- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Photoinduced collective mode, inhomogeneity, and melting in a charge-order system
摘要： We theoretically investigate photoresponses of a correlated electron system upon stimuli of a pulsed laser light. Real-time dynamics of an interacting spinless fermion model on a one-dimensional chain, as a model of charge order (CO), are numerically simulated using the time-dependent Hartree-Fock method. In particular, we discuss the differences between two situations as the initial state: the homogeneous order and the presence of a domain wall, i.e., a kink structure embedded in the CO bulk. Coherent dynamics are seen in the former case: When the frequency of the pump light ωp is varied, along with single particle excitations across the CO gap (ΔCO), the resonantly-excited collective phase mode near ωp ≈ ΔCO/2 efficiently destabilizes CO. In clear contrast, in the latter case, when ωp is tuned at such in-gap frequencies and the intensity of light is sufficiently large, inhomogeneity spreads out from the kink to the bulk region through kink creations. Moreover, even stronger intensity induces the inhomogeneous melting of CO where the CO gap is destroyed.
关键词： photoinduced phase transition,charge order,collective mode,inhomogeneity,time-dependent Hartree-Fock method
更新于2025-09-23 15:23:52
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Current-induced domain wall oscillations in a nanowire imaged by time-resolved photoemission electron microscopy
摘要： We study reversible domain wall motion in half-ring Ni80Fe20 nanowires on a nanosecond (ns) timescale in a truly current-induced pump-probe experiment using an energy filtered, aberration-corrected photoemission electron microscope. The x-ray magnetic circular dichroism signal is probed at different time delays before, during and after the current pulse in a stroboscopic mode with circularly polarized synchrotron radiation in the energy range of the Fe L3-edge (707 eV). We observe lateral domain wall oscillations with a frequency of ～ 0.4 GHz. Comparing the results to a proposed string model, we find that the domain wall oscillations can be described as string-like asymmetric oscillations.
关键词： Synchrotron radiation,Photoemission electron microscopy,X-ray magnetic circular dichroism,Pump-probe mode
更新于2025-09-23 15:23:52
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The effect of cut depth and distribution for abrasives on wafer surface morphology in diamond wire sawing of PV polycrystalline silicon
摘要： Due to the existence of an acid etch resistant thin amorphous silicon layer over the smooth grooves of the diamond wire sawing polycrystalline silicon wafer surface, the anti-re?ection e?ect is usually not ideal using the mature acidic texturization. The amorphous silicon layer will be produced on the machined surface by material ductile removal. Therefore, during the process of cutting photovoltaic polycrystalline silicon wafers, the material removed in the brittle way is expected and the surface topography of the wafers formed with the brittle fracture is better for the texture fabricating. In this paper, a mathematical model considering the in?uences of process parameters and wire saw parameters was developed based on indentation fracture mechanics. The variations of cutting groove pro?le formed by di?erent material removal modes were also included. The e?ect of abrasives distributed on the wire saw on material removal and surface formation of polysilicon was analyzed. The results showed that most of abrasives removed material with ductile removal mode, however, the volume of the material removed by abrasive in ductile mode is less than 10% of the total removal volume. Brittle fracture removal mode was still the major way of material removal in diamond wire sawing. With the same ratio of the feed rate and wire speed, the faster feed rate and wire speed will not only improve the cutting e?ciency, but also is easier to obtain a brittle fracture surface. There is a critical angle θc for the distribution of abrasives on the wire saw surface. Only when the position angle of the abrasive removing material in brittle mode is less than θc, the brittle fracture can be formed on the wafers surface.
关键词： Diamond wire sawing,Depth of cut,Material removal mode,Photovoltaic polycrystalline silicon
更新于2025-09-23 15:23:52
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Limitations of graphene nanocoated optical tapers for high-power nonlinear applications
摘要： In this letter, we investigate the limitations of graphene as a saturable absorber for high-power nonlinear optical applications. The response of graphene nanocoated optical tapers against the average optical power injected is tested. We point out that the power handled by such components is limited and their nonlinear properties are strongly and permanently modified when exposed to high optical power. The origin of the degradation of the components is discussed.
关键词： nonlinear optics,mode-locking,fiber laser,Graphene,optical tapers
更新于2025-09-23 15:23:52
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Blu-ray DVD as SERS substrate for reliable detection of albumin, creatinine and urea in urine
摘要： We report here the working of a simple reproducible surface enhanced Raman scattering (SERS) substrate by efficiently guiding localized plasmon resonance (LSPR) field of gold nanoparticles (AuNPs) through trapping it in the nano channels of a blu-ray digital versatile disc (BRDVD). SERS based sensing of the designed substrate has been performed. The trapped AuNPs in the channel of the BRDVD generate guided mode resonance (GMR) field and the photon lifetime of the coupled em field in the channel increases which accounts for overall enhancement of the local field intensity. These two factors are primarily responsible for enhancement of the scattered Raman signal from the substrate. The proposed SERS substrate yields reasonably stable signal intensity over a period of 45 days. With the designed substrate Raman signal intensities of three clinically important chemicals namely albumin, creatinine and urea in urine have been measured and quantified reliably. The minimum concentration of albumin, creatinine and urea which can be measured by Raman spectrometer are 0.1 μg/mL, 0.2 μg/mL and 0.6 μg/mL respectively. These values are well below the normal range and thus meet the requirement of detection and analysis of these chemicals for different clinical purposes.
关键词： SERS,Nanochannel,LSPR,BRDVD,Guided mode resonance,Urine sample
更新于2025-09-23 15:23:52
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Modified Sagnac imaging spectropolarimeter for full linear Stokes parameters
摘要： A modified Sagnac imaging spectropolarimeter is conceptually described. It consists of a spectral-polarimetric modulator, a modified Sagnac interferometer with large optical path difference, and a CCD camera. This design modulates the Stokes components of the input light into different wave numbers and obtains the modulated interferogram in snapshot mode, and the spectra of the Stokes components can be separated and demodulated from the interferogram. The performance of the system is demonstrated through a numerical simulation, and a novel method is proposed to detect the polarization parameters including the degree of polarization and polarization direction for eliminating the aliasing effects between linear Stokes parameters. Compared with the existing imaging spectrometers, the modified Sagnac imaging spectropolarimeter can acquire one-dimensional spatial information and its full linear spectropolarimetric information in one exposure, and some other spatial information can be obtained by push-broom mode.
关键词： imaging spectropolarimeter,snapshot mode,Stokes parameters,polarization,Sagnac interferometer
更新于2025-09-23 15:23:52
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Prediction of First Higher Order Modal Field for Graded Index Fiber in Presence of Kerr Nonlinearity
摘要： We report evaluation of first higher order modal field for dual mode optical fiber having step and parabolic index profiles. The study is carried out both in absence as well as in presence of Kerr nonlinearity. The analysis is based on a simple iterative method involving Chebyshev formalism. Taking some typical step- and parabolic-index fibers as examples, we show that our results agree excellently with the exact results which can be obtained by applying rigorous methods. Thus, our simple formalism stands the merit of being considered as an accurate alternative to the existing cumbersome methods. The prescribed formalism provides scope for accurate estimation of different propagation parameters associated with first higher order mode in such kinds of fibers in presence of Kerr nonlinearity. The execution of formalism being user friendly, it will be beneficial to the system engineers working in the field of optical technology.
关键词： first higher order modal field,dual mode graded-index fiber,Kerr nonlinearity,Chebyshev technique
更新于2025-09-23 15:23:52
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Polydopamine-Based Tumor-Targeted Multifunctional Reagents for Computer Tomography/Fluorescence Dual-Mode Bioimaging-Guided Photothermal Therapy
摘要： Development of multifunctional diagnosis and treatment reagents is very meaningful in clinical application. Herein, we developed a polydopamine-based (PDA-based) tumor targeted multifunctional reagent by surface-initiated atom transfer radical polymerization (ATRP) strategy. First, the targeted PDA nanoparticles were prepared via combining with folic acid (FA) and dopamine. Then ATRP technology was used to graft the europium(III) complexes onto PDA surface (defined as FEDA). A series of detections revealed that the FEDA nanoparticles had been successfully prepared and exhibited a bright X-ray computer tomography (CT) and photoluminescence (PL) dual-mode imaging efficiency and an excellent photothermal therapy (PTT) effect in vivo/in vitro.
关键词： europium(III) complexes,polydopamine,dual-mode imaging-guided photothermal therapy,folic acid targeted,atom transfer radical polymerization
更新于2025-09-23 15:23:52
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Theoretical demonstration of Single polarization single mode hollow core anti-resonance fiber using surface plasmon resonance
摘要： We designed a hollow core anti-resonance fiber based on surface plasmon resonance and optimized its characteristics by using the finite element method with perfectly matched layer boundary condition. A single mode single polarization bandwidth, up to 200 nm, is obtained by employing surface plasmon resonance which is produced by two embedded gold wires. Only the x-polarized fundamental mode of the fiber suffers a high loss because of the surface plasmon resonance. In addition, single mode guidance is obtained by adjusting the size of cladding tubes. Simulation results show that the designed fiber has an effective single polarization single mode guidance in the wavelength range from 1.3 to 1.5μm. In this range, both the higher order mode extinction ratio and the polarization mode extinction ratio are more than 100. The structure is shown to have a good fabrication tolerance with respect to variations in the position and size of the gold wires. The proposed fiber has many potential applications in polarization splitters, fiber-optic gyroscopes and polarization-dependent fiber systems.
关键词： Anti-resonance hollow core fiber,Surface plasmon resonance,Single polarization single mode.
更新于2025-09-23 15:23:52
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Minimally asymmetric state conversion around exceptional singularities in a specialty optical microcavity
摘要： Exploiting scattering matrix (S-matrix) formalism, a unique route for manipulating the exceptional points (EPs) has been reported in a trilayer open optical microcavity with non-uniform real refractive index. The boundaries of the intermediate index layer are appropriately tapered. The cavity is partially pumped by transverse distribution of a balanced gain-loss profile. With strict restriction of balanced gain-loss, controlling infinitesimally small variation of gain-coefficient with simultaneous tapering parameter an EP has been encountered; which is being encircled in cavity parameter space to study dynamics of the coupled states around the EP in the context of robust selective flip-of-state phenomena with lower-asymmetry in state conversion efficiencies. Such a specialty trilayer microcavity with tunable width is reported for the first time; which turns out to be a specific approach to achieve maximum efficiency in conversion with minimum asymmetry. Considering suitable state-of-the-art techniques, this exclusive proposal may open up a fabrication feasible platform for device level implementation of system control exploiting EPs.
关键词： Microcavity devices,Mode-converters,Exceptional points,Avoided resonance crossing,Optical resonators
更新于2025-09-23 15:23:52