising approach to design and optimize metasurface-based devices for their practical applications.

Sub-wavelength 􀀁ratings (SWGs) have the property of the laser induced damage threshold (LIDT) close to that of bulk optical medium material, which becomes the focus of research to improve the anti-laser damage properties of optical element in recent years. SWGs are the effective substitutes for the laser anti-reflection (AR) of multilayer dielectric (MLD) thin films. In this paper, a polarization-dependent SWG with anti-reflection and wide-spectrum properties based on optical glass was designed using rigorous coupled wave analysis (RCWA). Figure 1 shows the schematic of the 1D grating, h is the ridge height of the grating, w is the bottom width of the grating,Λ is the period of the grating, and θ is the incident angle. The spectral characteristics were simulated using finite element analysis (FEA). The results show that the transmittance is not less than 95% from 350 nm-2500 nm in 0°~40° incident angle when the polarization component z of the electric field (TE) is parallel to the ridge direction of the grating. And it is not less than 98.5% at 0° incident angle from 350 nm to 2500 nm. When the polarization component z of the magnetic field (TM) is parallel to the ridge direction of the grating, the transmittance is not less than 95% from 300 nm to 900 nm in 0°~40° incident angle.

Photonic integrated circuits (PICs) as potential candidate to overcome the “von Neumann bottleneck” of current electronic technologies beyond Moore’s law gain increasing applications in fields of optical communication, data exchange and highperformance interconnect networks etc. Currently, elementary active devices such as photonic switches and modulators play essential roles in light-flow control of optical interconnection network, but suffer from high static power consumption because of volatile control and large footprint that is hard to integrate. In this trend, optical phase change materials (OPCMs) based active devices emerge as promising solutions due to advantages of large optical contrast between the amorphous and crystalline states, optically or electrically switchable and non-volatile control, easy to integration etc. In this paper, we propose a non-volatile O-PCMs photonic switch by integrating a thin film of germanium antimony telluride (GST) alloy on top of a micro-ring resonator. As confirmed by our analytical and computational results, upon an amorphous-to-crystalline phase change, two output ports of the O-PCM microring switch exhibit gigantic transmission contrast with a ratio up to highest 47:1. Further, the O-PCM based photonic switch also demonstrates extremely low extinction ration to 13.58 dB and 14.40 dB for both output ports from 1.5 μm to 1.6 μm.

The edge roll off seriously restricts the further improvement of the overall surface figure accuracy in CP of large planar optics. Firstly, the half width and depth of large planar optics’ edge region is proposed to quantify the roll off degree by analyzing its radial equivalent profile. Then, a two-dimensional symmetrical model of the large planar optics and the pitch lap is established. Next, based on the finite element model, the influence of extension block’s bonding state on the large planar optics edge’s stress concentration is analyzed. Finally, the effectiveness of this proposed method is verified by CP of large planar optics with extension blocks.

Polarization imaging is one of the important means of target detection and recognition, and the polarization device is the core of the system.In this paper, based on Stokes theory, a far infrared polarizing device---Two dimensional four direction array subwavelength double layer grating,is designed, which can be used for real-time measurement. Based on the equivalent medium theory, the size parameters of the micro unit are calculated.On the basis of the initial parameters, the micro cell structure is simulated and optimized.Finally, the simulation results show that the TM transmittance of the optimized double-layer grating structure is about 12% higher than that of the original one, reaching more than 90%,the extinction ratio is 25.8dB.

The purpose of this paper is to make an overview of the development status of anti-reflective coating in optical coating. The preparation process of anti-reflective coating mainly includes the selection of coating materials and the design of the coating system based on the application requirements, and then the selection of appropriate preparation process for the preparation of the coating.Therefore, this paper first describes the principle of anti-reflective coating, then describes the design methods of single-layer and multilayer membrane systems, and compares the optical transmittance of the two methods in visible bands.Secondly, it describes the four kinds of coating preparation technology commonly used nowadays, including vacuum evaporation method, chemical vapor deposition method, sol-gel method, sputtering method, and its main application fields and advantages and disadvantages are summarized.Then the anti-reflection coating materials commonly used in coating technology and the film structures which are constantly updated and developed to adapt to different application fields are described.Finally, two applications of anti-reflective coating nowadays are listed, including multi-layer special optical coating applied by the space detection camera developed by our group and the application of the anti-reflective coating in solar cells.

Due to the spin-orbit Hall effect of light, the intensity distribution of the reflected light is related to the incident angle, spin-orbital angular momentum and the refractive index of the reflective surface. In this paper, we research the spin-orbit Hall effect in the reflection with incident vortex lights carrying spin and orbital angular momentum. Then, the orbital angular momentum (OAM) spectrum of the reflected light are calculated. Subsequently, owing to the fact that the light field is redistributed after reflection, we propose a method for measuring the refractive index of optical materials based on the OAM spectrum of the reflected light. This measurement technique has the advantage of high sensitivity and strong anti-interference ability. We expect this work to contribute to other fields of precise measurements.

A dual dispersion stitching method is proposed to extend the measuring range of chromatic confocal sensor without reducing the axial resolution. A novel chromatic confocal sensor with dual dispersion is presented and introduced. An X-shaped fiber coupler is employed to divide the light from light source into two beams. These two beams are used to generate two sets of staggered dispersion which extend the measuring range of chromatic confocal sensor. A dual-dispersive objective is designed with Zemax software for verifying the proposed method. The result indicates that the length of total dispersion is extended to 209.6 μm, which is 1.75 times the length of single dispersion. The coefficient of determination between the axial dispersion and wavelength is close to 1.0000.

In the testing of optical surfaces with large aperture or large aperture angle, sub-aperture stitching technology has been developed for a long time, while most testing analysis is for the rotationally symmetrical surface. In view of a cylindrical surface sub-aperture stitching algorithm based on discrete phase data, by using Legendre polynomials to fit the wave surface, numerical simulation and analysis for several main influencing factors have been carried out. For instance, a bicubic interpolation method has been used for non-numerical point in a discrete phase and fuzzy points in overlapping areas during the process of stitching sub-apertures, on account of its accuracy and calculation time. By considering alignment error, random noise, position error, especially rotation error in non-rotationally symmetrical cylindrical surface testing, we stimulate 9 sub-aperture phase data from a measured phase data to analyze the correction coefficient which determines the percentage of error correction in stitching algorithm. While the correction coefficient is approaching 1, the stitching result is most likely overcorrected. In order to achieve the best error correction, the correction coefficient should be set at around 0.6. Furthermore, combined with chaos particle swarm optimization, we reduce the possibility of the algorithm falling into the local optimum, and improve the accuracy of stitching.

Diffractive optical element (DOE) has been widely used in camera lens imaging systems such as mobile phone camera, Monitoring Camera, etc. The measurement of the DOE surface morphology is very important to evaluate the processing quality of the elements, optimize the manufacturing technology and improve the image quality of the imaging system. However, traditional DOE has a small diameter (about 10mm) and the base surface is a wavelength scale 3D relief microstructure. It is a great challenge to realize the high-precision, high-efficiency and multi-scale surface profile measurement of its full aperture. In this paper, new white light interferometry scanning stitching measurement device and method for the 3D surface topography measurement is proposed. Firstly, the white light interferometry scanning stitching measurement device was established. Then, a total of 67 subapertures of the full aperture of the element were measured based on the experimental device. Finally, the profile error of the full aperture was obtained by a microstructural subaperture stitching algorithm. The RMS normal error of the surface profile is 0.3717μm. The measurement results verify the effectiveness of the scanning stitching measurement system and method based on white light interferometer.

Cutting in ductile mode is a prerequisite for mirror machining of single crystal brittle materials. Under the condition that the cutting thickness is less than the critical undeformed chip thickness, the single crystal brittle material is removed in ductile mode. The critical undeformed chip thickness of single crystal brittle materials is not an intrinsic parameter, but a variable related to stress conditions, crystal orientation and other factors. In this paper, aiming at the critical undeformed chip thickness of single crystal germanium, the influence of the changes of crystal orientation, tool rake angle and linear velocity on the critical undeformed chip thickness of single crystal germanium is investigated by means of constant linear velocity single point diamond turning. The experimental results show that critical undeformed chip thickness of single crystal germanium varies in different crystal orientations. Large tool negative rake angle can increase the critical undeformed chip thickness of single crystal germanium. Increasing the linear velocity within a certain range can increase the critical undeformed chip thickness of single crystal germanium, however, excessive linear velocity will worsen the cutting state and reduce the critical undeformed chip thickness. This study provides some references for ductile mode cutting of single crystal germanium and other brittle materials.