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<jats:p>Electron-impact excitation integral cross sections play an important role in understanding the energy transfer processes in many applied physics. Practical applications require integral cross sections in a wide collision energy range from the excitation threshold to several keV. The recently developed BE-scaling method is able to meet the demands of integral cross sections for dipole-allowed transitions while the prerequisite relies on the accurate generalized oscillator strengths. Fast electron and x-ray scatterings are the conventional experimental techniques to approach the generalized oscillator strengths, and the joint study by both methods can provide credible cross-checks. The validated generalized oscillator strengths can then be used to extrapolate optical oscillator strengths by fitting the data with the Lassettre formula. The fitted curve also enables the integration of generalized oscillator strengths over the whole momentum transfer region to obtain the BE-scaled integral excitation cross sections. Here, experimental measurements by both fast electron and x-ray scattering of argon and carbon dioxide are reviewed. The integral cross sections for some low-lying states are derived from the cross-checked generalized oscillator strengths for the first time. The integral cross sections presented in this paper are openly available at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://doi.org/10.11922/sciencedb.01466" xlink:type="simple">https://doi.org/10.11922/sciencedb.01466</jats:ext-link>.</jats:p>

<jats:p>We propose a method for imaging a periodic moving/state-changed object based on computational ghost imaging with Hadamard speckle patterns and a slow bucket detector, named as PO-HCGI. In the scheme, speckle patterns are produced from a part of each row of a Hadamard matrix. Then, in each cycle, multiple speckle patterns are projected onto the periodic moving/state-changed object, and a bucket detector with a slow sampling rate records the total intensities reflected from the object as one measurement. With a series of measurements, the frames of the moving/state-changed object can be obtained directly by the second-order correlation function based on the Hadamard matrix and the corresponding bucket detector measurement results. The experimental and simulation results demonstrate the validity of the PO-HCGI. To the best of our knowledge, PO-HCGI is the first scheme that can image a fast periodic moving/state-changed object by computational ghost imaging with a slow bucket detector.</jats:p>

<jats:p>Ghost imaging (GI) offers great potential with respect to conventional imaging techniques. However, there are still some obstacles for reconstructing images with high quality, especially in the case that the orthogonal measurement matrix is impossible to construct. In this paper, we propose a new scheme based on the orthogonal-triangular (QR) decomposition, named QR decomposition ghost imaging (QRGI) to reconstruct a better image with good quality. In the scheme, we can change the randomly non-orthogonal measurement matrix into orthonormal matrix by performing QR decomposition in two cases. (1) When the random measurement matrix is square, it can be firstly decomposed into an orthogonal matrix <jats:italic> <jats:bold>Q</jats:bold> </jats:italic> and an upper triangular matrix <jats:italic> <jats:bold>R</jats:bold> </jats:italic>. Then let the off-diagonal values of <jats:italic> <jats:bold>R</jats:bold> </jats:italic> equal to 0.0, the diagonal elements of <jats:italic> <jats:bold>R</jats:bold> </jats:italic> equal to a constant <jats:italic>k</jats:italic>, where <jats:italic>k</jats:italic> is the average of all values of the main diagonal, so the resulting measurement matrix can be obtained. (2) When the random measurement matrix is with full rank, we firstly compute its transpose, and followed with above QR operation. Finally, the image of the object can be reconstructed by correlating the new measurement matrix and corresponding bucket values. Both experimental and simulation results verify the feasibility of the proposed QRGI scheme. Moreover, the results also show that the proposed QRGI scheme could improve the imaging quality comparing to traditional GI (TGI) and differential GI (DGI). Besides, in comparison with the singular value decomposition ghost imaging (SVDGI), the imaging quality and the reconstruction time by using QRGI are similar to those by using SVDGI, while the computing time (the time consuming on the light patterns computation) is substantially shortened.</jats:p>

<jats:p>A 1040 nm tapered laser with tapered distributed Bragg reflector (DBR) grating is designed and fabricated. By designing the grating with tapered layout, the tapered DBR grating exhibits the scattering effect on side backward-traveling waves, thus achieving additional suppression of parasitic oscillation. Under the suppression of parasitic oscillation, the spatial and spectral characteristics of the tapered laser are improved. The experimental results show that a near-Gaussian far-field distribution and a kink-free <jats:italic>P</jats:italic>–<jats:italic>I</jats:italic> characteristics are achieved, and a single peak emission with a wavelength of 1046.84 nm and a linewidth of 56 pm is obtained.</jats:p>

<jats:p>Electrical sensing systems, such as those involving eutectic salt, are mostly used in connection to leakage from existing airborne high-temperature air-conducting pipelines. Such complex structured systems are susceptible to external interferences and, thus, cannot meet the increasingly strict monitoring needs of a complex air-conducting pipeline system of an aircraft. In view of this point, this paper studies an alternative sensor system based on a dense array fiber grating. To obtain a compact and light-weight airborne signal processing system, a field programmable gate array is used as the main control core that controls the output of the light source. The functions of pulse modulation, analog-to-digital conversion, data buffering and transmission are integrated into a single system, while the linear sensing monitoring is obtained by detecting the time-division and wavelength-division wavelength drift signals of the fiber Bragg grating array. Our experiments show that the spatial resolution of the linear sensing system approaches 5 cm, the temperature measurement accuracy reaches 2 °C, the temperature measurement range is between 0–250 °C, and the response time is within 4 s. Compared with the existing electrical monitoring systems, various monitoring indicators have been greatly improved and have broad application prospects.</jats:p>

<jats:p>A high-efficiency and high-power vertical-cavity surface-emitting laser (VCSEL) side-pumped rod Nd:YAG laser with temperature adaptability are demonstrated. The VCSEL side-pumped laser module is designed and optimized. Five VCSEL arrays are symmetrically located around the laser rod and a large size diffused reflection chamber is designed to ensure a uniform pump distribution. Furthermore, the absorbed pump power distribution of the rod is simulated to verify the uniformity of the pump absorption. Finally, a proof-of-principle experiment is performed in short linear cavity laser with single laser module. A continuous-wave output power of 658 W at 1064 nm is obtained, the corresponding optical-to-optical efficiency is 52.6%, and the power variations are ±0.7% over 400 s and ±3.1% over the temperature range from 16 °C to 26 °C. To the best of our knowledge, this is the highest output power and the highest optical-to-optical efficiency ever reported for VCSEL pumped solid-state lasers. By inserting a telescopic module into the cavity and optimizing the TEM<jats:sub>00</jats:sub> mode volume, the average beam quality is measured to be <jats:italic>M</jats:italic> <jats:sup>2</jats:sup> = 1.34 under an output power of 102 W. The experimental results reveal that such a high power rod laser module with temperature stability is appropriate for field applications.</jats:p>

<jats:p>The optical control ability of photonic crystal fiber (PCF) is a distinctive property suitable for improving sensing and plasma performance. This article proposes a dual-core D-channel PCF sensor that can detect two samples simultaneously, which effectively solves the problems of coating difficulty and low wavelength sensitivity. The PCF has four layers of air holes, which dramatically reduces the optical fiber loss and is more conducive to the application of sensors in actual production. In addition, by introducing dual cores on the upper and lower sides of the central air hole, reducing the spacing between the core and the gold nanolayer, a stronger evanescent field can be generated in the cladding air hole. The optical fiber sensor can detect the refractive index of two samples simultaneously with a maximum sensitivity of 21300 nm/RIU. To the best of our knowledge, the sensitivity achieved in this work is the highest sensitivity with the dual sample synchronous detection sensors. The detection range of the refraction index is 1.35–1.41, and the resolution of the sensor is 4.695 × 10<jats:sup>−6</jats:sup>. Overall, the sensor will be suitable for medical detection, organic chemical sensing, analyte detection, and other fields.</jats:p>

<jats:p>High power supercontinuum (SC) is generated by focusing 800 nm and 400 nm femtosecond laser pulses in fused silica with a microlens array. It is found that the spectrum of the SC is getting broader compared with the case of a single laser pulse, and the spectral energy density between the two fundamental laser wavelengths is getting significantly higher by optimizing the phase matching angle of the BBO. It exceeds μJ/nm over 490 nm range which is from 380 nm to 870 nm, overcoming the disadvantage of relative lower power in the ranges far from the fundamental wavelength.</jats:p>

<jats:p>Large-scale topography, such as a seamount, substantially impacts low-frequency sound propagation in an ocean waveguide, limiting the application of low-frequency acoustic detecting techniques. A three-dimensional (3D) coupled-mode model is developed to calculate the acoustic field in an ocean waveguide with seamount topography and analyze the 3D effect. In this model, a correction is introduced in the bottom boundary, theoretically making the acoustic field satisfy the energy conservation. Furthermore, a large azimuth angle calculation range is obtained by using the operator theory and higher-order Padé approximation. Additionally, the model has advantages related to the coupling mode and parabolic equation theory. The couplings corresponding to the effects of range-dependent environment are fully considered, and the numerical implementation is kept feasible. After verifying the accuracy and reliability of the model, low-frequency sound propagation characteristics in the seamount environment are analyzed. The results indicate lateral variability in bathymetry can lead to out-of-plane effects such as the horizontal refraction phenomenon, while the coupling effect tends to restore the abnormal sound field and produces acoustic field diffraction behind the seamount. This model effectively considers the effects of the horizontal refraction and coupling, which are proportional to the scale of the seamount.</jats:p>

<jats:p>The scattering behavior of an anisotropic acoustic medium is analyzed to reveal the possibility of routing acoustic signals through the anisotropic layers with no backscattering loss. The sound-transparent effect of such a medium is achieved by independently modulating the anisotropic effective acoustic parameters in a specific order, and is experimentally observed in a bending waveguide by arranging the subwavelength structures in the bending part according to transformation acoustics. With the properly designed filling structures, the original distorted acoustic field in the bending waveguide is restored as if the wave travels along a straight path. The transmitted acoustic signal is maintained nearly the same as the incident modulated Gaussian pulse. The proposed schemes and the supporting results could be instructive for further acoustic manipulations such as wave steering, cloaking and beam splitting.</jats:p>