Polarization Selection Research Articles

Selection Rules of Linear and Nonlinear Polarization-Selective Absorption in Optically Dressed Matter

Dynamical symmetries of laser-dressed matter determine the selection rules that influence its absorption spectrum. We explore selection rules for polarization-sensitive absorption in Floquet matter, using Floquet group theory in synthetic dimensions. We present comprehensive tables of selection rules that polarization-structured light impose on Floquet dark states and Floquet dark bands. Notably, our tables encompass nonlinear absorption for all nonlinear orders, revealing that different nonlinear orders follow distinct polarization selection rules, potentially leading to polarization-tunable optical filters.

Highly sustainable water mist-responsive superwetting sponge (DTMO/FS-50/Hollow-CuCo-ZIF@Sponge) for speedy pollutants removal and solvent-free regeneration

Smart solvent-responsive superwetting materials are particularly favored due to their ability to handle different types of pollutants. However, most of them rely on organic solvent vapors, and neglect the desorption efficiency of pollutants, especially using the solvent-free desorption method. A responsive sponge was fabricated by coating hollow MOFs particles with different sizes, greatly enhancing roughness and porosity, and followed by modification with short-chain fluorinated surfactants, long-chain siloxanes, tannic acid, and polydopamine. There are several advantages in this paper: (I) a hollow MOFs structure was achieved, greatly enhancing specific surface area, porosity, and active sites, which acted as a superior container for responsive modifiers network. (II) the reactions among biomass dopamine hydrochloride (PDA), tannic acid (TA), long-chain siloxanes, short-chain fluorinated surfactants and PU substrate, formed smart responsive biomass macromolecular networks, not only greatly improved adhesion between hollow MOFs and sponge substrate, but also showed enhanced synergistic effects for smart wettability transition. (III) the coated sponge showed smart responsive superwetting behaviors under environmentally friendly water mist rather than organic vapors or unfriendly vapors. (IV) the coated sponge could handle various kinds of pollutants based on polarity selection, and also quickly desorb the pollutants after change the polarity under water mist activation. The intelligent sponge can quickly and selectively adsorbed various microplastics and efficiently deal with oil-in-water and oil-in-water emulsions. It has good mechanical durability, maintaining a separation capacity of more than 88 % after repeated adsorption and desorption of MPs180 times.

Harnessing complexity: Nonlinear optical phenomena in L-shapes, nanocrescents, and split-ring resonators.

We conduct systematic studies of the optical characteristics of plasmonic nanoparticles that exhibit C2v symmetry. In particular, we analyze three distinct geometric configurations: an L-type shape, a crescent, and a split-ring resonator shaped like the Greek letter π. Optical properties are examined using the finite-difference time-domain method. It is demonstrated that all three shapes exhibit two prominent plasmon modes associated with the two axes of symmetry. This is in addition to a wide range of resonances observed at high frequencies corresponding to quadrupole modes and peaks due to sharp corners. Next, to facilitate nonlinear analysis, we employ a semiclassical hydrodynamic model, where the electron pressure term is explicitly accounted for. This model goes beyond the standard Drude description and enables capturing nonlocal and nonlinear effects. Employing this model enables us to rigorously examine the second-order angular resolved nonlinear optical response of these nanoparticles in each of the three configurations. Two pumping regimes are considered, namely, continuous wave (CW) and pulsed excitations. For CW pumping, we explore the properties of the second harmonic generation (SHG). Polarization and angle-resolved SHG spectra are obtained, revealing strong dependence on the nanoparticle geometry and incident wave polarization. The C2v symmetry is shown to play a key role in determining the polarization states and selection rules of the SHG signal. For pulsed excitations, we discuss the phenomenon of broadband terahertz (THz) generation induced by the difference-frequency generation . It is shown that the THz emission spectra exhibit unique features attributed to the plasmonic resonances and symmetry of the nanoparticles. The polarization of the generated THz waves is also examined, revealing interesting patterns tied to the nanoparticle geometry. To gain deeper insight, we propose an analytical theory that agrees very well with the numerical experiments. The theory shows that the physical origin of the THz radiation is the mixing of various frequency components of the fundamental pulse by the second-order nonlinear susceptibility. An expression for the far-field THz intensity is derived in terms of the incident pulse parameters and the nonlinear response tensor of the nanoparticle. The results presented in this work offer new insights into the linear and nonlinear optical properties of nanoparticles with C2v symmetry. The demonstrated strong SHG response and efficient broadband THz generation hold great promise for applications in nonlinear spectroscopy, nanophotonics, and optoelectronics. The proposed theoretical framework also provides a valuable tool for understanding and predicting the nonlinear behavior of other related nanostructures.

Sub-picosecond, strain-tunable, polarization-selective optical switching via anisotropic exciton dynamics in quasi-1D ZrSe3

In cutting-edge optical technologies, polarization is a key for encoding and transmitting vast information, highlighting the importance of selectively switching and modulating polarized light. Recently, anisotropic two-dimensional materials have emerged for ultrafast switching of polarization-multiplexed optical signals, but face challenges with low polarization ratios and limited spectral ranges. Here, we apply strain to quasi-one-dimensional layered ZrSe3 to enhance polarization selectivity and tune operational energies in ultrafast all-optical switching. Initially, transient absorption on unstrained ZrSe3 reveals a sub-picosecond switching response in polarization along a specific crystal axis, attributed to shifting-recovery dynamics of an anisotropic exciton. However, its polarization selectivity is weakened by a slow non-excitonic response in the perpendicular polarization. To overcome this limitation, we apply strain to ZrSe3 by bending its flexible substrate. The compressive strain spectrally decouples the excitonic and non-excitonic components, doubling the polarization selectivity of the sub-picosecond switching and tripling it compared to that in the tensile-strained ZrSe3. It also effectively tunes the switching energy at a shift rate of ~93 meV %-1. This strain-tunable switching is repeatable, reversible, and robustly maintains the sub-picosecond operation. First-principles calculations reveal that the strain control is enabled by momentum- and band-dependent modulations of the electronic band structure, causing opposite shifts in the excitonic and non-excitonic transitions. Our findings offer a novel approach for high-performance, wavelength-tunable, polarization-selective ultrafast optical switching.

Polarization-Controlled Exciton-Polaritons in WS2 Strongly Coupled with Low-Symmetry Photonic Crystal Nanostructures.

Atomically thin transition metal dichalcogenides (TMDs) with ambient stable exciton resonances have emerged as an ideal material platform for exciton-polaritons. In particular, the strong coupling between excitons in TMDs and optical resonances in anisotropic photonic nanostructures can form exciton-polaritons with polarization selectivity, which offers a new degree of freedom for the manipulation of the light-matter interaction. In this work, we present the experimental demonstration of polarization-controlled exciton-polaritons in tungsten disulfide (WS2) strongly coupled with polarization singularities in the momentum space of low-symmetry photonic crystal (PhC) nanostructures. The utilization of polarization singularities can not only effectively modulate the polarization states of exciton-polaritons in the momentum space but also facilitate or suppress their far field coupling capabilities by tuning the in-plane momentum. Our results provide new strategies for creating polarization-selective exciton-polaritons.

Broadband Polarization Rotating Frequency Selective Surface With Polarization Selection

Broadband Polarization Rotating Frequency Selective Surface With Polarization Selection

Moving Real-Target Imaging of a Beam-Broaden ISAL Based on Orthogonal Polarization Receiver and Along-Track Interferometry

In response to the application requirement of wide-range high-resolution imaging of non-cooperative moving real targets by inverse synthetic-aperture ladar (ISAL), experiments were conducted on the depolarization effect of target materials, and the polarization selection of ISAL receiving and transmitting channels was discussed. Considering the impact of target depolarization and the demand for along-track interferometry, combined with beam-broaden and high-gain amplifiers, an ISAL system design method that can stably image multiple non-cooperative real targets has been proposed. Under the condition of broadening the transmitting and receiving beams to 3° in the elevation direction for non-cooperative moving vehicles, echo data with a duration of 1 s is obtained. The spatial correlation algorithm combined with along-track interferometry is used to estimate the vibration phase error. The sub-aperture Range-Doppler algorithm is used for imaging. The ISAL imaging results of the moving vehicle validated the high-resolution imaging ability of ISAL and its potential for stable imaging of non-cooperative moving real targets.

Dynamically Tunable Circularly Polarized Selectivity in Plasmon-Enhanced Halide Perovskite Nanocrystal Glasses.

Ultrafast spin manipulation for optical spin-logic applications requires material systems with strong spin-selective light-matter interactions. The optical Stark effect can realize spin-selective light-matter interactions by breaking the degeneracy of spin-selective transitions with an external electric field. Halide perovskites have large exciton binding energies, which enable a room-temperature optical Stark effect. However, halide perovskites are prone to degradation when interacting with light and polar solvents, limiting further integration with nanophotonic structures. We demonstrate a hybrid material system consisting of CsPbBr3 nanocrystal glass weakly coupled to resonant plasmonic silver nanoparticles, showing ultrafast tunable spin-based polarization selectivity at room temperature. We performed circularly polarized pump-probe characterizations to investigate the optical Stark effect in this material system, which resulted in a maximum energy shift of ∼3.67 meV (detuning energy of 0.11 eV and pump intensity of 0.62 GW/cm2). We show that halide perovskite nanocrystal glasses have excellent resistance to heat and moisture, which may be favorable for integration with nanophotonic structures for further engineering polarization states, energy tuning, and coherence time.

Observation of polarity changes in Sjogren's syndrome mice using a targeting lysosomes and ratiometric fluorescent probe

Utilizing non-invasive, real-time dynamic imaging and high-resolution detection tools to track polarity changes in Sjögren's syndrome (SS) contributes to a better understanding of the disease progression. Herein, a ratiometric polarity-sensitive fluorescent probe (DIM) was designed and synthesized, DIM consisted of dicyanoisophorone as the fluorophore and morpholine moiety as lysosome targeting. DIM showed a ratiometric response to polarity and high selectivity (unaffected by viscosity, pH, ROS, RNS, etc.), offering a more accurate analysis of intracellular polarity through a built-in internal reference calibration. The polarity abnormality of submandibular glands in non-obese diabetic (NOD) mice was revealed and verified by in vivo ratiometric fluorescence imaging of DIM, suggesting that fluorescent probe have great potential in the diagnosis of salivary gland abnormalities.

Terahertz bandpass and bandstop filter based on the babinet complementary metamaterials

In this study, we experimentally investigate the terahertz (THz) bandpass and bandstop filters based on the elliptical Babinet complementary structure, including an elliptical hole structure (EHS) and an elliptical ring structure (ERS). The experimental results indicate that the monolayer structure exhibits an obvious polarization selectivity with consistent filtering curves under TE and TM mode excitation, but the spectral line has an apparent shift of 0.1 THz. Based on Babinet's principle, the filtering mode matching is experimentally verified between bandpass and bandstop under a 90° change in polarization. Furthermore, we propose a double-layer filter by integrating EHS and ERS on both sides of the silicon substrate, and realize the bandpass and bandstop filtering simultaneously. The simulation results show that the isolation degree of bandpass and bandstop filtering has a maximum of nearly 40 dB based on the angle-tunable filtering performance, and the Q-value of the filter is further improved than that of the single-layer structure. The filter designed based on the Babinet principle has the advantages of simple structure, easy processing, and sharper filtering effect, and shows great applications in THz communication, imaging, and sensing systems.

Electrically reflectance-tunable circular polarization reflector based on thin polymer-stabilized cholesteric liquid crystals

This paper presents a reflectance-tunable circular polarization reflector that utilizes thin polymer-stabilized cholesteric nematic liquid crystals (PSCLCs) with negative anisotropy. The switching mechanism involves direct-current (DC) field-induced movement in the polymer network, which generates the mechanical force that causes a pitch-gradient helical structure and thus a distorted Bragg reflection. The pitch-gradient helical structure of the 5 μm-thick cells only allows for a limited number of pitch lengths, resulting in a decrease in reflectance at the designed Bragg reflectance and a reflectance tunable range determined by applying DC voltages. The PSCLCs reflecting red, green, and blue colors were measured for their reflectance tuning ability and circular polarization selectivity. A tunable polarization volume grating was fabricated using a PSCLC cell, and the ability of the grating to diffract light intensity was demonstrated.

High-efficiency polarization-selective two-dimensional diffraction gratings based on silver cuboid arrays

A two-dimensional (2D) diffraction grating based on silver cuboid arrays is demonstrated. With the structural optimization by three-dimensional (3D) finite-difference time-domain method, the proposed grating exhibits favorable polarization selectivity. At wavelength 1550 nm, high diffraction efficiency and polarization correlation can be realized in the case of two-port output ((0, ±1) or (±1, 0)) under TE polarization, as well as five-port output ((0, 0), (0, ±1) and (±1, 0)) under TM polarization. Under the two-port output state, the diffraction efficiency is nearly 48% with the extinction ratio of 16.44 dB and insertion loss of 0.20 dB. Under the five-port output status, the efficiency is larger than 19% for each diffraction order, meanwhile, the total efficiency and uniformity are 97% and 0.58%, respectively. The proposed grating with positive implications has good potentials in polarization multiplexing and polarization-correlated grating interferometry.

Palm vein imaging using a polarization-selective metalens with wide field-of-view and extended depth-of-field

Metalens is a flat, lightweight optical element that may replace traditional bulky refractive lenses and other components in imaging systems. However, a number of critical challenges still remain for most metalenses demonstrated to date, including limited field-of-view (FOV), depth-of-field (DOF), and working bandwidth, which restrict their use in a real-world application. Here, we propose and experimentally demonstrate a compact imaging system equipped with a metalens that simultaneously features a wide FOV of 140° and an extended DOF ranging from 33 to 150 mm. The metalens further allows polarization selectivity, which can be used to remove unwanted surface reflection of the target scene. Using a narrowband vertical-cavity surface-emitting laser for illumination, we show that the system is well-suited for near-infrared palm vein imaging, an emerging modality for biometric identification. The metalens-integrated imaging system provides uncompromised performance with a greatly simplified form factor compared to a traditional system, which may also be adopted for other applications such as depth sensing and endoscopy.

Electrically engineering synthetic magnetic fields for polarized photons

Polarized photons are, in essence, neutral particles and therefore do not couple directly to external fields, thus hampering the effective interaction of photons with external fields. Here, we theoretically identify an equivalent spin-1/2 model for polarized photons and synthesize a magnetization vector for coupling differently polarized photons in an engineered anisotropic medium. The synthetic magnetic field can be electrically engineered to manipulate the magnetic moments of the pseudo-spin-1/2 photons, leading to observation of the Lorentz force and analogous Stern–Gerlach effect. We experimentally demonstrate these fundamental effects by using different spins, including purely single-polarization spins and mutually two-polarization mixing spins. We also demonstrate the higher-order Stern–Gerlach effect by using spins having nontrivial topological structures. Our findings could enable polarization-based elements with potential applications in polarization selection and conversion, benefiting classical and quantum information processing.

Optically controllable deformation and phase change in VO2/Si3N4/Au hybrid nanostructures with polarization selectivity

Optically spatial displacement and material modification hold great potential for the appealing applications in nanofabrication and reconfiguration of functional optical devices. Here, we propose and demonstrate a scheme to achieve simultaneous deformation and phase change in vanadium dioxide (VO2)/Si3N4/Au hybrid nanostructures by laser stimuli. Low triggering threshold and significant deformation characteristics of VO2, based on controllable phase transition, are demonstrated in microscale cantilevers. The plasmonic properties of the nanostructure array are further utilized to achieve a polarization-selective dynamic response. The persistence of deformation and dynamical optical modulation are further demonstrated. Such high-precision fabrication methods and non-contact reconfiguration methods are useful for future applications in dynamic optical manipulation.

Polarizing beam splitter for vacuum ultraviolet to x-ray radiation.

We present a v-groove grating functioning as a polarizing beam splitter. The grating works in the off-plane or conical diffraction geometry. In order to guarantee polarization selectivity and efficiency, the v-groove is designed to split the incoming radiation with a single reflection at the Brewster angle of the grating coating. This geometry is conceptually the same as the one reported by Caretta etal. [Struct. Dyn. 8, 034304 (2021)], but it reduces the noise on the splitting ratio introduced by beam-shape variations or beam displacements. We calculate the groove size to simultaneously perform polarization and spectral analysis.

Cross polarization stability in multidimensional NMR spectroscopy of biological solids

Magic-angle spinning (MAS) solid-state nuclear magnetic resonance (SSNMR) spectroscopy is a powerful and versatile technique for probing structure and dynamics in large, insoluble biological systems at atomic resolution. With many recent advances in instrumentation and polarization methods, technology development in SSNMR remains an active area of research and presents opportunities to further improve data collection, processing, and analysis of samples with low sensitivity and complex tertiary and quaternary structures. SSNMR spectra are often collected as multidimensional data, requiring stable experimental conditions to minimize signal fluctuations (t1 noise). In this work, we examine the factors adversely affecting signal stability as well as strategies used to mitigate them, considering laboratory environmental requirements, configuration of amplifiers, and pulse sequence parameter selection. We show that Thermopad® temperature variable attenuators (TVAs) can partially compensate for the changes in amplifier output power as a function of temperature and thereby ameliorate one significant source of instability for some spectrometers and pulse sequences. We also consider the selection of tangent ramped cross polarization (CP) waveform shapes, to balance the requirements of sensitivity and instrumental stability. These findings collectively enable improved stability and overall performance for CP-based multidimensional spectra of microcrystalline, membrane, and fibrous proteins performed at multiple magnetic field strengths.

An ultra-thin tri-functional coding metasurface based on frequency and polarization selection

An ultra-thin tri-functional coding metasurface based on frequency and polarization selection

3D Directional Assembly of Liquid Crystal Molecules.

The precise construction of hierarchically long-range ordered structures using molecules as fundamental building blocks can fully harness their anisotropy and potential. However, the 3D, high-precision, and single-step directional assembly of molecules is a long-pending challenge. Here, a 3D directional molecular assembly strategy via femtosecond laser direct writing (FsLDW) is proposed and the feasibility of this approach using liquid crystal (LC) molecules as an illustrative example is demonstrated. The physical mechanism for femtosecond (fs) laser-induced assembly of LC molecules is investigated, and precise 3D arbitrary assembly of LC molecules is achieved by defining the discretized laser scanning pathway. Additionally, an LC-based Fresnel zone plate array with polarization selection and colorization imaging functions is fabricated to further illustrate the potential of this method. This study not only introduces a 3D high-resolution alignment method for LC-based functional devices but also establishes a universal protocol for the precise 3D directional assembly of anisotropic molecules.

Selection rules in the excitation of the divacancy and the nitrogen-vacancy pair in 4 H - and 6 H -SiC

In this study, we address selection rules with respect to the polarization of the optical excitation of two color centers in 4H−SiC and 6H−SiC with potential for applications in quantum technology, the divacancy and the nitrogen-vacancy pair. We show that the photoluminescence of the axial configurations of higher symmetry (C3v) than the basal ones (C1h) can be canceled using any excitation (resonant or nonresonant) with polarization parallel to the crystal axis (EL||c). The polarization selection rules are determined using group-theoretical analysis and simple physical arguments showing that phonon-assisted absorption with EL||c is prohibited despite being formally allowed by group theory. A comparison with the selection rules for the silicon vacancy, another defect with C3v symmetry, is also carried out. Using the selection rules, we demonstrate selective excitation of only one basal divacancy configuration in 4H−SiC, the PL3 line, and discuss the higher contrast and increased Debye-Waller factor in the selectively excited spectrum. Published by the American Physical Society 2024