Polarization State Of Incident Light Research Articles

Tunable polarization holographic gratings obtained by varying the ratio of intensities of the recording beams

Polarization holography has been extensively applied in many fields, such as optical science, metrology, and biochemistry, due to its property of polarization modulation. However, the modulated polarization state of diffracted light corresponds strictly to that of incident light one by one. Here, a kind of tunable polarization holographic grating has been designed in terms of Jones matrices, and intensity-based polarization manipulation has been realized experimentally. The proposed tunable polarization holographic grating is recorded on an azobenzene liquid-crystalline film by a pair of coherent light beams with orthogonal polarization states and asymmetrically controlled intensities. It is found that the diffracted light can be actively manipulated from linearly to circularly polarized based on the light intensity of the recording holographic field when the polarization state of incident light keeps constant. Our work could enrich the field of light manipulation and holography.

Information encryption driven by strength-switchable circular dichroism in vanadium dioxide based chiral metasurfaces

Switchable polarization selectivity in reconfigurable metasurfaces is highly required in the field of information encryption. In this paper, we proposed a scheme of information encryption by using the giant and strength-switchable circular dichroism (CD) in VO2-based chiral metasurfaces in the mid-infrared region. A bar code information is encrypted and hidden into a VO2-based bielliptic cylinder (BC) and bielliptic cylinder enantiomer (BCE) constructed array. The metallic VO2-based BC and BCE arrays with the rotation angles (α=±14°) exhibit opposite CD (−0.94/0.94) at 6330 nm. With the VO2 transition from metallic to insulator phase, the giant polarization selectivity of both BC and BCE arrays will disappear. Hence, only when the specific environment temperature (>68 °C) and polarization state of incident light (LCP) are simultaneously satisfied, the secret information could be decrypted. The reversible CD in VO2-based chiral metasurfaces possesses great potentials for the application of optical information encryption.

Polarization detection employing the spectra of composite vortex beams with multi-mode: associating the polarization handedness and topological charge sign

Polarization detection has been widely used in various fields, especially in free-space optical communication associating with orbital angular momentum (OAM). However, the bulky optical devices and the complexity of the detection process have hindered the integration and miniaturization of communication systems. Herein, a novel polarization detection method is proposed to directly identify the polarization state of incident light based on the normalized spectra of the sorted OAM modes which are converted from a composite vortex beam (CVB) to a set of spatial distinct strip type beams (STBs). The polarization states of light beam can be apparently distinguished via the combination of different STBs without redundant detection elements and the system demonstrates great robustness under specific atmospheric turbulence as well. The introduction of such a polarization detection method in future communication links will obtain lower complexity and consumption, which is very favorable regarding OAM communications.

Photogating-assisted tunneling boosts the responsivity and speed of heterogeneous WSe2/Ta2NiSe5 photodetectors

Photogating effect is the dominant mechanism of most high-responsivity two-dimensional (2D) material photodetectors. However, the ultrahigh responsivities in those devices are intrinsically at the cost of very slow response speed. In this work, we report a WSe2/Ta2NiSe5 heterostructure detector whose photodetection gain and response speed can be enhanced simultaneously, overcoming the trade-off between responsivity and speed. We reveal that photogating-assisted tunneling synergistically allows photocarrier multiplication and carrier acceleration through tunneling under an electrical field. The photogating effect in our device features low-power consumption (in the order of nW) and shows a dependence on the polarization states of incident light, which can be further tuned by source-drain voltages, allowing for wavelength discrimination with just a two-electrode planar structure. Our findings offer more opportunities for the long-sought next-generation photodetectors with high responsivity, fast speed, polarization detection, and multi-color sensing, simultaneously.

Visualization of Radiation Scattering Indicatrix on a Polydisperse System of Spherical Particles

The article is devoted to solving the direct problem of light scattering on an ensemble of spherical polydisperse particles. The paper presents an algorithm for computer simulation of the optical radiation scattering indicatrix by a particle system based on the theory of G. Mie. The influence of the relative complex refractive index of scattering centers and their size distribution, wavelength and polarization state of incident light on computer models of scattering indicatrix is investigated. The practical significance of the results obtained lies in the fact that computer models of scattering indicatrix are useful in the experimental study of dispersed systems by static light scattering for the optimal choice of installation parameters and experimental conditions and, more importantly, in solving the inverse problem of the static light scattering method to restore the characteristics of nanoparticles from experimental data.

Study on the Polarization Pattern Induced by Wavy Water Surfaces

In nature, the wavy ocean surface is a common polarizer, which can change the polarization state of incident light by refraction and reflection and form a new polarization pattern different from the atmosphere. In this paper, we establish the polarized optical transmission model of wavy ocean surface reflection and refraction and simulate polarization patterns induced by wavy ocean surfaces. We study the polarization patterns reflected by wavy water surfaces and polarization patterns inside and outside Snell’s window under wavy ocean surfaces. The correctness of the simulation results is verified by qualitative and quantitative analysis. The environmental factors affecting the corresponding polarization patterns are discussed. Through contrastive analysis, we find that polarization patterns induced by wavy water surfaces are predictable and regular, which has great potential for human application. This kind of polarization pattern is influenced by the sun’s position and water surface condition. The study will promote the development of remote sensing, target detection, and polarization navigation.

Investigation polarimetric scattering of light from the randomly rough surface based on the calculation of the Mueller matrix.

As the transmission matrix of scattering and incident light, the Mueller matrix reflects the polarimetric scattering characteristics of the rough surface, providing a significant reference for the study of light scattering. Currently, few calculations of the Mueller matrix for a two-dimensional randomly rough surface have been carried out by numerical methods. In this paper, we use six polarization states of incident light and calculate their scattering polarization states numerically by finite-difference time-domain method and obtain the rough surface Mueller matrix by combination. To verify the accuracy of the calculated Mueller matrix, the polarization state of the scattering light obtained by simulation is compared with the predicted result, and the maximum relative error is 0.0635, yielding a good result. In addition, we use this method to obtain the Mueller matrix at different incidence angles and investigate the polarization scattering characteristics. The results show that the derived parameters of the Mueller matrix of different media at different incidence angles have distinct trends. This polarization scattering property obtained from the Mueller matrix can be effectively applied to target recognition, material detection, and other fields.

Multi-functional dual-path self-aligned polarization interference lithography.

Manufacturing sharp features is one of the most desired requirements for lithography. Here, we demonstrate a dual-path self-aligned polarization interference lithography (Dp-SAP IL) for fabricating periodic nanostructures, featuring high-steepness and high-uniformization. Meanwhile, it can manufacture quasicrystals with adjustable rotation symmetry. We reveal the change of the non-orthogonality degree under different polarization states and incident angles. We find that incident light's transverse electric (TE) wave results in high interference contrast at arbitrary incident angles, with a minimum contrast of 0.9328, that is, realizing the self-alignment of the polarization state of incident light and reflected light. We experimentally demonstrate this approach by fabricating a series of diffraction gratings with periods ranging from 238.3 nm to 851.6 nm. The steepness of each grating is greater than 85 degrees. Different from the traditional interference lithography system, Dp-SAP IL realizes a structure color using two mutually perpendicular and non-interference paths. One path is for the photolithography of patterns onto the sample, and the other path is for generating nanostructures on the patterns. Our technique showcases the feasibility of obtaining high contrast interference fringes by simply tuning the polarization, with the potential for cost-effective manufacturing of nanostructures such as quasicrystals and structure color.

Two-dimensional polarization beam splitter based on cylindrical nano grating

In this paper, we report on a two-dimensional (2D) reflective grating with excellent polarization selectivity and high diffraction efficiency (DE). Based on silver cylindrical nano arrays, the grating is calculated by rigorous coupled wave analysis (RCWA). Optimized results show that the energy of transverse electric (TE) polarization is diffracted into (0, ±1) reflection orders and the energy of transverse magnetic (TM) polarization is diffracted into (±1, 0) reflection orders under normal incidence at 780 nm incident wavelength, with extinction ratio (ER) over 30 dB. To the best of our knowledge, this is the first time that a two-dimensional polarization beam splitter (2D-PBS) based on 2D grating is proposed, which opens up a new direction for the development of PBS. The holographic exposure technology, dry etching, and electron beam evaporation were used to fabricate the 2D-PBS. Preliminary experiments indicate that the 2D grating is sensitive to the polarization states of incident light and can be applied in the wide field of optical communication, high precision displacement measurement, and so on.

A Decade of Linear and Circular Polarimetry with the POLISH2 Polarimeter

The POLISH2 optical polarimeter has been in operation at the Lick Observatory 3 m Shane telescope since 2011, and it was commissioned at the Gemini North 8 m in 2016. This instrument primarily targets exoplanets, asteroids, and the Crab Pulsar, but it has also been used for a wide variety of planetary, galactic, and supernova science. POLISH2's photoelastic modulators, employed instead of rotating wave plates or ferroelectric liquid crystal modulators, offer the unprecedented ability to achieve sensitivity and accuracy of order 1 ppm (0.0001%), which are difficult to obtain with conventional polarimeters. Additionally, POLISH2 simultaneously measures the intensity (Stokes I), linear polarization (Stokes Q and U), and circular polarization (Stokes V), which fully describe the polarization state of incident light. We document our laboratory and on-sky calibration methodology and our archival on-sky database, and we demonstrate the conclusive detection of circular polarization of certain objects.

Ultraviolet-Visible Multifunctional Vortex Metaplates by Breaking Conventional Rotational Symmetry.

Metasurfaces have shown remarkable potential to manipulate many of light's intrinsic properties, such as phase, amplitude, and polarization. Recent advancements in nanofabrication technologies and persistent efforts from the research community result in the realization of highly efficient, broadband, and multifunctional metasurfaces. Simultaneous control of these characteristics in a single-layered metasurface will be an apparent technological extension. Here, we demonstrate a broadband multifunctional metasurface platform with the unprecedented ability to independently control the phase profile for two orthogonal polarization states of incident light over dual-wavelength spectra (ultraviolet to visible). In this work, multiple single-layered metasurfaces composed of bandgap-engineered silicon nitride nanoantennas are designed, fabricated, and optically characterized to demonstrate broadband multifunctional light manipulation ability, including structured beam generation and meta-interferometer implementation. We envision the presented metasurface platform opening new avenues for broadband multifunctional applications including ultraviolet-visible spectroscopy, spatially modulated illumination microscopy, optical data storage, and information encoding.

Grayscale Image Display Based on Nano-Polarizer Arrays.

Optical metasurfaces have shown unprecedented capabilities to control the two-dimensional distributions of phase, polarization, and intensity profiles of optical waves. Here, a TiO2 nanostructure functioning as a nano-polarizer was optimized considering that an anisotropic nanostructure is sensitive to the polarization states of incident light. We demonstrate two metasurfaces consisting of nano-polarizer arrays featured with different orientations, which can continuously manipulate the intensity distribution of the output light cell by cell according to Malus law and clearly display the detailed information of the target image. These metasurfaces have potential application in ultracompact displays, high-density optical information storage, and many other related polarization optics fields.

High-order orbital angular momentum mode conversion based on a chiral long period fiber grating inscribed in a ring core fiber.

A chiral long period fiber grating (CLPFG) was designed according to the phase-matching condition and conservation law of angular momentum, and was inscribed in a ring core fiber (RCF). This CLPFG was used to directly excite the ±2nd- and ±3rd-order orbital angular momentum (OAM) modes. The coupling efficiency of the OAM mode is up to 98.7% and the insertion loss is within 0.5 dB. The uniformity of the annular mode intensity distribution, polarization characteristics, and the mode purity of coupled OAM modes were investigated in detail. Results show that the coupled high-order OAM modes possess a relative uniform annular intensity distribution, its mode purity is up to 93.2%, and the helical phase modulation is independent on the polarization state of incident light. These results indicate that the RCF-based CLPFG is an ideal OAM mode converter for future high-capacity optical fiber communication systems.

20.2: 2D/3D Mixed Display Based on Polarization Division Multiplexing

We propose a two‐dimensional (2D)/ three‐dimensional (3D) mixed display system based on polarization division multiplexing. The polarization division multiplexing device is composed of a polarization switching layer, a polarization‐dependent liquid crystal micro‐lens array (LCMLA) and a scattering polarizer. According to the polarization state of incident light switched by the polarization switching layer, the combined action of polarization‐dependent LCMLA and scattering polarizer can form both point light source array for 3D display and scattered light source for 2D display. The 2D/3D mixed images can be reconstructed through the precise control of the polarization direction of each pixel. The advantage of the proposed system is that a point light source array and a surface light source are formed only by adjusting the state of the polarization switching layer. What's more, our proposed system has low driving voltage and relatively compact system volume.

Active Tuning of Plasmon Damping via Light Induced Magnetism.

Circularly polarized optical excitation of plasmonic nanostructures causes coherent circulating motion of their electrons, which in turn gives rise to strong optically induced magnetization, a phenomenon known as the inverse Faraday effect (IFE). In this study we report how the IFE also significantly decreases plasmon damping. By modulating the optical polarization state incident on achiral plasmonic nanostructures from linear to circular, we observe reversible increases of reflectance by up to 8% and simultaneous increases of optical field concentration by 35.7% under 109 W/m2 continuous wave (CW) optical excitation. These signatures of decreased plasmon damping were also monitored in the presence of an external magnetic field (0.2 T). We rationalize the observed decreases in plasmon damping in terms of the Lorentz forces acting on the circulating electron trajectories. Our results outline strategies for actively modulating intrinsic losses in the metal via optomagnetic effects encoded in the polarization state of incident light.

Mueller matrix of laser scattering by a two-dimensional randomly rough surface

It is difficult to accurately identify material of a target surface only by scattering light intensity distribution, and polarization can provide more information. Randomly rough surfaces change the polarization state of incident light. Mueller matrix can describe the change of polarization during the propagation of light. In order to reveal the meaning of Mueller matrix elements, a large number of randomly rough surfaces are generated to simulate targets. Every rough surface is separated into a combination of large numbers of surface elements. Kirchhoff approximation is used to calculate local fields. A numerical integration method is used to calculate Mueller matrix. The effects of roughness, refractive index, and incident angle on Mueller matrix are calculated. Results show that roughness can change intensity distribution of scattered light. Complex refractive index can change polarization state of incident light and make the incident light with 45∘ linear polarization appear circular polarization component. The effect of incident angle on intensity and polarization of scattered light is significant. m34 and m43 are key elements in Mueller matrix to identify material of target. Their influence on Stokes parameters of scattered light is studied. This research can provide a new method for laser detection device to identify target materials.

Full‐Stokes Polarimetry for Visible Light Enabled by an All‐Dielectric Metasurface

Decoding arbitrary polarization information from an optical field has triggered unprecedented endeavors in polarization imaging, remote sensing, and information processing. Therefore, developing a polarization detection device with full on‐chip integration and miniaturization holds tremendous potential for many areas of optical sciences. Herein, a full‐Stokes polarimetry device for visible light based on an all‐dielectric metasurface is proposed. By combining both geometric phase and propagation phase modulation, the metasurface to provide two uncorrelated phase profiles for the two orthogonal states of input polarization is designed, which is then used to spatially separate the various polarization states of incident light. Through the use of a millimeter‐scale multiplexed metasurface array, successful characterization of the full polarization distribution of space‐variant polarization fields is further achieved. This proof‐of‐concept ultracompact and ultrathin metasurface is expected to open new pathways in full‐Stokes polarization detection, machine vision, and navigation.

Depth-enhanced 2D/3D switchable integral imaging display by using n-layer focusing control units

ABSTRACT Depth of field (DOF) is one of the important parameters of three-dimensional (3D) displays. A two-dimensional (2D)/3D switchable display that can display both high-resolution 2D images and vivid 3D images with large DOF is an ideal purpose. In this paper, we propose a depth-enhanced 2D/3D switchable integral imaging display by using n-layer focusing control units (FCUs). Each layer of FCU is composed of a polarization switch and a polarization-dependent liquid crystal micro-lens array (LCMLA). According to the polarization state of incident light switched by the polarization switch, the polarization-dependent LCMLA can realize focusing effect or transmission effect, respectively. Because each layer of FCU has two optional optical effects and has different gap from the display panel, the combination of n-layer FCUs could generate 2 n -1 central depth planes, hence 2 n -1 sub-DOFs can be obtained for depth-enhanced 3D display. The 2D display mode can be easily realized when all layers of FCUs are transmission effect. We experimentally set up a prototype of the proposed 2D/3D switchable display with two-layer FCUs. The experimental results indicated that the proposed prototype can effectively increase the DOF of 3D display and realize 2D/3D switchable display as well.

Conditions for establishing the “generalized Snell’s law of refraction” in all-dielectric metasurfaces: theoretical bases for design of high-efficiency beam deflection metasurfaces

Abstract The generalized Snell’s law dictates that introducing a phase gradient at the interface of two media can shape incident light and achieve anomalous reflection or refraction. However, when the introduced phase gradient is realized via the scattering of nanoparticles in the metasurfaces, this law needs to be modified; certain conditions need to be met when the law is established. We present the conditions for establishing the “generalized Snell’s law of refraction” in all-dielectric metasurfaces under the incidence of different polarized light. These conditions can provide theoretical bases for the subsequent design of high-efficiency beam deflection metasurfaces. The relationship between the highest achievable anomalous refraction efficiency and the number of nanoparticles within one period of the metasurface is also summarized. In addition, the generalized refraction should not depend on the polarization states of incident light; however, the previous realization conditions of anomalous refraction were sensitive to the polarization states. Thus, conditions for establishing the polarization-independent generalized Snell’s law of refraction in all-dielectric metasurfaces are presented.

Polarization information landscapes expanded from single-shot images of ring-like diffraction patterns

In this paper, we propose a ring-type grating in which grating vectors formed by periodic molecular alignments are superimposed radially. Depending on incident polarization states, the anisotropic gratings generate polarization dependencies for the ring-like first order diffraction. To determine the polarization states of incident light for both single and multi-wavelengths, we attempted to extract the optical intensity distribution on the ring-like diffraction from each single-shot diffraction image. In addition, a system that enables the detection of spatial modulation of optical birefringence is proposed. Finally, we concluded that the optical intensity distribution on the circumference of the ring-like diffraction has sufficient potential to be available.