- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Cross-Section Analysis of the Composition of Sprayed Cu <sub/>2</sub> ZnSnS <sub/>4</sub> Thin Films by XPS, EDS, and Multi-Wavelength Raman Spectroscopy
摘要： A detailed cross-section analysis of the chemical composition of sprayed Cu2ZnSnS4 thin films is presented. X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy (with near-IR, visible, and UV-lasers) are used to demonstrate that while CZTS effectively forms within the bulk of the film, there is some degree of element segregation, formation of undesirable secondary phases, and the presence of a disordered kesterite structure across the film. Different penetration depths of the excitation signals correspond to the many different surface sensitive techniques employed in this work. XPS results reveal that the surface of Cu4ZnSnS4 (CZTS) films presents a high concentration of tin and zinc and a low sulfur concentration, while being highly depleted in copper. EDS, XRD, and infrared Raman spectroscopy confirm that the composition of as-sprayed and sulfurized films is close to stoichiometric Cu2ZnSnS4. Resonant UV-Raman spectroscopy helps to identify secondary phases located at the external surface of sprayed and sulfurized CZTS films (mainly ZnS, ZnO), while VIS-Raman spectroscopy helps to identify a disordered kesterite structure close to the surface. Secondary phases need to be chemically etched when aiming at incorporating kesterite films obtained by spray pyrolysis into photovoltaic devices.
关键词： multi-wavelength Raman spectroscopy,X-ray photoelectron spectroscopy,spray pyrolysis,thin films,kesterite
更新于2025-09-10 09:29:36
-
Dual wavelength optical duobinary modulation using GaAs–AlGaAs microring resonator
摘要： In this article, optical duobinary modulation technique has been used for modulating the dual-wavelength optical signal generated by the microring resonator system. The optical signals are de-multiplexed to two different optical signals with center wavelength of 1540 and 1545 nm afterward, these are modulated and transmitted over an optical fiber communication system, where the high performance of the transmitted signals is obtained. The NRZ binary signals are used to modulate the optical signals. The high-quality factor and performance of the system has been investigated by applying an optimization through the system parameters, where significant improvement could be obtained and highest quality factor of 32.871 shows the successful transmission. The second wavelength of the dual-wavelength has undergone the same modulation technique and has experienced the optical transmission after the system optimization has been performed, where the quality factor for the received optical signal at 1545 nm center wavelength is 39.282. These results show the introduced modulation technique is suitable to apply for the optical signals generated by the microring resonators.
关键词： microring resonators,dual-wavelength,Optical duobinary modulation technique
更新于2025-09-10 09:29:36
-
Binding effects in sulfur Kα and Kβ x-ray emission spectra
摘要： A systematic study has been carried out in order to investigate the influence of the chemical bond in the occurrence of the different sulfur decays to 1s vacancy states induced by electron impact. A number of samples in different oxidation states (+4, +6, 0 and ?2) were irradiated in a commercial microscope, acquiring Kα and Kβ spectra for all sulfur oxidation states. Special attention has been paid to the case of emissions associated to decays corresponding to multiple ionizations. An important achievement of the present study is the high resolution obtained in the wavelength-dispersive spectra acquired with a commercial spectrometer.
关键词： electron impact,chemical bond,wavelength-dispersive spectra,oxidation states,sulfur,Kα and Kβ spectra
更新于2025-09-10 09:29:36
-
Optical imaging and image analysis for high aspect ratio NEMS
摘要： A strategy for optical microscopy of high-aspect-ratio (HAR) nanoelectromechanical systems (NEMS) that combine large feature spacing and large height with sub-wavelength width is presented. Line images are simulated using a 2D model of incoherent imaging based on modal diffraction theory. Beyond a sufficient depth, it is shown that sub-wavelength features appear as dark lines, while wider features are visible as their edges. The results suggest NEMS and MEMS may be separated from background in images by detection of valleys in brightness. Results are confirmed by imaging of Si NEMS containing 100 nm wide features in a bright-field microscope. Algorithms for separation of NEMS, MEMS and background in microscope images based on valley detection, thresholding and masking are demonstrated.
关键词： MEMS,image segmentation,NEMS,sub-wavelength imaging
更新于2025-09-10 09:29:36
-
A comparative path establishment study on routing performance of MLR WDM optical networks
摘要： In this paper, we investigate the effect of path establishment method priorities over routing performance in mixed line rate (MLR) wavelength division multiplexed (WDM) optical networks. The survivable routing with rate and wavelength assignment (SRRWA) problem is presented and an efficient shared backup path protection solution is proposed. We prepared detailed simulation scenarios with all possible prioritizations and observed their performances. The simulation results show that assigning higher priority to single hop methods as compared with multi‐hop methods yields better performance. In both methods, it has been observed that assigning higher priority to grooming reduces the communication cost and the traffic blocking ratio while enhancing the resource utilization.
关键词： MLR,survivable communication,rate and wavelength assignment (RRWA),optical WDM networks,traffic grooming,shared backup protection,routing
更新于2025-09-10 09:29:36
-
Manufacturing of Volumetric Glass <b>-</b> Based Composites with Single- and Double-QD Doping
摘要： Quantum dot (QD)-based light-emitting materials are gaining increased attention because of their easily tunable optical properties desired for various applications in biology, optoelectronics, and photonics. However, few methods can be used to manufacture volumetric materials doped with more than one type of QD other than QD-polymer hybrids, and they often require complicated preparation processes and are prone to luminescence quenching by QD aggregation and separation from the matrix. Here, simultaneous doping of a volumetric glass-based nanocomposite with two types of QDs is demonstrated for the first time in a single-step process using the nanoparticle direct doping method. Glass rods doped with CdTe, CdSe/ZnS, or co-doped with both QDs, are obtained. Photoluminescence and lifetime experiments confirm temperature-dependent double emission with maxima at 596 and 720 nm with mean lifetimes up to 16 ns, as well as radiative energy transfer from the short wavelength–emitting QDs to the long wavelength–emitting QDs. This approach may enable the simple and cost-efficient manufacturing of bulk materials that produce multicolor luminescence with cascade excitation pumping. Applications that could benefit from this include broadband optical fiber amplifiers, backlight systems in LCD screens, high-power LEDs, or down-converting solar concentrators used to increase the efficiency of solar panels.
关键词： energy transfer,nanoparticle direct doping,quantum dots,volumetric material with embedded quantum dots,double wavelength luminescence
更新于2025-09-10 09:29:36
-
Numerical investigation and analysis of flattened dispersion for supercontinuum generation at very low power using Hexagonal shaped Photonic crystal fiber (H-PCF)
摘要： In this work, we report a design of hexagonal photonic crystal fiber (PCF) with eight hexagonal rings with modified air hole size at the innermost ring. We analyze and compare the major optical parameters of a PCF such as dispersion and nonlinearity over the span of wavelength ranges from 800 nm to 1600 nm at different core diameters. The designs exhibit a high nonlinearity of 220 W-1 km-1 at 800 nm for supercontinuum generation in designed PCF and along the dispersion in negative characteristics about ?650 ps/nm.km at 1310 nm with two zero dispersion wavelengths at 864 nm and at 1484 nm are numerically studied. In addition, we investigate the numerical modeling of supercontinuum (SC) generation in the designed PCFs and nearly 600 nm using 50 fs pulse with 2 kW pump power at 800 nm spectrum have been observed.
关键词： Soliton pulse,Supercontinuum generation,Photonic crystal fiber,Nonlinear Schr?dinger equation,Two zero dispersion wavelength
更新于2025-09-10 09:29:36
-
A feasible and accurate method for calculating the radiative properties of soot particle ensembles in flames
摘要： The accurate calculation of the radiative properties of soot particle ensembles in flames needs to exactly reconstruct the geometric structures of all soot particles and accurately calculate the radiative properties of all soot particles based on their reconstructed geometric structures. However, the enormous number of soot particles in real ensembles makes it practically impossible to implement this task. To solve this problem, a feasible and accurate method is proposed for calculating their main radiative properties except scattering matrix and depolarization ratio. Experimental and numerical results show that soot particles with the same number of primary particles from the same sampling point can be considered as equivalent soot particles, which have almost the same volume, absorption cross-section, scattering cross-section and scattering asymmetry cross-section. Moreover, the average values of these quantities of equivalent soot particles approximately linearly increase with the number of primary particles. These findings can dramatically reduce the difficulty of reconstruction and calculation. The radiative properties of 37 different morphologies of soot particle ensembles in the visible and near-infrared regions (λ = 0.40-3.00 μm) are calculated using this method, and it is shown that the increasing of the average diameter of primary particles and the average number of primary particles per soot particle can enhance the absorption coefficient, scattering coefficient, asymmetry factor and single-scattering albedo of soot particle ensembles 0.1-900 times. In addition, these radiative properties are found to decrease by at least 70% with the increasing of λ from 0.40 μm to 3.00 μm.
关键词： Incident wavelength,Radiative properties,Soot particle ensemble,Particle structure
更新于2025-09-10 09:29:36
-
Research on high resolution fiber Bragg grating sensing technology based on high speed parallel sampling
摘要： The high resolution fiber Bragg sensing system based on high speed parallel sampling technology is proposed. According to the Rayleigh criterion, it is generally believed that the number of the measured data of the fiber grating reflection spectrum is limited to the resolution of the wavelength measurement device. So, in order to achieve high spectral resolution, high resolution wavelength measurement devices, at the same time, to achieve small variations of the transmission wavelength of the Fabry–Perot (FP) filter, the high bit digital-to-analog converter (DAC) was adopted to generates small step drive voltages, these will greatly increase the cost of the system. However, in this paper, the fiber Bragg sensing system with the low resolution FP filter and low bit DAC achieves the high resolution wavelength measurement by using the high speed parallel sampling. In addition, the resolution of wavelength in fiber grating sensing system is analyzed theoretically.
关键词： Parallel sampling technology,Wavelength resolution,Fiber Bragg grating,Optical fiber sensing
更新于2025-09-10 09:29:36
-
Secondary Fluorescence in WDS: The Role of Spectrometer Positioning
摘要： Secondary fluorescence (SF), typically a minor error in routine electron probe microanalysis (EPMA), may not be negligible when performing high precision trace element analyses in multiphase samples. Other factors, notably wavelength dispersive spectrometer defocusing, may introduce analytical artifacts. To explore these issues, we measured EPMA transects across two material couples chosen for their high fluorescence yield. We measured transects away from the fluorescent phase, and at various orientations with respect to the spectrometer focal line. Compared to calculations using both the Monte Carlo simulation code PENEPMA and the semi-analytical model FANAL, both codes estimate the magnitude of SF, but accurate correction requires knowledge of the position of the spectrometer with respect to the couple interface. Positioned over the fluorescent phase or otherwise results in a factor of 1.2–1.8 of apparent change in SF yield. SF and spectrometer defocusing may introduce systematic errors into trace element analyses, both may be adequately accounted for by modeling. Of the two, however, SF is the dominant error, resulting in 0.1 wt% Zn apparently present in Al at 100 μm away from the Zn boundary in an Al/Zn couple. Of this, around 200 ppm Zn can be attributed to spectrometer defocusing.
关键词： defocusing,secondary fluorescence,spectrometer positioning,wavelength dispersive spectrometer,electron microprobe
更新于2025-09-10 09:29:36