35,078 results on '"Physics - Applied Physics"'
Search Results
2. Remote-sensing based control of 3D magnetic fields using machine learning for in-operando applications
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Sandoval, Miguel A. Cascales, Jurczyk, J., Skoric, L., Sanz-Hernández, D., Leo, N., Kovacs, A., Schrefl, T., Hierro-Rodríguez, A., and Fernández-Pacheco, A.
- Subjects
Physics - Applied Physics - Abstract
In-operando techniques enable real-time measurement of intricate physical properties at the micro- and nano-scale under external stimuli, allowing the study of a wide range of materials and functionalities. In nanomagnetism, in-operando techniques greatly benefit from precise three-dimensional (3D) magnetic field control, enabling access to complex magnetic states forming in systems where multiple energies are set to compete with each other. However, achieving such precision is challenging and uncommon, as specific applications impose constraints on the type and geometry of magnetic field sources, limiting their capabilities. Here, we introduce an approach that leverages machine learning algorithms to achieve precise 3D magnetic field control using a hexapole electromagnet that is composed of three independent, non-collinear dipole electromagnets. In our experimental setup, magnetic field sensors are placed at a distance from the sample position due to inherent constraints, leading to indirect field measurements that differ from the magnetic field experienced by the sample. We find that the existing relationship between the remote and sample frames of reference is non-linear, thus requiring a more complex calibration method. To address this, we employ a multi-layer perceptron neural network that processes multiple inputs from a dynamic magnetic field sequence, effectively capturing the time-dependent non-linear field response. The network achieves high calibration accuracy and demonstrates exceptional generalization to unseen magnetic field sequences. This study highlights the significant potential of machine learning in achieving high-precision control and calibration, crucial for in-operando experiments where direct measurement at the point of interest is not possible.
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- 2024
3. Indium tin oxide combined with anti-reflective coatings with high transmittance for wavelengths < 400 nm
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Jansson, Erik, Scheuer, Volker, Jordan, Elena, Kostourou, Konstantina, and Mehlstäubler, Tanja E.
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Physics - Optics ,Physics - Applied Physics - Abstract
The transparent and conductive properties of indium tin oxide (ITO) thin films, make them an attractive coating for optically integrated ion traps. However, the relatively low transmittance for wavelengths $<$ 400 nm, high scattering and high production temperature limits the usability in trapped-ion-based quantum technologies. Here we present ITO coatings and a combined ITO + anti-reflective (AR) coating system optimized for an ion trap applied using ion beam sputtering (IBS). The coatings feature a high transmittance for wavelengths $<$ 400 nm and additional wavelengths up to 1000 nm, low scattering and low production temperature $<$ 150 $^{\circ}$C. The transmission, reflection and absorption spectra are simulated and the resistance, transmittance and scattering at 370 nm are measured for different ITO coating thicknesses and the ITO + AR coating system. For the ITO + AR coating system a resistance of 115 $\pm$ 5 $\Omega/\Box$, transmittance of 80$\%$ and scattering of 0.012 $\pm$ 0.002$\%$ at 370 nm is achieved., Comment: 13 pages, 9 figures
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- 2024
4. Quantum sensing with duplex qubits of silicon vacancy centers in SiC at room temperature
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Tahara, Kosuke, Tamura, Shin-ichi, Toyama, Haruko, Nakane, Jotaro J., Kutsuki, Katsuhiro, Yamazaki, Yuichi, and Ohshima, Takeshi
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Quantum Physics ,Physics - Applied Physics - Abstract
The silicon vacancy center in Silicon Carbide (SiC) provides an optically addressable qubit at room temperature in its spin-$\frac{3}{2}$ electronic state. However, optical spin initialization and readout are less efficient compared to those of spin-1 systems, such as nitrogen-vacancy centers in diamond, under non-resonant optical excitation. Spin-dependent fluorescence exhibits contrast only between $|m=\pm 3/2\rangle$ and $|m=\pm 1/2\rangle$ states, and optical pumping does not create a population difference between $|+1/2\rangle$ and $|-1/2\rangle$ states. Thus, operating one qubit (e.g., $\left\{|+3/2\rangle, |+1/2\rangle \right\}$ states) leaves the population in the remaining state ($|-1/2\rangle$) unaffected, contributing to background in optical readout. To mitigate this problem, we propose a sensing scheme based on duplex qubit operation in the quartet, using microwave pulses with two resonant frequencies to simultaneously operate $\left\{ |+3/2\rangle, |+1/2\rangle \right\}$ and $\left\{ |-1/2\rangle, |-3/2\rangle \right\}$. Experimental results demonstrate that this approach doubles signal contrast in optical readout and improves sensitivity in AC magnetometry compared to simplex operation., Comment: 19 pages, 5 figures, 1 table
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- 2024
5. Erbium doped yttrium oxide thin films grown by chemical vapour deposition for quantum technologies
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Blin, Anna, Kolar, Alexander, Kamen, Andrew, Lin, Qian, Liu, Xiaogang, Benamrouche, Aziz, Bachelet, Romain, Goldner, Philippe, Zhong, Tian, Serrano, Diana, and Tallaire, Alexandre
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Condensed Matter - Materials Science ,Physics - Applied Physics - Abstract
The obtention of quantum-grade rare-earth doped oxide thin films that can be integrated with optical cavities and microwave resonators is of great interest for the development of scalable quantum devices. Among the different growth methods, Chemical Vapour Deposition (CVD) offers high flexibility and has demonstrated the ability to produce oxide films hosting rare-earth ions with narrow linewidths. However, growing epitaxial films directly on silicon is challenging by CVD due to a native amorphous oxide layer formation at the interface. In this manuscript, we investigate the CVD growth of erbium-doped yttrium oxide (Er:Y2O3) thin films on different substrates, including silicon, sapphire, quartz or yttria stabilized zirconia (YSZ). Alternatively, growth was also attempted on an epitaxial Y2O3 template layer on Si (111) prepared by molecular beam epitaxy (MBE) in order to circumvent the issue of the amorphous interlayer. We found that the substrate impacts the film morphology and the crystalline orientations, with different textures observed for the CVD film on the MBE-oxide/Si template (111) and epitaxial growth on YSZ (001). In terms of optical properties, Er3+ ions exhibit visible and IR emission features that are comparable for all samples, indicating a high-quality local crystalline environment regardless of the substrate. Our approach opens interesting prospects to integrate such films into scalable devices for optical quantum technologies., Comment: 15 pages, 8 figures, 2 tables
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- 2024
6. The Performance of Seeded Free-Electron Lasers Through Dispersion Strength Tuning
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Zeng, Li, Feng, Chao, Wang, Xiaofan, Yi, Huaiqian, and Zhang, Weiqing
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Physics - Accelerator Physics ,Physics - Applied Physics - Abstract
Over the last decade, external seeded free electron lasers (FELs) have achieved significant advancements across various disciplines, progressively establishing themselves as indispensable tools in fields ranging from fundamental science to industrial applications. The performance of seeded FELs is critically dependent on the quality of the frequency up-conversion process. Optimized conditions for seeded FELs are typically considered as the maximization of the bunching factor. This paper discusses alternative perspectives on the optimization criteria for seeded FELs by analyzing the impact of dispersion strength on their overall performance. We investigate the relationship among the required dispersion strength for achieving the maximum bunching factor, maximum pulse energy, and optimal energy stability through theoretical analysis, simulation calculations, and experimental explorations. Additionally, the direct observation of pulse splitting emphasizes the consideration of trade-off between pulse energy and temporal coherence in seeded FELs. These results provide valuable insights and practical guidance for controlling the pulse characteristics of seeded FELs, contributing to the tuning and optimization of FEL facilities.
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- 2024
7. Enhanced heat dissipation and lowered power consumption in electronics using two-dimensional hexagonal boron nitride coatings
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R, Karthik, Srivastava, Ashutosh, Midya, Soumen, Shanu, Akbar, Slathia, Surbhi, Vandana, Sajith, Sreeram, Punathil Raman, Kar, Swastik, Glavin, Nicholas R., Roy, Ajit K, Singh, Abhishek Kumar, and Tiwary, Chandra Sekhar
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Condensed Matter - Materials Science ,Physics - Applied Physics - Abstract
Miniaturization of electronic components has led to overheating, increasing power consumption and causing early circuit failures. Conventional heat dissipation methods are becoming inadequate due to limited surface area and higher short-circuit risks. This study presents a fast, low-cost, and scalable technique using 2D hexagonal boron nitride (hBN) coatings to enhance heat dissipation in commercial electronics. Inexpensive hBN layers, applied by drop casting or spray coating, boost thermal conductivity at IC surfaces from below 0.3 W/m-K to 260 W/m-K, resulting in over double the heat flux and convective heat transfer. This significantly reduces operating temperatures and power consumption, as demonstrated by a 17.4% reduction in a coated audio amplifier circuit board. Density functional theory indicates enhanced interaction between 2D hBN and packaging materials as a key factor. This approach promises substantial energy and cost savings for large-scale electronics without altering existing manufacturing processes., Comment: 27 Pages, 5 Figures
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- 2024
8. Manufacturing carbon nanotube transistors using lift-off process: limitations and prospects
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Gao, Xilong, Si, Jia, and Zhang, Zhiyong
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Physics - Applied Physics - Abstract
Carbon nanotube field-effect transistors (CNT FETs) are regarded as promising candidates for next-generation energy-efficient computing systems. While research has employed the lift-off process to demonstrate the performance of CNT FETs, this method now poses challenges for enhancing individual FET performance and is not suitable for scalable fabrication. In this paper, we summarize the limitations of the lift-off process and point out that future advancements in manufacturing techniques should prioritize the development of etching processes., Comment: 6 pages, 2 figures
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- 2024
9. Solvated Electrons and Hydroxyl Radicals at the Plasma-Liquid Interface
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Lee, Seungjun, Kang, Hyung-Gu, Kim, Minkwan, and Yun, Gunsu
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Physics - Plasma Physics ,Physics - Applied Physics - Abstract
While hydroxyl radicals ($\cdot$OH) play an important role as potent oxidizing agents in various plasma applications, their high reactivity confines them to a thin layer at the plasma-liquid interface, posing challenges in comprehending the intricate generation and transport processes. Similarly, solvated electrons ($\mathrm{e_{aq}}$), highly reactive reducing agents, are expected to exhibit distribution beneath the liquid surface and interact with $\cdot$OH in the thin layer. In this study, we have determined the penetration depth and concentration of ($\mathrm{e_{aq}}$) at the interface between an atmospheric argon plasma plume and an electrolyte anode via a lock-in amplification absorbance measurement. With bias voltages from 1000 to 2500 V, the penetration depth remains approximately 10 nm, and the peak concentration near the surface reaches 1 mM. Diffusion is the primary mechanism for $\cdot$OH generation in the electrolyte, with most $\cdot$OH reacting with ($\mathrm{e_{aq}}$) at the interface, thus influencing the ($\mathrm{e_{aq}}$) distribution. In contrast, the electrolyte cathode significantly boosts $\cdot$OH generation, leading to rapid recombination into hydrogen peroxide.
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- 2024
10. Comparative Study of InGaAs and GaAsSb Nanowires for Room Temperature Operation of Avalanche Photodiodes at 1.55 {\mu}m
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Sankar, Shrivatch, Murkute, Punam, Meleski, Micah, Gajowski, Nathan, Nooman, Neha, Sumon, Md. Saiful Islam, Arafin, Shamsul, Reano, Ron, and Krishna, Sanjay
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Physics - Optics ,Physics - Applied Physics - Abstract
III V semiconductor nanowire based photodetectors have significant potential for remote sensing and LiDAR applications, particularly due to their ability to operate at 1.55 {\mu}m. Achieving room temperature operation and near unity absorption using these nanowires at 1.55 {\mu}m is crucial for single photon detection, which offers a promising solution to the challenges posed by the existing superconducting nanowire single photon detectors. Key materials suited for this wavelength include lattice matched In0.53Ga0.47As and Ga0.5As0.5Sb to InP. This study reports a comparison between InGaAs and GaAsSb nanowires to achieve high absorption efficiency at room temperature. Through optimized nanowire arrangement and geometry, we aim to maximize absorption. Our approach features a comparative analysis of patterned InGaAs and GaAsSb nanowires with absorption characteristics modeled using finite difference time domain simulations to enhance absorption at the target wavelength. We also present the complete workflow for nanowire fabrication, modeling, and simulation, encompassing the production of tapered nanowire structures and measurement of their absorption efficiency. Our experimental results show that tapered InGaAs and GaAsSb nanowires exhibit an absorption efficiency of 93% and 92%, respectively, at room temperature around 1.55 {\mu}m.
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- 2024
11. A Density Functional Theory Study of Magnetic Transition in MnO2 adsorbed Vanadium Carbide (V$_2$C) MXene
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Fatima, Mahjabeen, Khan, Saleem Ayaz, and Rizwan, Syed
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Materials Science ,Physics - Applied Physics - Abstract
The work reports nonmagnetic behavior (0.04 $\mu$B) in two-dimensional (2D) V2C-OF MXene and ferromagnetism in MnO$_2$ adsorbed V2C-OF MXene. The density functional theory (DFT) calculations were carried out to study the magnetic moments of V$_2$C-OF and MnO$_2$@V$_2$C-OF MXene. The MXene, which is derived from the exfoliation of its parent V$_2$AlC MAX phase, shows a good potential to be a ferromagnetic when MnO$_2$ is adsorbed on it. The V$_2$C MXene and MnO$_2$ adsorbed V$_2$C MXene were successfully synthesized, as characterized using X-ray diffraction, showing an increased c-lattice parameter from 22.6{\AA} to 27.2{\AA} after MnO$_2$ adsorption. The DFT study confirmed that MnO$_2$ adsorbed V$_2$C MXene changed from nonmagnetic (in V$_2$C MXene) to a strong ferromagnetic with a magnetic moment of 4.48$\mu$B for Mn adsorbed V$_2$C-OF MXene. The current work is a step-forward towards understanding of magnetism in two-dimensional materials for future 2D spintronics.
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- 2024
12. Ultra-sensitive Short-Wave Infrared Single-Photon Detection using a Silicon Single-Electron Transistor
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Sudha, P., Miyagawa, S., Samanta, A., and Moraru, D.
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Physics - Applied Physics ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
Ultra-sensitive short-wave infrared (SWIR) photon detection is a crucial aspect of ongoing research in quantum technology. However, developing such detectors on a CMOS-compatible silicon technological platform has been challenging due to the low absorption coefficient for silicon in the SWIR range. In this study, a codoped silicon-based single-electron transistor (SET) in a silicon-on-insulator field-effect transistor (SOI-FET) configuration is fabricated, which successfully detects single photons in the SWIR range with ultra-high sensitivity. The detection mechanism is evidenced by the shift in the onset of the SET current peaks and by the occurrence of random telegraph signals (RTS) under light irradiation, as compared to the dark condition. The calculated sensitivity of our device, in terms of noise equivalent power, is approximately 10-19 W Hz-1/2.
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- 2024
13. Design and Process Analysis of a Split-Gate Trench Power MOSFET with Bottom-Trench Hk-Pillar Superjunction for Enhanced Performance
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Jiang, Yunteng, Xiao, Zhentao, Zhang, Zonghao, Zhang, Juncheng, Wang, Chenxing, Li, Wenjun, Huang, Haimeng, Islam, Aynul, and Yang, Hongqiang
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Physics - Applied Physics - Abstract
In this paper, we propose a simulation-based novel Split-Gate Trench MOSFET structure with an optimized fabrication process to enhance power efficiency, switching speed, and thermal stability for high-performance semiconductor applications. Integrating high-k pillars with superjunction structures beneath the split gate enhancing breakdown performance by reducing critical field intensity by up to 35%, the device achieves a 15% improvement in Figures of Merit (FOMs) for BV2/Ron,sp. Dynamic testing reveals approximately a 25% reduction in both input and output capacitance, as well as gate-to-drain charge (QGD). This reduction, coupled with an approximately 40% improvement in Baliga's High-Frequency Figure of Merit (BHFFOM) and over 20% increase in the New High-Frequency Figure of Merit (NHFFOM), underscores the design's suitability for high-speed, high-efficiency power electronics. Simulations examining the effects of high-k pillar depth indicate that an optimal depth of 3.5 um achieves a balanced performance between BV and Ron,sp. The influence of high-k materials on BT-Hk-SJ MOSFET performance was investigated by comparing hafnium dioxide (HfO2), nitride, and oxynitride. Among these, HfO2 demonstrated optimal performance across static, dynamic, and diode characteristics due to its high dielectric constant, while material choice had minimal impact, with variations kept within 5%., Comment: 8 pages, 12 figures
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- 2024
14. Vanadium Doped Magnetic MoS2 Monolayers of Improved Electrical Conductivity as Spin-Orbit Torque Layer
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Sahoo, Krishna Rani, Talluri, Manoj, Maity, Dipak, Mundlia, Suman, Lal, Ashique, Devapriya, M. S., Haldar, Arabinda, Murapaka, Chandrasekhar, and Narayanan, Tharangattu N.
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Physics - Applied Physics - Abstract
Two-dimensional (2D) transition metal di-chalcogenide layers with high electrical conductivity and spin-orbit coupling (SOC) can find huge potential in spintronic devices. With limited success of 2D spin Hall material development, we demonstrate vanadium (V) substitutionally doped monolayer MoS2 (VMS) as a potential spin Hall material having tunable electrical conductivity, SOC strength, and room temperature magnetism. Systematic enhancement in the electrical conductivity is observed with the extent of V doping, where it is enhanced from ~0.3 S/m of MoS2 to ~100000 S/m upon doping to the level of 9 atomic%. Ferromagnetic resonance (FMR) based spin-pumping experiments indicate the spin transport across the junction of permalloy (Py) and VMS. Spin-torque FMR measurements demonstrate the suggesting latter's potential as a spin-orbit torque layer in 2D spintronic devices.
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- 2024
15. Solid-state batteries enabled by ultra-high-frequency self-heating
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Zhang, Buyi, Chalise, Divya, Zeng, Yuqiang, Kaur, Sumanjeet, Dames, Chris, and Prasher, Ravi S.
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Physics - Applied Physics - Abstract
Solid-state batteries (SSBs) are promising next-generation batteries due to their high energy density and enhanced thermal stability and safety. However, their sluggish kinetics and transport at room temperature results in high internal impedance and critically reduces the attainable discharge energy density. Taking advantage of their strong temperature-dependent ionic conductivity, here we introduce ultra-high frequency ($>10^5$ Hz) self-heating (UHFSH) of SSBs, which can rapidly warm up the batteries from room temperature to operating temperature (~65 {\deg}C) in less than a minute. As proof of concept, UHFSH experiments were conducted on symmetric solid-state cells with lithium aluminum germanium phosphate (LAGP) electrolyte with different configurations. Using an experimentally validated model, pack-level simulations predict fast heating (50 K/min) and minimized heating energy consumption (less than 4%). Without any modification of the materials or structure of the batteries, our non-intrusive self-heating strategy enables the SSBs to discharge more than two-fold energy in 25 {\deg}C ambient.
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- 2024
16. Improvement in the Removal Efficiency of the Ultraviolet Laser Ablation by an Additional Simultaneous Irradiation of a Weak Infrared Laser
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Kawamura, Y. and Kai, Akihiro
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Physics - Optics ,Physics - Applied Physics - Abstract
Remarkable improvement in the removal efficiency of the ultraviolet laser (fourth harmonic wave of Nd:YAG laser) ablation was observed by irradiating a weak infrared laser (fundamental wave of Nd:YAG laser) simultaneously and additionally to various kinds of materials, such as copper, acrylic resin, alumina, silicon and amorphous carbon. The improvement ratio ranged from 50% to 280%, while the laser fluency of the infrared laser was as small as about 1.6% of that of the ultraviolet laser. Although, we have not succeed in explaining the reasons why this effect occurs, it will have the potentiality to decrease the photon cost in the wide range of ultraviolet laser machining, because the method and the phenomena are simple and clear. The improvement in the morphology was also observed, when it is applied to the laser lathe micromachining.
- Published
- 2024
17. Ferroelectric HfO$_2$-ZrO$_2$ multilayers with reduced wake-up
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Mandal, Barnik, Philippe, Adrian-Marie, Valle, Nathalie, Defay, Emmanuel, Granzow, Torsten, and Glinsek, Sebastjan
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Condensed Matter - Materials Science ,Physics - Applied Physics - Abstract
Since the discovery of ferroelectricity in HfO$_2$ thin films, significant research has focused on Zr-doped HfO$_2$ and solid solution (Hf,Zr)O$_2$ thin films. Functional properties can be further tuned via multilayering, however, this approach has not yet been fully explored in HfO$_2$-ZrO$_2$ films. This work demonstrates ferroelectricity in a 50 nm thick, solution-processed HfO$_2$-ZrO$_2$ multilayer film, marking it as the thickest such film to date exhibiting ferroelectric properties. The multilayer structure was confirmed through transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy, with high-resolution TEM revealing grain continuity across multiple layers. This finding indicates that a polar phase in the originally paraelectric ZrO$_2$ layer, can be stabilized by the HfO$_2$ layer. The film attains a remanent polarization of 8 uC/cm$^2$ and exhibits accelerated wake-up behavior, attributed to its higher breakdown strength resulting from the incorporation of multiple interfaces. These results offer a faster wake-up mechanism for thick ferroelectric hafnia films.
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- 2024
18. RSFQ All-Digital Programmable Multi-Tone Generator For Quantum Applications
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Barbosa, João, Brennan, Jack C., Casaburi, Alessandro, Hutchings, M. D., Kirichenko, Alex, Mukhanov, Oleg, and Weides, Martin
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Quantum Physics ,Physics - Applied Physics - Abstract
One of the most important and topical challenges of quantum circuits is their scalability. Rapid Single Flux Quantum (RSFQ) technology is at the forefront of replacing current standard CMOS-based control architectures for a number of applications, including quantum computing and quantum sensor arrays. By condensing the control and readout to SFQ-based on-chip devices that are directly connected to the quantum systems, it is possible to minimise the total system overhead, improving scalability and integration. In this work, we present a novel RSFQ device that generates multi tone digital signals, based on complex pulse train sequences using a Circular Shift Register (CSR) and a comb filter stage. We show that the frequency spectrum of the pulse trains is dependent on a preloaded pattern on the CSR, as well as on the delay line of the comb filter stage. By carefully selecting both the pattern and delay, the desired tones can be isolated and amplified as required. Finally, we propose architectures where this device can be implemented to control and readout arrays of quantum devices, such as qubits and single photon detectors., Comment: Submitted to IEEE Transactions on Quantum Engineering
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- 2024
19. Effect of Top Al$_2$O$_3$ Interlayer Thickness on Memory Window and Reliability of FeFETs With TiN/Al$_2$O$_3$/Hf$_{0.5}$Zr$_{0.5}$O$_2$/SiO$_x$/Si (MIFIS) Gate Structure
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Hu, Tao, Jia, Xinpei, Han, Runhao, Yang, Jia, Bai, Mingkai, Dai, Saifei, Chen, Zeqi, Ding, Yajing, Yang, Shuai, Han, Kai, Wang, Yanrong, Zhang, Jing, Zhao, Yuanyuan, Ke, Xiaoyu, Sun, Xiaoqing, Chai, Junshuai, Xu, Hao, Wang, Xiaolei, Wang, Wenwu, and Ye, Tianchun
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Condensed Matter - Materials Science ,Physics - Applied Physics - Abstract
We investigate the effect of top Al2O3 interlayer thickness on the memory window (MW) of Si channel ferroelectric field-effect transistors (Si-FeFETs) with TiN/Al$_2$O$_3$/Hf$_{0.5}$Zr$_{0.5}$O$_2$/SiO$_x$/Si (MIFIS) gate structure. We find that the MW first increases and then remains almost constant with the increasing thickness of the top Al2O3. The phenomenon is attributed to the lower electric field of the ferroelectric Hf$_{0.5}$Zr$_{0.5}$O$_2$ in the MIFIS structure with a thicker top Al2O3 after a program operation. The lower electric field makes the charges trapped at the top Al2O3/Hf0.5Zr0.5O$_2$ interface, which are injected from the metal gate, cannot be retained. Furthermore, we study the effect of the top Al$_2$O$_3$ interlayer thickness on the reliability (endurance characteristics and retention characteristics). We find that the MIFIS structure with a thicker top Al$_2$O$_3$ interlayer has poorer retention and endurance characteristics. Our work is helpful in deeply understanding the effect of top interlayer thickness on the MW and reliability of Si-FeFETs with MIFIS gate stacks., Comment: 7 pages, 12 figures
- Published
- 2024
20. Intelligent Adaptive Metasurface in Complex Wireless Environments
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Yang, Han Qing, Dai, Jun Yan, Li, Hui Dong, Wu, Lijie, Zhang, Meng Zhen, Shen, Zi Hang, Wang, Si Ran, Wang, Zheng Xing, Tang, Wankai, Jin, Shi, Wu, Jun Wei, Cheng, Qiang, and Cui, Tie Jun
- Subjects
Physics - Applied Physics ,Electrical Engineering and Systems Science - Systems and Control - Abstract
The programmable metasurface is regarded as one of the most promising transformative technologies for next-generation wireless system applications. Due to the lack of effective perception ability of the external electromagnetic environment, there are numerous challenges in the intelligent regulation of wireless channels, and it still relies on external sensors to reshape electromagnetic environment as desired. To address that problem, we propose an adaptive metasurface (AMS) which integrates the capabilities of acquiring wireless environment information and manipulating reflected electromagnetic (EM) waves in a programmable manner. The proposed design endows the metasurfaces with excellent capabilities to sense the complex electromagnetic field distributions around them and then dynamically manipulate the waves and signals in real time under the guidance of the sensed information, eliminating the need for prior knowledge or external inputs about the wireless environment. For verification, a prototype of the proposed AMS is constructed, and its dual capabilities of sensing and manipulation are experimentally validated. Additionally, different integrated sensing and communication (ISAC) scenarios with and without the aid of the AMS are established. The effectiveness of the AMS in enhancing communication quality is well demonstrated in complex electromagnetic environments, highlighting its beneficial application potential in future wireless systems.
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- 2024
21. Concurrent operando neutron imaging and diffraction analysis revealing spatial lithiation phase evolution in an ultra-thick graphite electrode
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Strobl, Markus, Baur, Monica E., Samothraktis, Stavros, Malamud, Florencia, Zhang, Xiaolong, Tung, Patrick K. M., Schmidt, Søren, Woracek, R., Lee, J., Kiyanagi, Ryoji, Kuhn, Luise Theil, Segev, Inbal Gavish, and Ein-Eli, Yair
- Subjects
Condensed Matter - Materials Science ,Physics - Applied Physics - Abstract
Energy efficient, safe and reliable Li-ion batteries (LIBs) are required for a wide range of applications. Charging capabilities of thick electrodes still holding their stored high-energy is a most desirable characteristic in future advanced LIBs. The introduction of ultra-thick graphite anode meets limitations in internal electrode transport properties, leading to Li-ion gradients with detrimental consequences for battery cell performance and lifetime. Yet, there is a lack of experimental tools capable of providing a complete view of local processes and evolving gradients within such thick electrodes. Here, we introduce a multi-modal operando measurement approach, enabling quantitative spatio-temporal observations of Li concentrations and intercalation phases in ultra-thick, graphite electrodes. Neutron imaging and diffraction concurrently provide correlated information from the macroscopic scale of the cell and electrode down to the crystallographic scale portraying the intercalation and deintercalation processes. In particular, the evolving formation of the solid electrolyte interphase (SEI), observation of gradients in total lithium content, as well as in the formation of ordered LixC6 phases and trapped lithium have been mapped throughout the first charge-discharge cycle of the cell. Different lithiation stages co-exist during charging and discharging of an ultra-thick composite graphite-based electrode; delayed lithiation and delithiation processes are observed at the central region of the electrode, while the SEI formation, potential plating and dead lithium are predominantly found closer to the interface with the separator. The study furthermore emphasizes the potential of the method to study Li ion diffusion and the kinetics of lithiation phase formation in advanced ultra-thick electrodes.
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- 2024
22. Flexible Thermoelectric Active Cooling Garment to Combat Extreme Heat
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Feng, Tianshi, Wang, Jiedong, Sun, Ethan, Di Buono, Antonio, and Chen, Renkun
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Physics - Applied Physics - Abstract
With the increasing frequency, intensity, and duration of extreme heat events due to climate change, heat-related diseases or even mortality have become more prevalent. An efficient personal cooling strategy can mitigate heat stress by regulating the skin temperature within the thermal comfort zone. However, lightweight, wearable, and sustainable cooling garments are unavailable today. Here, we developed a TED-based cooling garment and demonstrated its effectiveness in active personal cooling. The garment is shown to maintain the skin temperature within its thermal comfort zone in a hot environment of up to 40 oC under mild forced convection conditions (air flow speed of 2.2 m s-1). Furthermore, we demonstrated a portable cooling system with less than 700 grams of total weight, which includes the TED-based garment, a battery pack, and a temperature controller. The system showed long-term cooling on the skin with varying ambient temperatures from 35 to 40 oC. With the advantages of lightweight, flexible, controllable and long-term effective cooling, the TED cooling garments described in this work can contribute to enhanced health and comfort in an increasingly hotter climate.
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- 2024
23. Magnetic response of topological insulator layer with metamaterial substrate induced by an electric point source
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Sun, Qiang, Dvorquez, Eitan, Pinto, Felipe, Mathpal, Mohan C., Maze, Jerónimo R., Gibson, Brant C., and Greentree, Andrew D.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Physics - Applied Physics - Abstract
Topological insulators (TIs) are materials with unique surface conductive properties that distinguish them from normal insulators and have attracted significant interest due to their potential applications in electronics and spintronics. However, their weak magnetic field response in traditional setups has limited practical applications. Here, we show that integrating TIs with active metamaterial substrates can significantly enhance the induced magnetic field by more than 10^4 times. Our results demonstrate that selecting specific permittivity and permeability values for the active metamaterial substrate optimizes the magnetic field at the interface between the TI layer and the metamaterial, extending into free space. This represents a substantial improvement over previous methods, where the magnetic field decayed rapidly. The findings reveal that the TI-metamaterial approach enhances the magnetic field response, unveiling new aspects of TI electromagnetic behavior and suggesting novel pathways for developing materials with tailored electromagnetic properties. The integration of metamaterials with TIs offers promising opportunities for advancements in materials science and various technological applications. Overall, our study provides a practical and effective approach to exploring the unique magnetic field responses of TIs, potentially benefiting other complex material systems.
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- 2024
24. Quantum Nanophotonics with Energetic Particles:X-rays and Free Electrons
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Shi, Xihang, Lee, Wen Wei, Karnieli, Aviv, Lohse, Leon Merten, Gorlach, Alexey, Wong, Lee Wei Wesley, Saldit, Tim, Fan, Shanhui, Kaminer, Ido, and Wong, Liang Jie
- Subjects
Physics - Optics ,Physics - Applied Physics - Abstract
Rapid progress in precision nanofabrication and atomic design over the past 50 years has ushered in a succession of transformative eras for molding the generation and flow of light. The use of nanoscale and atomic features to design light sources and optical elements-encapsulated by the term nanophotonics-has led to new fundamental science and innovative technologies across the entire electromagnetic spectrum, with substantial emphasis on the microwave to visible regimes. In this review, we pay special attention to the impact and potential of nanophotonics in a relatively exotic yet technologically disruptive regime: high-energy particles such as X-ray photons and free electrons-where nanostructures and atomic design open the doors to unprecedented technologies in quantum science and versatile X-ray sources and optics. As the practical generation of X-rays is intrinsically linked to the existence of energetic free or quasi-free-electrons, our review will also capture related phenomena and technologies that combine free electrons with nanophotonics, including free-electron-driven nanophotonics at other photon energies. In particular, we delve into the demonstration and study of quantum recoil in the X-ray regime, the study of nanomaterial design and free-electron wave shaping as means to enhance and control X-ray radiation, examine the free-electron generation enabled by nanophotonics, and analyze the high-harmonic generation by quasi-free electrons. We also discuss applications of quantum nanophotonics for X-rays and free electrons, including nanostructure waveguides for X-rays, photon pair enhanced X-ray imaging, mirrors, and lenses for X-rays, among others.
- Published
- 2024
25. Perfect absorption of molecular vibration enabled by critical coupling in molecular metamaterial
- Author
-
Dayal, Govind and Pratap, Dheeraj
- Subjects
Physics - Optics ,Physics - Applied Physics - Abstract
The absorption and emission spectrum arising from the vibrational motion of a molecule is mostly in the infrared region. These fingerprint absorptions of polar bonds enable us to acquire bond-specific chemical information from specimens. However, the mode mismatch between the atomic-scale dimensions of the chemical bonds and the resonance wavelength limits the direct detection of tiny amounts of samples such as self-assembled monolayers or biological membranes. To overcome this limitation, surface-enhanced infrared absorption spectroscopy (SEIRA) has been proposed to enhance infrared absorption directly via local field enhancement. Here, we report on the perfect absorption of molecular vibration enabled by critical coupling in the metamaterials. Our molecular metamaterial design consists of a thin polymer layer sandwiched between a structured metal layer on top and a continuous metal layer at the bottom that supports the gap plasmon mode. The measured and simulated infrared spectra of the molecular metamaterial show broad and narrow absorption bands corresponding to the metamaterial and molecular vibration modes. We show that by tuning the structure's molecular film thickness and periodicity, vibrational absorption can be enhanced to near unity. We also show that for a particular periodicity of the array, metamaterial resonance can be completely suppressed, and only molecular vibrational absorption is excited, giving rise to an extremely narrow absorption band.
- Published
- 2024
26. Mathematical theory on multi-layer high contrast acoustic subwavelength resonators
- Author
-
Deng, Youjun, Kong, Lingzheng, Li, Hongjie, Liu, Hongyu, and Zhu, Liyan
- Subjects
Mathematical Physics ,Physics - Applied Physics - Abstract
Subwavelength resonance is a vital acoustic phenomenon in contrasting media. The narrow bandgap width of single-layer resonator has prompted the exploration of multi-layer metamaterials as an effective alternative, which consist of alternating nests of high-contrast materials, called ``resonators'', and a background media. In this paper, we develop a general mathematical framework for studying acoustics within multi-layer high-contrast structures. Firstly, by using layer potential techniques, we establish the representation formula in terms of a matrix type operator with a block tridiagonal form for multi-layer structures within general geometry. Then we prove the existence of subwavelength resonances via Gohberg-Sigal theory, which generalizes the celebrated Minnaert resonances in single-layer structures. Intriguingly, we find that the primary contribution to mode splitting lies in the fact that as the number of nested resonators increases, the degree of the corresponding characteristic polynomial also increases, while the type of resonance (consists solely of monopolar resonances) remains unchanged. Furthermore, we derive original formulas for the subwavelength resonance frequencies of concentric dual-resonator. Numerical results associated with different nested resonators are presented to corroborate the theoretical findings.
- Published
- 2024
27. Competing mechanisms of dominant radiative and Auger recombination in hot carrier generation in III-V semiconductor nanowires
- Author
-
Esmaielpour, Hamidreza, Schmiedeke, Paul, Isaev, Nabi, Doganlar, Cem, Döblinger, Markus, Finley, Jonathan J., and Koblmüller, Gregor
- Subjects
Physics - Applied Physics ,Condensed Matter - Materials Science - Abstract
One-dimensional structures such as nanowires (NWs) show great promise in tailoring the rates of hot carrier thermalization in semiconductors with important implications for the design of efficient hot carrier absorbers. However, fabrication of high-quality, phase-pure crystal structures and control of their intrinsic electronic properties can be challenging, raising concerns about the role of competing radiative and non-radiative recombination mechanisms that govern hot carrier effects. Here, we elucidate the impact of crystal purity and altered electronic properties on the hot carrier properties by comparing two classes of III-V semiconductor NW arrays with similar band-gap energies and geometries, yet different crystal quality: one composed of GaAsSb NWs, free of planar stacking defects, and the other InGaAs NWs with a high density of stacking defects. Photoluminescence spectroscopy demonstrates distinct hot carrier effects in both NW arrays; however, the InGaAs NWs with lower crystal quality exhibit stronger hot carrier effects, as evidenced by increased carrier temperature under identical photoabsorptivity. This difference arises from higher rates of Auger recombination in the InGaAs NWs due to their increased n-type conductivity, as confirmed by excitation power-dependent measurements. Our findings suggest that while enhancing material properties is crucial for improving the performance of hot carrier absorbers, optimizing conditions to increase the rates of Auger recombination will further boost the efficiency of these devices., Comment: 13 pages, 4 figures
- Published
- 2024
28. Topological Chiral-Gain in a Berry Dipole Material
- Author
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Prudêncio, Filipa R. and Silveirinha, Mário G.
- Subjects
Physics - Applied Physics - Abstract
Recent studies have shown that non-equilibrium optical systems under static electric fields offer a pathway to realize chiral gain, where the non-Hermitian response of a material is controlled by the spin angular momentum of the wave. In this work, we uncover the topological nature of chiral gain and demonstrate how a static electric bias induces topological bandgaps that support unidirectional edge states at the material boundaries. Curiously, in our system, these topological edge states consistently exhibit dissipative properties. We further show that, by operating outside the topological gap, the chiral gain can be leveraged to engineer boundary-confined lasing modes with orbital angular momentum, locked to the orientation of the applied electric field. Our results open new possibilities for loss-compensated photonic waveguides, enabling advanced functionalities such as unidirectional, lossless edge-wave propagation and the generation of structured light with intrinsic orbital angular momentum.
- Published
- 2024
29. Periodic phase diagrams in micromagnetics with an eigenvalue solver
- Author
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Ai, Fangzhou, Lin, Zhuonan, Duan, Jiawei, and Lomakin, Vitaliy
- Subjects
Condensed Matter - Materials Science ,Physics - Applied Physics - Abstract
This work introduces an approach to compute periodic phase diagram of micromagnetic systems by solving a periodic linearized Landau-Lifshitz-Gilbert (LLG) equation using an eigenvalue solver with the Finite Element Method formalism. The linear operator in the eigenvalue problem is defined as a function of the periodic phase shift wave vector. The dispersion diagrams are obtained by solving the eigenvalue problem for complex eigen frequencies and corresponding eigen states for a range of prescribed wave vectors. The presented approach incorporates a calculation of the periodic effective field, including the exchange and magnetostatic field components. The approach is general in that it allows handling 3D problems with any 1D, 2D, and 3D periodicities. The ability to calculated periodic diagrams provides insights into the spin wave propagation and localized resonances in complex micromagnetic structures.
- Published
- 2024
30. A Composite Hydrogel of Porous Gold Nanorods and Gelatin: Nanoscale Structure and Rheo-Mechanical Properties
- Author
-
Khan, Irfan, Panda, Snigdharani, Kumar, Sugam, and Srivastava, Sunita
- Subjects
Condensed Matter - Soft Condensed Matter ,Physics - Applied Physics - Abstract
Incorporating nanomaterials into hydrogels allows for the creation of versatile materials with properties that can be precisely tailored by manipulating their nanoscale structures, leading to a wide range of bulk properties. Investigating the structural and property characteristics of composite hydrogels is crucial in tailoring their performance for specific applications. This study focuses on investigating the correlation between the structural arrangement and properties of a composite hydrogel of thermoresponsive polymer, gelatin, and light-responsive antimicrobial porous gold nanorods, $PAuNR$. The rheo-mechanical properties of the composite hydrogels are correlated with their nanoscale structural characteristics, investigated using small-angle neutron scattering ($SANS$). Analysis of $SANS$ data reveals a decrease in the fractal dimension of $PAuNRs$ incorporated hydrogel matrix, as compared to pure gelatin. Incorporating $PAuNRs$ results in formation of softer composite hydrogel as evident from decrease in viscoelastic moduli, critical yield strain, denaturation temperature and swelling ratio. Our results demonstrates that the structural modulation at the nanoscale can be precisely controlled through adjusting $PAuNRs$ concentration and temperature providing an fabrication mechanism for hydrogels with desired elastic properties. The reduced elasticity of the composite hydrogel and light sensitive/antimicrobial property of the $PAuNRs$ makes this system suitable for specific biomedical applications, such as tissue engineering, device fabrication and stimuli based controlled drug delivery devices respectively., Comment: Under review: The Journal of Chemical Physics (JCP24-AR-04120)
- Published
- 2024
31. Wafer-scale Semiconductor Grafting: Enabling High-Performance, Lattice-Mismatched Heterojunctions
- Author
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Zhou, Jie, Zhang, Qiming, Gong, Jiarui, Lu, Yi, Liu, Yang, Abbasi, Haris, Qiu, Haining, Kim, Jisoo, Lin, Wei, Kim, Donghyeok, Li, Yiran, Ng, Tien Khee, Jang, Hokyung, Liu, Dong, Wang, Haiyan, Ooi, Boon S., and Ma, Zhenqiang
- Subjects
Physics - Applied Physics ,Condensed Matter - Materials Science - Abstract
Semiconductor heterojunctions are foundational to many advanced electronic and optoelectronic devices. However, achieving high-quality, lattice-mismatched interfaces remains challenging, limiting both scalability and device performance. Semiconductor grafting offers a promising solution by directly forming electrically active, lattice-mismatched heterojunctions between dissimilar materials. However, its scalability and uniformity at the wafer level have yet to be demonstrated. This work demonstrates the achievement of highly uniform, reproducible results across silicon, sapphire, and gallium nitride (GaN) substrates using wafer-scale semiconductor grafting. To illustrate this scalability, we conducted an in-depth study of a grafted Si/GaN heterojunction, examining band alignment through X-ray photoelectron spectroscopy and confirming crystallinity and interfacial integrity with scanning transmission electron microscopy. The resulting p-n diodes exhibit significantly enhanced electrical performance and wafer-scale uniformity compared to conventional approaches. This work establishes wafer-scale semiconductor grafting as a versatile and scalable technology, bridging the gap between laboratory-scale research and industrial manufacturing for heterogeneous semiconductor integration, and paving the way for novel, high-performance electronic and optoelectronic devices., Comment: 23 pages, 6 figures
- Published
- 2024
32. Optimizing Phononic Crystal Waveguides for Acoustically Induced Spin Transport
- Author
-
Singh, Karanpreet, Wilson, Gabe, and Stotz, James A. H.
- Subjects
Physics - Applied Physics ,Condensed Matter - Materials Science - Abstract
Through the use of strain and induced piezoelectric fields, surface acoustic waves have been shown to control quantum information processes, such as single photon emission and the coherent transport of electron spins. Regarding the latter, systems using plane surface waves have provided suitable demonstration systems, but to build complexity, more control over the acoustic wave may be required. One method for acoustic control is the use of phononic crystals consisting of periodic arrays of nanofabricated holes on the surface of a device. These inclusions form a metamaterial-like layer with properties different from the normal material to dictate the physics of wave motion. Exploiting these surface properties can lead to acoustic waveguides, which can be designed to control the path of the surface acoustic waves. The design parameters of a new type of phononic crystal waveguide is explored that uses 2-fold elliptical cylinder inclusions to create a slow region that also limits coupling and radiative loss to bulk acoustic modes. Such a waveguide would be the foundational piece in an acoustic circuit that could then mediate complex spin transport geometries., Comment: 11 pages, 7 figures
- Published
- 2024
33. Transparent and Electrically Switchable Thin Film Tactile Actuators Based on Molecular Orientation
- Author
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Nolin, Abigail, Lo, Chun-Yuan, Kayser, Laure V., and Dhong, Charles B.
- Subjects
Condensed Matter - Soft Condensed Matter ,Physics - Applied Physics - Abstract
Most tactile actuators create tactile sensations through vibrations or the mechanical and electrochemical formation of bumps. However, tactile sensations of real objects arise from friction which is derived not only from physical topography, but also surface chemistry. Here, we show that molecular rearrangement can be leveraged to create new classes of tactile actuators based on the phases of liquid crystals embedded in a solid and transparent polymer film. We found that humans can feel differences by touch, especially between planar alignment and its disrupted phase, as actuated by a DC electrical field. In subjective terms, the sensation was described as a tacky to polished-like feeling. We attribute the mechanism of tactile contrast to microscale phase separation and changes in molecular orientation, as the nanoscale differences in topography are too small to be detected on their own by humans. This molecular rearrangement occurs quicker (<17 ms) than actuation through ionic or fluid movement. This enables a new class of tactile actuators based on molecular orientation (TAMO) for haptic interfaces.
- Published
- 2024
34. Photonic Matrix Multiplier Makes a Direction-Finding Sensor
- Author
-
Zelaya, Kevin and Miri, Mohammad-Ali
- Subjects
Physics - Optics ,Physics - Applied Physics - Abstract
We introduce a photonic integrated circuit solution for the direction-of-arrival estimation in the optical frequency band. The proposed circuit is built on discrete sampling of the phasefront of an incident optical beam and its analog processing in a photonic matrix-vector multiplier that maps the angle of arrival into the intensity profile at the output ports. We derive conditions for perfect direction-of-arrival sensing for a discrete set of incident angles and its continuous interpolation and discuss the angular resolution and field-of-view of the proposed device in terms of the number of input and output ports of the matrix multiplier. We show that while, in general, a non-unitary matrix operation is required for perfect direction finding, under certain conditions, it can be approximated with a unitary operation that simplifies the device complexity while coming at the cost of reducing the field of view. The proposed device will enable real-time direction-finding sensing through its ultra-compact design and minimal digital signal processing requirements.
- Published
- 2024
35. Reconfigurable Acoustic Metalens with Tailored Structural Equilibria
- Author
-
Le, Dinh Hai, Kronowetter, Felix, Chiang, Yan Kei, Maeder, Marcus, Marburg, Steffen, and Powell, David A.
- Subjects
Physics - Applied Physics ,Physics - Classical Physics - Abstract
The ability to concentrate sound energy with a tunable focal point is essential for a wide range of acoustic applications, offering precise control over the location and intensity of sound pressure maxima. However, conventional acoustic metalenses are typically passive, with fixed focal positions, limiting their versatility. A significant obstacle in achieving tunable sound wave focusing lies in the complexity of precise and programmable adjustments, which often require intricate mechanical or electronic systems. In this study, we present a theoretical and experimental investigation of a reconfigurable acoustic metalens based on a bistable origami design. The metalens comprises eight flexible origami units, each capable of switching between two stable equilibrium states, enabling local modulation of sound waves through two distinct reflection phases. The metalens can be locked into specific symmetric or asymmetric configurations by manually tailoring the origami units to settle either of the two states. Each configuration generates a unique phase profile, focusing sound energy at a specific point. This concept allows the focal spot to be dynamically reconfigured both on and off-axis. Furthermore, the approach introduces a simple yet effective mechanism for tuning sound energy concentration, offering a solution for flexible acoustic manipulation.
- Published
- 2024
36. Multifunctional spintronic transistors: Sub-60 mV/dec switching, non-local GMR, and NDR in spin gapless semiconductor and/or spin gapped metal FETs
- Author
-
Şaşıoğlu, Ersoy, Bodewei, Paul, Hinsche, Nicki F., and Mertig, Ingrid
- Subjects
Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Physics - Applied Physics - Abstract
Spin-gapless semiconductors (SGSs) are a promising class of materials for spintronic applications, enabling functions beyond conventional electronics. This study introduces a novel design for multifunctional spintronic field-effect transistors (FETs) using SGSs and/or spin-gapped metals (SGMs) as source and drain electrodes. These devices operate similarly to metal-semiconductor Schottky barrier FETs, where a potential barrier forms between the SGS (or SGM) electrode and the semiconducting channel. Unlike traditional Schottky barrier FETs, these devices utilize the unique spin-dependent transport properties of SGS/SGM electrodes to achieve sub-60 mV/dec switching, overcoming the 60 mV/dec sub-threshold swing limit in MOSFETs for low-voltage operation. Additionally, SGMs contribute a negative differential resistance (NDR) effect with an ultra-high peak-to-valley current ratio. The proposed spintronic FETs combine sub-60 mV/dec switching, non-local giant magnetoresistance (GMR), and NDR, making them suitable for applications like logic-in-memory computing and multivalued logic. These properties support computing architectures beyond the von-Neumann model, enabling efficient data processing. Two-dimensional (2D) nanomaterials provide a promising platform for these multifunctional FETs. We screen a computational 2D materials database to identify suitable SGS and SGM materials, selecting VS$2$ as the SGS for simulations. Using a non-equilibrium Green's function method with density functional theory, we simulate transfer ($I{\mathrm{D}}$-$V_{\mathrm{G}}$) and output ($I_{\mathrm{D}}$-$V_{\mathrm{D}}$) characteristics of a VS$_2$/Ga$_2$O$_2$ FET based on 2D type-II SGS VS$_2$, predicting a sub-threshold swing of 20 mV/dec, a high on/off ratio of 10$^8$, and a notable non-local GMR effect, demonstrating potential for low-power, high-performance applications.
- Published
- 2024
37. Combining Entangled and Non-Entangled Based Quantum Key Distribution Protocol With GHZ State
- Author
-
Sykot, Arman, Rahman, Mohammad Hasibur, Anannya, Rifat Tasnim, Upoma, Khan Shariya Hasan, and Mahdy, M. R. C.
- Subjects
Quantum Physics ,Computer Science - Cryptography and Security ,Physics - Applied Physics - Abstract
This paper presents a novel hybrid Quantum Key Distribution ,QKD, protocol that combines entanglement based and non entanglement based approaches to optimize security and the number of generated keys. We introduce a dynamic system that integrates a three particle GHZ state method with the two state B92 protocol, using a quantum superposition state to probabilistically switch between them. The GHZ state component leverages strong three particle entanglement correlations for enhanced security, while the B92 component offers simplicity and potentially higher key generation rates. Implemented and simulated using Qiskit, our approach demonstrates higher number of generated keys compared to standalone protocols while maintaining robust security. We present a comprehensive analysis of the security properties and performance characteristics of the proposed protocol. The results show that this combined method effectively balances the trade offs inherent in QKD systems, offering a flexible framework adaptable to varying channel conditions and security requirements.This research contributes to ongoing efforts to make QKD more practical and efficient, potentially advancing the development of large scale, secured quantum networks., Comment: 14 pages, 24 equations, 9 figures
- Published
- 2024
38. External busbars for improving current generation in multijunction solar cells
- Author
-
Vuorinen, Marianna, Aho, Arto, Anttola, Elina, Fihlman, Antti, Polojärvi, Ville, Aho, Timo, Isoaho, Riku, Nikander, Veikka, Hietalahti, Arttu, Tukiainen, Antti, and Guina, Mircea
- Subjects
Physics - Applied Physics - Abstract
We report an improved device fabrication process employed in the development of an advanced front contact grid design employing external busbars. The advanced fabrication process results in enhanced solar cell performance measured at one-sun illumination. In this grid configuration the busbar area is located outside the active solar cell and the grid fingers travel across the mesa sidewalls. With this design the solar cell size can be scaled down without limitations as the area of the busbar is not restricting the component size. Thus, the demonstrated design is beneficial especially for micro-concentrator solar cells. In general, this approach minimizes the power losses originating from the grid shadowing and dark area related voltage losses. The performance of the proposed design is validated by fabricating GaInP/GaAs/GaInNAsSb triple-junction solar cells employing the grid design with external busbars. Light-biased current-voltage and electroluminescence characteristics of the cells reveal that an additional contact GaAs etching step prior to front contact metal deposition is needed to ensure good photovoltaic performance with a fill factor of 85% at one-sun illumination. The improvement is attributed to removing the plasma-damaged material layer that can extend to a depth beyond 100 nm, leading to resistive losses.
- Published
- 2024
39. Multifunctional 2d infrared photodetectors enabled by asymmetric singular metasurfaces
- Author
-
Semkin, Valentin, Shabanov, Aleksandr, Kapralov, Kirill, Kashchenko, Mikhail, Sobolev, Alexander, Mazurenko, Ilya, Myltsev, Vladislav, Nikulin, Egor, Chernov, Alexander, Kameneva, Ekaterina, Bocharov, Alexey, and Svintsov, Dmitry
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics ,Physics - Applied Physics ,Physics - Optics - Abstract
Two-dimensional materials offering ultrafast photoresponse suffer from low intrinsic absorbance, especially in the mid-infrared wavelength range. Challenges in 2d material doping further complicate the creation of light-sensitive $p-n$ junctions. Here, we experimentally demonstrate a graphene-based infrared detector with simultaneously enhanced absorption and strong structural asymmetry enabling zero-bias photocurrent. A key element for those properties is an asymmetric singular metasurface (ASMS) atop graphene with keen metal wedges providing singular enhancement of local absorbance. The ASMS geometry predefines extra device functionalities. The structures with connected metallic wedges demonstrate polarization ratios up to 200 in a broad range of carrier densities at a wavelength of 8.6 $\mu$m. The structures with isolated wedges display gate-controlled switching between polarization-discerning and polarization-stable photoresponse, a highly desirable yet scarce property for polarized imaging.
- Published
- 2024
40. A Finite-Element Model Showing Increased Carrier Mobility in Downscaled Amorphous Semiconductors for Flexible Microprocessors
- Author
-
Luo, Yuezhou and Flewitt, Andrew John
- Subjects
Physics - Applied Physics ,Condensed Matter - Disordered Systems and Neural Networks ,Condensed Matter - Materials Science - Abstract
It is shown that the carrier mobilities of amorphous semiconductors can be significantly increased through device downscaling without material-level optimization. This is based on a recently published scalable finite-element model for amorphous semiconductors. Using hydrogenated amorphous silicon (a-Si:H) in an ideal field effect transistor (FET) as an example, the intrinsic DC electron mobility at room temperature is estimated to increase by a factor of at least 8.33 when the channel length is decreased to 10 nm. Keeping a sufficient channel width ensures device-to-device (D2D) uniformity. The simulation is based on the multiple trapping and release (MTR) theory in combination with statistical equivalent analyses. The increased mobility is attributed to the short channel length relative to the characteristic length scale of band fluctuation that is determined by the medium-range order of the material. This paper may inspire the development of next-generation high-density, high-speed, flexible microprocessors based on low-cost amorphous semiconductors for Internet of Things devices., Comment: 6 pages, 6 figures. There are two prequels to this paper. For the first prequel, see https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.104203 . For the second prequel, see arXiv:2408.03678v2
- Published
- 2024
41. Billion-Fold Enhancement of Room-Temperature Ionic Conductivity in h-RMnO3/YSZ Heterostructures via Electric-Field-Assisted Oxygen Deficiency Engineering
- Author
-
Yang, Detian, Liu, Yaohua, Dai, Liang, Xu, Zhihang, and Xu, Xiaoshan
- Subjects
Condensed Matter - Materials Science ,Physics - Applied Physics - Abstract
Oxide heterostructures provide versatile platforms for manipulating electronic and ionic conductive states. In this study, we demonstrate a remarkable billion-fold enhancement in room-temperature ionic conductivity within h-RMnO3/YSZ heterostructures, achieved through electric-field-assisted oxygen deficiency engineering. This enhancement is closely linked to substantial oxygen depletion in YSZ and is tunable by varying the thickness of the h-RMnO3 film layer and the applied voltage bias. Our findings underscore the critical importance of interfacial design and vacancy control in enhancing ionic transport capabilities, paving the way for advanced applications in low-temperature energy harvesting, storage, and conversion technologies., Comment: Main text: 11 pages, 5 figures; Supplmental materials: 17 pages, 8 figures
- Published
- 2024
42. Observing a quantum magnetic effect in CaYAl3O7-X particles (X=Ni, Fe, Co)
- Author
-
Hildever, Luana, Laurentino, José, Araújo, José, Estrada, Francisco, and Holanda, José
- Subjects
Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Physics - Applied Physics - Abstract
Yttrium calcium aluminate, with the formula CaYAl3O7, has been extensively researched due to its remarkable luminescent properties when doped or co-doped. Additionally, it exhibits exceptional piezoelectric properties at high temperatures. However, the potential magnetic properties this material can acquire through doping or co-doping have largely gone unexplored until now. In this innovative study, we investigate the quantum magnetic characteristics of yttrium calcium aluminate particles doped with transition metals such as cobalt, iron, and nickel. Our magnetic measurements of hysteresis curves in the macroscopic regime reveal intriguing magnetic characteristics that have not been documented in the literature. Given the high applicability of this material in biological microelectromechanical systems, we conducted a detailed study to demonstrate these findings.
- Published
- 2024
43. Exploring Structural Nonlinearity in Binary Polariton-Based Neuromorphic Architectures
- Author
-
Sedov, Evgeny and Kavokin, Alexey
- Subjects
Condensed Matter - Disordered Systems and Neural Networks ,Computer Science - Emerging Technologies ,Computer Science - Machine Learning ,Computer Science - Neural and Evolutionary Computing ,Physics - Applied Physics - Abstract
This study investigates the performance of a binarized neuromorphic network leveraging polariton dyads, optically excited pairs of interfering polariton condensates within a microcavity to function as binary logic gate neurons. Employing numerical simulations, we explore various neuron configurations, both linear (NAND, NOR) and nonlinear (XNOR), to assess their effectiveness in image classification tasks. We demonstrate that structural nonlinearity, derived from the network's layout, plays a crucial role in facilitating complex computational tasks, effectively reducing the reliance on the inherent nonlinearity of individual neurons. Our findings suggest that the network's configuration and the interaction among its elements can emulate the benefits of nonlinearity, thus potentially simplifying the design and manufacturing of neuromorphic systems and enhancing their scalability. This shift in focus from individual neuron properties to network architecture could lead to significant advancements in the efficiency and applicability of neuromorphic computing.
- Published
- 2024
44. Influence of Photoemission Geometry on Timing and Efficiency in 4D Ultrafast Electron Microscopy
- Author
-
Willis, Simon A. and Flannigan, David J.
- Subjects
Physics - Applied Physics ,Condensed Matter - Materials Science - Abstract
Broader adoption of 4D ultrafast electron microscopy (UEM) for the study of chemical, materials, and quantum systems is being driven by development of new instruments as well as continuous improvement and characterization of existing technologies. Perhaps owing to the still-high barrier to entry, the full range of capabilities of laser-driven 4D UEM instruments has yet to be established, particularly when operated at extremely low beam currents (~fA). Accordingly, with an eye on beam stability, we have conducted particle tracing simulations of unconventional off-axis photoemission geometries in a UEM equipped with a thermionic-emission gun. Specifically, we have explored the impact of experimentally adjustable parameters on the time-of-flight (TOF), the collection efficiency (CE), and the temporal width of ultrashort photoelectron packets. The adjustable parameters include the Wehnelt aperture diameter (DW), the cathode set-back position (Ztip), and the position of the femtosecond laser on the Wehnelt aperture surface relative to the optic axis (Rphoto). Notable findings include significant sensitivity of TOF to DW and Ztip, as well as non-intuitive responses of CE and temporal width to varying Rphoto. As a means to improve accessibility, practical implications and recommendations are emphasized wherever possible.
- Published
- 2024
45. Corner cutting connects chiral colorimetry to net electric flux in lossless all-dielectric metasurfaces
- Author
-
Haddadin, Zaid, Nguyen, Anna My, and Poulikakos, Lisa V.
- Subjects
Physics - Optics ,Physics - Applied Physics - Abstract
All-dielectric metasurfaces can produce structural colors, but the most advantageous design criteria are still being investigated. This work numerically studies how the two-dimensional shape of nanoparticles affects the colorimetric response under circularly polarized light (CPL) to develop a sensor distinguishing CPL orientations. Using lossless dielectric materials (silicon nitride on silicon dioxide), we achieve far-field dichroism by modifying oblong nanoparticles into L-shaped structures through corner cuts. This design suppresses one electric dipole under CPL illumination, leading to differential colorimetric responses. We link these responses to a decoupling effect in the near-field net electric flux. Our findings provide design guidelines for all-dielectric, lossless colorimetric sensors of chiral light., Comment: This is an unedited version of a work submitted to Optics Express, with 46 pages (15 main text, 31 supplemental document), 28 figures (5 main text, 23 supplemental document), and 8 tables (all supplemental document). Dataset and Code files are with the Optics Express submission
- Published
- 2024
46. A High-Power Microwave Limiter Using A Self-Actuated Plasma-Based EIT Topology
- Author
-
Akram, Muhammad Rizwan and Semnani, Abbas
- Subjects
Physics - Applied Physics ,Physics - Plasma Physics - Abstract
This paper presents a novel metamaterial topology incorporating gas discharge tubes for high-power microwave protection. The design features two split ring resonators positioned side by side with their splits oriented orthogonally. When exposed to low-power microwaves, each split ring resonator induces a resonance that interacts to create a passband within a broad stopband, facilitated by a phenomenon known as electromagnetically induced transparency (EIT). At high power levels, the integrated gas discharge tubes become ionized, forming plasma that acts as a switch to eliminate the EIT window, thereby reinstating the stopband for protection. Several prototypes have been developed for S-band operation based on this concept. Analytical, numerical, and experimental results are in complete agreement. The proposed device demonstrates superior protection with lower insertion loss in the OFF mode and higher isolation in the ON mode. Its strong ability to handle high-power microwaves is achieved using plasma-based switches instead of diodes, providing a reasonable response time and a straightforward design that enables rapid prototyping. Additionally, the device demonstrates frequency and power threshold tunability, highlighting its versatility as a microwave protection device.
- Published
- 2024
47. Cascade hot carriers via broad-band resonant tunneling
- Author
-
Paul, Kamal Kumar, Mondal, Ashok, Kim, Jae Woo, Kim, Ji-Hee, and Lee, Young Hee
- Subjects
Physics - Applied Physics - Abstract
Extraction of hot carriers (HCs) over the band-edge is a key to harvest solar energy beyond Shockley-Queisser limit1. Graphene is known as a HC-layered material due to phonon bottleneck effect near Dirac point, but limited by low photocarrier density2. Graphene/transition metal dichalcogenide (TMD) heterostructures circumvent this issue by ultrafast carrier transfer from TMD to graphene2,3. Nevertheless, efficient extraction of photocurrent by means of HCs together with carrier multiplication (CM) is still missing. Here, we introduce an ultrathin broadband resonant tunneling (BRT) barrier, TiOX to efficiently extract photocurrent with simultaneous CM and HC measurements in MoS2/graphene/TiOX heterostructure. The BRT layer gives rise to boosting open circuit voltage which is linearly proportional to incident photon energy. Meanwhile, short circuit current rises rapidly over 2Eg with obvious CM feature. This was explained by defining the joint density of states between graphene and TiOX layer over positive and negative voltage. The broadband resonant tunneling states inherently constructed from oxidation states varying from Ti3+ to Ti4+ allow the ultrafast HCs to efficiently transfer from graphene to TiOX layer. We find that the number of available tunneling states is directly proportional to short circuit current, which is well corroborated with TiOX and MoS2 thickness variance. We obtained an optimum thickness of BRT layer of ~2.8 nm, yielding cascade open circuit voltage as high as ~0.7 V, two orders of magnitude higher than that without BRT layer to reach a record efficiency of 5.3% with improved fill factor owing to synergistic HC and CM conversion under 1-SUN with long-term stability.
- Published
- 2024
48. Using optical tweezer electrophoresis to investigate clay nanoplatelet adsorption on Latex microspheres in aqueous media
- Author
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Parmar, Vaibhav Raj Singh, Chanda, Sayantan, Sivasubramaniam, Sri Vishnu Bharat, and Bandyopadhyay, Ranjini
- Subjects
Condensed Matter - Soft Condensed Matter ,Physics - Applied Physics - Abstract
The adsorption of charged clay nanoplatelets plays an important role in stabilizing emulsions by forming a barrier around the emulsion droplets and preventing coalescence. In this work, the adsorption of charged clay nanoplatelets on a preformed Latex microsphere in an aqueous medium is investigated at high temporal resolution using optical tweezer-based single-colloid electrophoresis. Above a critical clay concentration, charged clay nanoplatelets in an aqueous medium self-assemble gradually to form gel-like networks that become denser with increasing medium salinity. In a previous publication [R. Biswas et. al., Soft Matter, 2023, 19, 24007-2416], some of us had demonstrated that a Latex microsphere, optically trapped in a clay gel medium, is expected to attach to the network strands of the gel. In the present contribution, we show that for different ionic conditions of the suspending medium, the adsorption of clay nanoplatelets increases the effective surface charge on an optically trapped Latex microsphere while also enhancing the drag experienced by the latter. Besides the ubiquitous contribution of non-electrostatic dispersion forces in driving the adsorption process, we demonstrate the presence of an electrostatically-driven adsorption mechanism when the microsphere was trapped in a clay gel. These observations are qualitatively verified via cryogenic field emission scanning electron microscopy and are useful in achieving colloidal stabilisation, for example, during the preparation of clay-armoured Latex particles in Pickering emulsion polymerisation., Comment: 32 pages, 14 figures and supporting information included
- Published
- 2024
49. Multiple-partition cross-modulation programmable metasurface empowering wireless communications
- Author
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Zhang, Jun Wei, Qi, Zhen Jie, Wu, Li Jie, Cao, Wan Wan, Gao, Xinxin, Fu, Zhi Hui, Chen, Jing Yu, Lv, Jie Ming, Wang, Zheng Xing, Wang, Si Ran, Wu, Jun Wei, Zhang, Zhen, Zhang, Jia Nan, Li, Hui Dong, Dai, Jun Yan, Cheng, Qiang, and Cui, Tie Jun
- Subjects
Physics - Applied Physics - Abstract
With the versatile manipulation capability, programmable metasurfaces are rapidly advancing in their intelligence, integration, and commercialization levels. However, as the programmable metasurfaces scale up, their control configuration becomes increasingly complicated, posing significant challenges and limitations. Here, we propose a multiple-partition cross-modulation (MPCM) programmable metasurface to enhance the wireless communication coverage with low hardware complexity. We firstly propose an innovative encoding scheme to multiply the control voltage vectors of row-column crossing, achieving high beamforming precision in free space while maintaining low control hardware complexity and reducing memory requirements for coding sequences. We then design and fabricate an MPCM programmable metasurface to confirm the effectiveness of the proposed encoding scheme. The simulated and experimental results show good agreements with the theoretically calculated outcomes in beam scanning across the E and H planes and in free-space beam pointing. The MPCM programmable metasurface offers strong flexibility and low complexity by allowing various numbers and combinations of partition items in modulation methods, catering to diverse precision demands in various scenarios. We demonstrate the performance of MPCM programmable metasurface in a realistic indoor setting, where the transmissions of videos to specific receiver positions are successfully achieved, surpassing the capabilities of traditional programmable metasurfaces. We believe that the proposed programmable metasurface has great potentials in significantly empowering the wireless communications while addressing the challenges associated with the programmable metasurface's design and implementation.
- Published
- 2024
50. Polarization-independent metasurfaces based on bound states in the continuum with high Q-factor and resonance modulation
- Author
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Yang, Xingye, Antonov, Alexander, Aigner, Andreas, Weber, Thomas, Lee, Yohan, Jiang, Tao, Hu, Haiyang, and Tittl, Andreas
- Subjects
Physics - Optics ,Physics - Applied Physics - Abstract
Metasurfaces offer a powerful platform for effective light manipulation, which is crucial for advanced optical technologies. While designs of polarization-independent structures have reduced the need for polarized illumination, they are often limited by either low Q factors or low resonance modulation. Here, we design and experimentally demonstrate a metasurface with polarization-independent quasi-bound state in the continuum (quasi-BIC), where the unit cell consists of four silicon squares arranged in a two-dimensional array and the resonance properties can be controlled by adjusting the edge length difference between different squares. Our metasurface experimentally achieves a Q factor of approximately 100 and a resonance modulation of around 50%. This work addresses a common limitation in previous designs, which either achieved high Q factors exceeding 200 with a resonance modulation of less than 10%, leading to challenging signal-to-noise ratio requirements, or achieved strong resonance modulation with Q factors of only around 10, limiting light confinement and fine-tuning capabilities. In contrast, our metasurface ensures that the polarization-independent signal is sharp and distinct within the system, reducing the demands on signal-to-noise ratio and improving robustness. Experiments show the consistent performance across different polarization angles. This work contributes to the development of versatile optical devices, enhancing the potential for the practical application of BIC-based designs in areas such as optical filtering and sensing.
- Published
- 2024
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