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Faraday polarization rotation control of 1529 nm wavelength has been obtained using the 5 S 1 / 2 → 5 P 3 / 2 → 4 D 5 / 2 transition of rubidium. The traditional off-resonant polarization rotation method commonly used in the Faraday effect for direct transitions of atoms is not applicable to the transitions between excited states. In this study, we proposed a near-resonant polarization rotation method using the Faraday effect between excited states of atoms, by which the polarization rotation of the rubidium 5 P 3 / 2 → 4 D 5 / 2 transition can be controlled from 0 ° to 90 ° with low distortion. The 780 nm pump light corresponding to the 5 S 1 / 2 → 5 P 3 / 2 transition can also be used simultaneously as a control source to manipulate the polarization state of the 1529 nm optical signal. [ABSTRACT FROM AUTHOR]

The 8 × 8 magneto-optical matrix has been derived to discuss the Faraday rotation (FR) effect, which is induced by the linear polarization wave passing through a sandwich structure composed of a dielectric layer and two identical Weyl semimetals (WSMs). The giant enhanced FR angle about 45° can be realized at the resonant tunneling wavelength of right hand circularly polarization (RCP) waves by enlarging the difference of the resonant tunneling wavelength of RCP and left hand circularly polarization waves suitably. It is shown that the resonant wavelengths depend on the Weyl node separation and tilt degree of Weyl cones in both type-I and type-II WSMs. More importantly, there exists a tunable one-to-one relationship between the Weyl node separation and the wavelength of the resonant FR angle, as well as the tilt degree and the wavelength of the resonant FR angle, which enables the characteristic of the Weyl node separation and tilt degree. Our research reveals an available method to determine the Weyl node separation and tilt degree of Weyl cones in both type-I and type-II WSMs. [ABSTRACT FROM AUTHOR]

Active galactic nuclei (AGNs) play an integral role in galaxy formation and evolution by influencing galaxies and their environments through radio jet feedback. Historically, interpreting observations of radio galaxies and quantifying radio jet feedback has been challenging due to degeneracies between their physical parameters. In particular, it is well established that different combinations of jet kinetic power and environment density can yield indistinguishable radio continuum properties, including apparent size and Stokes I luminosity. We present an approach to breaking this degeneracy by probing the line-of-sight environment with Faraday rotation. We study this effect in simulations of three-dimensional relativistic magnetohydrodynamic AGN jets in idealized environments with turbulent magnetic fields. We generate synthetic Stokes I emission and Faraday rotation measure (RM) maps, which enable us to distinguish between our simulated sources. We find enhanced RMs near the jet head and lobe edges. We show that increasing the environment density and the average cluster magnetic field strength broadens the distribution of Faraday rotation measure values. We study the depolarization properties of our sources, finding that the hotspot regions depolarize at lower frequencies than the lobes. We quantify the effect of depolarization on the RM distribution, finding that the frequency at which the source is too depolarized to measure the RM distribution accurately is a probe of environmental properties. This technique offers a range of new opportunities for upcoming surveys, including probing radio galaxy environments and determining more accurate estimates of the AGN feedback budget. [ABSTRACT FROM AUTHOR]

Highly magnetized neutron stars exhibit the vacuum non-linear electrodynamics effects, which can be well-described using the one-loop effective action for quantum electrodynamics. In this context, we study the propagation and polarization of pulsar radiation, based on the post-Maxwellian Lagrangian from the Heisenberg–Euler–Schwinger action. Given the refractive index obtained from this Lagrangian, we determine the leading-order corrections to both the propagation and polarization vectors due to quantum refraction via perturbation analysis. In addition, the effects on the orthogonality between the propagation and polarization vectors and the Faraday rotation angle, all due to quantum refraction are investigated. Furthermore, from the dual refractive index and the associated polarization modes, we discuss quantum birefringence, with the optical phenomenology analogous to its classical counterpart. [ABSTRACT FROM AUTHOR]

Coherent light-matter interactions mediated by opto-magnetic phenomena like the inverse Faraday effect (IFE) are expected to provide a non-thermal pathway for ultrafast manipulation of magnetism on timescales as short as the excitation pulse itself. As the IFE scales with the spin-orbit coupling strength of the involved electronic states, photo-exciting the strongly spin-orbit coupled core-level electrons in magnetic materials appears as an appealing method to transiently generate large opto-magnetic moments. Here, we investigate this scenario in a ferrimagnetic GdFeCo alloy by using intense and circularly polarized pulses of extreme ultraviolet radiation. Our results reveal ultrafast and strong helicity-dependent magnetic effects which are in line with the characteristic fingerprints of an IFE, corroborated by ab initio opto-magnetic IFE theory and atomistic spin dynamics simulations. Coherent light-matter interactions mediated by opto-magnetic phenomena like the inverse Faraday effect are expected to provide a non-thermal pathway for ultrafast manipulation of magnetism. The authors use intense and circularly polarized pulses of extreme ultraviolet radiation to induce particularly strong effects in a ferrimagnetic GdFeCo alloy. [ABSTRACT FROM AUTHOR]

Fiber Raman amplification (FRA) systems, based on the stimulated Raman scattering (SRS) effect, can effectively amplify the Raman signals with tremendous application potentials. The FRA systems can transmit the pump and signal simultaneously in the same Raman gain fiber, and effectively shift the optical power from the stronger pump light to the initial weaker signal through the nonlinear Raman process. However, there are always several other nonlinear processes co-existing and competing within the same Raman fiber. These nonlinear effects, in particular the stimulated Brillouin scattering (SBS), severely restrict the maximum output power of the FRA systems. Beginning with the general polarization states, the analysis of polarization mixing efficiency for stimulated Raman and Brillouin scatterings in optical fibers is firstly presented. Considering the polarization mixing efficiency and pump depletion effect, the Brillouin suppression effect induced by the polarization rotation under the influence of an external magnetic field in the fiber Raman amplification systems is fully explained. Based on the polarization mixing analysis, a novel technical scheme for Brillouin scattering suppression, utilizing the principle of Faraday rotation effect with an auxiliary magnetic field, is proposed and analyzed. The numerical analysis indicates that such a magnetic-field-induced suppression scheme can achieve an extra 3-dB Brillouin gain suppression without sacrificing the co-existing Raman amplification gain. [ABSTRACT FROM AUTHOR]

A series of GdIG ceramics with good infrared transparency have been fabricated by a hot-press sintering process with vacuum/oxygen atmosphere. The effects of the powder synthesizing temperature and the ceramic sintering temperature on the phase structure and microstructure of the GdIG ceramics were examined and analyzed. The GdIG ceramic sample sintered at 1275 °C from the Gd 2 O 3 and Fe 2 O 3 powders pre-synthesized at 1000 °C demonstrated an exceptionally high infrared transmittance, it is ≥ 68% within the wavelength range of 1500–5000 nm (t = 0.5 mm). Furthermore, the magnetic and magneto-optic property of the GdIG ceramic samples were investigated and discussed. When a saturation external magnetic field of ∼50 mT acting on the GdIG ceramic sample, the specific Faraday rotation angles are about 104 deg./cm and 51 deg./cm at 1064 and 1550 nm wavelength respectively. It exhibits a good faraday effect of GdIG ceramics which is rarely reported until now. [ABSTRACT FROM AUTHOR]

In this work, we obtain closed expressions for the transfer matrix and the transmittance of electromagnetic waves propagating in finite one-dimensional anisotropic periodic stratified media with an arbitrary number of cells. By invoking the Cayley–Hamilton theorem on the transfer matrix for the electromagnetic field in a periodic stratified media formed by N cells, we obtain a fourth-order recursive relation for the matrix coefficients that defines the so-called Tetranacci polynomials (TPs). In the symmetric case, corresponding to a unit-cell transfer matrix with a characteristic polynomial where the coefficients of the linear and cubic terms are equal, closed expressions for the solutions to the recursive relation, known as symmetric TPs, have recently been derived, allowing us to write the transfer matrix and transmittance in a closed form. We show as sufficient conditions that the 4 × 4 differential propagation matrix of each layer in the binary unit cell, Δ , a) has eigenvalues of the form ± p 1 , ± p 2 , with p 1 ≠ p 2 , and b) its off-diagonal 2 × 2 block matrices possess the same symmetric structure in both layers. Otherwise, the recursive relations are still solvable for any 4 × 4 matrix and provide an algorithm to compute the N th power of the transfer matrix without carrying out explicitly the matrix multiplication of N matrices. We obtain analytical expressions for the dispersion relation and transmittance, in closed form, for two finite periodic systems: the first one consists of two birefringent uniaxial media with their optical axis perpendicular to the z -axis, and the second consists of two isotropic media subject to an external magnetic field oriented along the z -axis and exhibiting the Faraday effect. Our formalism applies also to lossy media, magnetic anisotropy or optical activity. [ABSTRACT FROM AUTHOR]

The current study is dedicated to measuring the Verdet constant of pure and chromium and iron ions doped ZnSe using laser sources in the range from 632.8 to 2430 nm. An increase in the magneto-optical properties of ZnSe as a result of diffusion doping with transition metal ions was experimentally discovered. The results align with the Van Vleck-Hebb theory, which predicts a nearly linear rise in the Verdet constant with increasing of transition element concentration. [ABSTRACT FROM AUTHOR]

Thermally induced depolarization is known to be the principal factor limiting the usage of Faraday devices in laser radiation with high average power. In a number of practically important cases, the major contribution to the depolarization in Faraday devices is inhomogeneous Faraday rotation due to the temperature dependence of the Verdet constant. At the moment there are no satisfactory solutions to this problem. In this work a new scheme of a Faraday isolator with compensation of the contributions to thermally induced depolarization from the temperature dependence of the Verdet constant and thermally induced birefringence was proposed. The efficiency of using the proposed scheme and comparison with known schemes is analyzed analytically and numerically on an example of two magneto-optical crystals: TGG at cryogenic temperature and EuF2 in critical orientation at room temperature in which the contribution to thermally induced depolarization from non-uniform Faraday rotation due to the temperature dependence of the Verdet constant is major. [ABSTRACT FROM AUTHOR]

The nickel element doped holmium oxide (Ho2O3:Ni) transparent magneto‐optical ceramics were fabricated by vacuum sintering and the dopant impacts on structure features and Faraday effects were investigated. The starting oxide powders were synthesized by pyrolyzing the resulting layered holmium‐based hydroxide nanosheets prepared from a chemical precipitation route using the sodium hydroxide as precipitant at the freezing temperature. Upon high‐temperature sintering, the Nii••${\mathrm{Ni}}_i^{ \bullet \bullet }$ defect is introduced by Ni2+ substitution for Ho3+ to form the interstitial solid solution. The 1 at.% Ni2+ doped Ho2O3 ceramic sample exhibits an in‐line transmittance of ∼70.04% at 1 550 nm with a relative density of ∼99.88%, while more Ni2+ incorporation (e.g., 2‒5 at.%) even leads to a completely opaque state. The magneto‐optical transparent Ho2O3:1%Ni ceramic developed in this work has Verdet constants of ∼−195, −65, and −29 rad/(T·m) at 635, 1 064, and 1 550 nm, respectively, which are ∼1.8‐fold higher than the commercial terbium gallium garnet crystal or ∼1.4‐fold higher than the pure Ho2O3 ceramic. This material also possesses relatively large figure of merit of ∼14.6°/T at 1 064 nm and relatively high thermal conductivity of ∼7.5 W/(m·K) at room temperature. [ABSTRACT FROM AUTHOR]

L-band spaceborne polarimetric synthetic aperture radar (PolSAR) data has been well used for the high-resolution retrieval of the ionospheric Faraday rotation (FR). A vast majority of these retrievals were, however, conducted on PolSAR data of lands, with only a very few over oceans. For the global imaging of the Earth's ionosphere, the retrieval of oceanic ionosphere is indispensable. This paper aims to furnish a deep insight into the FR retrieval on oceans using the widely used Bickel-Bates estimator based on the two cross-circular polarizations ${Z_{12}}$ Z 12 and ${Z_{21}}$ Z 21 . The FR estimates (FRE) on oceans are evaluated in detail by comparing with those on lands on four ALOS PALSAR datasets. The achieved oceanic FRE are shown to possess comparable or even better quality than those on lands. It occurs in three of the four scenes that the selected ocean sub-area holds a smaller standard deviation (STD) of FRE (less than 0.7000°) than all the selected land sub-areas. Especially, the quality of FRE is shown to be closely linked to the dispersed degree of the magnitude of the conjugate product of ${Z_{12}}$ Z 12 and ${Z_{21}}$ Z 21 via the analysis of coefficient of variation (CV), according to which the unusual occurrence of larger magnitude level corresponding to larger STD of FRE can be explained. Nevertheless, compared with CV, the magnitude of the polarimetric coherence between ${Z_{12}}$ Z 12 and ${Z_{21}}$ Z 21 (i.e. $\left| \gamma \right|$ γ ) is identified as a better index to measure the quality of FRE. A smaller STD of FRE appears along with a larger $\left| \gamma \right|$ γ . Three of the four scenes show that the selected ocean sub-area bears a larger mean of $\left| \gamma \right|$ γ (greater than 0.9890) in comparison with all the selected land sub-areas. This work can promote the ionospheric research over oceans and to the correction of ionospheric effects in oceanic L-band spaceborne polarimetric radar data as well. [ABSTRACT FROM AUTHOR]

Electrically tunable metasurfaces with pixel-level phase control are good candidates for dynamic manipulation of the beam direction in the terahertz band, which is a critical and highly desired technique for next generation communications. Yet the complex biasing, limited aperture and cross talk hinders its progress. In this study, we propose a magnetic-field-globally controlled metasurface for beam switching. The metasurface is composed of a bi-layer silicon metagrating on a magneto-optical substrate InSb. The beam direction is governed by two physical processes: the magnetically-controlled polarization and the polarization-controlled diffraction. By utilizing the circular dichroism and Faraday rotation effects in InSb, the metasurface can operate at two frequency bands. The beam is switched among four directions by properly choosing the magnetic field biasing and the frequency. This study offers a promising solution for beam management using magnetic field biasing and in a global manner. [ABSTRACT FROM AUTHOR]

Reciprocity is a fundamental principle that follows the time reversal symmetry of physics. However, many practical applications require breaking time reversal symmetry, hence, are called nonreciprocal. This article aims at discussing time reversal symmetry, developing fundamental building block to achieve nonreciprocity leading to robust analytical model to explain electromagnetic rotation upon propagation through a nonreciprocal medium. Detailed mathematical derivation is presented for Faraday and Kerr rotation in the presence of external bias which breaks time reversal symmetry and leads to achieve nonreciprocal system. We validate our proposed model for conventional conditions and we compute the Faraday and Kerr rotation from a reported article using our proposed mathematical model and observed excellent agreement. [ABSTRACT FROM AUTHOR]

In the development of atomic physics, laser sources with Frequencies corresponding to atomic transition and high stability are essential. The Faraday laser is a special diode laser using the Faraday anomalous dispersion optical filter (FADOF) to realize frequency selection, so the output laser frequency is automatically limited to the atomic Doppler broadening. However, the frequency of a Faraday laser corresponds to the range around only one atomic hyperfine transition. Here, we realize a switchable Faraday laser with two isotopes laser frequencies corresponding to 85Rb 5 2 S 1 / 2 (F = 3) → 5 2 P 3 / 2 and 87Rb 5 2 S 1 / 2 (F = 2) → 5 2 P 3 / 2 transitions based on a single isotope 87Rb-FADOF. The laser has good robustness against the fluctuation of diode current and temperature, with wavelength fluctuating within 0.8 pm from 16 to 30 °C of diode temperature, and has a free-running linewidth of 18 kHz. We also lock the laser frequency to the two cycling transitions of 85Rb 5 2 S 1 / 2 (F = 3) → 5 2 P 3 / 2 (F ′ = 4) and 87Rb 5 2 S 1 / 2 (F = 2) → 5 2 P 3 / 2 (F ′ = 3) by the modulation transfer spectroscopy technique. The Allan deviation of the residual error signal is 3 × 10 − 14 / τ , and the frequency stability of the beat detection reaches 2.8 × 10 − 12 at 1 s integration time. This 780 nm switchable Faraday laser expands the application scenarios of Faraday lasers, which can be used in laser cooling atoms, optical frequency standards, and other quantum precision measurement fields. [ABSTRACT FROM AUTHOR]

The origin of the cosmic magnetic field remains an unsolved mystery, relying not only on specific dynamo processes but also on the seed field to be amplified. Recently, the diffuse radio emission and Faraday rotation observations reveal that there has been a microgauss-level magnetic field in intracluster medium in the early universe, which places strong constraints on the strength of the initial field and implies the underlying kinetic effects; the commonly believed Biermann battery can only provide extremely weak seed of 10-21 G. Here, we present evidence for the spontaneous Weibel-type magnetogenesis in laser-produced weakly collisional plasma with the three-dimensional synchronous proton radiography, where the distribution anisotropy directly arises from the temperature gradient, even without the commonly considered interpenetrating plasmas or shear flows. This field can achieve sufficient strength and is sensitive to Coulomb collision. Our results demonstrate the importance of kinetics in magnetogenesis in weakly collisional astrophysical scenarios. [ABSTRACT FROM AUTHOR]

The spin degree of freedom of charge carriers in halide‐perovskite semiconductors can be highly useful for information photonics applications. The Faraday effect is known to be the best indicator of paramagnetism of the material and of the spin‐light interaction. In this work, the Faraday effect is demonstrated, for the first time, in a hybrid organic–inorganic halide perovskite MAPbI3 (MA+ = CH3NH3+$_3^+$). The Faraday rotation and birefringence are measured across the tetragonal‐cubic phase transition at 327 K. The Faraday rotation is strongly suppressed below the phase transition temperature due to anisotropy (linear birefringence) of the tetragonal crystal phase. The situation changes drastically above the phase transition temperature, when the crystal becomes optically isotropic. The emerging Faraday rotation obeys the Curie law, demonstrating its population‐related paramagnetic nature. This observation opens new prospects for application of these systems and for their investigations using methods of the polarization noise spectroscopy applicable to optically anisotropic materials. [ABSTRACT FROM AUTHOR]

There is increasing interest in space domain awareness worldwide, motivating investigation of the use of non-traditional sensors for space surveillance. One such class of sensor is VHF wind profiling radars, which have a low cost relative to other radars typically applied to this task. These radars are ubiquitous throughout the world and may potentially offer complementary space surveillance capabilities to the Space Surveillance Network. This paper updates an initial investigation on the use of Buckland Park VHF wind profiling radars for observing resident space objects in low Earth orbit to further investigate the space surveillance capabilities of the sensor class. The radar was operated during the Australian Defence "SpaceFest" 2019 activity, incorporating new beam scheduling and signal processing functionality that extend upon the capabilities described in the initial investigation. The beam scheduling capability used two-line element propagations to determine the appropriate beam direction to use to observe transiting satellites. The signal processing capabilities used a technique based on the Keystone transform to correct for range migration, allowing the development of new signal processing modes that allow the coherent integration time to be increased to improve the SNR of the observed targets, thereby increasing the detection rate. The results reveal that 5874 objects were detected over 10 days, with 2202 unique objects detected, representing a three-fold increase in detection rate over previous single-beam direction observations. The maximum detection height was 2975.4 km, indicating a capability to detect objects in medium Earth orbit. A minimum detectable RCS at 1000 km of −10.97 dBm2 (0.09 m2) was observed. The effects of Faraday rotation resulting from the use of linearly polarised antennae are demonstrated. The radar's utility for providing total electron content (TEC) measurements is investigated using a high-range resolution mode and high-precision ephemeris data. The short-term Fourier transform is applied to demonstrate the radar's ability to investigate satellite rotation characteristics and monitor ionospheric plasma waves and instabilities. [ABSTRACT FROM AUTHOR]

An IR-transparent magneto-optical Dy 2 O 3 –MgO compositeceramics was fabricated by vacuum hot pressing of glycine-nitrate self-propagating high-temperature synthesized nanopowders. Composites significantly outperform dysprosium sesquioxide ceramics in terms of thermal conductivity and mechanical properties.The HV1 microhardness of the Dy 2 O 3 –MgO composite is 9.9 GPa and the fracture toughness K IC , calculated by the Palmquist method, is 1.7 MPa m½. The thermal conductivity of the composite was measured in the range of 50–300 K and is 10.6 W/(m K) at room temperature. The transmittance of 1.5 mm thick Dy 2 O 3 –MgO sample is about 70 % in the wavelength range ∼2.1–2.2 μm and more than 80 % in the range ∼3.6–6.5 μm, which is close to the theoretical value for dysprosium sesquioxide.The value of Verdet constant of Dy 2 O 3 –MgO composite ceramics is 7.0 ± 0.3 rad/(T∙m)at 1940 nm. [ABSTRACT FROM AUTHOR]

We propose an all-optical approach to realize a super-oscillatory longitudinal magnetization hotspot with about 0.1 λ in a 4 π focusing system using time-reversed dipole radiation and vector diffraction theory calculations. Such a magnetization behavior is induced by focal fields of opposite polarities in the central and peripheral regions based on the inverse Faraday effect. By regulating the destructive interference in the central and peripheral regions of the focal field, a super-oscillating magnetization field is generated. Moreover, two important parameters affect the size of the magnetization field are also explored. Superoscillating magnetization hotspots in the focal region can be achieved by either increasing δ (the intensity of electric field) or reducing d n (the distance of electric field). The achieved ultrasmall magnetization spot shows great prospects in high-density magnetic recording, magnetic resonance imaging, and magnetic sensors. [ABSTRACT FROM AUTHOR]

The work is motivated by the Faraday cage effect. We consider the Helmholtz equation over a 3D domain containing a thin heterogeneous interface of thickness $ \delta \ll 1 $ δ ≪ 1. The layer has a δ-periodic structure in the in-plane directions and is cylindrical in the third direction. The periodic layer has one connected component and a collection of isolated regions. The isolated region in the thin layer represents air or liquid, and the connected component represents a solid metal grid with a δ thickness. The main issue is created by the contrast of the coefficients in the air and in the grid and that the zero-order term has a complex-valued coefficient in the connected faze while a real-valued in the complement. An asymptotic analysis with respect to $ \delta \to 0 $ δ → 0 is provided, and the limit Helmholtz problem is obtained with the Dirichlet condition on the interface. The periodic unfolding method is used to find the limit. [ABSTRACT FROM AUTHOR]

An X-pinch load driven by an intense current pulse (> 100 kA in ∼100 ns) can result in the formation of a small radius, runaway compressional micro-pinch. A micro-pinch is characterized by a hot (>1 keV), current-driven (> 100 kA), high-density plasma column (near solid density) with a small neck diameter (1–10 µm), a short axial extent (< 1 mm), and a short duration (≲1 ns). With material pressures often well into the multi-Mbar regime, a micro-pinch plasma often radiates an intense, sub-ns burst of sub-keV to multi-keV x rays. A low-density coronal plasma immediately surrounding the dense plasma neck could potentially shunt current away from the neck and thus reduce the magnetic drive pressure applied to the neck. To study the current distribution in the coronal plasma, a Faraday rotation imaging diagnostic (1064 nm) capable of producing simultaneous high-magnification polarimetric and interferometric images has been developed for the MAIZE facility at the University of Michigan. Designed with a variable magnification (1–10×), this diagnostic achieves a spatial resolution of ∼35 µm, which is useful for resolving the ∼100-μm-scale coronal plasma immediately surrounding the dense core. This system has now been used on a reduced-output MAIZE (100–200 kA, 150 ns) to assess the radial distribution of drive current immediately surrounding the dense micro-pinch neck. The total current enclosed was found to increase as a function of radius, r, from a value of ≈ 50 ± 25 kA at r ≈ 140 µm (at the edge of the dense neck) to a maximal value of ≈ 150 ± 75 kA for r ≥ 225 µm. This corresponds to a peak magnetic drive pressure of ≈ 75 ± 50 kbar at r ≈ 225 µm. The limitations of these measurements are discussed in the paper. [ABSTRACT FROM AUTHOR]

Ultrasound is extremely efficient for wireless signal transmission through metal barriers due to no limit of the Faraday shielding effect. Echoing in the ultrasonic channel is one of the most challenging obstacles to performing high-quality communication, which is generally coped with by using a channel equalizer or pre-distorting filter. In this study, a deep learning algorithm called a dual-path recurrent neural network (DPRNN) was investigated for echo cancellation in an ultrasonic through-metal communication system. The actual system was constructed based on the combination of software and hardware, consisting of a pair of ultrasonic transducers, an FPGA module, some lab-made circuits, etc. The approach of DPRNN echo cancellation was applied to signals with a different signal-to-noise ratio (SNR) at a 2 Mbps transmission rate, achieving higher than 20 dB SNR improvement for all situations. Furthermore, this approach was successfully used for image transmission through a 50 mm thick aluminum plate, exhibiting a 24.8 dB peak-signal-to-noise ratio (PSNR) and a about 95% structural similarity index measure (SSIM). Additionally, compared with three other echo cancellation methods—LMS, RLS and PNLMS—DPRNN has demonstrated higher efficiency. All those results firmly validate that the DPRNN algorithm is a powerful tool to conduct echo cancellation and enhance the performance of ultrasonic through-metal transmission. [ABSTRACT FROM AUTHOR]

The MeerKAT International GigaHertz Tiered Extragalactic Exploration (MIGHTEE) is one of the MeerKAT large survey projects, designed to pathfind SKA key science. MIGHTEE is undertaking deep radio imaging of four well-observed fields (COSMOS, XMM -LSS, ELAIS S1, and CDFS) totaling 20 square degrees to μJy sensitivities. Broad-band imaging observations between 880 and1690 MHz yield total intensity continuum, spectro-polarimetry, and atomic hydrogen spectral imaging. Early science data from MIGHTEE are being released from initial observations of COSMOS and XMM –LSS. This paper describes the spectro-polarimetric observations, the polarization data processing of the MIGHTEE early science fields, and presents polarization data images and catalogues. The catalogues include radio spectral index, redshift information, and Faraday rotation measure synthesis results for 13 267 total intensity radio sources down to a polarized intensity detection limit of ∼20 μJy bm−1. Polarized signals were detected from 324 sources. For the polarized detections, we include a catalogue of Faraday Depth from both Faraday Synthesis and Q, U fitting, as well as total intensity and polarization spectral indices. The distribution of redshift of the total radio sources and detected polarized sources are the same, with median redshifts of 0.86 and 0.82, respectively. Depolarization of the emission at longer-wavelengths is seen to increase with decreasing total-intensity spectral index, implying that depolarization is intrinsic to the radio sources. No evidence is seen for a redshift dependence of the variance of Faraday depth. [ABSTRACT FROM AUTHOR]

Here, we consider the general radiative transfer theory in a magnetized atmosphere for any value of parameter |$x=\omega _B/\omega \simeq 0.933\times 10^{-8}\lambda (\mu \mathrm{m}) B(\text{G})$|⁠ , where ω B is the cyclotron frequency of electron rotation and ω is the angular frequency of considered monochromatic radiation. The main term of the radiative transfer equations  |$\textbf {J}_{\alpha \beta }$| for the Stokes parameters I, V, U , and Q describes the scattering of radiation coming from all directions and distances. All Stokes parameters of the incident radiation mutually transform into each other along their path due to interference and different cross-sections for them. To find this transformation of the Stokes parameters one has to solve the complex system of transfer equations without the sources and term |$\textbf {J}_{\alpha \beta }$|⁠. This is done in our paper. First, we present the general solution and then give the solution for the case of a homogeneous magnetic field, where the formulas have clear algebraic form. We note that for small parameter x our formulas describe the known Faraday rotation. Our formulas allow us to derive an integral equation for the density of polarized radiation, multiple scattered in a magnetized atmosphere for any values of the parameter x. The obtained correct radiation transfer equation allows us to calculate the Stokes parameters of radiation emerging from an atmosphere, in particular, for the Milne problem. [ABSTRACT FROM AUTHOR]

LOFAR (LOw Frequency ARray) has previously detected bursts from the periodically active, repeating fast radio burst (FRB) source FRB 20180916B down to unprecedentedly low radio frequencies of 110 MHz. Here, we present 11 new bursts in 223 more hours of continued monitoring of FRB 20180916B in the 110–188 MHz band with LOFAR. We place new constraints on the source's activity window |$w =4.3^{+0.7}_{-0.2}$|  d and phase centre |$\phi _{\mathrm{c}}^{\mathrm{LOFAR}} = 0.67^{+0.03}_{-0.02}$| in its 16.33-d activity cycle, strengthening evidence for its frequency-dependent activity cycle. Propagation effects like Faraday rotation and scattering are especially pronounced at low frequencies and constrain properties of FRB 20180916B's local environment. We track variations in scattering and time–frequency drift rates, and find no evidence for trends in time or activity phase. Faraday rotation measure (RM) variations seen between June 2021 and August 2022 show a fractional change >50 per cent with hints of flattening of the gradient of the previously reported secular trend seen at 600 MHz. The frequency-dependent window of activity at LOFAR appears stable despite the significant changes in RM, leading us to deduce that these two effects have different causes. Depolarization of and within individual bursts towards lower radio frequencies is quantified using LOFAR's large fractional bandwidth, with some bursts showing no detectable polarization. However, the degree of depolarization seems uncorrelated to the scattering time-scales, allowing us to evaluate different depolarization models. We discuss these results in the context of models that invoke rotation, precession, or binary orbital motion to explain the periodic activity of FRB 20180916B. [ABSTRACT FROM AUTHOR]

3C 84 is a well‐known supermassive black hole that can be used to explore jet and accretion physics. In this work, we model the multiwavelength spectral energy distribution (SED) of the 3C 84, and find that the SED is difficult to fit with pure advection dominated accretion flow (ADAF) or pure jet model. Using a coupled ADAF‐jet model to fit the SED of 3C 84, it is found that the radio emission and the millimeter emission can be naturally reproduced by the synchrotron radiation of nonthermal electrons in the jet, and that the X‐ray emission may predominantly come from inverse Compton radiation from electrons in ADAF. According to the Rotation Measure (RM) obtained by the polarization observation, we consider the possible location of the polarizing source and found that the calculated RM in the jet is roughly consistent with the observational constraints. These results will help us better understand jets produced by black holes. [ABSTRACT FROM AUTHOR]

Thin film samples like transparent conducting oxides (TCO) are typically investigated using measurements like Hall Effect and 4-point probe measurements. We use a sensitive AC Faraday rotation (FR) setup to study thin film samples for which a magneto-optic response is challenging to characterize. The experimental setup employs a stabilized He-Ne laser (633 nm) along with an AC magnetic field that enables lock-in detection. We investigate a series of TCO samples that are deposited on a glass substrate. The TCO samples include the more widely used Indium Tin Oxide (ITO) and the relatively newer Fluorine doped Tin Oxide films, usually referred to as FTO. These films have a magneto-optic response due to the presence of free carrier concentration and therefore measurement of this response (Verdet constant) could allow one to determine the carrier concentration of these films. Given that magneto optic responses like FR depend on the length of the sample length traveled by light, these sub-micron films pose considerable challenges in trying to extract the FR response of the film from that of the much thicker glass substrate. Furthermore, we present details of the design and FR characterization of samples using a Michelson interferometer-based measurement setup which enhances the Faraday rotation and affords a new means of studying harmonic peaks of the recorded optical signal in response to a sinusoidally-varying applied magnetic field. We compare some early results from this setup to the typical "single-pass" setup to highlight the difference in the recorded signals from the two setups. To showcase the advantages of the proposed measurements, we also include some early results from a very different type of sample, namely superparamagnetic nanoparticles (SNPs). [ABSTRACT FROM AUTHOR]

We investigated the time evolution of the density of giant spin polarons in a magnetic semiconductor. Spin polarons (SPs) were photoexcited and observed using time-resolved Faraday rotation. We find the existence of two types of SPs, a short-lived spin polaron with a lifetime of around τsl = 0.5 ns and a long-lived spin polaron with a lifetime of τll = 0.45 ± 0.03 µs, at T = 5 K. The stark difference of three order of magnitude between these lifetimes suggests that in the long lived SP the electron-hole pair is relaxed and its recombination is forbidden. The short-lived SP is probably associated with SP recombination before such relaxation has occured. An extraordinary finding is that the magnitude of τsl, as well as its decrease with increasing temperature, reproduces exactly the characteristic time for SP growth. This suggests that the thermal fluctuations, responsible for SP magnetic moment growth, are also responsible for increasing the recombination probability of SPs. [ABSTRACT FROM AUTHOR]

This paper presents a novel scheme to online measure the birefringence of the sensing fiber in all‐fiber optic current transformer (AFOCT) system, which monitors the current on direct current (DC) transmission lines using the Faraday magneto‐optic effect in sensing fibers. In this scheme, by purposefully varying the difference of square‐wave modulated phases via the phase modulator in the AFOCT system, different system transmittances can be obtained. On the basis of the relationship between the system transmittance and linear and circular birefringences, an online measurement scheme of both the linear and circular birefringences of the sensing fibers can be established. In this scheme, the AFOCT system is described by the transmission model based on the Jones matrices, with which the current on DC transmission lines can be measured from the phase shift caused by the Faraday effect. Then, under different square‐wave modulated phases, the system transmittance models are constructed with respect to the linear and circular birefringences of the sensing fiber. For a given sensing fiber with certain linear and circular birefringences, the specific system transmittances are determined and are the curves in space in the respective system transmittance models. Subsequently, these curves in space can be projected onto the coordinate plane composed of the linear and circular birefringence coordinate axes, where the intersection point of the projected plane curves gives the to‐be‐measured values of the linear and circular birefringences of the sensing fiber. The proposed scheme is validated by the preset linear and circular birefringences of the sensing fiber, with different linear birefringences of the polarization‐maintaining fiber. The measurement results show the values consistent with the preset ones. [ABSTRACT FROM AUTHOR]

We have developed the method of periodic principal components for signals with a quasi-periodic dynamic spectrum characteristic of radio pulsars. The method is based on an analysis of the eigenvectors and eigenvalues of the signal frequency–time correlation matrix averaged over many pulsar rotation periods. Using the observations of PSR B0329 54 with the radio telescope at Pushchino Radio Astronomy Observatory near a frequency of 111 MHz in a 2.5 MHz band as an example, we show that even for short data intervals (a few minutes) the developed method allows one to identify up to nine pulse components of the pulsar, to estimate the correlation between them, and to find the period of Faraday modulation for each component as well as its relative phase and frequency–time chirp rate, i.e., it allows the structure of the emission source to be judged. [ABSTRACT FROM AUTHOR]

Context. 3C 84 is a nearby radio source with a complex total intensity structure, showing linear polarisation and spectral patterns. A detailed investigation of the central engine region necessitates the use of very-long-baseline interferometry (VLBI) above the hitherto available maximum frequency of 86 GHz. Aims. Using ultrahigh resolution VLBI observations at the currently highest available frequency of 228 GHz, we aim to perform a direct detection of compact structures and understand the physical conditions in the compact region of 3C 84. Methods. We used Event Horizon Telescope (EHT) 228 GHz observations and, given the limited (u, v)-coverage, applied geometric model fitting to the data. Furthermore, we employed quasi-simultaneously observed, ancillary multi-frequency VLBI data for the source in order to carry out a comprehensive analysis of the core structure. Results. We report the detection of a highly ordered, strong magnetic field around the central, supermassive black hole of 3C 84. The brightness temperature analysis suggests that the system is in equipartition. We also determined a turnover frequency of νm = (113 ± 4) GHz, a corresponding synchrotron self-absorbed magnetic field of BSSA = (2.9 ± 1.6) G, and an equipartition magnetic field of Beq = (5.2 ± 0.6) G. Three components are resolved with the highest fractional polarisation detected for this object (mnet = (17.0 ± 3.9)%). The positions of the components are compatible with those seen in low-frequency VLBI observations since 2017–2018. We report a steeply negative slope of the spectrum at 228 GHz. We used these findings to test existing models of jet formation, propagation, and Faraday rotation in 3C 84. Conclusions. The findings of our investigation into different flow geometries and black hole spins support an advection-dominated accretion flow in a magnetically arrested state around a rapidly rotating supermassive black hole as a model of the jet-launching system in the core of 3C 84. However, systematic uncertainties due to the limited (u, v)-coverage, however, cannot be ignored. Our upcoming work using new EHT data, which offer full imaging capabilities, will shed more light on the compact region of 3C 84. [ABSTRACT FROM AUTHOR]

We report on 85−101 GHz light curves of the Galactic Center supermassive black hole, Sagittarius A* (Sgr A*), observed in April 2017 with the Atacama Large Millimeter/submillimeter Array (ALMA). This study of high-cadence full-Stokes data provides new measurements of the fractional linear polarization at a 1−2% level resolved in 4 s time segments, and stringent upper limits on the fractional circular polarization at 0.3%. We compare these findings to ALMA light curves of Sgr A* at 212−230 GHz observed three days later, characterizing a steep depolarization of the source at frequencies below about 150 GHz. We obtain time-dependent rotation measure (RM) values, with the mean RM at 85−101 GHz being a factor of two lower than that at 212−230 GHz. Together with the rapid temporal variability of the RM and its different statistical characteristics in both frequency bands, these results indicate that the Faraday screen in Sgr A* is largely internal, with about half of the Faraday rotation taking place inside the inner 10 gravitational radii, contrary to the common external Faraday screen assumption. We then demonstrate how this observation can be reconciled with theoretical models of radiatively inefficient accretion flows for a reasonable set of physical parameters. Comparisons with numerical general relativistic magnetohydrodynamic simulations suggest that the innermost part of the accretion flow in Sgr A* is much less variable than these models predict; in particular, the observed magnetic field structure appears to be coherent and persistent. [ABSTRACT FROM AUTHOR]

A magnetophotonic crystal (MPC) with a locally etched magnetic layer is proposed for all-optical excitation of magnetization precession in the confined area. When the sample is illuminated by circularly polarized monochromatic plane wave, the optical MPC mode and the effective magnetic field excited by the inverse Faraday effect are localized inside the etched area. Therefore, the optical impact on the spin system in a magnetically ordered medium becomes confined in both lateral directions on the order of tens of nanometers and along the film thickness serving as a nanoconfined source of spin waves. The dependence of the spatial distribution of the effective magnetic field and magnetization precession amplitude on the depth and dimensions of the etched area are addressed. A proposed design of the MPC can find its applications in the field of magnetization dynamics generation as a compact and stable source of the spin waves that allows compact arrangement of the sources for some complex spin waves excitations. [ABSTRACT FROM AUTHOR]

R 3 Fe 5 O 12 (RIG) crystals are the key elements for magneto-optical isolators in the near-infrared (NIR) to mid-infrared (MIR) region, with ever-growing demands for integrated photonics. However, the growth of high-quality single crystals is still a big obstacle. The effect of rare earths on the optical and magneto-optical properties of YIG crystals is not well understood. Herein, a series of high quality Tb3+ doped yttrium iron garnet (Y 3-x Tb x Fe 5 O 12 , x = 0, 0.5, 1.0, 1.5, 3.0) crystals have been successfully obtained by the flux-Bridgman method, with sizes over 20 mm. Tb:YIG crystals reserve typical cubic garnet structure, with spatial group of Ia3d. The lattice constants increase from 12.377 Å (YIG) to 12.448 Å (TbIG). The refractive index decreases from 2.38 (500 nm) to 2.11 (2500 nm) for YIG crystal, and it reduces from 2.51 (500 nm) to 2.17 (2500 nm) for TbIG crystal. The optical dispersion of the refractive indices was well fitted by the Wemple and DiDomenico (WDD) and the Sellmeier models, respectively. Relatively lower values of the absorption coefficient of the Tb:YIG crystals confirm the high transparency in the NIR region. The characteristic absorption of Tb3+ was observed from 1700 nm to 2500 nm. The specific Faraday rotation angles (θ F) of both YIG and TbIG decrease with increasing wavelength, reaching 235.4 and 366.5 °/cm at 1300 nm, respectively. Compared with that of YIG, θ F of TbIG crystal shows stronger wavelength dependence. This work provides more insight into the role of rare earths on the optical and magneto-optical behavior of RIG crystals, which will accelerate the design of high-performance magneto-optical crystals for application in NIR-MIR wavelength. [ABSTRACT FROM AUTHOR]

Epsilon‐near‐zero (ENZ) materials exhibit near‐zero permittivity and induce various intriguing linear and nonlinear optical phenomena. Magneto‐optical (MO) effects, which are notoriously weak in the optical domain, have been predicted to be significantly enhanced in ENZ materials, which can facilitate the realization of compact nonreciprocal devices. However, to date, enhanced MO effects have been predominantly observed in effective ENZ media, which are commonly based on complex combinations of photonic nanostructures. It is difficult for these effective media to achieve isotropic ENZ responses, which severely limits their use in the development of ENZ‐MO devices. Here, enhanced MO effects in pristine indium tin oxide (ITO) with ENZ properties at technologically important telecommunication wavelengths are demonstrated. MO transmission (reflection) spectroscopy of ITO films with different ENZ wavelengths reveal Faraday (Kerr) rotation peaks around the respective ENZ (EN‐one) wavelengths, demonstrating that these observations are due to the intrinsic properties of the ITO materials. The demonstrated mechanism of the MO effect enhancement is universal and can be applied to various ENZ materials, including those incorporating ferromagnetic materials. Native ENZ materials with enhanced MO responses will greatly expand the opportunities for the development of novel nonreciprocal nanophotonic devices, such as on‐chip optical isolators and one‐way topological waveguides. [ABSTRACT FROM AUTHOR]

Nonreciprocal materials and devices play an irreplaceable role in isolating, routing, and multiplexing. However, in the terahertz (THz) band, their active control mechanisms are still limited. Herein, a THz nonreciprocal photonic spin transmission is demonstrated in the undoped InSb actively manipulated by a light‐magneto‐joint modulation method, in which THz cyclotron resonance of the photoinduced carriers is conjunctively excited by both pump laser and external magnetic field. Moreover, a diffusion model of photoinduced non‐equilibrium carriers and its nonreciprocal dispersion model of magnetized plasma are established to interpret the experimental observation. The results indicate that the light‐magneto‐joint modulation achieves a broadband amplitude‐phase modulation with a higher modulation depth (>2π rad phase shift), as well as an active nonreciprocal spin transmission with magnetic circular dichroism (>20dB) and the Faraday rotation effect (>90°) in InSb, which is more efficient and faster than the traditional thermal excitation. Furthermore, the demonstration in a single‐frequency THz transmission system shows that this light‐magneto‐joint modulation mechanism in InSb can be multifunctionally applied in active control, isolation, and polarization conversion. [ABSTRACT FROM AUTHOR]

Nonreciprocal devices, including optical isolators, phase shifters, and amplifiers, are pivotal for advanced optical systems. However, exploiting natural materials is challenging due to their weak magneto‐optical (MO) effects, requiring substantial thickness to construct effective optical devices. In this study, it is demonstrated that subwavelength metasurfaces supporting bound states in the continuum (BICs) and made of conventional ferrimagnetic material can exhibit strong nonreciprocity in the Faraday configuration and near‐unity magnetic circular dichroism (MCD). These metasurfaces enhance the MO effect by 3–4 orders of magnitude compared to a continuous film of the same material. This significant enhancement is achieved by leveraging Huygens' condition in the metasurface whose structural units support paired electric and magnetic dipole resonances. The multi‐mode temporal coupled mode theory (CMT) is developed for the observed enhancement of the MO effect, and the findings with the full‐wave simulations are confirmed. [ABSTRACT FROM AUTHOR]

Does gravity affect the polarization of electromagnetic radiation in an observable way? The effect of gravity on the observed polarization of a ray of electromagnetic radiation is investigated for an arbitrary 4-dimensional spacetime and radiation with a frequency spectrum within the geometric optics limit and with arbitrary state of polarization. Focusing on effects observable by a single inertial observer, we show how the presence of curvature along the null geodesic of polarized electromagnetic radiation may induce observable changes in the state of polarization. We find a set of scalars that quantify the effect and derive their transport equations. Two of these scalars, the polarization degree and the circular polarization degree, are polarization state observables that are conserved along the radiation geodesic. Four observables that quantify time rate of change of the observed state of polarization are identified. One observable, the polarization axis rotation rate, measures angular motion of the polarization axis. The presence of curvature along the null geodesic of polarized electromagnetic radiation may induce rotation of the polarization axis of the radiation, as measured by an inertial observer. These observables quantify gravitational effects on electromagnetic polarization unambiguously. They are generally sensitive to gravity, which implies that polarized electromagnetic radiation can potentially be used to measure the gravitational fields it traverses. These observables and their corresponding transport equations provide a complete representation of how gravity affects the observed state of polarization of electromagnetic radiation with frequencies above the geometric optics limit. Polarization wiggling is sourced by curvature twist, which is a scalar derived from the Riemann tensor. Curvature twist is closely related to the magnetic part of the Weyl tensor, the second Weyl scalar as well as the rotation of the rest frame geodesic congruence. The results of this paper are valid for any metric theory of gravity. [ABSTRACT FROM AUTHOR]

Nonreciprocal devices, such as isolators, are of great importance for optical communication and optical information processing. To bypass the limitation of a strong magnetic field imposed by the traditional Faraday magneto-optic effect, many alternative mechanisms have been proposed to demonstrate magnetic-free nonreciprocity. However, limited by the drive-induced noise, the noiseless isolator capable of working in the quantum regime has yet to be realized in the experiment. Here, we show a noiseless all-optical isolator with genuine single photons in hot atoms. We experimentally study this mechanism using an open V-type level scheme and demonstrate a low insertion loss of 0.6 dB and high isolation of 30.3 dB with bandwidth up to hundreds of megahertz. Furthermore, the nonreciprocal direction can be truly reversed only by tuning the frequency of the pump laser with the same setup. Our scheme relies on widely used optical technology and is thus universal and robust. The single-photon isolator is in high demand for optical communications and optical information processing in the quantum regime, but the noise is still a limitation. Here, the author theoretically propose a noiseless single-photon isolator scheme and demonstrate experimentally using hot atoms. [ABSTRACT FROM AUTHOR]

We use the TNG50 cosmological magnetohydrodynamical simulation of the IllustrisTNG project to show that magnetic fields in the circumgalactic medium (CGM) have significant angular structure. This azimuthal anisotropy at fixed distance is driven by galactic feedback processes that launch strong outflows into the halo, preferentially along the minor axes of galaxies. These feedback-driven outflows entrain strong magnetic fields from the interstellar medium, dragging fields originally amplified by small-scale dynamos into the CGM. At the virial radius, z  = 0 galaxies with M⋆ ∼  |$10^{10}\, \rm {M_\odot }$| show the strongest anisotropy (∼0.35 dex). This signal weakens with decreasing impact parameter, and is also present but weaker for lower mass as well as higher mass galaxies. Creating mock Faraday rotation measure (RM) sightlines through the simulated volume, we find that the angular RM trend is qualitatively consistent with recent observational measurements. We show that rich structure is present in the circumgalactic magnetic fields of galaxies. However, TNG50 predicts small RM amplitudes in the CGM that make detection difficult as a result of other contributions along the line of sight. [ABSTRACT FROM AUTHOR]

We present full-track high-resolution radio observations of the jet of the galaxy M87 at 8 and 15 GHz. These observations were taken over three consecutive days in 2009 May using the Very Long Baseline Array (VLBA), one antenna of the Very Large Array (VLA), and the Effelsberg 100 m telescope. Our produced images have dynamic ranges exceeding 20 000:1 and resolve linear scales down to approximately 100 Schwarzschild radii, revealing a limb-brightened jet and a faint, steep spectrum counter-jet. We performed jet-to-counter-jet analysis, which helped estimate the physical parameters of the flow. The rich internal structure of the jet is dominated by three helical threads, likely produced by the Kelvin–Helmholtz (KH) instability developing in a supersonic flow with a Mach number of approximately 20 and an enthalpy ratio of around 0.3. We produce a clean imaging bias-corrected 8–15 GHz spectral index image, which shows spectrum flattening in regions of helical thread intersections. This further supports the KH origin of the observed internal structure of the jet. We detect polarized emission in the jet at distances of approximately 20 milliarcseconds from the core and find Faraday rotation which follows a transverse gradient across the jet. We apply Faraday rotation correction to the polarization position angle and find that the position angle changes as a function of distance from the jet axis, which suggests the presence of a helical magnetic field. [ABSTRACT FROM AUTHOR]

As the sample size of repeating fast radio bursts (FRBs) has grown, an increasing diversity of phenomenology has emerged. Through long-term multi-epoch studies of repeating FRBs, it is possible to assess which phenomena are common to the population and which are unique to individual sources. We present a multi-epoch monitoring campaign of the repeating FRB source 20180301A using the ultra-wideband low (UWL) receiver observations with Murriyang , the Parkes 64-m radio telescope. The observations covered a wide frequency band spanning approximately 0.7–4 GHz, and yielded the detection of 46 bursts. None of the repeat bursts displayed radio emission in the range of 1.8–4 GHz, while the burst emission peaked at 1.1 GHz. We discover evidence for secular trends in the burst dispersion measure, indicating a decline at a rate of |$-2.7\pm 0.2\, {\rm pc\, cm^{-3}\, yr^{-1}}$|⁠. We also found significant variation in the Faraday rotation measure of the bursts across the follow-up period, including evidence of a sign reversal. While a majority of bursts did not exhibit any polarization, those that did show a decrease in the linear polarization fraction as a function of frequency, consistent with spectral depolarization due to scattering, as observed in other repeating FRB sources. Surprisingly, no significant variation in the polarization position angles was found, which is in contrast with earlier measurements reported for the FRB source. We measure the burst rate and sub-pulse drift rate variation and compare them with the previous results. These novel observations, along with the extreme polarization properties observed in other repeating FRBs, suggest that a sub-sample of FRB progenitors possess highly dynamic magneto-ionic environments. [ABSTRACT FROM AUTHOR]

Radio waves propagating the ionosphere are subject to a number of unpredictable and corrupting effects, the most significant of which are phase path reduction, Faraday rotation, and scintillation. A method of measuring these effects is necessary in order to study and understand the solar-terrestrial connections, as well as to anticipate their impact on radio systems. However, limitations in current measurement solutions, most notably the lack of direct ionospheric Faraday rotation measurement capability, restricts the ability to characterize the ionosphere to a sufficient degree for applications such as the detection of coronal mass ejections. The rise in popularity of small satellites presents a new cost-effective opportunity to study and observe the ionosphere in detail, however the challenge of realizing a beacon within the constraints of a small satellite system must be overcome. In this paper, we introduce a measurement technique that builds on past multi-frequency beacons, incorporating the well established differential phase technique, as well as introducing a new differential polarization technique. We achieve this by employing linearly polarized beacon signals, which enables us to separate phase path reduction and Faraday rotation into a phase and polarization error respectively. The introduction of linear polarization overcomes a key limitations in current ionospheric measurement techniques: eliminating errors associated with indirect Faraday rotation measurement. The additional polarization data also enables absolute unambiguous measurement of both parameters with fewer and lower frequencies than conventional solutions, as well as without the need for precise satellite clock, phase biases and positioning data. These characteristics correspond with a reduction in the size, power and complexity of the satellite payload, and as a result, our technique better suited to small satellite applications. To validate the capability of measuring the ionosphere within the constraints of a small satellite package, we establish the influence of system noise, weak scattering, clock errors and antenna characteristics on the measurement technique. We then use this to inform a starting point for a CubeSat beacon and receiver design solution which achieves unambiguous and high-resolution measurement of ionospheric parameters with practicable system requirements and constraints. This starting point demonstrates that a resolution of 12 mTECU and 0.03 rad/m2 for the electron density and Faraday rotation estimates respectively, as well as useful scintillation measurements dominated by scintillation noise may be achieved utilizing a tri-band 3U CubeSat beacon with frequencies 144.2 MHz, 432.6 MHz, and 1297.8 MHz, a transmitter power of no more than 4 watts, and antenna requirements consistent with a dipole type antenna. [ABSTRACT FROM AUTHOR]

Magnetic susceptibility and the Faraday effect in orthorhombic DyAlO3 single crystals were studied along the crystallographic b-axis, the axis of easy magnetization, in a temperature range 78–300 K. The Faraday rotation was measured on the basis of the temperature and spectral dependencies of the rotation angles θ of the major axis of the ellipse of light radiation polarization in a wavelength range 440–750 nm. At a wavelength of 506 nm, the dependence of the Verdet constant V on the magnetic susceptibility χM was observed to be linear in a temperature range 85–300 K, and the paramagnetic Verdet constant Cp was calculated. A comparative analysis of the constants Cp and the effective frequencies ω0 of allowed transitions in cubic R3Al5O12 garnets and RAlO3 (R = Tb3+, Dy3+) orthoaluminate crystals was carried out in terms of the local site symmetry for rare-earth ions. The possibility of practical magneto-optical applications of the DyAlO3 crystals is briefly discussed. [ABSTRACT FROM AUTHOR]

Metal organic decomposition (MOD) for the metal oxides thin films fabrication has been used in various studies over the past 30 years. MOD is a simple and inexpensive method for manufacturing optical grade polycrystalline thin films, including bismuth-substituted yttrium iron garnet. We present a variant of the previously described MOD method and discuss a chemical route for fabricating thin porous oxide films with a thicknesses of more than 100 nm, which non-epitaxially crystallized on fused silica substrates into Bi x Y 3-x Fe 5 O 12 layers (x = 0.5 and 1.5). Studies of the structural and magneto-optical properties of the layers show that the garnet layers crystallized under optimal conditions are characterized by high values of the specific Faraday rotation. Importantly, crystallization can be done locally by laser irradiation, and wet etching makes possible to remove non-crystallized areas, thus extending microfabrication capabilities. [ABSTRACT FROM AUTHOR]

The results of the use of terahertz (THz) irradiation generated by a silicon nanosandwich under conditions of a stabilized source-drain current in the treatment of covid complications are presented. THz irradiation was used in addition to drug therapy for the treatment of patients with COVID-19, which made it possible to reduce the patient's stay in the intensive care unit, reduce the time of patient intubation and stay on mechanical ventilation, and reduce the radiological and pharmacological burden on the patient. An idea was obtained about the resonant response of a living biological tissue to THz irradiation, which made it possible to formulate requirements for irradiation parameters depending on the characteristics of the biological tissue under study. The characteristics of resonant frequencies for the pulmonary alveoli were determined, which made it possible to develop and use the proposed treatment method for the treatment of pneumonia caused by COVID-19. [ABSTRACT FROM AUTHOR]

We report five new fast radio bursts (FRBs) discovered from the Galactic Plane Pulsar Snapshot (GPPS) survey by the Five-hundred-meter Aperture Spherical radio Telescope (FAST): FRB 20210126, FRB 20210208, FRB 20210705, FRB 20211005, and FRB 20220306. To date, no repeating bursts from these FRB sources have been detected in the follow-up monitoring observations, leading to their classification as potential one-off events. We obtain the basic parameters for these bursts, including position, dispersion measure, pulse width, spectral index, scattering time-scale, etc. The fluences and flux densities are generally lower in comparison to the values observed in one-off bursts discovered by other telescopes. Among the observed bursts, polarization data for four bursts were recorded during observations. Consequently, we obtain polarization profiles and Faraday rotation measures for these bursts. [ABSTRACT FROM AUTHOR]

Coherent spin dynamics of electrons in CdSe colloidal nanoplatelets are investigated by time-resolved pump–probe Faraday rotation at room and cryogenic temperatures. We measure electron spin precession in a magnetic field and determine g-factors of 1.83 and 1.72 at low temperatures for nanoplatelets with a thickness of 3 and 4 monolayers, respectively. The dephasing time of spin precession T 2 * amounts to a few nanoseconds and has a weak dependence on temperature, while the longitudinal spin relaxation time T 1 exceeds 10 ns even at room temperature. Observations of single and double electron spin–flips confirm that the nanoplatelets are negatively charged. The spin–flip Raman scattering technique reveals g-factor anisotropy by up to 10% in nanoplatelets with thicknesses of 3, 4, and 5 monolayers. In the ensemble with a random orientation of nanoplatelets, our theoretical analysis shows that the measured Larmor precession frequency corresponds to the in-plane electron g-factor. We conclude that the experimentally observed electron spin dephasing and its acceleration in the magnetic field are not provided by the electron g-factor anisotropy and can be related to the localization of the resident electrons and fluctuations of the localization potential. [ABSTRACT FROM AUTHOR]

The radiation properties including size, intensity, and pulse width of the double-wire X-pinch were optimized using prepulse current. The optimization mechanism was investigated using optical diagnostics. The X-pinch driven by a current with a peak intensity of ∼250 kA and a rise rate of 0.95 kA/ns was difficult to produce strong radiation. The application of prepulse effectively enhances the current rise rate and intensity of the radiation source. The radiation source also exhibited reduced spatial dimensions and radiation duration, thereby improving spatial and temporal resolution while used in x-ray projection shadow radiography. The magnetic field and current distribution were measured using Faraday rotation. During the early stage, the current predominantly flows in the corona plasma at a larger radius generated by the prepulse current, consequently reducing the load inductance. As the time delay between the main and prepulse current increased, the intensity of the radiation source further increased. This study provides an approach for controlling radiation sources and enables different applications of X-pinches with adjustable prepulse current. [ABSTRACT FROM AUTHOR]