Using atmospheric turbulence transmission theory and partially coherent light cross spectral density function， the coupling efficiency of partially coherent light-fiber array is studied， and the influences of light source coherence， lens array sub-aperture number N， transmission distance， turbulence intensity， and wavelength on coupling efficiency are analyzed in this paper. Simulation results show that the lens array can well restrain the decrease of the coherence degree of the light source and the influence of atmospheric turbulence on the coupling efficiency of partially coherent light-fiber array. When the equivalent receiving aperture is the same， the increase of the N of the lens array can effectively improve the coupling efficiency of partially coherent light-fiber array. When N=37 and the transmission distance is greater than 3 km， the coupling efficiency curve tends to be stable. For a light source with a wavelength of 1550 nm and a coherence of 0.04 m， compared with single-lens reception， the lens array with N=37 can increase the coupling efficiency from 40% and 8% to 60% and 53% respectively in the case of moderate and strong turbulence. Compared with the long-wavelength light source， the coupling efficiency of the lens array to the short-wavelength light source is improved more obvious. For light sources with wavelengths of 850 nm and 1550 nm and a coherence of 0.04 m， compared with single-lens reception， the lens array with N=37 can increase the coupling efficiency from 18% and 41% to 57% and 60%， respectively.

The internal photoemission process of hot electrons generated by light excitation in metals can break the bandgap limitation of semiconductors and it is of great significance in the applications of photodetections， photovoltaics， and photocatalyses. However， the effects of the morphology， size， and Schottky junction barrier of metallic nanostructures on the injection efficiency of hot electrons are still unclear. Here， based on Monte Carlo simulations， the carrier transport behaviors in single- and double-junction planar structures and single- and double-junction core-shell nanowires are studied， and the effects of the morphology， size， and Schottky junction barrier on the injection efficiency of hot electrons are analyzed. The results show that in the planar hot electron device with a thick metal film， the double Schottky barrier configuration can reduce the hot electron thermalization loss and significantly increase the injection efficiency； with the thin metallic film， the thermalization loss of hot electrons is small， and the difference in injection efficiency between the double- and single-junction configurations is negligible. In the single-junction core-shell nanowires， the electron-phonon scattering significantly improves the hot electron injection efficiency， which decreases （increases） with the increasing metal thickness （nanowire radius）. In the double-junction core-shell nanowires， the injection angles of hot electrons at the outer Schottky junction interface are smaller than that of the inner junction interface， so the outer Schottky junction has a stronger hot electron harvesting capability. As the metal thickness （nanowire radius） increases， the number of hot electrons generated near the outer （inner） Schottky junction increases， resulting in an increase （decrease） in injection efficiency. This study provides an in-depth understanding of the hot electron transport behavior and the injection efficiency limit in various metallic nanostructures， and provides a guidance for the design of high-performance hot-electron devices.

Based on the theoretical basis of the interaction between particles and matter， the influence of charged particle energy， incident angle， detector thickness， and sensitive area on position sensitive silicon detector （PSSD） position resolution is analyzed by using FLUKA Monte Carlo simulation software. The simulation results show that as the electron energy increases， the position resolution capability of the detector becomes worse. When the electron energy increases to pass through the detector， the position resolution capability gradually increases with the increase of energy. For the detectors of different thickness， when the electron energy is completely deposited in the detector， the position resolution ability of the detector is basically the same. When the electron energy is not completely deposited in the detector， the position resolution ability of the detector with a larger thickness is relatively poor. The limited area of the detector will affect the position resolution. When electrons enter the detector at an incident angle α≤45°， the detected electron position will shift. The larger the incident angle， the more obvious the shift.

A stable formation communication network can improve the ability for UAV clusters to perform tasks. Therefore， it is necessary to design an information interaction topology that maintains the formation and minimizes communication costs. This research is aimed at optimizing the topology of a UAV formation network by integrating the benefits of ultraviolet optical communication. Thus an optimally rigid formation generation algorithm for UAVs based on ultraviolet communication is proposed. In analyzing the ultraviolet communication link model between UAVs， an ultraviolet hemispherical LED array is used to assist the UAVs in finding their neighbor nodes. This is achieved by first generating an optimal rigid subgraph and then forming a optimal rigid formation graph through the link deletion. Simulation results show that when compared to other algorithms， the proposed algorithm constructs a topology with both an appropriate average node degree and a small communication radius. The proposed algorithm improves the fault tolerance performance of the network， reduces communication complexity and decreases energy consumption of the formation network.

This study proposes an improved routing algorithm based on the neighbor table， called EMTR， to solve the problem that the packet transmission path is not being optimal in the tree routing algorithm of msstatePAN. The algorithm uses the information of the current， destination， and neighbor nodes in the neighbor table to find the path with the least number of hops from the source node to destination node， filters the node with a low energy through threshold， selects the optimal path with the same number of hops by comparing the link quality indication of nodes， and effectively avoids the conflicts in the path selection process. Experimental results show that the number of transmission hops is reduced by 35.8%； the network delay is reduced by 51.5%； and the node energy consumption is reduced by 16.1% at the end of the simulation. The algorithm not only provides an approximate optimal routing path but also maintains the advantages of tree routing， such as no routing table maintenance overhead and low memory consumption. In the case of the limited neighbor table maintenance overhead， the algorithm balances the energy of the network nodes， prolongs the network lifetime， and reduces the transmission delays and hops.

Herein， a pulse measurement system based on bent optical fibers was investigated. First， an optical fiber sensor head was designed according to the bending loss theory of the optical fiber. Then， the collected data were processed， and the feature points were extracted and analyzed. When the pulse signals for different people with different ages and genders were measured before and after exercise， the tidal wave disappeared after the exercise， and the frequency and amplitude of pulse obviously increased. The tidal wave， dicrotic wave peak， and dicrotic wave trough of middle-aged people were not as pronounced as those of young people. Women showed a significantly smaller pulse pressure difference than men. Experimental results showed that the pulse measurement system based on the bent optical fiber could reproduce the detailed parameters of the pulse signal and accurately measure the main wave， tidal wave， dicrotic wave peak， dicrotic wave trough， and other characteristic points. These properties are significant for developing digital pulse diagnosis technology.

In this study， we propose a type of photonic crystal fiber with a silicon nanocrystal core exhibiting improved nonlinearity and reduced dispersion slope and fabrication difficulty. The core and cladding air holes are round. The effects of the core diameter， the diameter of the air holes in the cladding， and the lattice constant on dispersion and nonlinearity are investigated using the plane wave expansion method. A photonic crystal fiber with high nonlinearity and low dispersion slope can be obtained through optimization when considering a zero-dispersion wavelength of 1550 nm. Here， the dispersion slope of fiber at 1550 nm wavelength is as low as 0.251 ps·nm-2·km-1， whereas the nonlinear coefficient is as high as 1.0×105 W-1·km-1. Further， the confinement loss is 0.39 dB/km. The structure of the photonic crystal fiber is simple and its fabrication is easy. In addition， it can maintain good performance even in the presence of small process errors.

Ice cloud is composed of tiny ice crystal particles， which generally appear at an altitude of more than 6 km. The interaction between ice crystal particles and light quantum signals will seriously affect the quantum satellite communication link. To study the influence of the ice crystal particles on the performance of quantum satellite communication， in this paper， first， according to the ice cloud light scattering model and the Mie scattering theory， the average extinction coefficient of the ice particles in the ice cloud is defined， and relationship between the link attenuation coefficient， ice cloud ice water content （IWC） and the transmission distance of quantum signal in the ice cloud are established ； then， for the amplitude damping channel， the relationship between channel capacity， channel average fidelity， channel survival function， channel error rate and ice cloud IWC and the transmission distance of quantum signal in ice cloud are established. Theoretical analysis and simulation results show that when the transmission distance of quantum signal in ice cloud is 20 km， with the increase of ice cloud IWC， the link attenuation factor increases from 4.6 dB to 14.7 dB， the quantum channel capacity decreases from 0.250 bit/s to 0.089 bit/s， the average channel fidelity decreases sharply， the survival function decreases from 1.00 to 0.58， and the quantum channel error rate increases from 0.015 to 0.075. This shows that the ice crystal particles in the ice cloud have a significant impact on the communication quality of the quantum satellite. In order to improve the reliability of the quantum satellite communication system， the parameters of the quantum satellite communication system should be adjusted adaptively according to the relevant parameters of the ice cloud.

A distributed Raman optic fiber sensing system based on field programmable gate array （FPGA） is proposed， which realizes signal acquisition， transmission， and processing. A cumulative iterative average filtering algorithm based on FPGA and a nonlinear wavelet transform threshold denoizing method are proposed to improve the signal-to-noise ratio （SNR） of the system. First， the amplified Stokes and anti-Stokes signals are accumulated iteratively and then averaged. After averaging of 8000 cumulative iterations， the SNR of the system is improved by 36.748 dB. Then the temperature is demodulated， and the temperature information is denoized by nonlinear wavelet transform threshold. Finally， the accuracy of the proposed system’s temperature measurement is ±1.5 °C from the heating experiment.

Aiming at the poor flexibility of traditional flexible three-dimensional（3D） morphology measuring system and the need to paste cooperative target points in advance. A multi-feature shape complex surface 3D shape measurement based on optical coordinate 3D measurement system is proposed. The overall design scheme of the proposed measurement system is introduced and mathematical model is established for it. And the research on flexible measurement technology of complex parts 3D morphology is realized. The measurement accuracy and repeatability measurement accuracy of the detection system are experimental verified. The experimental results show that the flexible measuring system has high reliability and precision. At the same time， the outer dimensions of parts with curvature and special-shaped holes are measured for the shape of the non-sticking cooperation target. And the experimental results show the feasibility of the measuring system.

In the cavity photomechanical system including the two-level atom ensemble， the neglected non-rotating wave approximation effect is used to discuss the optically induced transparency， dispersion and optically induced amplification in the unsolvable and solvable sideband regions nature. When the driving light field is red detuning， the perfect optically induced transparency and optically induced amplification can be achieved in the solvable and unsolvable sideband regions， respectively. The experimental results show that the full width at half maximum of the optically induced transparent window becomes very narrow with the increase of the dissipation rate of the optically mechanical cavity in both the solvable and the unsolvable sideband regions， but the full width at half maximum of the optically induced transparent window in the unsolvable sideband region is much smaller than that in the solvable sideband region. The change of the maximum value of photo induced amplification is just opposite to the change of the full width at half maximum of the photo induced transparent window. The maximum value of photo induced amplification in the solvable sideband region is less than that in the unsolvable sideband region.

Herein， nanosecond laser with different pulse frequencies and pulse widths was used to remove 150 μm thick epoxy coatings from a 2024 aluminum alloy surface. The macro and microsurface morphologies of the sample cleaned by laser were analyzed， and the paint removal effect and damage to the substrate under different laser parameters were discussed. The substrate damage threshold was calculated to be approximately 556.17 W under the pulse width and frequency of 60 ns and 20 kHz， respectively. Results show that the paint coating on the sample surface is completely removed， and the substrate surface is not melted when the laser power， pulse width， and pulse frequency are set to 500 W， 60 ns， and 20 kHz， respectively. The oxygen content in the sample surface cleaned under the above parameters is 43.44%， while that in the original substrate surface is 42.51%， which are close to each other. The oxygen content in the cleaned sample surface and original substrate surface is approximately equal， suggesting that the anodized film on the substrate surface is not damaged during the cleaning process. After removing the paint by the above laser parameters， the microhardness of the cleaned sample surface is 168.34 HV， which is 99.1% of the microhardness of the original substrate surface， indicating that the microhardness of the substrate surface is unaffected by the laser cleaning paint process.

A thermal-mechanical coupling simulation model of laser cladding high-entropy alloy is established herein to break through the technical bottleneck that the laser cladding high-entropy alloys on the surface of the inner cylinder of the pump easily form cracks. The model considers the changes of the material's thermal physical properties with temperature， latent heat， laser power， and laser scanning speed as the main independent variables. The simulation results show that the high temperature gradient is mainly concentrated in the laser cladding region and its vicinity because the laser cladding process has a local rapid heating and cooling characteristics. Due to the non-unifomity of the spatial distribution of the temperature of the laser cladding high-entropy alloy and the asymmetry of the geometric structure of the laser irradiated area， the maximum tensile residual stress in x direction is greater than that in y and z directions. The stress concentration exists in the interface region between the cladding region and the matrix because of the influence of the geometric structure mutation and the temperature gradient in the region. Due to the formation of residual stress is related to temperature gradient， temperature level， structure constraints， and other factors related， therefore， with the increase of laser power， the maximum residual stress in x direction increases， the maximum residual stress in y direction decreases and then increases，and the residual stress in z direction increases. The maximum residual stress in x direction decreases with the increase of the scanning speed， the maximum residual stresses in y and z directions increase and then decrease. With the increase of laser scanning speed， the maximum tensile residual stress increases under the comprehensive competition of the reduction of thermal expansion deformation caused by the decrease of temperature and the influence of uncoordinated deformation on stress. The simulation model is verified by experiments， and the verification result proved the correctness of the model.

To address the remanufacturing difficulties of QT700 nodular cast iron gear， such as the decrease of surface hardness， the accumulation of chill microstructure at the interface， the easy cracking of the cladding layer， and the occurrence of porosity defects in the cladding layer， new composite process of laser cladding preparation and laser quenching to improve hardness is proposed. The FeCrNiCu alloy is chosen for its similar chemical composition and excellent mechanical properties （e.g.， hardness）. We prepare cladding layer on QT700 ductile cast iron gear surface； the good mechanical properties of the remanufactured coating are verified by experiments that include analysis of cladding layer microstructure evolution， surface hardness comparison， and evaluation of friction and wear performance. Results of these experiments show that the coating has good fusion， without pores， cracks and other forming defects； the microstructure is presented as a remarkable laser cladding rapid condensation structure. After quenching the top of the cladding layer， the equiaxed grains are finer and the grain size is reduced. Dentritic crystals in the middle part of the cladding layer are refined， and parts of the branches are separated. The size of cellular crystals at the bottom of the coating basically keeps the shape after cladding， but the chill microstructure at the interface is transtriated to partial melting and intermittent separation. After cladding， the microhardness of the cladding layer is about 473?589 HV， which is increased to 666?735 HV after quenching； the friction coefficient of the cladding is 0.15?0.25， optimized to 0.05?0.15 after quenching. This study provides process and method reference for laser remanufacturing of nodular cast iron.

This study seeks to achieve rapid detection of the V-shaped crack depth on metal surfaces. To this end， this study investigates the action process of the V-shaped crack and the surface acoustic wave within a certain range and adopts the finite element method to simulate the transmission process of the surface acoustic wave signal excited by the linear pulse laser source in metal materials under the thermoelastic mechanism and the interaction process of surface acoustic wave and V-shaped crack. The study show that V-shaped cracks of different depths and surface acoustic waves have different interaction processes. By analyzing the mechanism of different depth cracks and surface acoustic wave， the crack depth information is divided to three range intervals， and the calculation method of corresponding crack depth is estimated. In accordance with different action processes， this study proposes a rapid judgment and detection method for the V-shaped crack depth on metal surfaces. By detecting the surface acoustic wave reflected echo signal RR and the converted shear wave signal RS peak size， the depth range of the V-shaped crack can be quickly judged， and then its depth information is detected. This method enables rapid location of the crack depth interval and improvement of the detection efficiency of V-shaped crack depth information on metal surfaces. The simulation shows that the error of the crack depth between the calculated value and actual one does not exceed 5%, and that this method can achieve efficient detection of metal surface V-shaped cracks.

To realize high-quality functional structures in ceramic materials， a short-pulse ultraviolet nanosecond laser was used to study the application of laser micromilling technology in the fabrication of blind holes in Al2O3 substrates. The influence of the laser-pulse energy density， scanning speed of scanner， and total number of repeat scanning on the taper angle of the hole and bottom surface roughness was investigated using field lenses of different focal lengths in the milling experiment. The experimental results show that the focal length plays a significant role in the micromilling process， while the other parameters can be used for optimizing the processing quality. Therefore， appropriate selection of the optical focal length can effectively improve the processing quality of micromilling blind holes， in particular， their taper angle. A blind hole with minimum taper angle of 5.4°， a hole depth of 0.83 mm and a bottom surface roughness of 2.48 μm was achieved at a focal length of f =160 mm with a laser-pulse energy density of 25.80 J/cm2， a scanning speed of 1000 mm/s， and a total number of repeat scanning of 400.

To optimize the process parameters of a non-uniform Fe45 powder laser cladding process， a 3-kW robot laser cladding system was used for the working process test. A 4-factor 3-level L9（43） orthogonal test plan was designed according to the reference range of the process parameters of the cladding system， and the effects of each process parameter on the surface morphology， internal defects， and dilution rate of the single-pass cladding layer were discussed by using the extreme value R analysis. Furthermore， the optimized parameters corresponding to the individual targets were also analyzed. Thereafter， the comprehensive optimal cladding process parameter combination was found through a multi-objective fuzzy comprehensive evaluation method. Finally， the effect of overlap rate （30%， 40%， and 50%） on surface morphology and internal quality of the multi-layer cladding were studied. The results show that the influence of the process parameters on the morphology of the cladding layer from large to small is scanning speed （B）， laser power （A）， defocusing amount （D）， and powder feeding speed （C）， and the optimal parameter is A3B2CD2； the influence of the process parameters on the defects of the cladding layer from large to small is scanning speed or defocusing amount， laser power， and power feeding speed， and the optimal parameter is A3B1C2D2； the influence of the process parameters on the dilution rate from large to small is powder feeding speed， defocusing amount， laser power and scanning speed， and the optimal parameter is A1B1C3D2. The optimal parameters for the comprehensive process are as follows： laser power is 2400 W， scanning speed is 5 mm/s， powder feeding speed is 20 g/min， and focal length is +5 mm. We could achieve a dense cladding structure with a continuous surface and no internal defects when cladding at different overlap rates with the optimized process parameters， and the laser cladding exhibited the best effect at the overlap rate （η） of 40%.

An integral valve seat is an essential component in ultra-super critical (USC) thermal power plants. Onsite remanufacturing of the valve-seat sealing face is a major focus of thermal power plant manufacturing. In this paper, a laser cladding Stellite 6 Co-based alloy repair study was carried out for the commonly used SA182 F91 heat resistant steel for nuclear valves. A series of cladding thick-size repair samples were prepared by changing the process parameters, and the metallographic observation, hardness testing, three-point bending testing, and impact testing at room temperature were performed. The cladding layers consisted of a face-centered-cubic γ-Co solid solution with epitaxial growth solidification characteristics. The hardness, bending strength, and impact energy of the repaired samples were 450‒500 HV, 1246‒1582 MPa, and 40‒60 J, respectively. Bonding strength between the cladding layer and substrate was very high. The gas pore and bad bonding often exist in a cladding layer. The selection of cladding process parameters should follow the principles of low power density and high reliability.

In this paper， we propose a metamaterial terahertz broadband bandpass filter based on dual metallic rings and the filter provides feasible solution for the insertion loss and bandwidth problems of a terahertz filter. A theoretical model of the dual metallic rings metamaterial can be constructed using a frequency-domain finite-difference method. By changing the distance between the two rings， the radii of two rings， and the thickness of the polyimide substrate， we can determine the geometric parameters of a broadband and high-transmittance terahertz filter. The results show that the filter can achieve a passband bandwidth of 0.54 THz at 0.1?1.2 THz and that the terahertz-wave transmittance in the passband can be as high as 93%， effectively improving the overall performance of the terahertz broadband filter.

Cubesat has the advantages of low launch cost， short cycle， small size， and low power requirement. It is highly suitable for the first verification of certain innovative technologies， satellite-borne integrations， or distributed space networks to provide remote sensing and communication services， such as constellations and flight formations. Herein， an optical camera system suitable for 3U cubic star platforms is designed. First， based on a comparison and analysis of different optical system structures， the proposed system uses a coaxial reflex structure. The focal length， field of view angle， and working waveband of the system are 460 mm， 4°， and 450-700 nm， respectively. Then， by analyzing the transfer function of the system， the corresponding relation between the system aperture and blocking ratio is obtained. The aperture and F number are determined to be 92 mm and 5， respectively. Finally， the system is optimized. The system uses the cassette system as the prototype， and the primary and secondary mirrors are Mankin mirrors. After optimization， the image quality of each field of view is close to the diffraction limit and the transfer function at the Nyquist frequency is greater than 0.3.

Aiming at the problem of high cross polarization level of traditional rectangular waveguide narrow edge inclined slot antenna， a rhombic slot antenna at ridge edge of single ridge waveguide with high radiation efficiency is designed in this paper. The effects of the ratio of waveguide narrow side to the wide side， the ratio of ridge depth to the waveguide narrow side， the ratio of ridge edge width to waveguide wide side， and the width side of the waveguide on the slot resonance are studied by the method of theoretical analysis and electromagnetic simulation. The results show that when the ratio of the narrow side to the wide side of the waveguide and the ratio of the ridge depth to the narrow side of the waveguide changes， the resonant cutting depth change in the opposite direction， and the resonance conductance change in the same direction； when the ratio of the wide side of the waveguide changes， the resonant cutting depth and the resonant conductance change in the opposite direction； when the ratio of the ridge edge width to the wide side of the waveguide changes， the resonant cutting depth and the resonant conductance change in the same direction. According to the influence law of waveguide geometric parameters on slot resonance， the optimal waveguide geometric parameters are selected， and a 16 element single ridge waveguide ridge edge slot array is designed. The slot is arranged in rhombic shape to reduce the cross polarization level. The gain is 18.02 dB， the side lobe level is lower than -19.64 dB， and the cross polarization level is lower than -46.51 dB. Compared with the traditional rectangular waveguide narrow edge slot antenna， the antenna has the advantages of light weight， low cross polarization level.

A terahertz biosensor based on Fano resonance is proposed. The sensor is composed of a graphene microdisk trimer structure. The finite element method is applied to investigate the transmission characteristics of the structure. Simulation results exhibit that the graphene trimer structure can excite Fano resonance. The structure yields a high sensitivity of 2 THz/RIU and a figure of merit （FOM） of 8 in the THz spectrum； the graphene chemical potential can be used to adjust the resonance peak. The band realizes the active regulation of the resonance peak. This structure provides a design idea for the ultra-sensitive terahertz sensor based on metamaterials， and has potential application value in the sensing and detection of materials with micro-nano thickness.

Pepsinogen I in human serum is a common biomarker for diagnosing gastroesophageal reflux in clinical medicine. Traditional detection methods for pepsinogen I have the disadvantages of being time-consuming and having high cost and low sensitivity. In this study， a fluorescence detection system for the rapid and quantitative measurement of pepsinogen I is designed. First， a portable microscope is used to take a fluorescence image of the samples， and then the R channel image-processing algorithm of the RGB color mode is used to detect and analyze the images. Finally， according to experimental data， a standard curve is fitted with a fitting degree of 99.556%， and the variation coefficient of the test results is <4.9%. The experimental results show that the designed detection system can accurately and rapidly quantify pepsinogen I concentration.

Quantum fidelity is one of the most important evaluation parameters in quantum teleportation protocols and can be used to evaluate the similarity between the initial state and the output state. Here， we propose one method to improve the teleportation fidelity in channels with Pauli noise based on a partial memory channel. According to the different parameters of Pauli noise， the average fidelity under three cases of bit-flip noise， xz dephasing noise， and two-Pauli noise is analyzed in detail. We construct the quantum logic circuit of a quantum teleportation scheme and analyze the relationship between quantum fidelity and noise parameters. In addition， as for the teleportation process under the effect of noise， the partial memory channel is introduced and the parameters of the partial memory channel are analyzed. The results show that the partial memory channel can effectively enhance the quantum teleportation fidelity under the influence of Pauli noise.

Quantum satellite communications in free space are susceptible to interference from ionosphere， space plasma and ice crystal particles. These factors can interfere with the normal communications of quantum satellites. In order to improve the anti-interference ability of quantum satellite links， this paper first proposes an optimization strategy based on quantum entanglement feedback control （QEFC）. In QEFC， the leaked photons in the cavity are measured and the information obtained by measure is used to estimate the states of atoms. Further the controller is adjusted to change the spin of atoms in the cavity. The relationship of different environmental factors with fidelity and bit error rate is established. Moreover，the system performance parameters before and after the adoption of QEFC are compared. Finally， the performance simulation is performed. The results show that QEFC can improve the fidelity of quantum satellite communication system under natural environmental interference in the amplitude damping channels and depolarization channels. In the space plasma environment， QEFC can reduce the bit error rate from 13.7×10-3 to 9.4×10-3 when the plasma particle radius is 10 μm and the transmission distance is 200 km. It follows that QEFC can effectively improve the link performance of quantum satellite communication systems.

In view of the problems of single data features， rough feature recognition ability， and blurred classification interval of lidar measurement technology， a ground object classification method based on compound derivative features and fuzzy Dempster-Shafer（DS）evidence synthesis theory was proposed. First， determine the recognizability of LiDAR data classification features for different types of features， and select source and derivative features with strong correlation and high discrimination in the feature space. Then， we compare the difference of the normalized difference vegetation index with green normalized difference vegetation index to ground reaction properties， and propose and construct a compound derivative feature compound normalized difference vegetation index with high identification ability. Finally， the combination of ridge-type trust allocation function performs fuzzy DS evidence synthesis and decision-making and achieves accurate classification of the ground. The experimental results show that the total classification accuracy is improved from 85.78% to 89.20%， which proves the effectiveness of the proposed method.

Free space laser communication technology has been a research hotspot in the field of satecom and payload technology for a long time， with characteristics such as large band width and high speed. High earth orbit relay satellites are the backbone nodes of data transmission between satellites. With the maturity of laser communication technology， laser communication link has become a reliable technical means for data transmission of high earth orbit relay satellites at home and abroad. This paper introduces the latest development trends of high earth orbit satellite laser relay links at home and abroad and its future development plans， which provides a reference for the construction of space laser information networks in China.

Fast development of photonic integration has promoted researches on grating couplers. Asymmetrical gratings can realize high-efficiency coupling because they break the symmetrical coupling conditions. Slanted gratings， blazed gratings， binary blazed gratings， and others have obtained important development， especially their structural design， manufacturing methods， and test methods have obtained improvement. The working principles and main features for various gratings as couplers between optical fibers and waveguides are introduced. The main types and the main problems and solution methods faced by each type of gratings are systematically analyzed， and some remarkable research results are enumerated. The aim is to help researchers know about the research status and potential development directions， and thus provide some reference for the future related researches.

As a significant micro-optical element， microlens arrays are widely used in optical communication， optical signal processing， wavefront sensing， optical field regulation， data storage， medical diagnosis， and other fields owing to their good imaging performance and miniaturization and lightening advantages. Femtosecond laser processing technology exhibits high controllability， good flexibility， no masking requirement， and high processing accuracy， and it has recently become an important processing method for microlens arrays. Herein， the research progress of femtosecond laser processing methods for microlens arrays， including two-photon polymerization and chemical-etching-assisted ablation， were summarized. Additionally， the application of microlens arrays was introduced， and the problems and development trends pertaining to the femtosecond laser processing method for microlens arrays were analyzed.

An ultra-dense wavelength division multiplexing passive optical network can substantially increase the number of users and transmission capacity because it exhibits a channel spacing of only a few GHz， power budget of up to tens of dB， and other superior performance characteristics. Herein， the recent progress on the ultra-dense wavelength division multiplexing passive optical networks at home and abroad was comprehensively reviewed based on several key research directions， such as the improved spectral efficiency， simplified coherent receivers， photonic integrated device application， and optimized digital signal processing. Moreover， possible research directions and development trends were discussed.

Atmospheric pressure and large volume non-equilibrium plasma technology has played a good role in promoting the development of combustion and laser fields. This article focuses on solving the problem of discharge instability at atmospheric pressure， and introduces the structural characteristics and design of array needle cathode discharge， capillary dielectric barrier discharge， plasma cathode discharge， micro hollow cathode discharge， and micro hollow cathode glow discharge generator. The advantages and disadvantages of different discharge devices has been analyzed， and the challenges facing the improvement of the characteristics of atmospheric pressure and large volume non-equilibrium plasmas in practical applications has been summarized in the article.

As an important laser application in industrial production， laser material removal has many advantages， such as no contact， high efficiency， and high processing accuracy. Herein， two aspects of the single-laser-beam removal material and laser hybrid reduction technology were elaborated. Further， four laser processing technologies of laser drilling， laser cutting， laser ablation， and laser lithography were introduced， and these technologies were compared with other processing technologies. The laser composite technology supplemented by the laser removal of materials and multiple energy fields is also introduced. Aiming at the problem of difficulty in efficiently processing grooves using single-laser-beam removal material technology， an electromagnetic-field-assisted laser groove processing method was introduced.

For a parametric inversion of standard or global rainbow signals， this study proposes a local minima-based general inversion algorithm， establishes a nonlinear optimized objective function with inequality constraints based on the complex angular momentum theory theory with correction coefficients and iteratively solves the function using sequential quadratic programming. Before the inversion， a different signal preprocessing， including the removal of the high-frequency structure and the inversion parameter range estimation， was performed for the standard and global rainbow signal. The rainbow signals of the droplets with different refractive indices and droplet size distributions （logarithmic and normal distributions） were numerically simulated based on the Lorenz-Mie theory. The proposed inversions with or without the size distribution were performed to verify the algorithm's effectiveness. The results show that the maximum absolute error of the refractive index of the standard rainbow signal inversion is less than 3×10-4， and the maximum relative error of the droplet size is 1.3%. Under various conditions， the error of the refractive index of the global rainbow signal inversion is less than 1×10-4， and the relative error of the mean droplet size is less than 1.67%. Finally， the algorithm was verified via the experimental standard and global rainbow data.

In order to study the polarization characteristics of polarized light after multiple scattering through the water body， this paper uses random sampling to fit the phase function of Monte Carlo simulation method to simulate， through model simulation and actual experiments to verify its authenticity. The simulation simulates the polarization state change data of the polarized light with the wavelength of 532 nm through the suspension of polystyrene beads whose particle size satisfies the Gaussian distribution of （600±10） nm. The number of photons in the simulation process is 106. In the experiment， the polarization states of 0° linear polarized light， 45° linear polarized light， left-handed circular polarized light， and right-handed circular polarized light in polystyrene pellet suspension were studied. Both the simulation results and the experimental data show that the degree of polarization decrease of circularly polarized light is at least 20% smaller than that of linearly polarized light. That is， the higher the density of polystyrene pellet suspension particles， the greater the fluctuation in the degree of polarization change，at the same time， the circular polarization is better than the linear polarization in terms of polarization preserving. In the same concentration of water， the polarization state of linearly polarized light with different polarization angles has little difference.

Herein， a polarizing cloud particle probe was developed to further understand the scale spectrum and shape distribution of cloud particles and investigate the microphysical properties of clouds. The probe can receive both forward and backward scattering energies of the particles， control the detection area through the forward quality control channel， and obtain the depolarization ratio of the particles based on the horizontal and vertical channels of backward scattering. The scattering of several types of ellipsoid and hexagon particles in the probe was simulated using the geometrical optics approximation method. Simulation results show that the forward scattering cross-section of the particles is positively related to its equivalent radius. The oblate particles exhibit a stronger forward scattering ability and a smaller backward scattering depolarization ratio than the slim particles. Therefore， the ellipsoid particles show a smaller backward scattering depolarization ratio than the hexagon particles. The simulation data verify the feasibility of the probe for cloud particle detection and provide an inversion basis for detecting the scale spectrum and shape distribution of nonspherical particles.

Today's market contains large quantities of flame-melting synthetic spinel， which cannot be effectively identified by conventional methods alone. To accurately identify natural and flame-melting synthetic spinels， we used Fourier transform infrared spectroscopy， X-ray fluorescence spectroscopy， absorption spectroscopy， and laser Raman spectroscopy to study the molecular structures， chemical compositions， and color mechanisms of the spinel specimens. The full-width-at-half-maximum （FWHM） was obtained by Lorentz fitting of the 405 cm-1 peak in the Raman spectrum and analyzed by one-way ANOVA（analysis of variance）. Although the conventional gemological characteristics of natural spinel and flame-melting synthetic spinel were almost identical， there are significant differences in molecular structures， chemical compositions， color mechanisms， and FWHMs. The results provide a theoretical basis for distinguishing natural spinel from flame-melting synthetic spinel.

In this paper， an F-shape electromagnetically induced transparency structure composed of one vertical indium antimonide （InSb） bar and two horizontal InSb bars is proposed. The electromagnetic properties of the model were calculated using the time-domain finite integration method. The calculation show that the vertical InSb bar functioned as the bright mode resonator in the electromagnetically induced transparency structure， while the two horizontal InSb bars functioned as dark mode resonators. To study the variation in the electromagnetically induced transparency window， we varied the distance between the two horizontal InSb bars and the distance between the vertical InSb bar and the horizontal InSb bars. We found that the electromagnetically induced transparency window changes from on to off. Meanwhile， on varying the temperature of InSb that is highly temperature-sensitive， the center frequency of the electromagnetically induced transparent window moved toward high frequencies to achieve active tuning of terahertz waves. This study has significant application prospects in optical signal processing， optical storage， and slow light devices.

Based on the non-cosine film thickness distribution formula of the small area source in electron beam evaporation， the distribution uniformity of optical thin film thickness of the electron beam evaporation spherical fixture system is studied in this paper. At the same time， the mathematical model is established， the shape and position of the correction mask are corrected by MathCAD programming， so as to control the thickness distribution uniformity of the optical thin film. Set the evaporated Ta2O5 thin films as an example， the position and shape of the correction mask are optimized， and Ta2O5 single-layer thin film with thickness of 600 nm is fabricated. Experimental results show that the actual thickness nonuniformity of the modified baffle optimized by the model is 0.6%， which validates the feasibility and correctness of the model.

In order to analyze the influence of process parameters on the surface polishing results of ultrafast laser polishing hard and brittle optical materials during the polishing process， based on the interaction mechanism of ultrafast laser and hard and brittle dielectric materials， according to the analytical model of the removal function of ultrafast laser polishing dielectric materials， a single-pulse material removal model related to the two processing parameters of defocus and incident angle is established. Using the software and according to the change law of the multi-pulse ablation threshold of dielectric materials， a computational model of ultrafast-laser polishing of hard and brittle optical materials is established， and the results of ultrafast-laser polishing of the material surface under different incident angles and advance lengths are calculated by using the model. This calculation model can directly explain the results of ultrafast laser polishing optical materials， and provide new theoretical guidance for the selection of appropriate laser polishing process parameters and methods.

To solve the problem of the color difference caused by fabric diversity in the digital printing process， an improved regularization extreme learning machine algorithm is proposed to realize quick and flexible conversion from L*a*b* to CMYK color space. First， select the PANTONE textile TCX color card as the sample data of the experiment， randomly select 800 color patches， the L*a*b* values of these color patches are used as input， and the corresponding C， M， Y， and K values are used as output， respectively. The network is trained to establish a nonlinear mapping， and the optimal regularized penalty coefficient is obtained according to the ridge trace graph observation method of the ridge regression model to optimize the model. Then， 100 color patches are randomly selected from the remaining color patches of the TCX color card as the test samples of the model for testing and verification. Experimental results show that the proposed method has high conversion accuracy and efficiency. The minimum conversion color difference is 0.221， the maximum conversion color difference is 6.965， the average conversion color difference is 1.645， and the average training time is 1.489 s， which can meet the actual requirements of digital printing color management.