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The Sensing Applications in U-Shape Structure Based on Dual Transparency Windows
摘要： We have researched a U-shape structure that consists of three vertical cavities coupled with bus wave-guide. The theoretical results based on the coupled mode theory are consistent with simulation results. We demonstrate that the interaction among two bright and one dark modes lead to dual plasmon induced transparency. Meanwhile, it is found that the lateral displacement S plays an important role in the transmission property, and the transmission dip with different transmittance in various lateral displacement S has been explained theoretically. Moreover, the nano sensor has a sensitivity of 1225 nm shift per refractive index unit, and the ?gure of merit is up to 62.5. The proposed structure has the advantages of simple and compact structure, easy fabrication, and the ultra-compact structure holds great potential to the control of light in highly integrated optical circuits and nano sensor.
关键词： Surface plasmons,nano sensors,coupled mode theory
更新于2025-09-23 15:23:52
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Single Flip-Chip Packaged Dielectric Resonator Antenna for CMOS Terahertz Antenna Array Gain Enhancement
摘要： A single dielectric resonator antenna (DRA) capable of enhancing the antenna gain of each element of a 2×2 THz antenna array realized in a 0.18-μm CMOS technology is proposed in this work. The DRA implemented in a low-cost integrated-passive-device (IPD) technology is flip-chip packaged onto the CMOS antenna array chip through low-loss gold bumps. By designing the DRA to work at the higher-order mode of TE3,δ,9, only single DRA instead of conventionally needing four DRAs is required to simultaneously improve the antenna gain of each element of the 2×2 antenna array. This not only simplifies the assembly process but it can also reduce the assembly cost. Moreover, the DRA can provide great antenna gain enhancement because of being made of high-resistivity silicon material and higher-order mode operation. The simulated antenna gain of each on-chip patch antenna of the 2×2 CMOS antenna array can be increased from 0.1 to 8.6 dBi at 339 GHz as the DRA is added. To characterize the proposed DRA, four identical power detectors (PDs) are designed and integrated with each element of the 2×2 THz antenna array, respectively. By measuring the voltage responsivity of each PD output, the characteristics of each antenna of the antenna array with the proposed DRA, including the gain enhancement level and radiation pattern, can be acquired. The measurement results follow well with the simulated ones, verifying the proposed DRA operation principle. The four PDs with the proposed DRA are also successfully employed to demonstrate a THz imaging system at 340 GHz. To the best of the authors’ knowledge, the proposed DRA is the one with the highest-order operation mode at THz frequencies reported thus far.
关键词： Silicon,Flip-chip packaging,Terahertz,CMOS,Terahertz imaging system,Antenna,Higher-order mode,Power detector,Dielectric resonator antenna
更新于2025-09-23 15:23:52
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Control of plasmon dephasing time using stacked nanogap gold structures for strong near-field enhancement
摘要： The construction of metallic nanostructures with strong near-field enhancement is becoming increasingly significant for the practical use of plasmonic devices, such as plasmonic sensors and light-energy conversion systems. Importantly, the near-field enhancement effect depends on the plasmon dephasing time. Here, we propose a method for controlling plasmon dephasing time by utilizing plasmonic coupling for stronger near-field enhancement. Ordered arrays of stacked nanogap gold (Au) structures composed of a metal/insulator/metal nanostructure were fabricated by electron beam lithography and dry etching processes on a niobium-doped titanium dioxide substrate. The dark plasmon mode was excited by the near-field coupling between the upper and lower Au nanostructures separated by an alumina layer with a thickness of 15 nm. A strong near-field enhancement effect was induced by the localization of the electromagnetic field between the upper and lower Au nanostructures and the longer plasmon dephasing time based on the excitation of the dark plasmon mode. It is noteworthy that the dephasing time of the dark plasmon mode measured by time-resolved photoemission electron microscopy was extended 3-fold compared with that of the plasmon mode of the Au nanoblock, which can be controlled by the structural design of the stacked nanogap Au structures.
关键词： Dark plasmon mode,Plasmon dephasing,Near-field enhancement,Photoemission electron microscopy (PEEM),Surface plasmon resonance
更新于2025-09-23 15:23:52
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On-demand CO release for amplification of chemotherapy by MOF functionalized magnetic carbon nanoparticles with NIR irradiation
摘要： Carbon monoxide (CO) gas therapy combined with chemotherapy and photothermal therapy (PTT) is a promising treatment mode for malignant tumor. Herein, we firstly reported doxorubicin (DOX) loaded Mn carbonyl modified Fe (III)-based nanoMOFs (MIL-100) coated PEGylated magnetic carbon nanoparticles (denoted as MCM@PEG-CO-DOX NPs) as theranostics nanoplatforms for near-infrared (NIR)-responded CO-DOX combination therapy. MIL-100 as a good nanocarrier of DOX with high loading capacity can also chelate the Mn carbonyl after a smart modification. Meanwhile, magnetic carbon core possessed photothermal effect, which can convert the NIR light to heat by an 808 nm laser irradiation, resulting in the on-demand release of CO and DOX. As a result, combining with PTT, MCM@PEG-CO-DOX NPs killed tumor efficiently. Moreover, our synthesized MCM@PEG-CO-DOX NPs were capable of realizing tumor dual-mode imaging including magnetic resonance imaging (MRI) and photoacoustic imaging (PAI).
关键词： synergistic treatment,dual-mode imaging,MOFs,CO gas therapy,carbon nanoparticles
更新于2025-09-23 15:23:52
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Femtosecond pump-probe spectroscopy investigation of carrier dynamics in GaAlAs photocathods
摘要： Based on the study of GaAs photocathode, the carrier dynamics of re?ection-mode GaAlAs photocathode has been investigated. In this paper, the re?ection-mode GaAlAs/GaAs photocathode is grown by metal organic chemical vapor deposition (MOCVD) epitaxial technology. The femtosecond pump-probe spectroscopy is performed to measure carrier dynamics in GaAlAs and GaAs photocathods. After laser excitation the surfaces of GaAlAs/GaAs photocathode, the re?ectivity of photocathode surface is changed. At the same time, the dynamic processes of the non-equilibrium carrier distribution in semiconductor material is obtained by the transient re?ectance spectrum. Compared with GaAs photocathode, the Al element in GaAlAs photocathode is unfavorable to photoemission under some conditions, while it solves the problem that the spectrum response range of binary compounds is not adjustable. The change trend of initial relaxation transient of GaAs photocathode in the 22 ps range is the same as GaAlAs, while the change of GaAs and GaAlAs relaxation state is signi?cantly di?erent with the change of delay time after 22 ps. The results show that the GaAlAs increases band gap due to a signi?cantly slower than GaAs photocathode in initial process. Meanwhile, this paper provides a reference for the preparation of the GaAlAs photocathode that only respond to blue and green light range.
关键词： Re?ectivity,Dynamic processes,Femtosecond,Re?ection-mode,Photocathodes
更新于2025-09-23 15:23:52
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Modulating Electrical Performances of In <sub/>2</sub> O <sub/>3</sub> Nanofiber Channel Thin Film Transistors via Sr Doping
摘要： Although In2O3 nanofibers (NFs) are considered as one of the fundamental building blocks for future electronics, the further development of these NFs devices is still seriously hindered by the large leakage current, low on/off current ratio (Ion/Ioff), and large negative threshold voltage (VTH) due to the excess carriers existed in the NFs. A simple one-step electrospinning process is employed here to effectively control the carrier concentration of In2O3 NFs by selectively doping strontium (Sr) element to improve their electrical device performance. The optimal devices (3.6 mol% Sr doping concentration) can yield the high field-effect mobility (μfe ≈ 3.67 cm2 V?1 s?1), superior Ion/Ioff ratio (≈108), and operation in the energy-efficient enhancement-mode. High-κ Al2O3 thin films can also be employed as the gate dielectric to give the gate voltage greatly reduced by 10× (from 40 to 4 V) and the μfe substantially increased by 4.8× (to 17.2 cm2 V?1 s?1). The electrospun E-mode Sr-In2O3 NF field-effect transistors (NFFETs) can as well be integrated into full swing of inverters with excellent performances, further elucidating the significant advance of this electrospinning technique toward practical applications for future low-cost, energy-efficient, large-scale, and high-performance electronics.
关键词： enhancement mode,Sr element,high performance,In2O3 nanofiber,inverter
更新于2025-09-23 15:23:52
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Color image encryption method based on 2D-variational mode decomposition
摘要： In order to reduce the correlation between adjacent pixels in a plaintext image, and to solve the small key space problem of image encryption algorithms when a low-dimension chaotic map is used, a new encryption method for color images is proposed based on two-dimensional variational mode decomposition (2D-VMD) combined with eight-dimensional (8D) hyper-chaotic systems. 2D-VMD decomposes R, G and B components of a color image respectively. The 8D hyper-chaotic system is constructed by means of variable coupling. After improving and combining the original sequences obtained by iterating the system, two groups of key sequences associated with the plain-image are obtained. One group is used to scramble each mode image obtained by 2D-VMD; the other is used to replace the pixel values of the scrambled mode images. For different mode images, different key sequences are adopted. The encrypted images whose number is equal to the number of the modes can then be obtained. The experimental results show that, compared with the existing methods, the correlation coefficients between the pixels in the spatial domain of the plain-image can be reduced by 2D-VMD, as it’s more difficult to crack. In addition, the encryption method has better statistical and differential characteristics, as well as large enough key space, and better plain-image sensitivity.
关键词： Encryption method,Image decomposition,Two-dimensional variational mode decomposition,Color image,Hyper-chaotic system
更新于2025-09-23 15:23:52
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A cavity depth sensitized Rossiter mode formula
摘要： A depth sensitized Rossiter mode expression for compressible resonant cavity ?ows is derived based on simple shear layer and acoustic concepts. The physics-based result is compared to relevant experiment measurements and empirical models and shows reasonable agreement. Though simple, the cavity depth sensitized Rossiter mode estimate demonstrates the connection between shear layer ?ow and cavity acoustics; moreover, the model provides a useful analytically-based validation metric for detailed resonant cavity simulations.
关键词： Vortex sheet,Rossiter mode,Resonant cavity
更新于2025-09-23 15:23:52
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Synthesis and formation mechanism of amorphous silica particles via sol–gel process with tetraethylorthosilicate
摘要： Silica microspheres with narrow particle size distribution and average diameter of 80-200 nm were prepared by hydrolysis and condensation of tetraethylorthosilicate (TEOS) in ethanol solution. Effects of TEOS, ammonia, water concentration, and temperature on particle size and morphology were investigated by laser particle size analysis and field emission scanning electron microscopy (FESEM), in conjunction with energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) spectroscopy. Monomer addition model was employed to analyze the stability of intermediate, as well as the direction in which the reaction of silica particles proceeds. The analysis was carried out by Materials Studio. Results demonstrated that particle size of Nano-silica increases with increasing concentrations of H2O, NH3.H2O, and TEOS in ethanol, whereas the size decreases with increasing temperature. In addition, when proper amount of H2O was added into NH3.H2O at suitable temperature, silicic acid can act as a nucleus for amorphous Nano-silica particles, forming microspheres with round and smooth surfaces. By contrast, when TEOS was used, resultant nanoparticles have poor surfaces. During nucleation process of Nano-silica, silicic acid can also acts as nucleating agent providing a platform for the growth of nanoparticles with symmetric structure. Findings further indicated that the reaction proceeds by first silicic acid participates in the reaction, and the dimer and trimer molecules then react with the surface of silicic acid molecules; the same products could be produced by different reactions.
关键词： Amorphous,St?ber Method,TEOS,Nano-silica,Monomer addition mode
更新于2025-09-23 15:23:52
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Reduced order derivation of the two-dimensional band structure of a mixed-mode resonator array
摘要： In this paper, the 2D band structure of a mixed-mode metamaterial resonator array for in-plane waves is investigated. The band structure in the interior and on the boundary of the irreducible Brillouin zone and 1D dispersion diagrams for different propagation angles are calculated numerically and presented. Additionally, a reduced order analytical method is established to compare and approximate the band structure. The studied metamaterial, with a T-shaped cantilever beam as the resonator in its square array repeating unit cells, exhibits branches with mixed P and SV waves except at exactly one angle of propagation. This paper also reports on the occurrence of avoided level crossings, which are related to the existence of exceptional points in the complex domain. A reduced order analytical approach is used that can generate partial (low branches) band structure with relatively little computational effort. The reduced order model agrees well with the numerical results for these low branches and can provide support in mode identification and band sorting. With proper adjustments in parameters, this analytical method will be applicable to other metamaterials that have a similar unit cell structure.
关键词： band structure,reduced order model,resonator array,metamaterial,avoided level crossings,mixed-mode waves
更新于2025-09-23 15:23:52