Polarization Of Incident Light Research Articles

Nanostructured Color Filters: A Review of Recent Developments.

Color plays an important role in human life: without it life would be dull and monochromatic. Printing color with distinct characteristics, like hue, brightness and saturation, and high resolution, are the main characteristic of image sensing devices. A flexible design of color filter is also desired for angle insensitivity and independence of direction of polarization of incident light. Furthermore, it is important that the designed filter be compatible with the image sensing devices in terms of technology and size. Therefore, color filter requires special care in its design, operation and integration. In this paper, we present a comprehensive review of nanostructured color filter designs described to date and evaluate them in terms of their performance.

Raman spectroscopy study of manganese oxides: Tunnel structures

Abstract Raman spectra were collected for an extensive set of well-characterized tunnel-structure Mn oxide mineral species employing a range of data collection conditions. Using various laser wavelengths, such as 785, 633, and 532 nm at low power levels (30–500 µW), as well as the comprehensive database of standard spectra presented here, it is generally possible to distinguish and identify the various tunnel structure Mn oxide minerals. The Raman mode relative intensities can vary significantly as a function of crystal orientation relative to the incident laser light polarization direction as well as laser light wavelength. Consequently, phase identification success is enhanced when using a standards database that includes multiple spectra collected for different crystal orientations and with different laser light wavelengths. For the hollandite-group minerals, the frequency of the Raman mode near 630 cm–1 shows a strong linear correlation with the fraction of Mn3+ in the octahedral Mn sites. With the comprehensive Raman database of well-characterized Mn oxide standards provided here (and available online as Supplemental Materials1), and use of appropriate data collection conditions, micro-Raman is a powerful tool for identification and characterization of biotic and abiotic Mn oxide phases from diverse natural settings, including on other planets.

Selective excitation of localized surface plasmons by structured light.

We investigated the selective excitation of localized surface plasmons by structured light. We derive selection rules using group theory and propose a fitting integral to quantify the contribution of the eigenmodes to the absorption spectra. Based on the result we investigate three nano oligomers of different symmetry (trimer, quadrumer, and hexamer) in detail using finite-difference time-domain simulations. We show that by controlling the incident light polarization and phase pattern we are able to control the absorption and scattering spectra. Additionally, we demonstrate that the fitting between the incident light and the oligomer modes may favor a number of modes to oscillate. Dark modes produce strong changes in the absorption spectrum and bright modes in the scattering spectrum. The experimental precision (axial shift error) may be on the same order as the oligomer diameter making the orbital angular momentum selection rules robust enough for experimental observation.

All‐Optical Polarization‐Controlled Nanosensor Switch Based on Guided‐Wave Surface Plasmon Resonance via Molecular Overtone Excitations in the Near‐Infrared

AbstractSemiconductor transistors for sensors are considered the most widely manufactured device in history. Being invented to switch electronic signals they revolutionized electronics and paved the way for smaller and cheaper sensors, radios, calculators, and computers. However, electric switches are hampered by damage from very brief electrical and thermal effects or electromagnetic interference. For this reason, modern communication systems devote considerable attention to all‐optical switches, yet, the state‐of‐the‐art switching of photonic signals is fulfilled electronically. All‐optical switching allows light‐controls‐light through unique optical effects. Here, an all‐optical sensor switch, engineered to operate at telecommunication wavelengths, caused by the excitation of molecular overtones in a hybrid plasmonic–dielectric configuration is demonstrated. This configuration possesses a unique property: to control the sensor switch with the polarization state of light for two different plasmonic modes to co‐exist while exciting a single overtone. Control of the sensor switch is realized by tuning the polarization of incident light from transverse magnetic (switch‐on) to transverse electric (switch‐off). This switch provides a miniature, affordable, and fast chip‐scale polarization‐activated sensor device for a wide range of applications from optics communication to all‐optical computing and sensing.

Goos–Hanchen shift in a metasurface of core–shell nanoparticles

Metasurfaces are periodic subwavelength structures that have found applications in functional devices such as image sensors, cameras, and microscopes. They are able to modulate the amplitude, phase, and polarization of incident light. Reflected light from a surface exhibits a deviation from the rules governed by geometric optics and displaces in directions parallel and perpendicular to plane of incidence. The sharp phase changes at reflection from a metasurface would be useful in enhancing the longitudinal reflection shifts, known as Goos–Hanchen​ (GH) shift. In this article, using generalized sheet transition conditions, we study GH shift in a metasurface composed of spherical metal-oxide core with plasmonic shell nanoparticles in a square array. A detailed analysis reveals that reflection shifts of this type of nanostructures can be tuned delicately by varying the size, core-to-shell ratio and periodicity of particles as well as light wavelength and angle of radiation. Large reflection shifts are achievable in both visible and ultraviolet ranges due to plasmonic resonance of metallic shell. Such sensitivity could be useful in very sensitive beam deflection measurements like in AFM or in reflective UV sensors.

The measurement and modeling investigation on the spectral polarized BRDF of brass

Bidirectional reflectance distribution function (BRDF) offers complete description of the visual appearance properties of materials including the spectral and spatial characteristics. Numerous studies on BRDF have been performed for its important role in computer graphics, remote sensing, object characteristics analysis, and other fields. A few of these studies focus on the spectral polarized BRDF, which contains more optical information of materials than the unpolarized BRDF and the polarized BRDF at single wavelength. In this paper, the spectral polarized BRDF measurement of brass is studied based on a self-designed device in visible light band. The influences of wavelength, angle, polarization of incident, and reflected light on the BRDF are discussed in detail. The results indicate that the effect of wavelength on BRDF depends on the color of the sample. The polarization of incident light has little influence on the variation tendency of BRDF versus incident zenith angle and wavelength. In addition, the exponential model of BRDF is built according to material surface characteristics. The fitting results show that the calculated values are in good agreement with the measured values at different incident zenith angles. This work may be beneficial to the study of optical properties and process design of brass.

Advanced encryption method realized by secret shared phase encoding scheme using a multi-wavelength metasurface

Abstract Multi-channel information encryption technology has been implemented by optical metasurfaces owing to their superior ability to control the phase, amplitude, wavelength and polarization of incident light. However, current metasurface-based multi-channel encryption technologies suffer from information leakage in non-full channel decoding processes. To better increase the security of the encrypted information, we develop a secret shared phase encoding scheme by combining a visual secret sharing scheme with a metasurface-based phase-encoding technique. Our method achieves its high-concealment through mapping the target image into a set of unrecognizable phase-only keys that are subsequently encoded by a multi-wavelength metasurface. In the decryption process, the secret information can be reconstructed only by decoding and stacking all the wavelength channels of the metasurface. At the same time, chaotic images can be extracted from the other channels without revealing any original information. The simulated results and the theoretical analysis show the strong robustness and high security of our encryption setup, which is sure to find applications in emerging optical encryption schemes.

Modulation instability in waveguides doped with anisotropic nanoparticles

We exploit the anisotropic plasmonic behavior of gold nanorods (AuNRs) to obtain a waveguide with a nonlinear coefficient dependent on both the frequency and polarization of incident light. The optical properties of the waveguide are described by an extension of the Maxwell Garnett model to nonlinear optics and anisotropic nanoparticles. Then, we perform a study of modulation instability (MI) in this system by resorting to the recently introduced photon-conserving nonlinear Schrödinger equation (pcNLSE), as the pcNLSE allows us to model propagation in nonlinear waveguides of arbitrary sign and frequency dependence of the nonlinear coefficient. Results show that the anisotropy of the nanorods leads to two well-differentiated MI regimes, a feature that may find applications in all-optical devices.

Achieving the polarization-manipulated multispectral perfect absorption and sensitive sensing via a metal/insulator/metal elliptical nanocavity array

We present a polarization-manipulated multispectral perfect absorber based on a 2D metal/insulator/metal nanocavity array, in which a periodic structure of stacked Au–Al2O3 elliptical nanodisk is deposited on a bulk flat Au substrate. Theoretical analysis of the electromagnetic property showed that both the dipolar plasmon resonance and the plasmon cavity mode are the physical origins of the near-perfect absorption. Owing to the azimuthally symmetry breaking, the reflectivity difference can reach up to 90% through an orthogonal rotation of the incident light polarization. In addition, the central wavelength of these absorption bands is highly sensitive to variation of the surrounding liquid sample’s refractive index. This proposed sub-wavelength plasmonic platform with both features of the polarized manipulation and the sensitive sensing may provide promising applications in multi-wavelength filtering and bio-sensing.

Origin of the Kerr effect: investigation of solutions by polarization-dependent Z-scan

The nonlinear refractive index dependence on the incident light polarization state has been studied for pure chloroform and chloroform solutions of aminobenziliden-1,3-indandione derivatives. Measurements were done with linearly, elliptically, and circularly polarized light using 8 ns and 30 ps pulse duration 1064 nm lasers. This allows us to separate the electronic response, molecular reorientation, and thermo-optical components of the nonlinear refractive index. The refractive index variations with the change of laser pulse repetition rate were employed to identify the presence of the thermo-optical effect. Quantum chemical calculations of linear polarizability were used to estimate the magnitude of molecular-reorientation-induced refractive index changes for solvents and solutions. Overall, in this paper we have outlined various essential aspects that need to be taken into account to correctly interpret Z-scan measurement results for organic solvents and solutions.

Optical intersubband properties of a core–shell semiconductor–topological insulator quantum dot described by θ-electrodynamics

The optical properties of a spherical topological insulator embedded concentrically in a single-electron system consisting of a core-shell GaAs quantum dot are analyzed, when the system is under a uniform external magnetic field. The topological insulator's magnetoelectric response is computed in the effective framework of $\theta$-electrodynamics, which allows analytical calculations for the induced electric and magnetic potentials by Green's Function method. The GaAs Hamiltonian is constructed in the effective-mass approximation, and its corresponding Schr\"odinger equation is numerically solved through the Lagrange-mesh method. We compute the total absorption coefficients and refractive index changes given by the non-linear iterative density matrix formalism up to third order. Our results show that the presence of the magnetoelectric material causes new dipolar transitions otherwise not allowed. Also, an enhancement of the photon absorption is found when the incident light polarization is oriented parallel to the external magnetic field, in comparison with perpendicular polarization. Moreover, we report an appreciable blue shift in the optical functions when the values of the $\theta$-parameter are increased. These results can be useful for indirect experimental measures of the magnetoelectric polarizability which is proportional to the QED fine-structure constant $\alpha$.

Motion-picture recording of ultrafast behavior of polarized light incident at Brewster\u2019s angle

Observing light propagation plays an important role in clarifying ultrafast phenomena occurring on femtosecond to picosecond time scales. In particular, observing the ultrafast behavior of polarized light is useful for various fields. We have developed a technique based on Polarization Light-in-Flight Holography, which can record light propagation as a motion picture that can provide information about the polarization direction. Here we demonstrate motion-picture recording of a phenomenon, which is characteristic of polarized light, by using the proposed technique. As a phenomenon, we adopted the behavior of a light pulse incident at Brewster’s angle. We succeeded in recording the light reflection of specific polarized light by the proposed optical setup. The method of recording the motion-picture, reconstruction procedure, and the quantitative evaluation of the results are demonstrated.

Broadband infrared circular dichroism in chiral metasurface absorbers

Chirality is ubiquitous in nature and it is essential in many fields, but natural materials possess weak and narrow-band chiroptical effects. Here, chiral plasmonic metasurface absorbers are designed and demonstrated to achieve large broadband infrared circular dichroism (CD). The broadband chiral absorber is made of multiple double-rectangle resonators with different sizes, showing strong absorption of left-handed or right-handed circularly polarized (LCP or RCP) light above 0.7 and large CD in absorption more than 0.5 covering the wavelength range from 1.35 µm to 1.85 µm. High broadband polarization-dependent local temperature increase is also obtained. The switchable infrared reflective chiral images are further presented by changing the wavelength and polarization of incident light. The broadband chiral metasurface absorbers promise future applications in many areas such as polarization detection, thermophotovoltaics, and chiral imaging.

Neural Network Reflectance Prediction Model for Both Open Ocean and Coastal Waters

Remote sensing of global ocean color is a valuable tool for understanding the ecology and biogeochemistry of the worlds oceans, and provides critical input to our knowledge of the global carbon cycle and the impacts of climate change. Ocean polarized reflectance contains information about the constituents of the upper ocean euphotic zone, such as colored dissolved organic matter (CDOM), sediments, phytoplankton, and pollutants. In order to retrieve the information on these constituents, remote sensing algorithms typically rely on radiative transfer models to interpret water color or remote-sensing reflectance; however, this can be resource-prohibitive for operational use due to the extensive CPU time involved in radiative transfer solutions. In this work, we report a fast model based on machine learning techniques, called Neural Network Reflectance Prediction Model (NNRPM), which can be used to predict ocean bidirectional polarized reflectance given inherent optical properties of ocean waters. This supervised model is trained using a large volume of data derived from radiative transfer simulations for coupled atmosphere and ocean systems using the successive order of scattering technique (SOS-CAOS). The performance of the model is validated against another large independent test dataset generated from SOS-CAOS. The model is able to predict both polarized and unpolarized reflectances with an absolute error (AE) less than 0.004 for 99% of test cases. We have also shown that the degree of linear polarization (DoLP) for unpolarized incident light can be predicted with an AE less than 0.002 for 99% of test cases. In general, the simulation time of SOS-CAOS depends on optical depth, and required accuracy. When comparing the average speeds of the NNRPM against the SOS-CAOS model for the same parameters, we see that the NNRPM is able to predict the Ocean BRDF 6000 times faster than SOS-CAOS. Both ultraviolet and visible wavelengths are included in the model to help differentiate between dissolved organic material and chlorophyll in the study of the open ocean and the coastal zone. The incorporation of this model into the retrieval algorithm will make the retrieval process more efficient, and thus applicable for operational use with global satellite observations.

Tunable Graphene Split-Ring Resonators

A split-ring resonator is a prototype of meta-atom in metamaterials. Though noble metal-based split-ring resonators have been extensively studied, up to date, there is no experimental demonstration of split-ring resonators made from graphene, an emerging intriguing plasmonic material. Here, we experimentally demonstrate graphene split-ring resonators with deep subwavelength (about one hundredth of the excitation wavelength) magnetic dipole response in the terahertz regime. Meanwhile, the quadrupole and electric dipole are observed,depending on the incident light polarization. All modes can be tuned via chemical doping or stacking multiple graphene layers. The strong interaction with surface polar phonons of the SiO2 substrate also significantly modifies the response. Finite-element frequency domain simulations nicely reproduce experimental results. Our study moves one stride forward toward the multi-functional graphene metamaterials, beyond simple graphene ribbon or disk arrays with electrical dipole resonances only.

Quantum theory of polarimetry: From quantum operations to Mueller matrices

Quantum descriptions of polarization show the rich degrees of freedom underlying classical light. While changes in polarization of light are well-described classically, a full quantum description of polarimetry, which characterizes substances by their effects on incident light's polarization, is lacking. We provide sets of quantum channels that underlie classical polarimetry and thus correspond to arbitrary Mueller matrices. This allows us to inspect how the quantum properties of light change in a classical polarimetry experiment, and to investigate the extra flexibility that quantum states have during such transformations. Moreover, our quantum channels imply a new method for discriminating between depolarizing and nondepolarizing Mueller matrices, which has been the subject of much research. This theory can now be taken advantage of to improve estimation strategies in classical polarimetry and to further explore the boundaries between classical and quantum polarization.

A comparative theoretical investigation of optoelectronic and mechanical properties of KYS2 and KLaS2

The ternary sulfides KYS2 and KLaS2 are two promising candidates for numerous applications, as much as white LED, X-ray phosphor and transparent conductor materials. However, theoretical studies on these materials are lacking, and many of their physical properties are still unknown. The aim of this work is to investigate the physical properties of the ternary sulfides KYS2 and KLaS2 namely, structural, elastic, optoelectronic, thermodynamic analysis, and set the substitution effect of Y and La elements in the two compounds. The fundamental properties calculations are based on ab-initio pseudopotential framework, with both local density approximation (LDA) and generalized gradient approximations (GGA) along with an expanded set of plane waves. The Becke, 3-parameter, Lee–Yang–Parr (B3LYP) hybrid functional is also employed to describe the electronic structures and optical properties. The optimized crystal parameters are correlated very well with the existing experimental data. The predicted values of the elastic constants demonstrate that the two compounds are mechanically stable and can be classified as brittle materials. The band structure analysis reveals that both KYS2 and KLaS2 have indirect band gap. The optical properties, like the refractive index, extinction, absorption and reflectivity coefficients, are determined for various polarizations of incident light, while both compounds present optical anisotropy. The obtained optical properties indicate the high transparency of KYS2 and KLaS2 in the infrared and visible regions, which makes them promising candidates for many of transparent applications. The thermodynamic properties are investigated with the help of quasiharmonic Debye model approximation. KYS2 has a larger bulk modulus value, which make it more beneficial in engineering applications. Calculations of thermodynamical properties indicate that KYS2 compound has better thermal conductivity, stronger chemical bonds and bigger hardness.

Isosbestic light absorption by metallic dimers: effect of interparticle electromagnetic coupling.

Isosbestic plasmonic nanostructures, which feature an invariance of optical absorption and heat generation upon varying the incident light polarization, have broad application in many fields such as nanochemistry, optical nanoantennas, and microbubble formation. In this study, we focus on the isosbestic optical absorption by metallic dimers and systematically investigate the coupling between two interacting particles by using both the superposition T-matrix method and dipole approximation model. We observe that the interparticle coupling effects on particle absorption can be both positive and negative, compared to an isolated particle. Meanwhile, the optical absorption properties of spheres with small size parameters can realize more flexible control through changing the sphere size, interparticle distance, and incident light wavelength. For illuminations with incident light propagating perpendicularly to the line joining the centers of the two spheres, isosbestic conditions will be satisfied as long as the absorption efficiencies for transverse and longitudinal illuminations are equal. For transverse illuminations along the dimer axis, the ratio of absorption efficiency of the two metallic spheres presents the fluctuation change with the interparticle distance. Owing to the strong interparticle coupling effects, it even leads to the absorption efficiency of the far sphere being higher than that of the near sphere. Our results are aimed at expanding our understanding of the interparticle electromagnetic coupling effects on isosbestic light absorption in plasmonic nanoparticle systems.

Polarization and direction-controlled asymmetric multifunctional metadevice for focusing, vortex and Bessel beam generation.

Integrating multiple independent functionalities into one single photonic device has been an important part in optoelectronic system. In this paper, we here propose a kind of asymmetric multifunctional metadevice operating at 1550 nm (in optical communication band), which can manipulate the light with four different functions, depending on the polarization and illumination direction of incident light. As a proof of our concept, we design this metadevice composed of the upper metasurface layer, middle grating layer and lower metasurface layer. For x-polarized incident light, the metadevice under forward illumination works as transmissive focusing lens and vortex beam generator of y-polarized light, while under backward illumination it acts as a reflective vortex beam generator. In contrast, for y-polarized incident light, the metadevice under forward illumination behaves as a reflective Bessel beam generator, while a combination of transmissive vortex beam generator and focusing lens of x-polarized light under backward illumination. Our findings may motivate the realization of high-performance multifunctional metadevices and extend the application in complex integrated optical system.

Multi-resonance and ultra-wideband terahertz metasurface absorber based on micro-template-assisted self-assembly method.

As a promising platform for multi-functional terahertz devices, metasurface absorbers have received widespread attention in recent years. However, due to the existence of manufacturing difficulties, high cost, fragility, single or narrow absorption and other disadvantages, their application ranges are severely limited. Therefore, to effectively solve these problems, we have designed a flexible and high-precision terahertz metasurface absorber based on the micro-template assisted self-assembly method. Free from high cost, complicated process and time-consumption, the sandwich structure terahertz metasurface absorber consisting of a ceramic microspheres layer, a dielectric spacer layer, and a metal copper film is fabricated economically. On the one hand, through assembling the microspheres on the dielectric spacer in a periodic pattern arrangement, multiple resonances can be observed with a maximum absorption rate of up to 92.5% at 0.745 THz and are insensitive to the polarization of incident light. On the other hand, by attaching the microspheres to the dielectric layer in a compact configuration, 90% absorption bandwidth beyond 1.2 THz can be observed with a central frequency of 1.8 THz. The theoretical model of multiple reflection and interference is employed to explain these absorption characteristics. Considering the flexible design and high-throughput manufacturing processes, this work provides a promising platform for the development of high-efficiency and multi-functional terahertz devices.