Wave Plate Research Articles

On-Chip Polarization Light Microscopy

Polarization light microscopy (PLM) enables detailed examination of birefringent materials and reveals unique features that cannot be observed under non-polarized light. Implementation of this technique for quantitative PLM (QPLM) assessment of samples is challenging and requires specialized components and equipment. Here, we demonstrate QPLM on a semiconductor imaging chip that is suitable for point-of-care/need applications. A white LED illumination was used with crossed polarizers and a full wave plate to perform on-chip, non-contact-mode QPLM. Polarization complexity is probed by assessing the multispectral phase shift experienced by white light through the distinct optical paths of the sample. This platform can achieve micrometer-scale spatial resolution with a Field of View determined by the size of the semiconductor sensor. Visualization of a biological sample (Euglena gracilis) was demonstrated, as well as the detection of Monosodium Urate crystals, where the presence of negative birefringence of crystals in synovial fluid is important for the diagnosis of gout.

Crystal Structural Editing: Novel Biaxial MgTe2O5 Crystal as Zero-Order Waveplates.

Waveplates are important optical components to control the polarization of light. Currently, they are often fabricated from uniaxial crystals, and there is no report about waveplates based on the biaxial crystals. In this work, a novel biaxial crystal MgTe2O5 with a structure constructed by 0D Te2O5 groups is designed and grown as waveplate materials for the first time. The exciting result is that the birefringence in the (001)-plane is smaller than 0.0028 in the range from 0.4 to 5 µm, which is significantly smaller than that of the current waveplate materials. The polarization modulations of the MgTe2O5 devices working at 532 nm indicate that excellent zero-order half and quarter waveplates have been successfully prepared. In addition, achromatic waveplates used in the visible, near-infrared, and mid-infrared ranges have also been calculated. The MgTe2O5 crystal not only exhibits a high laser damage threshold of up to 2.7 GWcm-2 but also shows a wide transmission range from 0.37 to 6.3 µm. These results provide an excellent waveplate crystal and explore the applications of biaxial crystals.

Ultrabroadband, ultranarrowband and ultrapassband composite polarisation half-wave plates, ultrabroadband composite polarisation pi-rotators and on the quantum-classical analogy

Ultrabroadband, ultranarrowband and ultrapassband composite polarisation half-wave plates, ultrabroadband composite polarisation pi-rotators and on the quantum-classical analogy

Improvement in the Sagnac-loop laser frequency stabilization

The laser frequency stability locked to the D2 transition of 85Rb at 780 nm using a Doppler-free Sagnac-loop stabilization scheme has been improved. In a previous work [J. Opt. Soc. Am. B 40, 667 (2023)JOBPDE0740-322410.1364/JOSAB.482223], changes in birefringence at the absorption cell windows, influenced by the cell temperature, and in the rubidium vapor, affected by magnetic field fluctuations, significantly influenced the laser frequency stability. By aligning the polarization, the short-term stability (<10s) of the locked laser frequency was improved; however, the long-term stability remained unaffected. We attribute this long-term stability to temperature-induced changes in the optical path length of the wave plates. By removing the wave plates from the setup, the long-term stability has been successfully improved.

Dispersion and attenuation characteristics of Lamb waves in multilayered piezoelectric semiconductor plates with imperfect interfaces

Lamb waves in piezoelectric semiconductor multilayered plates with imperfect interfaces are investigated using the generalized linear spring model. The Legendre polynomial method with analytical integration, accounting for imperfect interfaces, is used to derive field quantities for each layer, corresponding to displacement and traction at the plate interfaces. The complex wave partial differential equations are converted into a generalized eigenvalue problem. The study of Lamb waves in ZnO/GaN bilayer piezoelectric semiconductor plates with imperfect interfaces elucidates the influence of carrier concentration, interface coefficients, plate thickness, and bias electric fields on phase velocity dispersion and attenuation curves.

Broadband, multiaxial-mode, passively-stable continuous wave optical parametric oscillator design consideration and dispersion compensation analysis

Broadband, multiaxial-mode, passively-stable continuous wave optical parametric oscillator design consideration and dispersion compensation analysis

A Periodic Extension to the Fokas Method for Acoustic Scattering by an Infinite Grating

The Fokas method (also known as the unified transform method) is used to investigate acoustic scattering by thin, infinite grating by extending the methodology to apply to spatially periodic domains. Infinite grating is used to model a perforated screen, a material of interest in aeroacoustics and noise reduction. Once the method is established, its numerical results are verified against the Wiener–Hopf (WH) technique, which has solved the problem only for a special case. A key benefit of the novel approach is that the scatterer, modelled as an infinitely repeating unit cell consisting of a thin, rigid plate, can take any length. This is in contrast to the WH method, where the plate length is restricted to half the width of the unit cell (for this method, no such restriction exists). The numerical method is an over-sampled collocation method of the integral equation resulting from applying the Fokas method: the global relation. The only increase in complexity in adapting the Fokas method to more complicated cell geometries is a higher number of terms in the global relation. The proportion of energy transmitted and reflected by the grating structure is assessed for varying incident wave angles, frequencies, and plate lengths.

Multi-Tap Optical Delay Line-Based Optical-Electrical Dispersion Compensation Scheme in High-Speed IM/DD Systems

Multi-Tap Optical Delay Line-Based Optical-Electrical Dispersion Compensation Scheme in High-Speed IM/DD Systems

Влияние геометрических параметров на распространение SH-волн в пьезоэлектрической/пьезомагнитной пластине

The propagation features of horizontally polarized shear waves in a magnetoelectroelastic composite plate in contact with vacuum are investigated within the quasi-static approximation. The plate consists of rigidly coupled piezoelectric and piezomagnetic layers. It is assumed that there are no mechanical stresses on the outer surfaces, and the magnetic potential is zero. Depending on the nature of the specified electrical conditions, problems with electrically open and electrically closed external surfaces are considered. The wave process is initiated by the action of a remote source of harmonic oscillations and is assumed to be steady. The solution of the problems is constructed in Fourier images as an expansion into a set of exponentials. Dispersion equations of the problems, which are presented in a matrix form convenient for numerical implementation, were obtained. Using the example of the PZT-5H/CoFe2O4 plate, the effect of the thickness of each of its layers on the transformation features of phase and group velocities of surface acoustic waves with horizontal polarization (SH-SAW) is established. When changing the geometric parameters, either the plate thickness or the thickness of one of its layers was fixed. Within the framework of the problem with electrically closed external surfaces, significant differences in the behavior of velocities were established depending on the thickness of the piezoelectric and piezomagnetic layers. The conditions for the maximum and minimum effect of the thickness of each layer on the behavior of the 2nd and subsequent SH-SAW modes were determined. It is shown that in the presence of a very thin piezomagnetic layer in the plate, the behavior of the 2nd SAW mode changes significantly: both the mode output frequency and the asymptotic value of the velocity increase. The regularities of the effect of changing the thickness of the piezoelectric and piezomagnetic layers of the plate on the transformation of the electromagnetic-mechanical coupling coefficient in a wide frequency range were revealed. The obtained results are given in dimensionless parameters and can be of interest in the development of new functionally oriented materials, the assessment of their performance characteristics, as well as in the creation of highly efficient devices operating on surface acoustic waves.

Dispersion characteristics of Lamb wave in a multilayered magnetoelectroelastic plate with an imperfect interface

In this study, we investigate Lamb wave propagation in a multilayered magnetoelectroelastic plate with an imperfect magnetoelectroelastic interface using the generalized linear spring model (GLSM). The dispersion relation of the Lamb wave is obtained using an improved Legendre polynomial expansion method, which converts the wave problem into a linear eigenvalue system. The effectiveness of the present method was verified through comparison with two existing cases: SH wave in a bilayer plate with an imperfect interface and Lamb wave in a bilayer plate with a perfect interface. Numerical examples were presented for various multilayered plates composed of BaTiO3/CoFe2O4. The effects of the spring constant combinations, including the degree of mechanical, electric, and magnetic interface imperfections, layer thickness ratio, electromagnetic boundary condition, and stacking sequence on the dispersion characteristics are illustrated. The effect of the thickness ratio on the magneto-electromechanical coupling factor and the sensitivity of the phase velocity at different frequencies to changes in the interface characteristics are also discussed. The present investigation is of practical interest for developing new layered composite structures made of smart piezoelectric and piezomagnetic materials for engineering applications.

Resolving Artifacts and Improving the Detection Limit in Circular Differential Scattering Measurement of Chiral and Achiral Gold Nanorods.

Circular differential scattering (CDS) spectroscopy has been developed as a powerful method for the characterization of the optical activity of individual plasmonic nanostructures and their complexes with chiral molecules. However, standard measurement setups often result in artifacts that have long raised concerns on the interpretation of spectral data. In fact, the detection limit of CDS setups is constrained by the high level of artifacts, to ±10%. We address this issue by means of a detailed theoretical description of changes in the polarization state when circularly polarized light is reflected at a dark-field condenser. As a result, we propose a modified CDS configuration based on sequentially placing the quarter-wave plate and linear polarizer within the detection optical path, to analyze the circular polarization state of the light scattered by individual particles. Extensive analysis demonstrates a detection limit of ±1.5% for the modified configuration, which is significantly lower than that for the conventional setup. As a standard system for CDS measurements, both achiral and chiral gold nanorods (AuNRs) were characterized using both setups. With achiral AuNRs, linear dichroism (LD) artifacts in the conventional setup are found to originate from LD present in the excitation light and are only present if anisotropic excitation is produced as a result of the misalignment of the excitation light to the condenser. With chiral AuNRs, CDS spectra recorded with the conventional setup depend on the orientation of the chiral AuNRs with respect to the x-axis of the microscope and are reversed compared to those on the colloid and measured in the modified configuration. The results are in good agreement with theoretical simulations for both configurations.

Sensitivity of Lamb waves in viscoelastic polymer plates to surface contamination.

Detecting surface contamination on thin thermoformed polymer plates is a critical issue for various industrial applications. Lamb waves offer a promising solution, though their effectiveness is challenged by the strong attenuation and anisotropy of the polymer plates. This issue is addressed in the context of a calcium carbonate (CaCO3) layer deposited on a polypropylene (PP) plate. First, the viscoelastic properties of the PP material are determined using a genetic algorithm inversion of data measured with a scanning laser vibrometer. Second, using a bi-layer plate model, the elastic properties and thickness of the CaCO3 layer are estimated. Based on the model, the sensitivity analysis is performed, demonstrating considerable effectiveness of the A1 Lamb mode in detecting thin layers of CaCO3 compared to Lamb modes A0 and S0. Finally, a direct application of this work is illustrated through in-situ monitoring of CaCO3 contaminants using a straightforward inter-transducer measurement.

Active invisible metamaterial of elastic waves with double targets in a thick plate

Wave invisibility has received increasing attention due to its great theoretical value and application to aerospace, military and other fields. In this work, the invisible flexural cloak for double hole targets in an elastic thick plate is proposed and proportional integral derivative (PID) active control is applied. Based on Mindlin thick plate theory and wave function expansion method, the wave equation for the thick plate is derived and scattering mode coefficients are obtained. The influences of structural and material parameters on dynamic stress concentration, scattering amplitude and scattering cross section (SCS) for double targets are investigated. With the consideration of specific hole targets, the cloaking configuration includes cloaks 1 and 2 and consists of periodically arranged piezoelectric (PZT) patches. Every PZT patch is attached to the active circuit with PID control function. The theoretical and experimental results illustrate that the cloak can achieve an invisible function for double targets within multiple frequency regions. On the other hand, the cloak can reduce the dynamic stress concentration, scattering amplitude and SCS of the thick plate. Different from the original structure without control, the effective frequency range of the PID active cloak can be widely extended.

Incremental Optical Encoder Error Modeling and Compensation for Accurate Speed Acquisition in Non-Stationary Conditions

Incremental Optical Encoder Error Modeling and Compensation for Accurate Speed Acquisition in Non-Stationary Conditions

SH1 mode plate wave resonator on −27°YX LiTaO3 single crystal plate with phase velocity of 12 km s−1

Abstract This study presents a first shear horizontal (SH1) mode plate acoustic wave resonator on a −27°YX LiTaO3 (LT) thin plate. The SH1 wave is generated when a backside electrode is formed on the opposite side of an interdigital transducer (IDT). Two resonators, one with Cu and the other with an Al backside electrodes, along with a Cu IDT were simulated and fabricated. Both fabricated SH1 resonators exhibited high phase velocities of 12 km s−1 and bandwidth (BW) of around 4.5%. The temperature coefficient of frequency is −38 ppm °C−1 at resonance and −56 ppm °C−1 at anti-resonance on a 0.13λ thick LT plate. Although the backside electrode is necessary for high coupling of the SH1 wave, it increases the clamp capacitance of the devices, resulting in low impedance characteristics of around 10 Ω and low impedance ratios around 30 dB. Additionally, the suppression of spurious responses is necessary for filter application.

Polarization Imaging Method for Detection of Lung Cancer Based on Symmetrical Single LCVR

ABSTRACTLung cancer ranks among the three most prevalent cancers worldwide. Polarization imaging technology can effectively distinguish between cancerous and normal tissues. The most commonly applied method for cancer detection is the dual‐rotating wave plate polarization imaging system (DWRPIS), which is cumbersome and prone to significant error due to 60 mechanical rotations. To address this, our experiment leveraged the stability of the Liquid Crystal Variable Retarder (LCVR) and, based on existing theoretical foundations for simplifying the use of LCVRs, designed a symmetric single‐LCVR polarization imaging system (SSLPIS) for the first time to detect lung cancer images. The SSLPIS is easy to operate, completing the entire acquisition process in just 150 s, with effective Mueller matrix imaging and an overall accuracy rate of over 90%, offering a faster and more precise detection method. This new approach provides an innovative pathway for the rapid detection of lung cancer.

Multi-angle and full-Stokes polarization multispectral images using quarter-wave plate and tunable filter

Polarization multispectral imaging has advanced significantly due to its robust information representation capability. Imaging application requires rigorous simulation evaluation and experimental validation using standardized datasets. However, the current full-Stokes polarization multispectral images (FSPMI) dataset, while providing simulation data, is limited by image drift and spectral bands. To overcome these limitations and supplement experimental data, this paper introduces the multi-angle and full-Stokes polarization multispectral images (MAFS-PMI) dataset. The imaging system utilizes a rotatable quarter-wave plate (QWP) and a fixed liquid crystal tunable filter (LCTF) to modulate polarization information. Meanwhile, the LCTF allows switching between multiple spectral bands. The acquired multi-angle polarization multispectral images facilitate the experimental validation of encoding strategies and reconstruction algorithms. Additionally, the derived full-Stokes polarization multispectral images enable the simulation evaluation of imaging methods. The MAFS-PMI dataset involves 73 fast axis angles (0° to 180°), four Stokes parameters, five polarization parameters, 35 spectral bands (520 nm to 690 nm), 400 × 400 pixels, and 12 distinct objects. This dataset offers a valuable resource for developing advanced imaging methods.

Physics-driven untrained neural network for vortex beam compensation in adaptive optics aided underwater wireless optical communications.

Orbital angular momentum (OAM) multiplexing is emerging as a critical technique for achieving high data capacity in underwater wireless optical communications (UWOC). Nonetheless, wavefront distortions induced by underwater turbulence compromise the orthogonality of OAM modes. In this paper, we introduce a physics-driven untrained learning approach for adaptive optics that operates independently of extensive amplitude datasets. Without iterative processing and pre-trained datasets, the underwater turbulence characteristics can be retrieved accurately by only relying on a one-shot distorted probe beam and a priori known amplitude of the probe beam. By leveraging a single distorted diffraction pattern and a priori known amplitude of the probe beam, the characteristics of underwater turbulence can be accurately retrieved without iterative processing or pre-trained datasets. Furthermore, by implementing a hybrid input/output alternating projection algorithm with a square constraint area, the retrieved underwater turbulence phase screen beyond the [0, 2π] range aligns with the target pattern. This consistency indicates that the proposed wavefront recovery technology is validated across a broad range of turbulence strengths. As a demonstration of feasibility, numerical simulations, and optical experiments were conducted to validate the compensation of OAM beams. Furthermore, the theoretical bit error rate (BER) and channel capacity were inferred based on the purity of OAM modes and the level of crosstalk.

Rotation-induced plasmonic chiral quasi-bound states in the continuum

Nanoscale light manipulation using plasmonic metasurfaces has emerged as a frontier in photonic research, offering strongly enhanced light–matter interactions with potential applications in sensing, communications, and quantum optics. Here, we unveil the realization and control of chiral quasi-bound states in the continuum (quasi-BICs) by judiciously rotating one of the paired plasmonic bricks and thereby influencing structural asymmetry. By precisely controlling the rotation angle, we enable continuous modulation of the radiation loss in quasi-BICs and transition from a perfect half-wave plate to a good absorber for the left-handed circularly polarized light. This transformation leverages the intrinsic chirality with moderately high circular dichroism of ∼0.35 in both simulation and experimental observations, manifesting unprecedented control over the chiral light within sub-wavelength scales. Theoretical modeling and numerical simulations complement our experimental findings, offering deep insights into underlying mechanisms and the role of symmetry breaking in realizing chiral quasi-BICs. The observed phenomena open new pathways for developing ultra-compact chiral photonic devices with tailored optical properties, including highly sensitive chiral biosensors, circular dichroism spectroscopy, and chiral flat optical components for information processing.

The effect of a magnetic field on the generation of free radicals in the interaction of quaternary ammonium compounds with hydroperoxides

The magnetic effects (ME) of a moderate magnetic field (MF, 600 mT) on the rate of radical generation (Wi) in mixed micellar systems of quaternary ammonium compounds with hydroperoxides (QAC-ROOH), measured by the inhibitor method, and the effect of magnetic field on the rate of radical polymerization initiated by radicals, generated from the surface by QAC chemisorbed on a solid carrier upon interaction with hydroperoxide dissolved in the monomer are compared. It has been established that in micellar solutions MF reduces Wi, ME ≈ –0.45. In the case of radical polymerization of styrene containing cumyl hydroperoxide on the surface of mica plates with a chemisorbed monolayer of QAC (CTAB or ACh), the polymerization rate increases in MF.