Polarization Rotation Research Articles

Eye lens dosimetry: does the direction of rotation (vertical or horizontal) play a role in type testing?

With the International Commission on Radiological Protection (ICRP) lowering the annual dose limit for the eye lens to 20 mSv, precise monitoring of eye lens exposure has become essential. The personal dose equivalent at a depth of 3 mm, Hp(3), is the measurement method for monitoring the dose to the lens of the eye. Traditional dosimetry methods primarily address lateral radiation exposure scenarios, where radiation approaches from the left or right, necessitating the rotation of the phantom during type testing around the vertical axis. However, these methods do not adequately account for bottom-to-top radiation exposures which are common in real-world situations (such as radiation scattered by the patient reaching medical staff).
This study examines oblique radiation exposure conditions using a typical eye lens thermoluminescent dosemeter (TLD), Eye-D, placed on a cylindrical phantom to assess dose responses at different angles and exposure energies. The study employs both lower-energy (N-30 radiation quality) and higher-energy (N-100 radiation quality) X-rays at irradiation angles of -60°, 0°, and +60°, measured along the vertical and horizontal rotation axes of the phantom.
The results show no significant differences between horizontal and vertical (polar and radial) rotation orientations of the dosemeter-phantom setup: recorded relative doses stayed well within ±1%, i.e., by far within the attributed combined uncertainty of ±2%.&#xD.

Narrow Linewidth All-Optical Microwave Oscillator Based on Torsional Radial Acoustic Modes of Single-Mode Fiber

A Hz level narrow linewidth all-optical microwave oscillator based on the torsional radial acoustic modes (TR2,m) of a single-mode fiber (SMF) is proposed and validated. The all-optical microwave oscillator consists of a 20 km SMF main ring cavity and a 5 km SMF sub ring cavity. The main ring cavity provides forward stimulated Brillouin scattering gain and utilizes a nonlinear polarization rotation effect to achieve TR2,7 mode locking. By combining the sub ring cavity with the main ring cavity and utilizing the Vernier effect, the TR2,7 mode microwave photonic single longitudinal mode (SLM) output can be ensured. Meanwhile, the 6.281 Hz narrow linewidth of the TR2,7 mode is achieved by reducing the intrinsic linewidth of the passive resonant cavity. The acoustic mode suppression ratio and side mode suppression ratio of the TR2,7 mode were 43 dB and 54 dB, respectively. The power and frequency fluctuations of within 40 min were approximately ±0.49 dB and ±0.187 kHz, indicating good stability. At a frequency offset of 10 kHz, the TR2,7 mode had a low phase noise value of −110 dBc/Hz. This solution can be used in various fields, such as high-precision radar detection, long-distance optical communication, and high-performance fiber optic sensing.

Magneto-optical polarization texturing

Left and right circularly polarized transverse electromagnetic waves propagate at slightly different speeds in a magnetic material leading to a polarization rotation by an amount proportional to the projection of the magnetic field along the direction of the wave propagation. We show how this magneto-optical effect can serve as a vectorial polarization shaper if the input mode is either a radially-polarized or an azimuthally-polarized Laguerre-Gaussian (LG) mode. The specific polarization map of the output field can be achieved by choosing appropriately the magnetic material and/or its geometry. We show further that when the LG beam waist is comparable to the wavelength (i.e. w 0 ≈ λ ) the fields are no longer purely transverse but acquire an additional longitudinal (axial) component. We demonstrate how this modifies the polarization texturing.

Low-polarization-sensitive 1 × 2 carrier-injection-type silicon photonic switch consisting of input-/ output-side polarization splitter/rotators and a single Mach-Zehnder interferometer.

We propose a low-polarization-sensitive 1 × 2 carrier-injection-type silicon photonic switch consisting of a single Mach-Zehnder interferometer, an input-/output-side polarization splitter and rotators, bidirectional light injection, and an external optical circulator. A polarization-dependent loss (PDL) of 1.3 dB was achieved using the proposed structure, whereas a PDL exceeding 17 dB was observed without the structure. In addition, owing to the large birefringence of the silicon waveguide, a differential group delay (DGD) of 10 ps for a 10 Gbps OOK signal was observed. However, a reduced polarization dependence was confirmed through bit error rate measurements, with the power penalty difference lower than 1 dB.

Metasurface‐Enabled Cascaded Multispectral Polarization Structures Along the Longitudinal Direction

AbstractGeneration and manipulation of polarization structures have attracted significant interest due to their unusual optical features and extensive applications. Multispectral information can further increase the information capacity of polarization structures. However, generating multiple cascaded multispectral polarization numbers (letters) at multiple planes arranged along light propagation has not been reported. A geometric metasurface is used to experimentally realize eight cascaded multispectral polarization numbers (letters) at predesigned observation planes along the longitudinal direction. The efficacy of this approach is demonstrated by encoding a single polarization number (letter) with two wavelengths and cascading two polarization numbers with orthogonal polarization rotation angles. Different two‐color polarization numbers (letters) are generated by controlling the incident wavelength, while their polarization distributions are modulated by controlling the incident linear polarization. This approach integrates two‐dimentional (2D) polarization generation, multiple colors, longitudinal control, and cascading design, providing extra degrees of freedom for customized polarization design and enabling small‐volume polarization systems for color display, image steganography, and optical encryption.

Electron beam characterization via quantum coherent optical magnetometry

We present a quantum optics-based detection method for determining the position and current of an electron beam. As electrons pass through a dilute vapor of rubidium atoms, their magnetic field perturbs the atomic spin's quantum state and causes polarization rotation of a laser resonant with an optical transition of the atoms. By measuring the polarization rotation angle across the laser beam, we recreate a 2D projection of the magnetic field and use it to determine the e-beam position, size, and total current. We tested this method for an e-beam with currents ranging from 30 to 110 μA. Our approach is insensitive to electron kinetic energy, and we confirmed that experimentally between 10 and 20 keV. This technique offers a unique platform for noninvasive characterization of charged particle beams used in accelerators for particle and nuclear physics research.

Field-Induced Polarization Rotation in Order-Disorder (K,Na)NbO3-Based Ferroelectrics.

Phase boundary is highly recognized for its capability in engineering various physical properties of ferroelectrics. Here, field-induced polarization rotation is reported in a high-performance (K, Na)NbO3-based ferroelectric system at the rhombohedral-tetragonal phase boundary. First, the lattice structure is examined from both macroscopic and local scales, implementing Rietveld refinement and pair distribution function analysis, respectively. The macroscopic phase coexistence at the phase boundary can be interchangeably rationalized with an average projection of collective local disordered units, exhibiting the order-disorder nature. The structural evidence of field-induced polarization rotation is provided by the in situ synchrotron study. Theoretical studies including density functional theory calculation and molecular dynamics simulation also predict the polarization rotation mechanism. The simulation result reveals the variation of the degree of ordering during the polarization rotation as a key feature of the boosted electrical properties in the order-disorder ferroelectric system. The discovery provides meaningful insight into the design of ferroelectrics with enhanced physical properties.

Silicon Nitride-on-Insulator Photonics Polarisation Convertor

Photonic integrated circuits constitute a vital component of contemporary telecommunications systems, facilitating traffic management and reducing energy consumption. However, the integration of these components presents a significant challenge in the form of high polarization sensitivity, which has the potential to limit the overall performance of the device. The objective of this study was to develop a design method and fabrication technology for polarization converters based on silicon nitride-on-insulator. The design of the polarization converters was optimised through the utilisation of finite element method simulations, conducted using the ANSYS Lumerical software. The device features an asymmetric rib waveguide, which facilitates efficient polarisation rotation. The technological implementation comprised plasma chemical vapor deposition of silicon nitride films, three-dimensional laser lithography, and reactive ion etching. A technological assessment determined that the reproducibility tolerance was ± 60 nm. To address this limitation, a mirrored section was incorporated into the polarization converter design, thereby increasing the allowable fabrication tolerance to ± 215 nm without compromising device performance. The optimised polarization converter exhibited a high level of polarization rotation efficiency, reaching 96.3 %, and an output power of 98.32 %. The utilisation of an asymmetric rib waveguide was pivotal in attaining these outcomes, facilitating the transfer of optical power from fundamental transverse electric to fundamental transverse magnetic modes. The incorporation of a mirrored section enhanced the device's manufacturability, maintaining performance despite geometric deviations. These findings highlight the robustness of the proposed design under typical fabrication constraints. This study presents a novel design and fabrication method for silicon nitride on insulator-based polarization converters. The proposed approach improves efficiency and stability. These results provide a foundation for future advancements in integrated photonics, with potential applications in telecommunications and beyond.

Low-noise tunable high-repetition-frequency fiber laser based on an active–passive hybrid mode-locking mechanism

A hybrid mode-locked fiber laser that effectively combines the nonlinear polarization rotation (NPR) effect and active mode locking is designed and constructed. In the experiments, mode-locked pulse trains of first to 64th order with selectable harmonic mode locking, corresponding to repetition rates from 16.09 MHz to 1.029 GHz, were realized, and a signal-to-noise ratio of up to 69.45 dB at 1.029 GHz proved the excellent stability of the laser output. The birefringence filter, consisting of a bias-preserving pigtail at the input of the modulator and a polarization controller, allows the laser to achieve a multi-wavelength output of up to eight channels. The inclusion of an NPR structure in the cavity effectively improves the SNR of the actively mode-locked harmonic pulses compared to a single-mechanism mode-locked laser. The laser provides a stable light source for the development of practical optical frequency combs.

Spatiotemporal mode-locked intelligent fiber laser based on cascaded photonic lanterns.

An intelligent controlled spatiotemporal mode-locked (STML) fiber laser based on a photonic lantern (PL) is proposed and experimentally demonstrated. A pair of in-house developed PLs is spliced into the cavity in a back-to-back structure. This PL-based structure functions as a mode multiplexer/demultiplexer to generate higher-order spatial modes. Owing to the strong polarization-dependent loss structural characteristics, the structure also serves as an equivalent saturable absorber based on nonlinear polarization rotation. The STML fiber laser delivers pulsed high-order modes at a center wavelength of 1555.4 nm with a pulse duration of 6.99 ps. With the deployment of a motorized polarization controller and a time-domain signal feedback system, the laser enables intelligent control via a stochastic global polarization search algorithm. Experimental results indicate that the proposed laser can effectively evade disturbances from complex intracavity states and accurately lock onto the fundamental mode-locking state within only 2 min.

A Wideband High Gain Transmit‐Array Antenna Exploiting Polarization‐Rotated Metasurface Cell

ABSTRACTA novel polarization‐insensitive transmit‐array (TA) antenna using linear polarization‐rotated (PR) metasurface (MS) unit cells has been proposed in this article. Firstly, we design a wideband polarization‐insensitive polarization‐rotated MS unit cell. The MS cell can provide high transmission for incident linear polarized waves with polarization rotation by 90°. Then, we investigate the stability of the MS cell under the oblique incident wave. The proposed MS cell keeps a stable response under oblique incident wave over ± 30°. To verify the excellent performance of the proposed MS. We design a high‐gain TA antenna consisting of a standard feed horn and an aperture with a gradient phase. The gradient phase compensation is provided by varying the geometric dimension of the proposed MS. The obtained TA antenna works in a wide band with high gain. We fabricated the aperture and set up a prototype of TA antenna to verify our work. We measure the TA antenna and the results show a wide operating band from 14.2 to 18 GHz with a pick gain of 23.9 dBi. The favorable performance of the TA antenna is a good candidate in satellite systems and long‐distance satellite system. Furthermore, the angular stability of the MS cell is also verified by realizing the beam scanning performance. An over ± 30° scan range is obtained. Good beam scanning can be used in radar detection and expand signal coverage.

Piezoelectric Property Amplification in 0.46PNN-0.23PIN-0.31PT Ceramics via Optimized Low-Temperature Sintering and Defect Chemistry

The sintering temperature of piezoelectric ceramics plays a pivotal role in their cost and efficacy within the realm of multilayer actuator applications. While being conducive to piezoelectric capabilities of ceramics, the increase in sintering temperature entails higher fabrication costs. In contrast, a lower sintering temperature can reduce costs, but the performance of the actuator may be compromised. To address these issues, the Li-Sc co-doped 0.46PNN-0.23PIN-0.31PT ceramics were produced in the present work. At a relatively low sintering temperature (950 °C), the synergy of multiple ferroelectric phases and defect polarization could be achieved, thereby augmenting the electromechanical properties of the material. At an optimal doping ratio of 0.6 mol% for both Li and Sc, the ceramics demonstrated superior performance metrics, including d33 = 1000 pC/N, d33* = 1050 pm/V, kp = 0.53, and εr = 8001. Applying the Rietveld refinement and Rayleigh analysis, it was established that the incorporation of Li is essential in the formation of a rhombohedral phase-dominated morphotropic phase boundary (MPB), which decreases polarization anisotropy amidst the coexisting phases, facilitating polarization rotation and significantly enhancing the piezoelectric properties of ceramics. The nanodomains within the material were detected through SS-PFM and PFM testing. Notably, Sc3+-induced defects disrupted the extended ferroelectric domains, fostering the emergence of nanodomains with higher activity, which in turn enabled to markedly improve the electromechanical performance of the ceramics even at the lower sintering temperature. This investigation not only provides a viable strategy for curtailing the manufacturing costs of multilayer actuators but also opens up new prospects for the low-temperature fabrication of piezoelectric materials and their applications.

Spin injection from a magnetically near-compensated state in GdFeCo and inverse spin Hall effect in electron–hole compensated metal YH2

Rare-earth-transition-metal (RE-TM) ferrimagnets are excellent materials for spin encode/decode operations via spin transport in nonmagnetic regions. This superior performance stems from two key factors. First, the antiferromagnetic coupling between RE4f and TM3d sublattices reduces both the spin-transfer-torque switching time and inter-device magnetic-coupling. Second, the RE-TM ferrimagnets function as spin injectors/ejectors, with the TM3d sublattice solely responsible for carrier spin polarization (p), similar to conventional ferromagnetic metals. We performed spin transport experiments using the sign change ofpin RE-TM, which exhibits a positive value above the magnetization compensation temperature and a negative value below it. We measured temperature dependencies of the transverse resistances (RT) of electron-hole compensated metal YH2under out-of-plane spin-polarized current injection/ejection from GdFeCo (Gd:Fe:Co = 25:66:9). The abrupt change in loop polarity of the out-of-plane field dependence ofRTin YH2between 290 and 300 K, which aligns with the out-of-field curve of the polar Kerr rotation in GdFeCo electrodes, strongly suggests that the observedRTresults from the inverse spin Hall effect (ISHE) in YH2. We analytically formulated ISHE in terms of the electron and hole spin currents injected from the spin sources, enabling regression analysis to assess the spin transport characteristics of a GdFeCo/YH2/GdFeCo magnetic double heterostructure. To explain the observed Hall voltages, enhancements in both the spin diffusion length of YH2and the spin injection efficiency are necessary.

Layered Babinet complementary patterns acting as asymmetric negative index metamaterial

Azimuthal orientation and handedness dependence of the optical responses, accompanied by asymmetric transmission and asymmetric dichroism, were demonstrated on multilayers constructed with subwavelength periodic arrays of Babinet complementary miniarrays, illuminated by linearly and circularly polarized light. In case of single-sided illumination asymmetric optical responses were observed at the spectral location of maximal cross-polarization that is accompanied by radiative electric dipoles and weak, slowly-rotating in-plane magnetic dipoles on the nano-objects; where the outgoing waves are elliptically (almost circularly) polarized. The negative index material phenomenon was demonstrated, where the electric and magnetic dipoles overlap both spatially and spectrally. The negative index material (NIM) phenomenon is accompanied by electric multipoles that add up non-radiatively and correlates with the strong, pronouncedly-tilted, rotating magnetic dipoles characteristic on the nano-entities, where the outgoing waves are linearly (slightly elliptically) polarized. By illuminating the multilayer with two counter-propagating circularly polarized beams it was proven that asymmetrical normal component displacement currents at the bounding interfaces, arising along flat and tilted bands, accompany the asymmetric copolarized and cross-polarized transmission. The latter correlates with the asymmetric dichroism in the cross-polarized signal observed in case of single-sided circularly polarized light illumination. The dispersion maps in the single-sided asymmetrical co-polarized reflectance and absorptance indicate flat bands of analogous and complementary extrema, proving the partially dichroic nature of the observed asymmetric phenomena. The Tellegen (chirality) coefficients exhibit a maximum in a spectral region coincident with the asymmetric transmission (maximal polarization rotation in the 90° azimuthal orientation). The multilayer is proposed as an ultrathin NIM and nonreciprocal nanophotonic element.

Directional ciliary beats across epithelia require Ccdc57-mediated coupling between axonemal orientation and basal body polarity

Motile cilia unify their axonemal orientations (AOs), or beat directions, across epithelia to drive liquid flows. This planar polarity results from cytoskeleton-driven swiveling of basal foot (BF), a basal body (BB) appendage coincident with the AO, in response to regulatory cues. How and when the BF-AO relationship is established, however, are unaddressed. Here, we show that the BF-AO coupling occurs during rotational polarizations of BBs and requires Ccdc57. Ccdc57 localizes on BBs as a rotationally-asymmetric punctum, which polarizes away from the BF in BBs having achieved the rotational polarity to probably fix the BF-AO relationship. Consistently, Ccdc57-deficient ependymal multicilia lack the BF-AO coupling and display directional beats at only single cell level. Ccdc57 −/− tracheal multicilia also fail to fully align their BFs. Furthermore, Ccdc57 −/− mice manifest severe hydrocephalus, due to impaired cerebrospinal fluid flow, and high mortality. These findings unravel mechanisms governing the planar polarity of epithelial motile cilia.

Assessing the Ubiquity of Bloch Domain Walls in Ferroelectric Lead Titanate Superlattices

The observation of unexpected polarization textures such as vortices, skyrmions, and merons in various oxide heterostructures has challenged the widely accepted picture of ferroelectric domain walls as being Ising-like. Bloch components in the 180° domain walls of PbTiO3 have recently been reported in PbTiO3/SrTiO3 superlattices and linked to domain wall chirality. While this opens exciting perspectives, the ubiquity of this Bloch component remains to be further explored. In this work, we present a comprehensive investigation of domain walls in PbTiO3/SrTiO3 superlattices, involving a combination of first- and second-principles calculations, phase-field simulations, diffuse scattering calculations, and synchrotron-based diffuse x-ray scattering. Our theoretical calculations highlight that the previously predicted Bloch polarization in the 180° domain walls in PbTiO3/SrTiO3 superlattices might be more sensitive to the boundary conditions than initially thought and is not always expected to appear. Employing diffuse scattering calculations for larger systems, we develop a method to probe the complex structure of domain walls in these superlattices via diffuse x-ray scattering measurements. Through this approach, we investigate depolarization-driven ferroelectric polarization rotation at the domain walls. Our experimental findings, consistent with our theoretical predictions for realistic domain periods, do not reveal any signatures of a Bloch component in the centers of the 180° domain walls of PbTiO3/SrTiO3 superlattices, suggesting that the precise nature of domain walls in the ultrathin PbTiO3 layers is more intricate than previously thought and deserves further attention. Published by the American Physical Society 2024

Robust Sodium Carboxymethyl Cellulose-Based Neuromorphic Device with High Biocompatibility Engineered through Molecular Polarization for the Emulation of Learning Behaviors in the Human Brain.

Sodium carboxymethyl cellulose (CMC-Na), derived from natural cellulose and frequently employed as a biocompatible coating, thus renders it an ideal component for the construction of highly biocompatible neuromorphic devices aimed at biomachine interfaces. Here, an array of Mo/CMC-Na/ITO neuromorphic devices is fabricated, with CMC-Na serving as the functional layer. The devices exhibit capabilities to emulate various synaptic learning rules and demonstrate high endurance performance among biomaterial-based electronics, achieving stability over 2 × 104 pulses. Then, simulations of human brain-inspired learning and forgetting paradigms are conducted, highlighting the versatility of the device array in mimicking learning processes. Applications in pattern recognition leverage "learning-forgetting" paradigms, showcasing the potential of the device in cognitive tasks. Electrical measurements elucidate the mechanism of molecular polarization rotation, which offers insights into the modulation of synaptic weights within biocompatible biomaterial-based devices. Furthermore, the biocompatible properties of the devices are evaluated using human embryonic kidney 293 cells, confirming their excellent biocompatibility. The biodegradability of the devices is assessed by using physical transient tests to evaluate their sustainability in biomedical applications. Such advances represent pivotal improvements in implantable bioinspired electronics and show potential in biomachine interface and cognitive computing applications.

A continuous plane of polarization rotator and detector based on the liquid crystal Θ-cell

Modulation of the polarization state of optical beams is crucial in advanced optical applications such as polarization microscopy, polarization rotation, and medical imaging. We demonstrate a continuous polarization rotator (PR) by utilizing the liquid crystals (LC) in Θ-cell configuration comprising of circular and parallel alignment of LC on two aligning glass substrates. A rotation of plane of polarization (PoP) up to ∼ 160˚ is observed using Stokes polarimetry. This is further substantiated by the mathematical analysis using Mueller matrix formalism. Further, the device is demonstrated as a PoP detector with high precision detection angle. The PoP is analyzed through single-shot imaging of the intensity distribution of transmitted light through the LC Θ-cell.

Photothermal Spectroscopy in Attenuated Total Internal Reflection Geometry by Polarization Rotation and Deflection

Photothermal Spectroscopy in Attenuated Total Internal Reflection Geometry by Polarization Rotation and Deflection

Optimized detection modality for radio-frequency sensing with a double-resonance alignment magnetometer

In this work, we present a comprehensive and comparative analysis of two detection modalities, i.e., polarization rotation and absorption measurement of light, for a double-resonance alignment magnetometer (DRAM). We derive algebraic expressions for magnetometry signals based on the description of multipole moments. Experiments are carried out using a room-temperature paraffin-coated cesium-vapor cell and measuring either the polarization rotation or absorption of the transmitted laser light. A detailed experimental analysis of the resonance spectra is performed to validate the theoretical findings for various input parameters. The results signify the use of a single isotropic relaxation rate, thus simplifying the data analysis for optimization of the DRAM. The sensitivity measurements are performed and reveal that the polarization-rotation detection mode yields larger signals and better sensitivity than absorption measurement of light. Published by the American Physical Society 2024