Phase Superposition Research Articles

Full-Dimensional Geometric-Phase Spatial Light Metamodulation.

Full-dimensional spatial light modulation requires simultaneous, arbitrary, and independent manipulation of the spatial phase, amplitude, and polarization. This is crucial for leveraging the complete physical dimension resources of light. However, full-dimensional metamodulation can be challenging due to the need for multiple independent control factors. To address this challenge, here we propose parallel-tasking metasurfaces to enable full-dimensional spatial light metamodulation based fully on the geometric-phase concept. Indeed, the meta-atoms are divided into several subphases, each of which serves as an independent control factor to manipulate light phase, amplitude, and polarization through geometric phase, interference, and orthogonal polarization superposition, respectively. Therefore, the macroscopic group of meta-atoms leads to metasurfaces that can achieve broadband full-dimensional spatial light metamodulation, as demonstrated by various types of structured light generation. This approach paves the way to future wide applications of light manipulation enabled by full-dimensional spatial light metamodulation.

Four-channel near-field focusing metasurface lens based on frequency-polarization multiplexing

In response to the issue of traditional near-field focusing metasurfaces having a single working frequency band and limited focusing functionality, this paper proposes a four-channel focusing metasurface based on frequency-polarization multiplexing. Utilizing the principles of anisotropy and metasurface resonant phase, a metasurface unit composed of two sets of orthogonal resonators was designed. The designed units have independent transmission amplitude and phase at 15 GHz and 23 GHz, with the transmission phase of the two sets of resonators encoded in 2-bit and 1-bit based on phase differences of 90° and 180°, respectively. Based on the units, combined with the focusing principle of metasurface lenses and the principle of phase superposition, a four-channel near-field focusing metasurface lens was designed. The lens is composed of 20 × 20 units, measuring 200 × 200 mm2. Numerical simulations and experimental results demonstrate that the designed metasurface lens achieves single-point and dual-points focusing at 15 GHz under x- and y-polarized wave incidence, with the focus at the z = 70 mm plane and a maximum focusing efficiency of 48.5%. At 23 GHz under x- and y-polarized wave incidence, metasurface lens focuses electromagnetic waves at different positions, with the focus at the z = 80 mm plane and a maximum focusing efficiency of 27.8%. The metasurface lens designed by this method is expected to find applications in fields such as Medical Sensing, Microwave Imaging, and Integrated Optics.

Mode reconfigurable OAM helical array antenna for higher mode generation

AbstractIn this paper, an orbital angular momentum (OAM) mode reconfigurable antenna based on a uniform circular array (UCA) is presented. The phase superposition method is presented to overcome the limitation of the number of array units on the mode order in the conventional four‐element UCA antenna, which is limited to generating first‐order OAM beams. The unit phase is introduced by a bifilar helical antenna in this method, and the unit phase is superimposed with the feed phase of the UCA to enable the generation of 3rd‐order OAM beams from the four‐element UCA. At the same time, the DC signal‐controlled feed network assigns three distinct feed phases to the UCA, which realizes the reconfigurability of the three OAM beams. To achieve mode reconfigurability, 20 p‐i‐n diodes were integrated as switches in the feed network for controlling the ON/OFF status of p‐i‐n diodes in the feed network using DC signals. Finally, simulated and measured results show that three OAM beams (lz = −1, −2, and −3) have been generated in the frequency band from 10.6 to 11.8 GHz.

Switchable Diffraction Pattern Based on Cascaded Metasurfaces

AbstractMetasurfaces have great advantages in the field of laser detection because of their ability to generate large amounts of point sources or various diffraction patterns. Here,cascaded metasurfaces (CM) for generating switchable spatial light distributions is utilized, which can be used for optical scanning and identifications. The light distribution is composed of several distinct diffraction patterns, and the scanning of the diffraction space is realized by multiple pixel‐scale alignment strategies between two pieces of CM. Through combining Dammann optimization and the gradient descent method, various diffraction patterns under different matching situations can be guaranteed by phase superposition. Various diffraction conditions with highly identifiable intensity distribution are guaranteed by using the optimization method. Such optical scanning devices based on CM have small footprints, high integration, flexible composition, and stable diffractive combination features. By manipulating CM to generate changeable spatial diffraction phenomenon may provide flexible modulation properties to optical scanning, measurement, and other applications.

A Novel Approach Extracting Extreme Points Combining Multidirection Phase Superposition and Weighted Moment Diagram for Matching Multi-Modal Images

A Novel Approach Extracting Extreme Points Combining Multidirection Phase Superposition and Weighted Moment Diagram for Matching Multi-Modal Images

Multi-mode vortex beams generation with single-layer transmissive metasurface

Orbital angular momentum (OAM) is a phenomenon of vortex phase distribution in free space, the infinity of whose modes and the orthogonality between modes allow it to possess great potential in enhancing channel capacity. A transmissive metasurface consisting of a single-layer substrate and a two-layer metallic structure is proposed to enable vortex beam generation based on the concept of the Pancharatnam-Berry (PB) phase. The phase response is achieved by continuous phase modulation under circularly polarised (CP) wave incidence due to the simultaneous rotation of the upper and lower metal structures. Besides, through the introduction of both phase compensation on the metasurface and phase superposition of the beams to the array design, multi-beam generation is expected to be realized. A metasurface sample composed of 30 30 elements (450 mm 450 mm) is fabricated and measured in a microwave darkroom on the basis of the simulation results. Both the simulation and measurement results provide firm demonstration that the designed metasurface is capable of simultaneously generating four beams carrying OAM mode numbers of and different beam directions at the same aperture. The designed metasurface in this paper utilized for generating multi-mode vortex multi-beams will be of wide application in multi-channel transmission in wireless communication systems.

Harmonic Analysis and Cancellation of Inverter Systems with Linear Phase‐Shifting Transformer

In order to improve the electrical performance of the inverter system and make its output waveform close to a sinusoidal waveform, an inverter based on a linear phase‐shifting transformer is proposed, which can eliminate the low harmonics with opposite phase by the effect of phase shift and superposition. Firstly, the components and working process of the multiple superposition inverter system are introduced, and the working principle and winding structure of the linear phase‐shifting transformer are analyzed; Secondly, the Fourier decomposition of the inverter output voltage is carried out to obtain the harmonic currents at the same frequency as it, and it is demonstrated that the inverter is capable of eliminating most of the harmonics below the 23rd order by calculating the magneto‐dynamic potential synthesized in the air gap; Again, in order to overcome the harmonic electric potential caused by the edge‐end effect and the tooth slot structure of the linear phase‐shifting transformer, the secondary side winding of the linear phase‐shifting transformer adopts a short pitch structure, and it is proved that this structure has a significant suppression effect on the 5th and 7th harmonics without reducing the fundamental wave amplitude; Then, the model of multiple superposition inverter system is built based on Maxwell simulation software, and the effectiveness of the inverter device and winding structure on harmonic suppression is proved through spectral analysis of voltage waveforms with different load types and power factors; Finally, its reasonableness and accuracy are verified by experiments. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Verifying Ray Tracing Amplitude Methods for Global Magnetospheric Modeling

AbstractRay tracing is a commonly used method for modeling the propagation of electromagnetic waves in Earth's magnetosphere. To apply ray tracing results to global models of wave‐particle interaction such as energetic electron scattering, it is useful to map the discrete rays to a volume filling mesh. However, some methods have inherent losses of energy from the wave source, or do not account for the full range of wave properties within a sample volume. We have developed and tested a 3D magnetospheric ray tracing code “MESHRAY” which resolves these issues. MESHRAY uses the conservation of Poynting flux through ray triplets with finite volume to determine the local field amplitudes. Electromagnetic wave energy density from all ray data points is mapped to a mesh and verified against the wave source power for energy conservation varying time step length, number of rays, and total time steps. We find that the method is self‐consistent and numerically robust. We further investigate whether the neglect of phase information and superposition has a significant impact on the accuracy of mapping wave intensity to a mesh. We find excellent agreement between the analytic solution for waves emitted by a line source in a plane‐stratified medium and an equivalent ray tracing solution. When phase information is excluded, ray tracing reproduces an average amplitude spread over regions of coherent constructive and destructive interference. This may be an important consideration for interpolating ray tracing results of longer wavelength waves such as magnetosonic, electromagnetic ion cyclotron, or ULF waves.

Multiple Orbital Angular Momentum Beams with High‐Purity of Transmission‐Coding Metasurface (Adv. Theory Simul. 4/2023)

Broadband Transmission-Coding Metasurface with Multi-Vortex-Beam In article number 2200842, Si Jia Li and co-workers develop a new type of transmission-coding metasurface by changing the size of metal patches based on the principle of propagation phase and phase superposition, which digitally realize the vortex waves with wide-band, high-purity, and multiple orbital angular momentum (OAM) beams simultaneously. This transmission-coding metasurface with multi-vortex-beam has potential applications in the OAM multiplexing communication and multi-target positioning in wireless systems.

Multiple Orbital Angular Momentum Beams with High‐Purity of Transmission‐Coding Metasurface

AbstractVortex electromagnetic wave carrying orbital angular momentum (OAM) is expected to break through the shortage of spectrum resource because of its multiple independent modes. Nowadays, there are various methods to generate OAM vortex beam. Based on the concepts of digital metasurface and propagation phase, a broadband 3‐bit coding transmission metasurface is designed and illustrated by simulation and measurement. The elements exhibit the different phase by changing the size of metal patch, and the focusing phase is introduced to reduce the divergence of OAM beams. Based on the principle of phase superposition, the wide‐band, high‐purity, and multi‐beam OAM vortex waves can be generated by the transmission‐coding metasurface (TCMS). The experimental results verify that TCMS realizes the multiple OAM beams along different directions simultaneously from 9 to 10.5 GHz, which are consistent with the theoretical results. The high purity more than 90% of OAM mode is demonstrated by both the simulated and measured results. The TCMS provides a potential and effective scheme for OAM multiplexing and multi‐target positioning in wireless systems.

Creation and Control of Vortex‐Beam Arrays in Atomic Vapor

AbstractOptical vortices, which are beams with spiral‐shaped wavefronts and screw phase dislocations, have potential for supporting high‐capacity optical communications. In this study, the generation of 1D and 2D vortex‐beam arrays is theoretically proposed and experimentally demonstrated by introducing novel forked‐photonic lattices in a three‐level 85Rb atomic medium. Such forked‐photonic lattices are established through the interference of Gaussian and vortex coupling beams. The input Gaussian probe beam that travels through this lattice experiences phase superposition and is diffracted into vortex‐beam arrays. Moreover, the relative efficiency of the high‐order diffractions can be enhanced by tuning the two‐photon detuning and power of the coupling beams. The enriched diffractive arrays of a vortex probe beam propagating in such forked‐photonic lattices are also presented. The experimental results agree well with those of the numerical simulations. This work suggests that atomic systems are a fertile platform for creating and controlling vortex‐beam arrays, and that they can shed light on ongoing exploration in the fields of optical manipulation and quantum information processing.

Anomalous supercurrent modulated by interfacial magnetizations in Josephson junctions with ferromagnetic bilayers

Based on the Bogoliubov-de Gennes equations, we investigate the transport of the Josephson current in a S/$f_L$-F$_1$-$f_C$-F$_2$-$f_R$/S junction, where S and F$_{1,2}$ are superconductors and ferromagnets, and $f_{L, C, R}$ are the left, central, and right spin-active interfaces. These interfaces have noncollinear magnetizations, and the azimuthal angles of the magnetizations at the $f_{L, C, R}$ interfaces are $\chi_{L, C, R}$. We demonstrate that, if both the ferromagnets have antiparallel magnetizations, the critical current oscillates as a function of the exchange field and the thickness of the ferromagnets for particular $\chi_L$ or $\chi_R$. By contrast, when the magnetization at the $f_C$ interface is perpendicular to that at the $f_L$ and $f_R$ interfaces, the critical current reaches a larger value and is hardly affected by the exchange field and the thickness. Interestingly, if both the ferromagnets are converted to antiparallel half-metals, the critical current maintains a constant value and rarely changes with the ferromagnetic thicknesses and the azimuthal angles. At this time, an anomalous supercurrent can appear in the system, in which case the Josephson current still exists even if the superconducting phase difference $\phi$ is zero. This supercurrent satisfies the current-phase relation $I=I_c\sin(\phi+\phi_0)$ with $I_c$ being the critical current and $\phi_0=2\chi_C-\chi_L-\chi_R$. We deduce that the additional phase $\phi_0$ arises from phase superposition, where the phase is captured by the spin-triplet pairs when they pass through each spin-active interface. In addition, when both the ferromagnets are transformed into parallel half-metals, the $f_C$ interface never contributes any phase to the supercurrent and $\phi_0=\chi_R-\chi_L+\pi$. In such a case, the current-phase relation is similar to that in a S/$f_L$-F-$f_R$/S junction.

Encrypted holographic metasurface based on Pancharatnam–Berry phase superposition

As a new type of planar micro-nano photonics device, metasurfaces can precisely modulate light at the subwavelength scale, which are considered as an ideal computational holographic encoding carrier. In this paper, based on the Pancharatnam–Berry (PB) phase, 2D arrayed metasurface with nanopillar cells is designed by superimposing the phase of focus and holographic imaging, and its focusing and holographic properties are investigated. Different from the method of alternately arranging nanopillars to achieve functional superposition, this method can further reduce the size of the integrated device and improve the functional density of the optical system greatly, which has broad development prospects in the fields of encryption and anti-counterfeiting.

Metasurface-Based Beam Scanning Array With In-Band Co-Polarized Scattered Field Shaping

In this article, a novel array of radiation and scattering function-integrated metasurface antenna (RSIMA) elements is proposed, simulated, and measured for radiation beam scanning and two examples of in-band co-polarized (IBCP) scattered field shaping. The RSIMA consists of a slot-connected metasurface (SCMS) subarray of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\times $ </tex-math></inline-formula> 3 unit cells and a substrate integrated slot waveguide (SISW). When illuminated by plane waves, each SCMS unit cell can independently obtain a wide range of reflection phases by tuning structural parameters. When excited by the coaxial port of SISW, the SCMS subarray will also act as a radiation carrier of RSIMA. Moreover, the layout change of SCMS subarray will not significantly affect the radiation performance of RSIMA. Based on the principle of phase compensation and the phase superposition method, the phase distribution for two examples of scattered field shaping can be designed. In simulations and experiments, the array of 12 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times12$ </tex-math></inline-formula> RSIMAs radiates an IBCP beam scanning over ±31.5° in the E-plane and shapes the IBCP scattered fields into a deflected vortex beam (DVB) and a deflected high-gain multi-beam (DHMB). It is worth mentioning that the SCMS layout change between two examples of scattered field shaping does not significantly affect the radiation performance of the RSIMA array.

Facet-Based Hybrid Method for Electromagnetic Scattering From Shallow Water Waves Modulated by Submarine Topography

This article presents a mechanism model of synthetic aperture radar (SAR) remote sensing imaging of submarine topography in shallow areas. According to the shallow water effect and complex geographical factors, a 3-D geometric model of multiscale wave is generated by combining sea spectrum separation and phase superposition methods. It has the advantage of reflecting the random fluctuation characteristics of waves and the refraction phenomenon influenced by submarine topography. In addition, the modulation relationship among submarine topography, tidal current, and sea surface microroughness is established. This constitutes hydrodynamic modulation. The facet-based hybrid method that combines the geometry optics (GO) and the integral equation method (IEM) is adopted to solve the electromagnetic (EM) scattering of super electrically large sea surface. This contains tilt modulation. The effectiveness of the proposed model is demonstrated through the comparisons with the measured results. The influence of the parameters of radar, sea state, water depth, and tidal current direction on the scattering intensity of sea surface is studied as well. It is revealed that the shallower the water depth, the more significant the hydrodynamic and tilt effect. In addition, the velocity bunching (VB) modulation is a special modulation method in SAR imaging. According to the simulated results, the contributions of tilt, hydrodynamic, and VB modulation in SAR imaging mechanism are compared. The VB is the main factor, hydrodynamic is second, and tilt is the least.

Controllable multi-point light focusing of feedback wavefront shaping based on phase superposition Hadamard encoding algorithm

To achieve controllable multi-point light focusing, we develop a new feedback wavefront shaping optimization algorithm called phase superposition Hadamard encoding algorithm (PS-HEA). This algorithm combines the phase superposition method with the Hadamard encoding algorithm, and uniformity coefficient H is introduced to improve the uniformity of multi-point focusing. With the PS-HEA algorithm, we experimentally realized uniform focusing and multi-point customized intensity ratio focusing of light through the scattering medium and demonstrated the strong anti-noise and light control capabilities of PS-HEA in multi-point light focusing. Our research may pave the way for potential applications of optical manipulation and optogenetics.

Quantum Single-Photon Control, Storage, and Entanglement Generation with Planar Atomic Arrays

While artificially fabricated patterned metasurfaces are providing paradigm-shifting optical components for classical light manipulation, strongly interacting, controllable, and deterministic quantum interfaces between light and matter in free space remain an outstanding challenge. Here we theoretically demonstrate how to achieve quantum control of both the electric and magnetic components of an incident single-photon pulse by engineering the collective response of a two-dimensional atomic array. High-fidelity absorption and storage in a long-lived subradiant state, and its subsequent retrieval, are achieved by controlling classically or quantum mechanically the ac Stark shifts of the atomic levels and suppressing the scattering during the absorption. Quantum wavefront control of the transmitted photon with nearly zero reflection is prepared by coupling the collective state of the array to another photon in a cavity and by engineering a Huygens' surface of atoms using only a single coherent standing wave. The proposed schemes allow for the generation of entanglement between the cavity, the lattice, and hence the state of the stored, reflected or transmitted light, and for quantum-state transfer between the cavity and propagating photons. Bipartite entanglement generation is explicitly calculated between a stored single-photon excitation of the array and the cavity photon. We illustrate the control by manipulating the phase, phase superposition, polarization, and direction of a transmitted or reflected photon, providing quantum-optical switches and functional quantum interfaces between light and atoms that could form links in a larger quantum information platform.

Modifications of structural, dielectric and ferroelectric properties induced by porosity in BaTiO3 ceramics with phase coexistence

The modifications of structural and functional properties induced by the gradual increase of porosity from 4 vol% to 26 vol% produced by addition of polymeric sacrificial templates in BaTiO3 ceramics were investigated in detail. With respect to other previous studies concerning porous ceramics, the present ones show a phase superposition around room temperature, whose relative amount impact on their functional properties. Low/high porosity favours the orthorhombic/tetragonal symmetry, respectively. Permittivity and polarisation (both irreversible and reversible ones) regularly decrease when reducing ceramic density, while dc tunability and P(E) loops of denser ceramics have shown peculiar features at intermediate fields, i.e. modifications of hysteretic-nonhysteretic character of ε(E) dependences at about± (8–10) kV/cm and wasp-waisted P(E) loops. To explain such effects, a simplified Landau-based approached considering variable shear stress contributions (higher in dense ceramics, lower in porous ones) was developed to examine the stability of orthorhombic/tetragonal states as a function of stress and applied field levels. The simulations indicated for dense ceramics the possibility of a field-induced structural transformation at intermediate field range overlapped on the general trend of stress-induced increasing of orthorhombic amount. The porosity-induced modification of properties in BaTiO3 ceramics is related to the value of porosity itself which reduces the amount of ferroelectric active phase, to possible modifications of pore connectivity at various porosity levels, but also by modifications of internal stress level induced by porosity, which impact on the polymorph phase composition.

Design of high-resolution near-field focusing metasurface lens

A high-resolution near-field focusing metasurface lens (MSL) was proposed to meet the high-resolution and miniaturization requirements of focusing devices in the Ka-band passive millimeter wave (PMMW) imaging system. Based on coaxial ring structure with polarization insensitivity, the design of a single refraction surface phase gradient MSL capable of focusing on plane waves is completed. Furthermore, the near-field focusing is realized by the method of phase superposition. The overall size of the lens s is 80 × 80 mm2, composed of 25 × 25 unit with the thickness of only 0.24λ. The feed source used a tapered slot antenna based on substrate integrated waveguide. The simulation results indicate a good spatial resolution of the presented lens, which can focus the electromagnetic wave radiated from the feed antenna at 70 mm with the focal spot size of 9 mm. The lens can effectively reduce the system volume and achieve high resolution imaging when utilized in PMMW imaging system.

Planar efficient metasurface for generation of Bessel beam and super-resolution focusing

In this paper, we propose a device generating Bessel beam that can assist microscope to enhance resolution of microscope to λ/3. As the conventional optical devices of generating Bessel beam have some drawbacks, such as low efficiency, and bulky volume, we design plane-axicons for generating Bessel beam using the principle of phase superposition. The designed plane-axicons can generate Bessel beams with zero-order and higher-order by changing topological charge n. We also demonstrate the FWHMs of plane-axicons about as small as λ/3 and have FWHMs with weak fluctuations independent of wavelength across the visible spectrum, which means the Bessel beam can be used to increase resolution of microscope. These performances make the plane-axicons can also enable other advanced research and applications related to Bessel beams ranging from laser fabrication to optical manipulation.