Localized waves in three-component coupled nonlinear Schrödinger equation
Statistical second-order two-scale analysis and computation for heat conduction problem with radiation boundary condition in porous materials
Finite-difference time-domain modeling of curved material interfaces by using boundary condition equations method
Discord and entanglement in non-Markovian environments at finite temperatures
Generating periodic interference in Bose-Einstein condensates
The ground states and pseudospin textures of rotating two-component Bose-Einstein condensates trapped in harmonic plus quartic potential
Current and efficiency optimization under oscillating forces in entropic barriers
A flux-controlled model of meminductor and its application in chaotic oscillator
Inverse full state hybrid projective synchronizationfor chaotic maps with different dimensions
Period-control and chaos-anti-control of a semiconductor laser using the twisted fiber
Fiber-based multiple-access frequency synchronization via 1f-2f dissemination
Ultrafast optical beam deflection in a pump probe configuration
Propagation of a signal beam in an AlGaAs/GaAs waveguide multiple-prism light deflector is theoretically investigated by solving the scalar Helmholtz equation to obtain the dependences of the temporal and spatial resolvable characteristics of the ultrafast deflector on the material dispersion of GaAs including group velocity dispersion and angular dispersion, interface reflection, and interface scattering of multiple-prism deflector. Furthermore, we experimentally confirm that, in this ultrafast beam deflection device, the deflecting angle of the signal light beam is linear with the pump fluence and the temporal resolution of the ultrafast deflection is 10 ps. Our results show that the improvement of the temporal and spatial resolvable performances is possible by properly choosing the structural parameters and enhancing the quality of the device.
Calibration chain design based on integrating sphere transfer radiometer for SI-traceable on-orbit spectral radiometric calibration and its uncertainty analysis
Random lasing from dye-doped negative liquid crystals using ZnO nanoparticles as tunable scatters
Influence of amphotericin B on liquid crystal state of the Cholesterol/Dipalmitoylphosphatidylcholine monolayer in the presence of different metal cations
Behavior of lysozyme adsorbed onto biological liquid crystal lipid monolayer at the air/water interface
Analysis of the induction of the myelin basic protein binding to the plasma membrane phospholipid monolayer
High signal-to-noise ratio sensing with Shack-Hartmann wavefront sensor based on auto gain control of electron multiplying CCD
Phase-only stereoscopic hologram calculation based on Gerchberg-Saxton iterative algorithm
Holographic storage of three-dimensional image and data using photopolymer and polymer dispersed liquid crystal films
Random lasing in dye-doped polymer dispersed liquid crystal film
A high precision phase reconstruction algorithm for multi-laser guide stars adaptive optics
Liquid crystal Fresnel lens display
A novel see-through display with a liquid crystal lens array was proposed. A liquid crystal Fresnel lens display (LCFLD) with a holographic screen was demonstrated. The proposed display system has high efficiency, simple fabrication, and low manufacturing cost due to the absence of a polarizer and color filter.
Configuration optimization of laser guide stars and wavefront correctors for multi-conjugation adaptive optics
Bichromatic coherent random lasing from dye-doped polymer stabilized blue phase liquid crystals controlled by pump light polarization
Asymmetric dynamic phase holographic grating in nematic liquid crystal
Determining the imaging plane of a retinal capillary layer in adaptive optical imaging
Optical simulation of in-plane-switching blue phase liquid crystal display using the finite-difference time-domain method
Bridging the terahertz near-field and far-field observations of liquid crystal based metamaterial absorbers
Low voltage transflective blue-phase liquid crystal display with a non-uniform etching substrate
Azobenzene mesogens mediated preparation of SnS nanocrystals encapsulated with in-situ N-doped carbon and their enhanced electrochemical performance for lithium ion batteries application
Effect of fluorine groups and different terminal chains on the electro-isomerization of azobenzene liquid crystals
Phase behaviors of binary mixtures composed of electron-richand electron-poor triphenylene discotic liquid crystals
Synthesis of ZnO quantum dots and their agglomeration mechanisms along with emission spectra based on ageing time and temperature
Fullerene solar cells with cholesteric liquid crystal doping
Magic wavelengths for the 7s1/2-6d3/2,5/2 transitions in Ra+
The dynamic polarizabilities of the 7s and 6d states of Ra+ are calculated using a relativistic core polarization potential method. The magic wavelengths of the 7s1/2-6d3/2,5/2 transitions are identified. Comparing to the common radio-frequency (RF) ion traps, using the laser field at the magic wavelength to trap the ion could suppress the frequency uncertainty caused by the micromotion of the ion, and would not affect the transition frequency measurements. The heating rates of the ion and the powers of the laser for the ion trapping are estimated, which would benefit the possible precision measurements based on all-optical trapped Ra+.
First principle calculations of thermodynamic properties of pure graphene sheet and graphene sheets with Si, Ge, Fe, and Co impurities
Photoelectron angular distributions of H ionization in low energy regime: Comparison between different potentials
Controlling the contributions to high-order harmonic generation from different nuclei of N2 with an orthogonally polarizedtwo-color laser field
Branching ratio and angular distribution of ejected electrons from Eu 4f76p1/2nd auto-ionizing states
The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f76p1/2nd auto-ionizing states are investigated with the velocity-map-imaging technique. To populate the above auto-ionizing states, the relevant bound Rydberg states have to be detected first. Two new bound Rydberg states are identified in the region between 41150 cm-1 and 44580 cm-1, from which auto-ionization spectra of the Eu 4f76p1/2nd states are observed with isolated core excitation method. With all preparations above, the branching ratios from the above auto-ionizing states to different final ionic states and the angular distributions of electrons ejected from these processes are measured systematically. Energy dependence of branching ratios and anisotropy parameters within the auto-ionization spectra are carefully analyzed, followed by a qualitative interpretation.
Intrinsic product polarization and branch ratio in theS(1D, 3P)+HD reaction on three electronic states
The intrinsic product polarization and intramolecular isotope effect of the S(1D, 3P)+HD reaction have been investigated on both the lowest singlet state (1A') and the triplet state (3A' and 3A'') potential energy surfaces by using quasi-classical trajectory and quantum mechanical methods. The calculations indicate that intramolecular isotope effects are different on the three electronic states. The stereodynamics study shows that the P(θr) distributions, P(φr) distributions, and polarization-dependent differential cross sections (PDDCSs) (00) are sensitive to mass factor and the product angular momentum vectors are not only aligned but also oriented.
Helix-like structure formation of a semi-flexible chain confined in a cylinder channel
Molecular dynamics method is used to study the conformation behavior of a semi-flexible polymer chain confined in a cylinder channel. A novel helix-like structure is found to form during the simulation. Moreover, the detailed characteristic parameters and formation probability of these helix-like structures under moderate conditions are investigated. We find that the structure is not a perfect helix, but a bundle of elliptical turns. In addition, we conduct a statistical analysis for the chain monomer distribution along the radial direction. This research contributes to our understanding of the microscopic conformation of polymer chains in confined environments filled with a solvent.
Ultra-thin single-layer transparent geometrical phase gradient metasurface and its application to high-gain circularly-polarized lens antenna
Model of bidirectional reflectance distribution function for metallic materials
Controllable all-optical stochastic logic gates and their delay storages based on the cascaded VCSELs with optical-injection
Coherent population trapping magnetometer by differential detecting magneto-optic rotation effect
Generation of 15 W femtosecond laser pulse from a Kerr-lens mode-locked Yb: YAG thin-disk oscillator
High-energy femtosecond Yb-doped all-fiber monolithic chirped-pulse amplifier at repetition rate of 1 MHz
A high-energy femtosecond all ytterbium fiber amplifier based on a chirped-pulse amplification (CPA) technique at a repetition rate of 1 MHz seeded by a dispersion-management mode-locked picosecond broadband oscillator is studied. We find that the compressed pulse duration is dependent on the amplified energy, the pulse duration of 804 fs corresponds to the maximum amplified energy of 10.5 μJ, while the shortest pulse duration of 424 fs corresponds to the amplified energy of 6.75 μJ. The measured energy fluctuation is approximately 0.46% root mean square (RMS) over 2 h. The low-cost femtosecond fiber laser source with super-stability will be widely used in industrial micromachines, medical therapy, and scientific studies.
Spectroscopy system based on a single quantum cascade laser for simultaneous detection of CO and CO2
A quantum cascade laser (QCL) based system for simultaneous detection of CO and CO2 is developed. The QCL can scan over two neighboring CO (2055.40 cm-1) and CO2 (2055.16 cm-1) lines with a single current scan. The wavelength modulation spectroscopy (f = 20 kHz) is utilized to enhance the signal-to-noise ratio. A white cell with an effective optical path length of 74 m is used. The calibration of the sensor is performed and minimum detection limits of 1.3 ppb (1×10-9) for CO and 0.44 ppm (1×10-6) for CO2 are achieved.
Correction of walk-off-induced wavefront distortion for continuous-wave laser
Influence of alkali metal superoxides on structure, electronic, and optical properties of Be12O12 nanocage: Density functional theory study
Characteristics and generation of elastic turbulence in a three-dimensional parallel plate channel using direct numerical simulation
Direct numerical simulations (DNSs) of purely elastic turbulence in rectilinear shear flows in a three-dimensional (3D) parallel plate channel were carried out, by which numerical databases were established. Based on the numerical databases, the present paper analyzed the structural and statistical characteristics of the elastic turbulence including flow patterns, the wall effect on the turbulent kinetic energy spectrum, and the local relationship between the flow motion and the microstructures' behavior. Moreover, to address the underlying physical mechanism of elastic turbulence, its generation was presented in terms of the global energy budget. The results showed that the flow structures in elastic turbulence were 3D with spatial scales on the order of the geometrical characteristic length, and vortex tubes were more likely to be embedded in the regions where the polymers were strongly stretched. In addition, the patterns of microstructures' elongation behave like a filament. From the results of the turbulent kinetic energy budget, it was found that the continuous energy releasing from the polymers into the main flow was the main source of the generation and maintenance of the elastic turbulent status.
Latest development of display technologies
In this review we will focus on recent progress in the field of two-dimensional (2D) and three-dimensional (3D) display technologies. We present the current display materials and their applications, including organic light-emitting diodes (OLEDs), flexible OLEDs quantum dot light emitting diodes (QLEDs), active-matrix organic light emitting diodes (AMOLEDs), electronic paper (E-paper), curved displays, stereoscopic 3D displays, volumetric 3D displays, light field 3D displays, and holographic 3D displays. Conventional 2D display devices, such as liquid crystal devices (LCDs) often result in ambiguity in high-dimensional data images because of lacking true depth information. This review thus provides a detailed description of 3D display technologies.
Kerr effect and Kerr constant enhancement in vertically aligned deformed helix ferroelectric liquid crystals
In this article, we review recently achieved Kerr effect progress in novel liquid crystal (LC) material: vertically aligned deformed helix ferroelectric liquid crystal (VADHFLC). With an increasing applied electric field, the induced inplane birefringence of LCs shows quadratic nonlinearity. The theoretical calculations and experimental details are illustrated. With an enhanced Kerr constant to 130 nm/V2, this VADHFLC cell can achieve a 2π modulation by a small efficient electric field with a fast response around 100 μs and thus can be employed in both display and photonics devices.
Research progress of cholesteric liquid crystals with broadband reflection characteristics in application of intelligent optical modulation materials
Cholesteric liquid crystals (CLCs) have recently sparked an enormous amount of interest in the development of soft matter materials due to their unique ability to self-organize into a helical supra-molecular architecture and their excellent selective reflection of light based on the Bragg relationship. Nowadays, by the virtue of building the self-organized nanostructures with pitch gradient or non-uniform pitch distribution, extensive work has already been performed to obtain CLC films with a broad reflection band. Based on authors' many years' research experience, this critical review systematically summarizes the physical and optical background of the CLCs with broadband reflection characteristics, methods to obtain broadband reflection of CLCs, as well as the application in the field of intelligent optical modulation materials. Combined with the research status and the advantages in the field, the important basic and applied scientific problems in the research direction are also introduced.
Thermo- and photo-driven soft actuators based on crosslinked liquid crystalline polymers
Crosslinked liquid crystalline polymers (CLCPs) are a type of promising material that possess both the order of liquid crystals and the properties of polymer networks. The anisotropic deformation of the CLCPs takes place when the mesogens experience order to disorder change in response to external stimuli; therefore, they can be utilized to fabricate smart actuators, which have potential applications in artificial muscles, micro-optomechanical systems, optics, and energy-harvesting fields. In this review the recent development of thermo- and photo-driven soft actuators based on the CLCPs are summarized.
Optimization of multi-color laser waveform for high-order harmonic generation
Investigation of molecular penetration depth variation with SMBI fluxes
We study the molecular penetration depth variation with the SMBI fluxes. The molecular transport process and the penetration depth during SMBI with various injection velocities and densities are simulated and compared. It is found that the penetration depth of molecules strongly depends on the radial convective transport of SMBI and it increases with the increase of the injection velocity. The penetration depth does not vary much once the SMBI injection density is larger than a critical value due to the dramatic increase of the dissociation rate on the fueling path. An effective way to improve the SMBI penetration depth has been predicted, which is SMBI with a large radial injection velocity and a lower molecule injection density than the critical density.
Formation and dissociation of dust molecules in dusty plasma
Dust molecules are observed in a dusty plasma experiment. By using measurements with high spatial resolution, the formation and dissociation of the dust molecules are studied. The ion cloud in the wake of an upper dust grain attracts the lower dust grain nearby. When the interparticle distance between the upper dust grain and the lower one is less than a critical value, the two dust grains would form a dust molecule. The upper dust grain always leads the lower one as they travel. When the interparticle distance between them is larger than the critical value, the dust molecule would dissociate.
Influence of tip geometry on the spatial resolution of tip enhanced Raman mapping
In 2013, a breakthrough experiment pushed the Raman mapping of molecules via the tip-enhanced Raman scattering (TERS) technique to a sub-nanometer spatial resolution, going into the single-molecule level. This surprising result was well explained by accounting for the critical role of elastic molecule Rayleigh scattering within a plasmonic nanogap in enhancing both the localization and the intensity level of the Raman scattering signal. In this paper, we theoretically explore the influence of various geometric factors of the TERS system on the spatial resolution of Raman mapping, such as the tip curvature radius, tip conical angle, tip-substrate distance, and tip-molecule vertical distance. This investigation can help to find out the most critical geometric factor influencing the spatial resolution of TERS and march along in the right direction for further improving the performance of the TERS system.
Conditions for laser-induced plasma to effectively remove nano-particles on silicon surfaces
Influence of air pressure on the performance of plasma synthetic jet actuator
Monte Carlo simulation of asymmetrical growth of cube-shaped nanoparticles
Stable single helical C- and I-chains inside single-walled carbon nanotubes
The helicity of stable single helical carbon chains and iodine chains inside single-walled carbon nanotubes (SWCNTs) is studied by calculating the systematic van der Waals interaction energy. The results show that the optimal helical radius increases linearly with increasing tube radius, which produces a constant separation between the chain structure and the tube wall. The helical angle exhibits a ladder-like decrease with increasing tube radius, indicating that a large tube can produce a small helicity in the helical structures.
Influence of Tb on easy magnetization direction and magnetostriction of ferromagnetic Laves phase GdFe2 compounds
The crystal structure, magnetization, and spontaneous magnetostriction of ferromagnetic Laves phase GdFe2 compound have been investigated. High resolution synchrotron x-ray diffraction (XRD) analysis shows that GdFe2 has a lower cubic symmetry with easy magnetization direction (EMD) along  below Curie temperature TC. The replacement of Gd with a small amount of Tb changes the EMD to . The Curie temperature decreases while the field dependence of the saturation magnetization (Ms) measured in temperature range 5-300 K varies with increasing Tb concentration. Coercivity Hc increases with increasing Tb concentration and decays exponentially as temperature increases. The anisotropy in GdFe2 is so weak that some of the rare-earth substitution plays an important role in determining the easy direction of magnetization in GdFe2. The calculated magnetostrictive constant λ100 shows a small value of 37×10-6. This value agrees well with experimental data 30×10-6. Under a relatively small magnetic field, GdFe2 exhibits a V-shaped positive magnetostriction curve. When the field is further increased, the crystal exhibits a negative magnetostriction curve. This phenomenon has been discussed in term of magnetic domain switching. Furthermore, magnetostriction increases with increasing Tb concentration. Our work leads to a simple and unified mesoscopic explanation for magnetostriction in ferromagnets. It may also provide insight for developing novel functional materials.
Electronic structure and magnetic properties of (Cu, N)-codoped 3C-SiC studied by first-principles calculations
Pattern dependence in synergistic effects of total dose onsingle-event upset hardness
Comparison of radiation degradation induced by x-rayand 3-MeV protons in 65-nm CMOS transistors
Growth condition optimization and mobility enhancement through inserting AlAs monolayer in the InP-based InxGa1-xAs/In0.52Al0.48As HEMT structures
The structure of InP-based InxGa1-xAs/In0.52Al0.48As pseudomorphic high electron mobility transistor (PHEMT) was optimized in detail. Effects of growth temperature, growth interruption time, Siδ-doping condition, channel thickness and In content, and inserted AlAs monolayer (ML) on the two-dimensional electron gas (2DEG) performance were investigated carefully. It was found that the use of the inserted AlAs monolayer has an enhancement effect on the mobility due to the reduction of interface roughness and the suppression of Si movement. With optimization of the growth parameters, the structures composed of a 10 nm thick In0.75Ga0.25As channel layer and a 3 nm thick AlAs/In0.52Al0.48As superlattices spacer layer exhibited electron mobilities as high as 12500 cm2·V-1·s-1 (300 K) and 53500 cm2·V-1·s-1 (77 K) and the corresponding sheet carrier concentrations (Ns) of 2.8×1012 cm-2 and 2.9×1012 cm-2, respectively. To the best of the authors' knowledge, this is the highest reported room temperature mobility for InP-based HEMTs with a spacer of 3 nm to date.
Strain effect on graphene nanoribbon carrier statistic in the presence of non-parabolic band structure
Controllable preparation of vertically standing graphene sheets and their wettability and supercapacitive properties
Vertically standing graphene (VSG) sheets have been fabricated by using plasma enhanced chemical vapor deposition (PECVD) method. The lateral size of VSG nanosheets could be well controlled by varying the substrate temperature. The higher temperature usually gives rise to a smaller sheet size. The wettability of VSG films was tuned between hydrophobicity and hydrophilicity by means of oxygen and hydrogen plasma treatment. The supercapacitor electrode made of VSG sheets exhibited an ideal double-layer-capacitor feature and the specific capacitance reached a value up to 9.62 F·m-2.
Carrier transport in III-V quantum-dot structures for solar cells or photodetectors Hot!
According to the well-established light-to-electricity conversion theory, resonant excited carriers in the quantum dots will relax to the ground states and cannot escape from the quantum dots to form photocurrent, which have been observed in quantum dots without a p-n junction at an external bias. Here, we experimentally observed more than 88% of the resonantly excited photo carriers escaping from InAs quantum dots embedded in a short-circuited p-n junction to form photocurrent. The phenomenon cannot be explained by thermionic emission, tunneling process, and intermediate-band theories. A new mechanism is suggested that the photo carriers escape directly from the quantum dots to form photocurrent rather than relax to the ground state of quantum dots induced by a p-n junction. The finding is important for understanding the low-dimensional semiconductor physics and applications in solar cells and photodiode detectors.
Effect of NO annealing on charge traps in oxide insulator and transition layer for 4H-SiC metal-oxide-semiconductor devices
Unified semiclassical approach to electronic transport from diffusive to ballistic regimes Hot!
We show that by integrating out the electric field and incorporating proper boundary conditions, a Boltzmann equation can describe electron transport properties, continuously from the diffusive to ballistic regimes. General analytical formulas of the conductance in D=1,2,3 dimensions are obtained, which recover the Boltzmann-Drude formula and Landauer-Büttiker formula in the diffusive and ballistic limits, respectively. This intuitive and efficient approach can be applied to investigate the interplay of system size and impurity scattering in various charge and spin transport phenomena, when the quantum interference effect is not important.
Spectral response modeling and analysis of p-n-p In0.53Ga0.47As/InP HPTs
Different optical properties in different periodic slot cavity geometrical morphologies
A high-quality factor hybrid plasmonic nanocavity based on distributed Bragg reflectors Hot!
Herein, we propose a high-quality (Q) factor hybrid plasmonic nanocavity based on distributed Bragg reflectors (DBRs) with low propagation loss and extremely strong mode confinement. This hybrid plasmonic nanocavity is composed of a high-index cylindrical nanowire separated from a metal surface possessing shallow DBRs gratings by a sufficiently thin low-index dielectric layer. The hybrid plasmonic nanocavity possesses advantages such as a high Purcell factor (Fp) of up to nearly 20000 and a gain threshold approaching 266 cm-1 at 1550 nm, promising a greater potential in deep sub-wavelength lasing applications.
Charge susceptibilities of armchair graphene nanoribbon in the presence of magnetic field
Scaling dependence of memory windows and different carrier charging behaviors in Si nanocrystal nonvolatile memory devices
Based on the charge storage mode, it is important to investigate the scaling dependence of memory performance in silicon nanocrystal (Si-NC) nonvolatile memory (NVM) devices for its scaling down limit. In this work, we made eight kinds of test key cells with different gate widths and lengths by 0.13-μm node complementary metal oxide semiconductor (CMOS) technology. It is found that the memory windows of eight kinds of test key cells are almost the same of about 1.64 V @ ± 7 V/1 ms, which are independent of the gate area, but mainly determined by the average size (12 nm) and areal density (1.8×1011/cm2) of Si-NCs. The program/erase (P/E) speed characteristics are almost independent of gate widths and lengths. However, the erase speed is faster than the program speed of test key cells, which is due to the different charging behaviors between electrons and holes during the operation processes. Furthermore, the data retention characteristic is also independent of the gate area. Our findings are useful for further scaling down of Si-NC NVM devices to improve the performance and on-chip integration.
Structural, electronic, and magnetic properties of transition-metal atom adsorbed two-dimensional GaAs nanosheet
X-band inverse class-F GaN internally-matched power amplifier
An X-band inverse class-F power amplifier is realized by a 1-mm AlGaN/GaN high electron mobility transistor (HEMT). The intrinsic and parasitic components inside the transistor, especially output capacitor Cds, influence the harmonic impedance heavily at the X-band, so compensation design is used for meeting the harmonic condition of inverse class-F on the current source plane. Experiment results show that, in the continuous-wave mode, the power amplifier achieves 61.7% power added efficiency (PAE), which is 16.3% higher than the class-AB power amplifier realized by the same kind of HEMT. To the best of our knowledge, this is the first inverse class-F GaN internally-matched power amplifier, and the PAE is quite high at the X-band.
Thermal fluctuation conductivity and dimensionality in iron-based superconductors
The time-dependent Ginzburg-Landau Lawrence-Doniach model is used to investigate the superconducting fluctuation electrical conductivities. The theoretical result based on the self-consistent Gaussian approximation is used to fit the transport measurement data of iron-based superconductors F-doped LaOFeAs and BaFe2-xNixAs2. We demonstrate that LaOFeAs shows layered behavior, while BaFe2-xNixAs2 is more of a 3D feature. The conductivity in the region near Tc is well described by the theoretical formula.
Observation of selective surface element substitution in FeTe0.5Se0.5 superconductor thin film exposed to ambient air bysynchrotron radiation spectroscopy
Novel 0-π transitions in Josephson junctions between noncentrosymmetric superconductors
Manipulating magnetic anisotropies of Co/MgO(001) ultrathin films via oblique deposition
We present a systematic investigation of magnetic anisotropy induced by oblique deposition of Co thin films on MgO (001) substrates by molecular beam epitaxy at different deposition angles, i.e., 0°, 30°, 45°, 60°, and 75° with respect to the surface normal. Low energy electron diffraction (LEED), surface magneto-optical Kerr effect (SMOKE), and anisotropic magnetoresistance (AMR) setups were employed to investigate the magnetic properties of cobalt films. The values of in-plane uniaxial magnetic anisotropy (UMA) constant Ku and four-fold magnetocrystalline anisotropy constant K1 were derived from magnetic torque curves on the base of AMR results. It was found that the value of Ku increases with increasing deposition angle with respect to the surface normal, while the value of K1 remains almost constant for all the samples. Furthermore, by using MOKE results, the Ku values of the films deposited obliquely were also derived from the magnetization curves along hard axis. The results of AMR method were then compared with that of hard axis fitting method (coherent rotation) and found that both methods have almost identical values of UMA constant for each sample.
Room-temperature ferromagnetism observed in Nd-doped In2O3 dilute magnetic semiconducting nanowires
Effects of (La, Sr) co-doping on electrical conduction and magnetic properties of BiFeO3 nanoparticles
Effects of dispersion and filtering induced by periodic multilayer mirrors reflection on attosecond pulses
Using temporal and spectral methods, the effects of dispersion and filtering induced by Mo/Si multilayer mirrors reflection on incident attosecond pulses were studied. First, two temporal parameters, the pulse broadening factor, and the energy loss factor, were defined to evaluate the effects of dispersion and filtering. Then, by analyzing these temporal parameters, we investigated and compared the dispersion and filtering effects on attosecond pulses. In addition, we explored the origins of pulse broadening and energy loss by analyzing the spectral and temporal characteristics of periodic Mo/Si multilayer mirrors. The results indicate that the filtering effect induced by Mo/Si multilayer mirrors reflection is the dominant reason for pulse broadening and energy loss.
Mid/far-infrared photo-detectors based on graphene asymmetric quantum wells
We conducted a theoretical study on the electronic properties of a single-layer graphene asymmetric quantum well. Quantification of energy levels is limited by electron-hole conversion at the barrier interfaces and free-electron continuum. Electron-hole conversion at the barrier interfaces can be controlled by introducing an asymmetry between barriers and taking into account the effect of the interactions of the graphene sheet with the substrate. The interaction with the substrate induces an effective mass to carriers, allowing observation of Fabry-Pérot resonances under normal incidence and extinction of Klein tunneling. The asymmetry, between barriers creates a transmission gap between confined states and free-electron continuum, allowing the large graphene asymmetric quantum well to be exploited as a photo-detector operating at mid- and far-infrared frequency regimes.
Phonon-assisted excitation energy transfer in photosynthetic systems
Non-ionizing energy loss calculations for modeling electron-induced degradation of Cu(In, Ga)Se2 thin-film solar cells
Self-organized phenomena of pedestrian counterflow through a wide bottleneck in a channel