Phase Manipulation Research Articles

Magnetism and berry phase manipulation in an emergent structure of perovskite ruthenate by (111) strain engineering

The interplay among symmetry of lattices, electronic correlations, and Berry phase of the Bloch states in solids has led to fascinating quantum phases of matter. A prototypical system is the magnetic Weyl candidate SrRuO3, where designing and creating electronic and topological properties on artificial lattice geometry is highly demanded yet remains elusive. Here, we establish an emergent trigonal structure of SrRuO3 by means of heteroepitaxial strain engineering along the [111] crystallographic axis. Distinctive from bulk, the trigonal SrRuO3 exhibits a peculiar XY-type ferromagnetic ground state, with the coexistence of high-mobility holes likely from linear Weyl bands and low-mobility electrons from normal quadratic bands as carriers. The presence of Weyl nodes are further corroborated by capturing intrinsic anomalous Hall effect, acting as momentum-space sources of Berry curvatures. The experimental observations are consistent with our first-principles calculations, shedding light on the detailed band topology of trigonal SrRuO3 with multiple pairs of Weyl nodes near the Fermi level. Our findings signify the essence of magnetism and Berry phase manipulation via lattice design and pave the way towards unveiling nontrivial correlated topological phenomena.

Phase Engineering of 2D Materials.

Polymorphic 2D materials allow structural and electronic phase engineering, which can be used to realize energy-efficient, cost-effective, and scalable device applications. The phase engineering covers not only conventional structural and metal-insulator transitions but also magnetic states, strongly correlated band structures, and topological phases in rich 2D materials. The methods used for the local phase engineering of 2D materials include various optical, geometrical, and chemical processes as well as traditional thermodynamic approaches. In this Review, we survey the precise manipulation of local phases and phase patterning of 2D materials, particularly with ideal and versatile phase interfaces for electronic and energy device applications. Polymorphic 2D materials and diverse quantum materials with their layered, vertical, and lateral geometries are discussed with an emphasis on the role and use of their phase interfaces. Various phase interfaces have demonstrated superior and unique performance in electronic and energy devices. The phase patterning leads to novel homo- and heterojunction structures of 2D materials with low-dimensional phase boundaries, which highlights their potential for technological breakthroughs in future electronic, quantum, and energy devices. Accordingly, we encourage researchers to investigate and exploit phase patterning in emerging 2D materials.

Magnitude‐Controlled Phase Based on Euler's Formula

AbstractPhase manipulation plays a fundamental role in electromagnetic (EM) and optics research, i.e., the wavefront shaping depends heavily on phase modulation. However, the previous phase manipulation methods are limited to phase‐angle dimensionality, and the magnitude and phase are generally deemed as two distinct characters that should be controlled separately. Herein, a phase manipulation method in which phase is modulated by magnitude is proposed that follows an EM expression of Euler's formula. A rotation phase of linearly‐polarized waves is presented. Using this method, several unique applications in this research are demonstrated. First, a Hall effect of non‐angular‐momentum waves is obtained; second, an interdigital topology model with a unique topological‐charge control strategy is presented; and finally, the method is applied to holographic imaging, of which information of the hologram is recorded as a distribution of magnitude. Furthermore, as this method is applicable to all forms of harmonic waves, it can be potentially applied to other areas of wave phenomena such as acoustics and mechanics.

Seismic time-frequency masking for suppression of seismic speckle noise

Seismic speckle noise is the primary factor causing severe reflection distortions caused by small-scale near-surface scattering. As in the case of speckle noise in optics and acoustics, deterministic velocity model-building techniques cannot recover these heterogeneities which are much smaller than a wavelength. Conventional processing techniques struggle to perform when multiplicative noise remains unsuppressed. Although local and global stacking mitigates the effects of speckle noise, it leads to a severe loss of higher frequencies reducing the vertical resolution of the seismic data. The foundation for attacking speckle noise is a recently proposed mathematical model that includes two concurrent random multiplicative noise types: type 1 defining residual statics and type 2 describing random frequency-dependent phase perturbations that mimic small-scale near-surface scattering. Using this model, we have developed seismic time-frequency masking to suppress speckle noise on prestack data. The time-dependent and non-surface-consistent nature of scattering noise dictates window-based approaches borrowed from local stacking techniques. Separate manipulation of phase and amplitude spectra is achieved through modified time-frequency masking inspired by speech processing. A beamformed data set from local stacking is used as a guide for designing phase and amplitude masks that are directly applied to raw data in the time-frequency domain. The phase mask allows the restoration of coherency by repairing phase distortions caused by near-surface scattering. The amplitude mask corrects power spectrum (PS) distortions caused by multiplicative and additive noises. An amplitude mask is implemented using a data-driven minimum statistic approach that estimates the noise PS in each local window. The minimum statistics approach is adapted from speech processing using beamformed data as an initial signal estimate and as a guide to designing an improved amplitude mask. Synthetic and field data examples suggest significant improvements in coherency and signal-to-noise ratio after the suppression of multiplicative noise, which makes the data processable by conventional techniques subsequently.

Single chip simultaneous chiral and achiral imaging based on high efficiency 3D plasmonic metalens

Abstract We propose and experimentally demonstrate a single chip metasurface for simultaneous chiral and achiral imaging and polarimetric detecting using a high efficiency three dimensional plasmonic metalens (3D-PM) with capability of designed separation of different circular polarizations. The proposed 3D-PM combines both propagating and geometric phases so that two orthogonal circular polarization components of the incidence can be precisely separated and imaged into two channels and the incident polarization state can be detected with differentiation of the two channels. One single set of an array of Au layer covered anisotropic polymethyl methacrylate elliptical nanopillars is employed, in which height of each nanopillar is added as a new design degree of freedom to realize both full phase manipulation (0–2π) and high efficiency (>0.85) with coupled equivalent Fabry–Pérot cavity and localized surface plasmons. At design wavelength of 1550 nm, experimental results show that optical resolution of both chiral and achiral images approaches the diffraction limit, extinction ratio of circular polarizations in two channels is ∼33:1, and the energy efficiency reaches ∼63 %. The proposed 3D-PM provides a new and simple way for chiral/achiral imaging and polarimetric measurement, and can be applied in integrated optics, optical communication, and biomolecule detection.

Помехоустойчивость когерентного приема сигналов с многопозиционной фазовой манипуляцией и синусоидальной огибающей в гидроакустическом канале связи

Goals: The main purpose of this work is to develop a methodology for determining the parameters of signals with multi-position phase manipulation (M-PSK), in which the signals become relatively invariant to frequency distortions in the marine environment. The frequency distortion of the signals is caused by the uneven frequency response of the attenuation of the marine environment. The main part of this technique is to assess the effect of frequency distortion of signals on the noise immunity of reception. To do this, the error probabilities of the M-PSK signal receiver are determined, which is optimal in the absence of distortion. Methods: The provisions of applied hydroacoustics, the theory of random processes and the theory of transmission of discrete messages are used. The main content: The paper considered a model of a single-beam hydroacoustic communication channel, characteristic of the deep sea, when the receiver or transmitter is located in the depths of the sea. The transmission coefficient of the channel is used as a transmission coefficient with a Gaussian amplitude -frequency response and a linear phase-frequency response. The additive boundary of the error probability for coherent reception of M-PSK signals with a sinusoidal envelope is determined. As a receiver, a coherent receiver is considered, optimal by the criterion of maximum likelihood under the action of white Gaussian noise and the absence of distortion in the marine environment. A logarithmic measure of increasing the probability of error is introduced, which characterizes the deterioration of noise immunity due to frequency distortions in the channel. For some typical cases, the values of signal parameters that are relatively invariant to frequency distortions in the marine environment are determined. Results: Expressions are found for the upper bound of the error probability of coherent receivers of M-PSK signals with a sinusoidal envelope for M = 2, 4, 8, 16, 32. A logarithmic measure of the relative increase in the probability of error compared to the case of no distortion is introduced. The functional dependence of this measure on the duration of sending the signal, the carrier frequency and the number of phases of the signal, as well as on the communication range and the signal-to-noise ratio is determined. On the plane of the carrier frequency, the duration of sending the signal, for each type of signal, a boundary of the region above which the signals are relatively invariant to frequency distortions in the marine environment is constructed. A comparison is made with the case of receiving M-PSK signals with a rectangular envelope. It is shown that invariant signals with a sinusoidal envelope have a shorter duration than signals with a straight-angle envelope. In addition, the duration of signals with a sinusoidal envelope is significantly less dependent on the number of phases of the signal.

Ti3C2 MXenes meta-film switching ultra-broadband and high-efficiency green EMI shielding

Green electromagnetic interference (EMI) shielding is embarking on a new direction to promote harmony with nature, especially in nowadays' booming big data, artificial intelligence, etc. However, the irreconcilable contradiction between strong electromagnetic attenuation and weak secondary reflection inevitably blocks its development. Herein, a new synergistic strategy of manipulating and attenuating the reflected wave is proposed for the first time in the field of EMI shielding, which successfully breaks through the bottleneck and realizes efficient and ultra-broadband green EMI shielding. The maximal EMI shielding effectiveness (SE) reaches up to ∼68.3 dB, and gs > 1 covers ∼10.4 GHz, enshrouding ∼65% of the investigated frequency range from 2 to 18 GHz. The bandwidth for gs > 10 even spans over ∼2.5 GHz. More importantly, it has great flexibility and robustness. The configured Ti3C2 MXenes-based meta-film can maintain good green EMI shielding ability regardless of being bent by the y-axis or x-axis torque. All these advantages arise from the synergistic effect between the phase manipulation of Ti3C2 MXenes-based Pancharatnam–Berry (PB) meta-atoms and the strong electromagnetic attenuation of Ti3C2 MXenes nanosheets take full advantage of the high conductivity and dipole polarization of Ti3C2 MXenes, leading to significant suppression of secondary reflection as implementing efficient EMI shielding. This finding provides a pathway to realize promising flexible, high-efficiency, ultra-broadband EMI shielding materials, or even dual-functional materials for electromagnetic shielding and absorption.

Magnetic‐Electric Metamirror and Polarizing Beam Splitter Composed of Anisotropic Nanoparticles

AbstractThe emergence of new materials and fabrication techniques provides progress in the development of advanced photonic and communication devices. Transition metal dichalcogenides (e.g., molybdenum disulfide, MoS2) are novel materials possessing unique physical and chemical properties promising for optical applications. In this paper, a metasurface composed of particles made of bulk MoS2 is proposed and numerically studied considering its operation in the near‐infrared range. In the bulk configuration, MoS2 has a layered structure being a uniaxial anisotropic crystal demonstrating an optical birefringence property. It is supposed that the large‐scale and uniform MoS2 layers are synthesized in a vertical‐standing morphology, and then they are patterned into a regular 2D array of disks to form a metasurface. The natural anisotropy of MoS2 is utilized to realize the splitting of electric and magnetic dipole modes of the disks while optimizing their geometric parameters to bring the desired modes into overlap. At the corresponding resonant frequencies, the metasurface behaves as either an electric or a magnetic mirror, depending on the polarization of incident light. Based on the extraordinary reflection characteristics of the proposed metasurface, it can be considered an alternative to traditional mirrors and optical splitters when designing compact and highly efficient metadevices, which provide polarization and phase manipulation of electromagnetic waves on a subwavelength scale.

Refractive plasma optics for relativistic laser beams

The high intensities reached today by powerful lasers enable us to explore the interaction with matter in the relativistic regime, unveiling a fertile domain of modern science that is pushing far away the frontiers of plasma physics. In this context, refractive-plasma optics are being utilized in well established wave guiding schemes in laser plasma accelerators. However, their use for spatial phase control of the laser beam has never been successfully implemented, partly due to the complication in manufacturing such optics. We here demonstrate this concept which enables phase manipulation near the focus position, where the intensity is already relativistic. Offering such flexible control, high-intensity high-density interaction is becoming accessible, allowing for example, to produce multiple energetic electron beams with high pointing stability and reproducibility. Cancelling the refractive effect with adaptive mirrors at the far field confirms this concept and furthermore improves the coupling of the laser to the plasma in comparison to the null test case, with potential benefits in dense-target applications.

Enhancing Sustainable Arts Education: Comparative Analysis of Creative Process Measurement Techniques

Contemporary research indicates that student creativity is crucial to the success of arts education. Self-regulated learning has become one of educational psychology’s most critical research areas. However, there is limited research on creativity in arts education in self-regulated learning. Therefore, this study aims to define the creativity characteristics that determine the quality of students’ work. This study implemented a creative competition in painting and composition for first-year undergraduates. It was conducted at a Chinese university with the participation of 178 first-year students aged 18 to 26. It evaluated the characteristics of creativity during the three main phases of the task: planning, execution, and completion. We investigated the subject by employing semi-open questionnaires (n = 178) and using the content analysis method and quantitative analysis. According to the competition results, the students with the highest scores in flow, inspiration, and idea generation in the performance phase had the best quality work. In the forethought phase, analogical thinking and idea generation worked best for most students, while in the performance phase, flow sense, idea generation, and idea manipulation worked best. Data on creativity characteristics at different work phases and final quality might adequately guide and organize educational procedures. These findings can serve as a theoretical foundation for quantifying the creativity phase in self-regulated learning and offer arts educators a reference for creativity instruction.

Estimation of Probabilistic Characteristics of Reception of Frequency-Effective Signals during Propagation along a Radio Line with Fog

A model of a radio line with fog, which is used to represent distortions of complex envelopes of digital signals because of the absorbing and dispersive properties of the propagation medium, has been considered. It is shown that with an increase in the frequency band of digital signals and with an increase in their order of manipulation (when using frequency-efficient signals), the influence of these distortions leads to energy losses in relation to propagation in free space. The quantitative estimation of energy losses for the digital signals used in applications with multi-position phase, quadrature-amplitude, and amplitude-phase manipulations and for a radio line with fog with a variation of its parameters has been carried out. It has been shown that for signals with multiposition phase and amplitude-phase manipulations (the frequency efficiency coefficient of the signals is 4 bits/s/Hz), the energy losses reach 3.5 and 1.0 dB, respectively.

Leaky-wave metasurfaces for integrated photonics.

Metasurfaces have been rapidly advancing our command over the many degrees of freedom of light; however, so far, they have been mostly limited to manipulating light in free space. Metasurfaces integrated on top of guided-wave photonic systems have been explored to control the scattering of light off-chip with enhanced functionalities-namely, the point-by-point manipulation of amplitude, phase or polarization. However, these efforts have so far been limited to controlling one or two optical degrees of freedom at best, as well as device configurations much more complex compared with conventional grating couplers. Here we introduce leaky-wave metasurfaces, which are based on symmetry-broken photonic crystal slabs that support quasi-bound states in the continuum. This platform has a compact form factor equivalent to the one of grating couplers, but it provides full command over the amplitude, phase and polarization (four optical degrees of freedom) across large apertures. We present devices for phase and amplitude control at a fixed polarization state, and devices controlling all the four optical degrees of freedom for operation at a wavelength of 1.55 μm. Merging the fields of guided and free-space optics through the hybrid nature of quasi-bound states in the continuum, our leaky-wave metasurfaces may find applications in imaging, communications, augmented reality, quantum optics, LIDAR and integrated photonic systems.

Mechanical Properties Enhancement of Biomedical Au–Cu–Al Shape Memory Alloys by Phase Manipulation

β-type Au-Cu-Al alloy, which is known as Spangold, has been developed for biomedical applications due to its high biocompatibility and X-ray contrast. Despite that, the workability of the polycrystalline functional phases (i.e., L21 parent and martensite phases) is limited by grain boundary embrittlement. To enhance the mechanical properties of the martensite phase (M-phase) alloy, this study aims to introduce a ductile α-fcc phase with various fractions into the M-phase alloy by manipulating the alloy chemical composition. Fundamental analysis such as phase identifications, thermal analysis, microstructure observations, and tensile tests were performed. As a result, the dual-phase M+α-fcc alloys with varying α-fcc phase fractions were successfully practiced. Among all alloys, their lattice parameters and phase transformation temperatures showed merely slight alteration, suggesting that the chemical compositions of the functional M-phases are similar for all alloys. Hence, the variations in the mechanical properties mainly originate from the different α-fcc phase fractions. The tensile test results indicate that both the ultimate tensile strength and fracture strain are promoted as the α-fcc phase fraction increases. The 50Au-38Cu-12Al alloy with the highest α-fcc phase fraction performs the most optimized mechanical properties.

Parameter representation of group delay towards glottal-flow-based phase manipulation for channel vocoder

Parameter representation of group delay towards glottal-flow-based phase manipulation for channel vocoder

Topotactic transition of Ti4AlN3 MAX phase in Lewis acid molten salt

MAX phases and its derived two-dimensional MXenes have attracted considerable interest because of their rich structural chemistry and multifunctional applications. Lewis acid molten salt route provides an opportunity for structure design and performance manipulation of new MAX phases and MXenes, Although a series of new MAX phases and MXenes were successfully prepared via Lewis acid melt route in recent years, few work is explored on nitride MAX phases and MXenes. Herein, a new copper-based 413-type Ti4CuN3 MAX phase was synthesized through isomorphous replacement reaction using Ti4AlN3 MAX phase precursor in molten CuCl2. In addition, it was found that at high temperature Ti4N3Clx MXene will transform into two-dimensional cubic TiNα nanosheets with improved structural stability.

Polarization Converters Composed of Metasurfaces with Independent Manipulation of Polarization and Phase

Polarization Converters Composed of Metasurfaces with Independent Manipulation of Polarization and Phase

Strain and strain gradient engineering in membranes of quantum materials

Strain is powerful for discovery and manipulation of new phases of matter; however, elastic strains accessible to epitaxial films and bulk crystals are typically limited to small (<2%), uniform, and often discrete values. This Perspective highlights emerging directions for strain and strain gradient engineering in free-standing single-crystalline membranes of quantum materials. Membranes enable large (∼10%), continuously tunable strains and strain gradients via bending and rippling. Moreover, strain gradients break inversion symmetry to activate polar distortions, ferroelectricity, chiral spin textures, superconductivity, and topological states. Recent advances in membrane synthesis by remote epitaxy and sacrificial etch layers enable extreme strains in transition metal oxides, intermetallics, and Heusler compounds, expanding beyond the natively van der Waals (vdW) materials like graphene. We highlight emerging opportunities and challenges for strain and strain gradient engineering in membranes of non-vdW materials.

Spectroscopic visualization and phase manipulation of chiral charge density waves in 1T-TaS2

The chiral charge density wave is a many-body collective phenomenon in condensed matter that may play a role in unconventional superconductivity and topological physics. Two-dimensional chiral charge density waves provide the building blocks for the fabrication of various stacking structures and chiral homostructures, in which physical properties such as chiral currents and the anomalous Hall effect may emerge. Here, we demonstrate the phase manipulation of two-dimensional chiral charge density waves and the design of in-plane chiral homostructures in 1T-TaS2. We use chiral Raman spectroscopy to directly monitor the chirality switching of the charge density wave—revealing a temperature-mediated reversible chirality switching. We find that interlayer stacking favours homochirality configurations, which is confirmed by first-principles calculations. By exploiting the interlayer chirality-locking effect, we realise in-plane chiral homostructures in 1T-TaS2. Our results provide a versatile way to manipulate chiral collective phases by interlayer coupling in layered van der Waals semiconductors.

Multiresonant metasurfaces for arbitrarily broad bandwidth pulse chirping and dispersion compensation

We show that ultrathin metasurfaces with a specific multiresonant response can enable simultaneously arbitrarily strong and arbitrarily broadband dispersion compensation, pulse (de)chirping, and compression or broadening. This breakthrough overcomes the fundamental limitations of both conventional nonresonant approaches (bulky) and modern singly resonant metasurfaces (narrowband) for quadratic phase manipulations of electromagnetic signals. The required nonuniform trains of resonances in the electric and magnetic sheet conductivities that completely control phase delay, group delay, and chirp are rigorously derived and the limitations imposed by fundamental physical constraints are thoroughly discussed. Subsequently, a practical, truncated approximation by finite sequences of physically realizable linear resonances is constructed and the associated error is quantified. By appropriate spectral ordering of the resonances, operation can be achieved either in transmission or reflection mode, enabling full space coverage. The proposed concept is not limited to dispersion compensation, but introduces a generic and powerful ultrathin platform for the spatiotemporal control of broadband real-world signals with a myriad of applications in modern optics, microwave photonics, radar, and communication systems.

Gain enhancement of circularly polarized Fabry-Perot resonator antenna using simple superstrate

This communication presents a method to enhance the gain of a circularly polarized (CP) Fabry-Perot resonator antenna (FPRA) by using a simple superstrate. The proposed superstrate is a polarization conversion metasurface (PCM) which is capable of partial reflection and CP transmission phase manipulation. The partial reflection property of PCM is used to form FPRA with a feed, and the linear to circular polarization conversion capacity make the antenna realize CP radiation. Furthermore, the PCM can also correct the aperture field phase distribution of the antenna through tuning the CP transmission phase of each unit. Then the gain of the CP FPRA can be further improved. Finally, the CP radiation and gain enhancement of the FPRA are achieved by a simple superstrate without the need to add additional antenna structure. This makes the proposed antenna keep a simple structure. The performance of the antenna is verified by comparing the test results of the fabricated antenna with the simulation results. Measured results show that the antenna can realize well CP radiation at 10 GHz. After phase correction, the measured peak gain of the antenna is increased by 1 dB, reaches 18.2 dBic. The method proposed in this communication provides a new idea for improving the gain of CP FPRA while maintaining simple antenna structure.