Phase Control Research Articles

Topological Metasurface for Spin‐Decoupled Wavefront Manipulation of Terahertz Surface Plasmons

AbstractOn‐chip wavefront manipulation of terahertz surface plasmons is crucial for the miniaturization and practical application of terahertz technology. Recently, topological metasurfaces have emerged as a promising avenue for spin‐decoupled wavefront manipulation, leveraging the unique topological properties of non‐Hermitian matrices near their singular points. Despite their innovative phase control mechanisms, topological metasurfaces have not yet been explored for surface plasmon devices. Here, spin‐decoupled wavefront manipulation of terahertz surface plasmons is experimentally achieved using freestanding topological metasurfaces. This approach promises to expand the control methods of surface plasmons and broaden the application scenarios of topological metasurfaces, providing a new paradigm for the design of integrated on‐chip terahertz devices.

Nanogap-Induced Phase Control Reveals the Momentum of Light Inside the Dielectric Medium

Nanogap-Induced Phase Control Reveals the Momentum of Light Inside the Dielectric Medium

All-Optical Ultrafast Arbitrary Rotation of Hole Orbital Qubits with Direct Phase Control

All-Optical Ultrafast Arbitrary Rotation of Hole Orbital Qubits with Direct Phase Control

Magnetic order in nanogranular iron germanium (Fe0.53Ge0.47) films

We study the effect of strain on the magnetic properties and magnetization configurations in nanogranular FexGe1-xfilms (x=0.53±0.05) with and without B20 FeGe nanocrystals surrounded by an amorphous structure. Relaxed films on amorphous silicon nitride membranes reveal a disordered skyrmion phase while films near and on top of a rigid substrate favor ferromagnetism and an anisotropic hybridization of Fedlevels and spin-polarized Gespband states. The weakly coupled topological states emerge at room temperature and become more abundant at cryogenic temperatures without showing indications of pinning at defects or confinement to individual grains. These results demonstrate the possibility to control magnetic exchange and topological magnetism by strain and inform magnetoelasticity-mediated voltage control of topological phases in amorphous quantum materials.

MEMS-tunable topological bilayer metasurfaces for reconfigurable dual-state phase control

Tunable optical metasurfaces (MSs) have demonstrated exceptional capabilities in actively manipulating light fields. However, most existing tunable MSs are limited to controlling only one functionality. Here, by combining a MEMS mirror with a plasmonic bilayer MS (BMS), we develop an electrically driven MEMS-BMS platform enabling complete reflection phase transformation and switching between two encoded functionalities by actuating the MEMS mirror. This capability stems from different optical responses of each MS layer at distinct MEMS-BMS separations, due to evolving topological singularities in a defined parameter space. With this tunable topological MEMS-BMS platform, we demonstrate polarization-independent MEMS-BMS for reconfigurable diffraction gratings, achieving ∼25% efficiency, ∼0.75 contrast at 850-nm wavelength, and fast response (∼5µs). The MEMS-BMS arrangement for generating vortex beams with switchable topological charges of ±1 is also demonstrated, evidenced by distinct near- and far-field interferograms. Our work expands the scope of tunable MSs by exploiting dynamic topological phases in the MEMS-BMS arrangement, paving the way for multifunctional tunable meta-optics.

Programmable metasurface based phase-modulating reflector for 2.4GHz wireless communications

Abstract This paper presents an innovative programmable metasurface structure that achieves precise phase control within the 2 to 2.7 GHz frequency range by adjusting the state of varactor diodes embedded in the unit cells. The design employs a single diode, which simplifies the structure, reduces manufacturing costs, and minimizes reflection loss. At 2.4 GHz, the metasurface achieves 1-bit phase responses of 0° and 180°, with a reflection amplitude exceeding 0.72, demonstrating excellent reflective performance. Moreover, as the 2.4 GHz frequency is closely related to wireless communication bands, this programmable metasurface shows significant potential in the field of wireless communication encryption. By integrating dual varactor diodes, the design enables 2-bit phase control with reflection phase angles of 0°, 90°, 180°, and 270°. To validate the design, a 1-bit metasurface structure was fabricated and tested, with experimental results showing a high degree of consistency with simulations, highlighting the potential of this structure in enhancing wireless communication security.

Ivacaftor ameliorates mucus burden, bacterial load, and inflammation in acute but not chronic P. aeruginosa infection in hG551D rats

BackgroundNewly approved highly effective modulation therapies (HEMT) have been life-changing for people with CF. Although these drugs have resulted in significant improvements in lung function and exacerbation rate, bacterial populations in the lung have not been eradicated. The mechanisms behind the continued colonization are not completely clear.MethodsWe used a humanized rat to assess the effects of ivacaftor therapy on infection outcomes. Rats harbor an insert expressing humanized CFTR cDNA, including the G551D mutation. hG551D rats were treated with ivacaftor either during or before infection with P. aeruginosa. The response to infection was assessed by bacterial burden in the lung and mucus burden in the lung.ResultsWe found that hG551D rats treated with ivacaftor had reduced bacteria present in the lung in the acute phase of the infection but were not different than vehicle control in the chronic phase of the infection. Similarly, the percentage of neutrophils in the airways were reduced at the acute, but not chronic, timepoints. Overall weight data indicated that the hG551D rats had significantly better weight recovery during the course of infection when treated with ivacaftor. Potentiation of the G551D mutation with ivacaftor resultant in short-circuit current measurements equal to WT, even during the chronic phase of the infection. Despite the persistent infection, hG551D rats treated with ivacaftor had fewer airways with mucus plugs during the chronic infection.ConclusionsThe data indicate that the hG551D rats have better outcomes during infection when treated with ivacaftor compared to the vehicle group. Rats have increased weight gain, increased CFTR protein function, and decreased mucus accumulation, despite the persistence of infection and inflammation. These data suggest that ivacaftor improves tolerance of infection, rather than eradication, in this rat model.

Enhanced Thermoelectric Properties in Cu₁.₈Se Thin Films: Achieving Superior Power Factor through Phase Control and Optimal Deposition Temperature

Thermoelectric thin films are vital for efficient energy conversion and thermal management. XRD analysis reveals that Cu₁.₈Se films exhibit a mixed α-phase when deposited at room temperature, 100°C, and 300°C, but transition to a pure β-phase at 200°C. The formation of the pure β-Cu₁.₈Se phase at 200°C significantly improves the crystallinity of the films. Increased annealing temperatures lead to greater surface roughness and grain size as observed by AFM and FESEM. Electrical conductivity decreases with higher measurement temperatures, reflecting degenerate semiconductor behavior due to Cu vacancies. The sample deposited at 200°C, exhibiting the pure β-phase, achieves the highest power factor of 5456 μWm⁻1K⁻2 and improved Seebeck coefficient, underscoring the importance of phase purity and controlled surface roughness for optimal thermoelectric performance. Keywodsannealing temperature; Surface Roughness; β-Cu1.8Se thin films; Thermoelectric

Energy efficiency of reactive species generation in radio frequency atmospheric pressure plasma jets driven by tailored voltage waveforms in a He/O2 mixture

Abstract The effect of the shape of the applied voltage waveform on the energy efficiency of reactive species generation is investigated in an atmospheric pressure RF microplasma jet operated in a He/O2 mixture (99.5%/0.5%) based on a one-dimensional hybrid fluid-kinetic simulation method. Using a tailored waveform synthesized from four consecutive harmonics (with a base frequency of f b = 13.56 MHz and amplitudes of ( 160 / k ) V for the k-th harmonic), it is shown that by changing the identical phases of the even harmonics in the waveform, ϕ, the generation efficiencies of three specific reactive species (helium metastables, atomic and vibrationally excited oxygen), defined as the ratio of mean density and input plasma power, attain their maxima for different values of ϕ, due to changes in the Electron Energy Probability Function (EEPF). The phase control of the EEPF and its critical role in modulating generation energy efficiencies are explained in detail. The simulation results are verified by experimental (Phase Resolved Optical Emission Spectroscopy and Two Photon Absorption Laser Induced Fluorescence) data.

MOF-derived phase-selective synthesis of ln2O3 with appropriate surface atomic arrangement for CO2 photoreduction

Crystal phase engineering emerges as a powerful strategy to enhance photocatalytic activity, yet controlled phase-selective synthesis and phase-dependent performance understanding remain challenging. In this study, we introduce a novel method for synthesizing phase-engineered In2O3 via the pyrolysis of metal–organic frameworks (MOFs). We demonstrate that the functional groups and pyrolysis temperatures of MOFs are critical for phase-selective synthesis. Specifically, pyrolysis of MIL-68(ln)–NH2 at optimal temperatures yields In2O3 with rhombohedral (rh-In2O3), cubic (c-In2O3), and rhombohedral/cubic heterophase (rh/c-In2O3) structures. Our photocatalytic CO2 reduction tests reveal that c-In2O3 outperforms rh-In2O3 and rh/c-In2O3, achieving a CO production rate of 29.19 μmol g-1h−1 with 94.47 % selectivity. Spectroscopic and theoretical analyses show that c-In2O3 has superior charge transfer efficiency and lower reaction energy barriers, particularly for the rate-determining *CO intermediate, which exhibits a lower Gibbs free energy on its surface. This work provides a significant advancement in optimizing photocatalytic CO2 reduction efficiency through precise phase engineering, underscoring the vital role of phase control in enhancing catalytic performance.

Real-time fully digital control scheme for pulse coherent beam combining.

A fully digital control scheme for non-polarization-maintaining (non-PM) nanosecond pulse coherent beam combining (CBC) is proposed, where digital locking of optical coherence by single-detector electronic-frequency tagging (LOCSET) for active phase control and stochastic parallel gradient descent (SPGD) for active polarization control is proposed. The fully digital control scheme is integrated on a real-time field-programmable gate array (FPGA) empowered hardware platform and then experimentally validated in a four-channel all-fiber non-fully polarization-maintaining nanosecond pulse CBC system. Consequently, the system can be fully locked in 9.5 ms, and the polarization extinction ratio (PER) of the combined beam is 21.5 dB with a CBC efficiency of 95.3%. The fully digital control scheme integrates the advantages of digital LOCSET and multi-channel active polarization control, enhancing the channel scalability and the potential output power of the non-PM pulse CBC system.

Boron-Intercalation Engineering toward Defected 1T Phase-Rich MoBxS2-x-Supported IrOx Clusters for Acidic OER.

The construction of supported Ir-based catalysts can effectively reduce the amount of Ir and generate a synergistic effect that enhances the oxygen evolution reaction (OER) activity and stability, making it one of the effective solutions for optimizing acidic OER catalysts. However, most reported metal oxide supports suffer from poor acid resistance and low electrical conductivity, which are critical for the OER process. Herein, we synthesized a nanosheet-like defected 1T phase-rich MoBxS2-x via a molten salt calcination process, during which the 1T phase was formed, and B was intercalated into MoS2 to protect the 1T phase structure during annealing procedure. After the wet refluxing process, IrOx clusters were uniformly deposited on the surface of MoBxS2-x to form IrOx@MoBxS2-x, which exhibited an overpotential of 168 mV at a current density of 10 mA cm-2 with an Ir loading amount of 25.8 wt %. By comparing the OER performance of IrOx@MoBxS2-x, IrOx@MoS2(Calcinated), and IrOx@MoS2, it is demonstrated that calcination and B intercalation of MoS2 can significantly increase acidic OER performance. This work digs into the application of 1T-MoS2 as an OER catalyst support, providing strategies for the phase and morphology control of 1T-MoS2.

Active Disturbance Rejection Control for Flux Weakening in Interior Permanent Magnet Synchronous Motor Based on Full Speed Range

To address the impact of load disturbances on the full-speed-range control of an interior permanent magnet synchronous motor (PMSM), an active disturbance rejection control (ADRC) method is proposed. The speed loop employs phased field-weakening control (FW) based on ADRC, while the current loop utilizes proportional-integral-derivative (PID) control. Starting from the motor parameters, the Lagrange multiplier method was used to derive the critical speeds for the maximum torque per ampere (MTPA) and maximum torque per voltage (MTPV) ratios, and the timing for the field-weakening control was analyzed. A full-speed-range control model of the motor was established, and an ADRC-based speed loop controller was designed to achieve smooth transitions between high speeds and anti-disturbance solid capabilities. Based on the proposed control strategy, a 21 kW PMSM was used as the research object, and a full-speed-range control simulation model was developed in MATLAB/SIMULINK to verify the strategy. Compared to the traditional PID control, the simulation results demonstrate that the proposed strategy effectively observes and compensates for load disturbances, significantly reducing initial torque oscillations under three different operating conditions. After a sudden load increase, torque oscillations were reduced by 16%, with the stator current reaching steady state 0.03 s faster, response speed improving by 0.02 s, smooth transitions between speed ranges, and enhanced anti-disturbance performance.

Phase Engineering of ZnSe by Small Molecules as a High-Performance Protective Layer for Zn Anode.

The practical application of aqueous zinc ion batteries is still hampered by the side reactions and dendrite growth on Zn anode. Herein, the phase engineering of ZnSe coating layer by incorporating small molecules is developed to enhance the performance of Zn anode. The unique electronic structure of ZnSe⋅0.5N2H4 promises strong adsorption for Zn atoms and enhanced ability to inhibit hydrogen evolution, thereby promoting uniform Zn deposition and preventing by-product and dendrite growth. Meanwhile, fast Zn2+ transfer and deposition kinetics are also demonstrated by ZnSe⋅0.5N2H4. As a result, the ZnSe⋅0.5N2H4@Zn symmetric cell achieves long-term cycling stability up to 1900 h and 300 h at high current densities of 5 mA cm-2 and 20 mA cm-2, respectively. The assembled ZnSe⋅0.5N2H4@Zn||NH4V4O10 full cell presents outstanding cycling stability and rate capability. This work highlights the key role of crystal phase control of protective layer for high-performance zinc anode.

Harnessing the Unconventional Cubic Phase in 2D LaNiO3 Perovskite for Highly Efficient Urea Oxidation

AbstractPhase engineering is a critical strategy in electrocatalysis, as it allows for the modulation of electronic, geometric, and chemical properties to directly influence the catalytic performance. Despite its potential, phase engineering remains particularly challenging in thermodynamically stable perovskites, especially in a 2D structure constraint. Herein, we report phase engineering in 2D LaNiO3 perovskite using the strongly non‐equilibrium microwave shock method. This approach enables the synthesis of conventional hexagonal and unconventional trigonal and cubic phases in LaNiO3 by inducing selective phase transitions at designed temperatures, followed by rapid quenching to allow precise phase control while preserving the 2D porous structure. These phase transitions induce structural distortions in the [LaO]+ layers and the hybridization between Ni 3d and O 2p states, modifying local charge distribution and enhancing electron transport during the six‐electron urea oxidation process (UOR). The cubic LaNiO3 offers optimal electron transport and active site accessibility due to its high structural symmetry and open interlayer spacing, resulting in a low onset potential of 1.27 V and a Tafel slope of 33.1 mV dec−1 for UOR, outperforming most current catalysts. Our strategy features high designability in phase engineering, enabling various electrocatalysts to harness the power of unconventional phases.

Harnessing the Unconventional Cubic Phase in 2D LaNiO3 Perovskite for Highly Efficient Urea Oxidation

AbstractPhase engineering is a critical strategy in electrocatalysis, as it allows for the modulation of electronic, geometric, and chemical properties to directly influence the catalytic performance. Despite its potential, phase engineering remains particularly challenging in thermodynamically stable perovskites, especially in a 2D structure constraint. Herein, we report phase engineering in 2D LaNiO3 perovskite using the strongly non‐equilibrium microwave shock method. This approach enables the synthesis of conventional hexagonal and unconventional trigonal and cubic phases in LaNiO3 by inducing selective phase transitions at designed temperatures, followed by rapid quenching to allow precise phase control while preserving the 2D porous structure. These phase transitions induce structural distortions in the [LaO]+ layers and the hybridization between Ni 3d and O 2p states, modifying local charge distribution and enhancing electron transport during the six‐electron urea oxidation process (UOR). The cubic LaNiO3 offers optimal electron transport and active site accessibility due to its high structural symmetry and open interlayer spacing, resulting in a low onset potential of 1.27 V and a Tafel slope of 33.1 mV dec−1 for UOR, outperforming most current catalysts. Our strategy features high designability in phase engineering, enabling various electrocatalysts to harness the power of unconventional phases.

Global Selection Rules and Giant Enhanced Harmonic Generations in LiNbO3 Nonlinear Meta‐Optics

AbstractNonlinear optical metasurfaces provide nanoscale‐level control of harmonic waves, making them highly promising platforms for both fundamental research and applications in nonlinear optics. However, the traditional selection rules theory, which has long served as a guiding principle for nonlinear meta‐optics, is local and neglects the significance of meta‐atomic lattice symmetry. In addition, achieving high‐efficiency harmonic generation along with nonlinear optical Pancharatnam‐Berry (PB) phase control remains challenging. To this end, a novel global selection rule jointly determined by the symmetries of both meta‐atom and lattice is proposed. Nonlinear metasurfaces designed based on this theory enable frequency conversions forbidden by previous local selection rules. A more comprehensive relationship between the nonlinear PB phase and the meta‐atomic rotation angle is revealed. Moreover, an efficient nonlinear PB metasurface platform for second harmonic generations is first demonstrated using LiNbO3 thin films with aligned crystal orientations in a hybrid design. The normalized conversion efficiency reaches approximately two orders of magnitude higher than that of existing nonlinear PB metasurfaces working in the near‐infrared band. These findings not only shed light on the underlying mechanisms of nonlinear light‐matter interactions, but also open up exciting possibilities in terahertz, entangled photon pairs, and high harmonic generations.

Research on Phase Stabilization Algorithm of Femtosecond Timing System

This paper presents the design, implementation, and validation of a femtosecond timing system aimed at achieving precise time control and phase synchronization for large particle accelerators. A prototype system utilizing a continuous wave laser was developed, focusing on minimizing timing jitter and long-term phase drift. Key components include an optical delay line for coarse adjustments and a fiber stretcher for fine-tuning, achieving an adjustment precision of 1 femtosecond. The system incorporates a phase detection module with a non-In-phase/Quadrature downconversion approach, enabling high-accuracy phase measurements. A collaborative algorithm was designed to optimize the interplay between the optical delay line and the fiber stretcher, utilizing a proportional-integral-derivative (PID) control algorithm to enhance adjustment precision. A Field Programmable Gate Array (FPGA) served as the core interface converter, facilitating data communication and real-time phase information acquisition. Experimental results demonstrated significant improvements in phase stability, with average phase deviation reduced from 1374.104 fs to 15.782 fs, showcasing the effectiveness of the proposed system in achieving high precision and stability in phase control. This research provides a solid foundation for future advancements in timing systems for high-frequency reference signals.

Laser-induced reconfigurable wavefront control with a structured Ge2Sb2Te5-based metasurface

Phase change materials have been widely exploited in active metasurfaces due to their large index contrast. Despite recent advances in phase-change metasurfaces, it remains a challenge to integrate diverse reconfigurable optical functionalities into a single metasurface. Here, we demonstrate an effective strategy to realize reconfigurable wavefront control by combining a Ge2Sb2Te5-rod array with laser writing technology. Through arbitrarily modifying the position and power of laser source, the laser writing process helps to realize site-selective and multi-level phase change of Ge2Sb2Te5 rods. Due to multi-level switching for optical properties of Ge2Sb2Te5 material, the Ge2Sb2Te5-rod array offers complete phase control and high amplitude modulation. Subsequently, various optical devices are designed in numerical simulation, including a phase-only hologram, dynamic meta-deflectors, a grayscale image and a perfect absorber. The structured Ge2Sb2Te5-based metasurface with the combination of laser writing technology offers an effective way to explore various types of optical functionalities in the same device.

Fundamental Study of Phased Array Ultrasonic Cavitation Abrasive Flow Polishing Titanium Alloy Tubes.

A new method of machining ultrasonic cavitation abrasive flow based on phase control technology was proposed for improving the machining efficiency of the inner wall of TC4 (Ti-6Al-4V) titanium alloy tubes. According to ultrasonic phase control theory and Hertzian contact theory, a model of ultrasonic abrasive material removal rate under phase control technology was established. Using COMSOL Multiphysics 6.1 software, the phase control deflection effect, acoustic field distribution, and the size of the phase control cavitation domain on the inner wall surface were examined at different transducer frequencies and transducer spacings. The results show that the inner wall polishing has the most excellent effect at a transducer frequency of 21 kHz and spacing of 100 mm. In addition, the phased deflection limit was explored under the optimal parameters, and predictive analyses were performed for voltage control under uniform inner wall polishing. Finally, the effect of processing time on polishing was experimented with, and the results showed that the polishing efficiency was highest from 0 to 30 min and stabilized after 60 min. In addition, the change in surface roughness and material removal of the workpiece were analyzed under the control of the voltage applied, and the experimental results corresponded to the voltage prediction analysis results of the simulation, which proved the viability of phase control abrasive flow polishing for the uniformity of material removal of the inner wall of the tube.