Accepted
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Surface nanobubbles, as nanoscale gaseous domains spontaneously formed at solid-liquid interfaces, exhibit significant application potential in the biomedical field owing to their unique nanoscale size effects, rapid dynamic response characteristics, and favorable biocompatibility. In ultrasonic imaging, surface nanobubbles enhance tissue acoustic contrast by generating strong harmonic scattering signals through nonlinear oscillation under stable cavitation. In antibacterial disinfection applications, the rupture of surface nanobubbles produces transient high pressure, synergizing with reactive oxygen species/hydroxyl radical mediated oxidative damage to achieve high-efficiency bacterial inactivation. However, in physiological environments, blood flow shear stress and pH fluctuations may induce premature rupture of surface nanobubbles, leading to imaging signal attenuation or risks of non-specific tissue damage, rendering their stability a critical factor determining functional efficacy and biosafety. Notably, the experimental observation of surface nanobubble lifetimes (ranging from hours to days) significantly contradicts the dissolution behavior within microseconds predicted by classical thermodynamic theory, which urgent demand for the construction of stability theoretical models. Existing theoretical models, though elucidating surface nanobubble stability mechanisms from multiple perspectives, are constrained by a lack of intrinsic correlation and inherent limitations, thereby limiting targeted optimization toward stability:the contamination barrier model emphasizes that surfactant adsorption inhibits gas diffusion; the dynamic equilibrium model explains that stability arises from the dynamic balance of gas exchange at the gas-liquid interface; the contact line pinning model reveals that substrate heterogeneity constrains the evolution of the three-phase contact line; the local supersaturation model proposes that local high-concentration gas layers formed by substrate adsorption delay dissolution; the interfacial charge enrichment model suggests that electrostatic pressure from the double layer counteracts the Laplace pressure driving dissolution; and the internal high-density model posits that condensed high-density gas inside reduces diffusion rate and partially counteracts the Laplace pressure. This review systematically summarizes the research progress on the stability mechanisms of surface nanobubbles:it first reviews the discovery history of surface nanobubbles; then deeply analyzes the core mechanisms, intrinsic correlations, and limitations of the aforementioned theoretical models; finally, combined with application examples in the biomedical field, it examines the technical challenges faced by surface nanobubbles and proposes potential optimization strategies and future perspectives based on their stability theoretical models.
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Elastic scattering is one of the useful approach to control the transmission behavior of microwave photons transporting in microwave quantum networks without energy consumption. Therefore, it has practical significance for the development of microwave quantum devices and the construction of multi-node microwave quantum networks. In view of the existence of the same device, specifically the transmission line embedded by a single Josephson junction, could be described by different circuit models (the series and parallel ones), in this paper we first theoretically analyze the transporting feature for the microwave photons being scattered by the different elastic scattering model, described by either the series or the parallel embedding models, generated by a single LC loop and a nonlinear Josephson junction device, respectively. The classical microwave transport theory predicts that, the series LC loop and the parallel LC loop lead to different microwave photon elastic scattering behaviors, i.e., the series LC circuit yields the resonant reflection and the parallel LC circuit leading alternatively to the resonant transmission. Recently, the transport properties of microwave photons scattered by a Josephson junction embedded in a transmission line had been discussed, and the results suggested that the Josephson junction embedded in the transmission line should be described by a series embedding circuit, which implies the resonant reflection. We argue here that, if the Josephson junction is embedded in parallel in the transmission line, the elastically scattered microwave photons should be transmitted by resonant transmission. In order to test which of the above two different embedding circuit models, yielding the completely different elastic scattering behaviors, is physically correct, we then fabricated such a device, i.e., a single Joseph junction device embedded in a transmission line is prepared, and measured its elastic scattering transmission coeffcient at extremely low temperature. The results are consistent with the expected effects of the parallel embedding circuit model, but conflicted with the behaviors predicted by the series embedding circuit model in the literature. Based on the above theoretical and experimental analysis on the elastic scattering of a single Josephson junction device, we further propose a scheme to control the elastic scattering behavior of microwave photons by modulating a DC superconducting quantum interference device with a bypass current, which could be applied to the construction of a microwave quantum network based on elastic scattering node controls.
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Machine vision, serving as the "eyes" of artificial intelligence (AI), is one of the key windows for AI to acquire external information. However, traditional machine vision relies on the Von Neumann architecture, where sensing, storage, and processing are separated. This architecture necessitates constant data transfer between different units, inevitably leading to high power consumption and latency. To address these challenges, A PtSe2 photosynaptic device with negative light response was prepared. The device showed an inhibitory postsynaptic current (IPSC) under light pulse stimulation, and achieved optically tunable synaptic behaviors, including double pulse facilitation (PPD), short-range plasticity (STP), and long-range plasticity (LTP). In addition, the device exhibits dependence on light duration, and the image in-situ sensing and storage functions are demonstrated and verified using a 3×3 sensor array. By using 28×28 device array combined with artificial neural network (ANN), the integrated perception-storage-preprocessing function of visual information is realized. The experimental results show that the image after preprocessing (denoising) reaches 91% accuracy after 100 epochs training. Finally,lasers with two representative wavelengths of 405 and 532 were chosen as the light sources in the experiment, and the I-V characteristic curves changes most under the blue light pulse of 450 nm, which is because the blue light has higher photon energy to produce negative light effect. Based on the different photocurrent of the device responding to different wavelengths of light, the photoelectric synaptic logic gates 'NOR','NAND' and 'XOR' are established, which enables image processing functions such as dilation, erosion and difference recognition. The device's power consumption is calculated to be 0.111nJ per spike. The research results show great potential to provide simplified information processing and effectively promote the application of negative photoconductivity of PtSe2, which should help advance more integrated and efficient NVS.
, , Received Date: 2024-11-08
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Amorphous gallium oxide (a-GaOx) exhibits excellent electrical conductivity, a wide bandgap, high breakdown field strength, high visible light transmittance, high sensitivity to specific ultraviolet wavelengths, low preparation temperatures, relatively simple processing, wide substrate applicability, and ease of obtaining high-quality thin films. These attributes make it a suitable candidate for applications in transparent electronic devices, ultraviolet detectors, high-power devices, and gas sensors. Presently, the research on a-GaOx remains limited, focusing primarily on films with an O/Ga ratio less than or equal to 1.5. Increasing the concentration of oxygen vacancies to enhance the conductivity of the material often leads to a reduction in its bandgap, which is undesirable for high-power applications. Variations in O/Ga in the films can affect the formation of chemical bonds and significantly influence the band structure. In this study, five groups of a-GaOx thin films with high oxygen-to-gallium ratios are successfully fabricated by increasing the gas flow rate at low sputtering power. The elemental compositions of the films are analyzed using energy dispersive spectroscopy (EDS), revealing the O/Ga ratio gradually decreasing from 3.89 to 3.39. Phase analysis by using X-ray Diffraction (XRD) confirms the amorphous nature of the films. Optical properties are characterized using an ultraviolet-visible spectrophotometer (UV-Vis), indicating that the optical bandgap and the density of localized states gradually increase. X-ray photoelectron spectroscopy (XPS) is utilized to analyze the elemental compositions, chemical states, and valence band structures of the films, showing that the valence band maximum decreases and the content of Ga2O within the material increases. Subsequently, Au/a-Ga2Ox/Ti/Au Schottky devices are fabricated under the same processing conditions. The I-V characteristics of these devices are measured using a Keithley 4200, revealing changes in the electron transport mechanism at the metal-semiconductor (MS) interface, with the gradual increase in electron affinity calculated. C-V characteristics are measured using a Keithley 590, and the donor concentration (density of localized states) at the interface is calculated to gradually increase. In summary, by controlling appropriate process parameters, it is possible to improve the conductivity of electronic devices while increasing the bandgap of a-GaOx, which is significant for high-power applications.
, , Received Date: 2025-02-14
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In the past few decades, achieving room-temperature superconductivity has become an unremitting pursuit of scientists. Guided by the “chemical precompression” theory, hydrogen-rich compounds have emerged as the main candidates for high-temperature superconductors, positioning them at the forefront of superconducting materials research. Extensive computational studies have identified numerous binary hydrides with predicted superconducting transition temperatures (Tc) exceeding 200 K, such as CaH6, H3S, MgH6, YH6, YH9, YH10, and LaH10. Significantly, the high-Tc super-conductivities of H3S, LaH10, CaH6, YH6, YH9 have been experimentally confirmed. Compared with binary hydrides, ternary hydrides offer more diverse chemical compositions and structures, potentially leading to enhanced properties. Zhang et al. [Zhang Z, Cui T, Hutcheon M J, Shipley A M, Song H, Du M, Kresin V Z, Duan D F, Pickard C J, Yao Y 2022 Phys. Rev. Lett. 128 047001] theoretically designed a series of AXH8-type (A = Sc, Ca, Y, Sr, La, Ba; X = Be, B, Al) ternary hydrides with “fluorite-type” backbone, which were predicted to have high-Tc values under moderate pressure. Among those ternary hydrides, LaBeH8 has been experimentally confirmed to achieve a Tc value of 110 K at 80 GPa. The Tc values of ternary clathrate hydrides of Li2MgH16 and Li2NaH17 have been predicted to greatly exceed the room temperature, while the required stabilization pressures all exceeded 200 GPa. Xie et al. [Xie H, Duan D F, Shao Z J, Song H, Wang Y C, Xiao X H, Li D, Tian F B, Liu B B, Cui T 2019 J. Phys. Condens. Matter. 31 245404] and Liang et al. [Liang X W, Bergara A, Wang L Y, Wen B, Zhao Z S, Zhou X F, He J L, Gao G Y, Tian Y J 2019 Phys. Rev. B 99 100505(R)] independently predicted CaYH12 compounds with $ Pm\bar 3m $ and $ Fd\bar 3m $ space groups, both of which exhibited high-Tc above 200 K at about 200 GPa. Other ternary hydrides, such as La-B-H, K-B-H, La-Ce-H, and Y-Ce-H, have also been extensively investigated. At current stage, a major focus of superconducting hydrides is to achieve high-temperature superconductivity at lower pressures. In this study, taking $ Pm\bar 3m $ (CaYH12) as a representative, we systematically investigate the effects of electron and hole doping on the dynamical stability and superconductivity in ternary hydride by first-principal calculations. The $ Pm\bar 3m $ (CaYH12) exhibits a Tc value of 218 K at 200 GPa, which is consistent with that reported previously. When decompressing to below 180 GPa, imaginary phonons emerge. The analysis of doping simulations demonstrates that the electron doping exacerbates the softening of the imaginary phonons, whereas hole doping eliminates the imaginary frequencies. At the pressures of 130, 100 and 70 GPa, the $ Pm\bar 3m $ (CaYH12) phase can be stabilized by hole doping at the concentrations of 0.9, 0.8, and 1.1 e/cell, respectively. Further electron-phonon coupling calculations show that the Tc values of $ Pm\bar 3m $ (CaYH12) at 130, 100 and 70 GPa are 194, 209, and 194 K at the corresponding doping level, which are only 10–20 K less than the Tc at 200 GPa. At the pressure of 70 GPa, Tc slightly decreases to 189 K at a doping level of 1.2 e/cell, primarily due to the reduced ωlog compared with that in the case of 1.1 e/cell. And the enhanced λ at 1.2 e/cell is mainly contributed by the average electron-phonon coupling matrix element $ \langle {I^2}\rangle $ and average phonon frequency $ {\langle {\omega ^2}\rangle ^{1/2}} $, rather than the electronic density of states at the Fermi level N(εF). These results indicate that hole doping represents a promising and effective strategy for optimizing the superconductivity of $ Pm\bar 3m $ (CaYH12) by maintaining high-Tc at low pressures. Our study paves an avenue for realizing high-temperature superconductors at low pressure.
, , Received Date: 2025-02-25
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, , Received Date: 2025-02-20
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Packed bed dielectric barrier discharge (PB-DBD) is extremely popular in plasma catalysis applications, which can significantly improve the selectivity and energy efficiency of the catalytic processes. In order to achieve some complex chemical reactions, it is necessary to mix different materials in practical applications. In this work, by using the two-dimensional particle-in-cell/Monte Carlo collision (PIC/MCC) method, the discharge evolution in PB-DBD packed with two mixed dielectrics is numerically simulated to reveal the discharge characteristics. Due to the polarization of dielectric columns, the enhancement of electric field induces streamers at the bottom of the dielectric columns with high electrical permittivity (εr). The streamers propagate downward in the voids between the dielectric columns with low εr, which finally converts into volume discharges. Then, a new streamer forms near the upper dielectric plate and propagates downward along the void of the dielectric columns with high εr. Moreover, electron density between the columns with high εr is lower than that between the dielectric columns with low εr. In addition, the numbers of e, $ {\text{N}}_{2}^{+} $, $ {\text{O}}_{2}^{+} $ and $ {\text{O}}_{2}^{-} $ present different profiles versus time. All of e, $ {\text{N}}_{2}^{+} $ and $ {\text{O}}_{2}^{+} $ increase in number before 0.8 ns. After 0.8 ns, the number of electrons decreases with time, while the numbers of $ {\text{N}}_{2}^{+} $ and $ {\text{O}}_{2}^{+} $ keep almost constant. In the whole process, the number of $ {\text{O}}_{2}^{-} $ keeps increasing with time increasing. The reason for the different temporal profiles can be analyzed as follows. The sum of electrons deposited on the dielectric and those lost in attachment reaction is greater than the number of electrons generated by ionization reaction, resulting in the declining trend of electrons. Comparatively, the deposition of $ {\text{N}}_{2}^{+} $ and $ {\text{O}}_{2}^{+} $ on the dielectric almost balances with their generation, leading to the constant numbers of $ {\text{N}}_{2}^{+} $ and $ {\text{O}}_{2}^{+} $. In addition, the variation of averaged electron density ($ {\bar{n}}_{{\mathrm{e}}} $) and averaged electron temperature ($ {\bar{T}}_{{\mathrm{e}}} $) in the voids between the dielectric columns are also analyzed under different experimental parameters. Simulation results indicate that both of them decrease with pressure increasing or voltage amplitude falling. Moreover, they increase with dielectric column radius enlarging. In addition, $ {\bar{n}}_{{\mathrm{e}}} $ increases and then decreases with the increase of N2 content in the working gas, while $ {\bar{T}}_{{\mathrm{e}}} $ monotonically increases. The variations of $ {\bar{n}}_{{\mathrm{e}}} $ and $ {\bar{T}}_{{\mathrm{e}}} $ in the voids can be explained as follows. With the increase of pressure, the increase of collision frequency and the decrease of average free path lead to less energy obtained per unit time by electrons from the electric field, resulting in the decreasing of $ {\bar{T}}_{{\mathrm{e}}} $. Moreover, the first Townsend ionization coefficient decreases with the reduction in $ {\bar{T}}_{{\mathrm{e}}} $, resulting in less electrons produced per unit time. Hence, both $ {\bar{n}}_{{\mathrm{e}}} $ and $ {\bar{T}}_{{\mathrm{e}}} $ decrease with pressure increasing. Additionally, $ {\bar{T}}_{{\mathrm{e}}} $is mainly determined by electric field strength. Therefore, the rising voltage amplitude results in the increase of and $ {\bar{T}}_{{\mathrm{e}}} $. Based on the same reason for pressure, $ {\bar{n}}_{{\mathrm{e}}} $ also increases with the augment of voltage amplitude. Consequently, both $ {\bar{n}}_{{\mathrm{e}}} $ and $ {\bar{T}}_{{\mathrm{e}}} $ increase with voltage amplitude increasing. In addition, the surface area of dielectric columns increases with dielectric column radius enlarging. Therefore, more polarized charges are induced on the inner surface of the dielectric column, inducing a stronger electric field outside. Accordingly, the enlarging of dielectric column radius leads $ {\bar{n}}_{{\mathrm{e}}} $ and $ {\bar{T}}_{{\mathrm{e}}} $ to increase. Moreover, the variation of $ {\bar{n}}_{{\mathrm{e}}} $ with N2 content is analyzed from the ionization rate, and that of $ {\bar{T}}_{{\mathrm{e}}} $ is obtained by analyzing the ionization thresholds of N2 and O2.
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Coherent population transfer in quantum systems is of fundamental importance in many fields spanning atomic and molecular collision dynamics, information processing for qubit systems. Stimulated Raman nonadiabatic passage technique, when implemented in an externally driven three-level system, provides an efficient approach for realizing accelerated population transfer while maintaining robust quantum coherence, without the rotating wave approximation. However, previous protocols employ multiple pulses and imply that Rabi frequencies have a few oscillations during dynamical evolution. In this paper, under two-photon resonance, we utilize the gauge transformation method to inversely design a Λ-configuration three-level system that can be solved exactly. By invoking a $SU(3)$ transformation, we establish the connection between Schrödinger representation and gauge representation with which the effective Hamiltonian is an Abelian operator. Subsequently, we construct the desired Hamiltonian and further investigate its dynamic behavior. The result demonstrate that, by imposing appropriate boundary conditions on the control parameters, high-fidelity population transfer can be achieved in ideal evolution. In addition, for the practical case with pulse truncation and intermediate state decay, the fidelities of specific models can reach about $99.996\%$ and for $99.983\%$. Compared to other existing nonadiabatic quantum control schemes, we show that the present scheme has the distinctive advantages. Firstly, instead of introducing an additional microwave field, we achieve the desired quantum control by applying only a few sets of Stokes and pump pulses. Moreover this approach does not exhibit Rabi oscillations in the dynamic process, nor does it present singularities in the pulse itself.
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In this paper, the first-principles method based on density functional theory and non-equilibrium Green's function is used to design and investigate transport properties of multifunctional spintronic devices based on zigzag SiC nanoribbon via edge asymmetric dual-hydrogenation. The zigzag SiC nanoribbon via edge asymmetric dual-hydrogenation is selected as electrodes, and SiC atomic single chain are connected at the above, middle upper, middle lower, and below positions of the electrodes to form four molecular devices: M1, M2, M3 and M4. The study found that the maximum spin current value of the device in the P-magnetic configuration decreases sequentially as the connection position transitions from top to bottom. The spin-down current-voltage curves of M1, M2, and M4 exhibit significant spin rectification effects, with maximum rectification ratios of 9.8×105, 5.2×105, and 6.7×104, respectively. The spin-up current-voltage curve of M3 shows the best rectification effect, with a maximum rectification ratio of 6.9×106. More importantly, the spin-up current-voltage curve of M3 exhibits a unique negative differential resistance effect in the negative voltage range. The spin-up currents of the four devices in the AP magnetic configuration are very weak throughout the bias region and hardly changes with increasing voltage. Although there are differences in the spin-down current of the four devices within the positive and negative bias ranges, they are not significant, thus failing to exhibit excellent rectification effects. In addition, M2 exhibits perfect spin filtering effect in the negative voltage range in both P and AP magnetic configurations, with a spin filtering efficiency close to 100%. This article integrates spin rectification and spin filtering, as well as spin rectification and negative differential resistance, into a single molecular device, achieving the theoretical design of a composite spin device with two functions. The research results provide an important solution for the practical preparation and control of zigzag SiC nanoribbon spin devices in the future.
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Fe-based amorphous alloys offer exceptional properties such as low coercivity and core losses. In recent years, interest has focused on developing amorphous alloys using selective laser melting (SLM) technology. However, the glass-forming ability (GFA) and mechanical properties pose challenges for fabricating Fe-based amorphous alloys with complex geometries. This work aims to establish fundamental processing-(micro)structure-property links in Fe-based amorphous alloys processed by selective laser melting (SLM). With that purpose, a low-energy-input melt pool was achieved and the overlap quality between adjacent melt tracks and successive deposited layers is enhanced., through optimization of printing parameters. The Fe-based amorphous alloy was obtained with a high relative density of 94.3% and a low coercivity of 0.5 Oe. Furthermore, the saturation magnetization of the printed alloy increased to 0.89 T compared to the powder feedstock. This work overcomes the mutually restrictive relationship between the glass-forming ability (GFA) and part quality during fabricating the complex-structure Fe-based amorphous alloys, holding significant implications for advancing the application of Fe-based amorphous alloys.
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Wavelength-tunable lasers play a crucial role in fields such as precision interferometry and ultra-stable laser applications. The precision of wavelength tuning and the accuracy of frequency stabilization in lasers serve as key indicators of their performance. To enhance these aspects, closed-loop control with dual-beam paths, such as saturated absorption spectrum spatial stabilization, is commonly employed. The signal-to-noise ratio (SNR) of the control beam detection significantly impacts the control precision. Investigating parameters that influence this SNR and analyzing their relationships hold great engineering significance for further improving the tuning precision and frequency stabilization accuracy of lasers.
To increase the SNR, this article examines intensity noise in wavelength-modulation systems based on the polarizer — phase-delay — polarizer model. A polarization beam splitter (PBS) cannot achieve a zero polarization extinction ratio (PER), thus introducing intensity noise from the interference of p and s polarization light. Additionally, non-ideal stray light, such as back-reflected and scattered light from optical components, further reduces the SNR of the detection signal when it converges on the detector's active area. This chapter provides a detailed analysis of these two types of noise, exploring the effects of factors such as PER, wavelength-modulation range, beam diameter, laser polarization direction, and modulation frequency. Building on theoretical analysis, it also simulates optical phenomena involving half-wave plates with different tilt and rotation angles, as well as dual-frequency Gaussian elliptically polarized light under various modulation parameters.
Theoretical analysis indicates that the intensities of p and s polarization light undergo periodic variations as the angles between the half-wave plate's optical axis and the PBS's slow-axis direction and between the linear-polarization direction and the half-wave plate's optical axis change. The positions of the extreme values of these intensities shift with variations in PER. At certain specific angles, destructive interference leads to extremely low intensities in both transmitted and reflected light. Furthermore, when the detector receives stray light of multiple frequencies, the synthesized phase varies periodically with wavelength tuning. This implies that as time progresses (corresponding to the center wavelength being tuned to different values), the interference intensity exhibits periodic changes from constructive interference to destructive interference and back to constructive interference. Consequently, abnormal dips and peaks may appear in the optical signal intensity.
The experiment employed a 633-B-A81-SA-PZT laser from LD-PD INC with a 10mW output. Simulation used a true zero-order half-wave plate model centered at 633 nm. The laser wavelength was tunable within 633 nm±10 pm, with a 10kHz sine-wave current modulation under wavelength-current tuning coefficient of 1 pm/mA. After an isolator, a 90:10 coupler split the beam into a 9mW output and a 1mW experiment beam, which was collimated and adjusted by a polarizer, a true zero-order half-wave plate, and a PBS to set the p and s light power ratio. Two Thorlabs FDS100 detectors captured the beams, with signals collected via a data acquisition card. PD1 and PD2 signals showed significant differences under certain conditions, and the p and s light signals varied periodically with half-wave plate rotation. Adding a polarizer at the laser exit and adjusting its angle improved signal consistency. After alignment, the SNR rose by 10 dB to 31 dB .
In this study, wavelength tuning of a 633nm semiconductor laser was performed using a saturated absorption spectrum ring light path. Under different modulation conditions, inconsistencies in the two-beam intensity signals were observed. Polarization control raised the SNR to 31 dB, confirming the theoretical model. Additionally, time domain analysis of stray light from the wavelength-tuned source revealed that reducing the wavelength tuning range and modulation frequency effectively suppresses high frequency noise.
To increase the SNR, this article examines intensity noise in wavelength-modulation systems based on the polarizer — phase-delay — polarizer model. A polarization beam splitter (PBS) cannot achieve a zero polarization extinction ratio (PER), thus introducing intensity noise from the interference of p and s polarization light. Additionally, non-ideal stray light, such as back-reflected and scattered light from optical components, further reduces the SNR of the detection signal when it converges on the detector's active area. This chapter provides a detailed analysis of these two types of noise, exploring the effects of factors such as PER, wavelength-modulation range, beam diameter, laser polarization direction, and modulation frequency. Building on theoretical analysis, it also simulates optical phenomena involving half-wave plates with different tilt and rotation angles, as well as dual-frequency Gaussian elliptically polarized light under various modulation parameters.
Theoretical analysis indicates that the intensities of p and s polarization light undergo periodic variations as the angles between the half-wave plate's optical axis and the PBS's slow-axis direction and between the linear-polarization direction and the half-wave plate's optical axis change. The positions of the extreme values of these intensities shift with variations in PER. At certain specific angles, destructive interference leads to extremely low intensities in both transmitted and reflected light. Furthermore, when the detector receives stray light of multiple frequencies, the synthesized phase varies periodically with wavelength tuning. This implies that as time progresses (corresponding to the center wavelength being tuned to different values), the interference intensity exhibits periodic changes from constructive interference to destructive interference and back to constructive interference. Consequently, abnormal dips and peaks may appear in the optical signal intensity.
The experiment employed a 633-B-A81-SA-PZT laser from LD-PD INC with a 10mW output. Simulation used a true zero-order half-wave plate model centered at 633 nm. The laser wavelength was tunable within 633 nm±10 pm, with a 10kHz sine-wave current modulation under wavelength-current tuning coefficient of 1 pm/mA. After an isolator, a 90:10 coupler split the beam into a 9mW output and a 1mW experiment beam, which was collimated and adjusted by a polarizer, a true zero-order half-wave plate, and a PBS to set the p and s light power ratio. Two Thorlabs FDS100 detectors captured the beams, with signals collected via a data acquisition card. PD1 and PD2 signals showed significant differences under certain conditions, and the p and s light signals varied periodically with half-wave plate rotation. Adding a polarizer at the laser exit and adjusting its angle improved signal consistency. After alignment, the SNR rose by 10 dB to 31 dB .
In this study, wavelength tuning of a 633nm semiconductor laser was performed using a saturated absorption spectrum ring light path. Under different modulation conditions, inconsistencies in the two-beam intensity signals were observed. Polarization control raised the SNR to 31 dB, confirming the theoretical model. Additionally, time domain analysis of stray light from the wavelength-tuned source revealed that reducing the wavelength tuning range and modulation frequency effectively suppresses high frequency noise.
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The diamond/graphene composite electrode has garnered significant attention due to its ability to synergistically combine the low background current and broad potential window of the diamond component with the high electrochemical activity of the graphitic component. In this study, argon-oxygen plasma etching was employed to treat nanodiamond/graphite composite films, and the surface structure of the few-layer graphene-coated nanodiamond is obtained by adjusting the etching time to control the number of graphite layers on the surface of the film, and then the surface layer of the few-layer graphene-coated nanodiamond and the bottom layer with good conductivity with more graphite components are constructed to form a double-layer structure. The experimental findings demonstrate that when the argon/oxygen plasma treatment time reaches 5 min, the graphite components on the surface layer of the film are etched into a structure of small-layer graphite coated nanodiamond, which increased the resistivity (2918.3 Ω·cm) and potential window (3.43 V). In addition, the surface state is changed from hydrogen termination to oxygen termination, so that the diamond grain has a positron affinity potential, and the electrochemical active area increases from 387 to 2893 μC/cm2. As the treatment time continued to extend to 20 min, the number of graphite layers on the surface of the film decreased, the diamond phase content increased, the resistivity of the film increased, and the electrochemically active area decreased. When the etching time reaches 25 min, the graphite layer under the composite film is exposed, and the graphite on the surface of the diamond is transformed into few-layer graphene, forming a double-layer structure of the top layer of few-layer graphene-coated diamond and the bottom layer of graphite, which synergistically improves the electrochemical activity (775 μC/cm2), reduces the resistivity of the composite film (1060.0 Ω··cm) and widens the potential window (3.50 V). This work presents a novel plasma-etching strategy for fabricating diamond/graphene hybrid electrodes, offering new insights into harnessing the complementary advantages of these carbon allotropes for advanced electrochemical applications.
, , Received Date: 2025-02-16
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Spin-orbit torque (SOT) based on the spin-orbit coupling (SOC) effect has received increasing attention in magnetic information storage, logical operation and neuron simulation devices because it can effectively manipulate magnetization conversion, chiral magnetic domain walls, and magnetic skyrmion motions. Further improvement of the SOT efficiency and reduction of the driving current density are crucial scientific problems to be solved for high-density and low-power applications of SOT-based spintronic devices. The heavy rare-earth metal dysprosium (Dy) possesses a relatively strong SOC due to the partially filled f orbital electrons (4f10), which is expected to generate spin Hall torques. In this work, the influences of Dy thickness on the SOT efficiency and SOT-driven magnetic reversal are explored in the Dy/Pt/[Co/Pt]3 magnetic multilayers, where the rare-earth Dy and [Co/Pt]3 are used as a spin-source layer and a perpendicularly magnetized ferromagnetic layer, respectively. A series of Dy/Pt/[Co/Pt]3 heterostructures with the values of Dy layer thickness (tDy) of 1, 3, 5 and 7 nm is fabricated by ultrahigh-vacuum magnetron sputtering. The perpendicular magnetic anisotropy, SOT efficiency, spin Hall angle and current-induced magnetization switching are characterized using the magnetic property and electrical transport measurements. The results show that the conversion field and magnetic anisotropic field decrease with the increase of tDy, revealing that the magnetic parameters can be regulated by the bottom Dy layer due to their structural sensitivity. However, both damping-like SOT efficiency and effective spin Hall angle (θeff SH) gradually increase with the increase of tDy, indicating that the rare-earth Dy can provide additional spin current to enhance the SOT efficiency apart from the contribution of Pt/[Co/Pt]3. Particularly, the maximum value of θeff SHof 0.379±0.008 is achieved when tDy is 7 nm. According to the fitting analysis of the drift-diffusion model, the intrinsic spin Hall angle and spin diffusion length of the rare-earth Dy are extracted to be 0.260±0.039 and (2.234±0.383) nm, respectively, suggesting that Dy can be used as an ideal spin-source material. In addition, the critical conversion current density (Jc) gradually decreases with the increase of tDy, and Jc reaches a minimum value of approximately 5.3×106 A/cm2 at tDy = 7 nm, which is mainly attributed to the increase of the damping-like SOT and slight decrease of the switching field. These results experimentally demonstrate a strong spin Hall effect of the rare-earth Dy, and provide a feasible route for designing SOT-based spintronic devices with low-power dissipation.
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