The aerosol optical depth (AOD), Angstrom exponent (AE), single scattering albedo (SSA), and fine mode fraction (FMF) were extracted through six AERONET long-term observation sites, including Beijing-RADI, Beijing-CAMS, Xuzhou-CUMT, Taihu, Hong~~Kong~~PolyU, and Hong~~Kong~~Sheung locating along the coastline of eastern China, and were processed using the Terra/Aqua MODIS level2 C6 AOD products to study the aerosol variation characteristics and type characteristics of aerosols in eastern China. It is found that 1) the annual average value of AOD decreases from Xuzhou to Taihu, Beijing, and Hong Kong in the order 0.805±0.129、0.775±0.069、0.664±0.197, and 0.519±0.125, respectively; 2) at the AERONET site location, the annual average value of MODIS AOD decreases from Taihu to Xuzhou, Hong Kong, and Beijing in the order 0.902±0.227, 0.772±0.082, 0.547±0.064, and 0.517±0.234 and the ground detection differences are 22.2%, 4.1%, 5.5%, and 16.3%, respectively; 3) the annual average AE value decreases from Hong Kong to Taihu, Xuzhou, and Beijing in the order 1.314±0.054、1.213±0.084、1.198±0.104、and 1.118±0.078, respectively, indicating that the average size of air pollutant particulates in eastern China decreases from north to south; 4) the proportions of weakly absorbable fine particles are 38.29%, 44.99%, 44.30%, and 48.14% in the four regions of Beijing, Xuzhou, Taihu, and Hong Kong, respectively, followed by moderate absorption fine particles and strong scattering fine particles. Other types of particles are found in lower concentrations.

In order to study the application of optical fiber sensors in ultrasonic detection, a diaphragm optical fiber Fabry-Perot (F-P) sensor, including its structure and fabrication method, is proposed. In this study, the influence of the placement distance and angle on the acoustic vibration sensitive shape change of the diaphragm optical fiber F-P sensor is first investigated. The sensing effect of the sensor decreases with an increase in the distance and angle. Then, a method to fabricate the diaphragm optical fiber F-P sensor based on welding, cutting, and polishing is proposed. Finally, the sensing performance of the sensor is experimentally verified. The experimental results show that the frequency detection range of the proposed sensor is 20-80 kHz, and the signal-to-noise ratio is not lower than 25 dB. This sensor is prepared using an all-welded method, which provides it with a more stable structure and longer service life than one prepared using the traditional adhesive connection method. Therefore, the proposed sensor can be used for a wide range of applications, such as partial discharge detection in power grids.

A three-dimensional (3D) positioning and orientating method based on an adaptive parameter and adaptive mutation particle swarm optimization is proposed in this study to solve the 3D positioning and orientating problem in visible light communication. First, a hybrid 3D visible light positioning (VLP) model based on a ranging model in a complex environment is analyzed, and the positioning problem is transformed into an optimization problem of the joint probability density function. Second, an adaptive parameter and adaptive mutation particle swarm optimization method are designed by calculating the fuzzy closeness between the solution of the particle and the optimal solution of the population. Finally, the theoretical lower bound of the positioning and orientating error of the proposed 3D VLP model, called the Cramer-Rao lower bound (CRLB), is accurately analyzed using mathematical methods. The results show that the time complexity of the proposed algorithm is low, and the positioning and orientating errors are close to the CRLB. The average positioning and average orientating convergence errors of the proposed algorithm are 5.99 cm and 6.65°, respectively, which are significantly better than those of four other iterative-based VLP algorithms.

A triangular pulse signal generation scheme with variable symmetry based on a dual-polarization quadrature phase-shift keying (DP-QPSK) modulator is proposed. The triangular pulse signal with a tunable symmetry coefficient can be generated by adjusting the modulation index of two sub modulators of the DP-QPSK modulator and the phase shift of three electrical phase shifters. The tunable range of the symmetry coefficient is 0%-100%, and the repetition rate of the generated triangular pulse signal is twice the frequency of the input driving signal, which shows that a triangular pulse signal with variable symmetry and high repetition rate can be generated using a driving signal with lower frequency. The feasibility of the proposed scheme is verified through a simulation, and the similarity between the pulse waveform generated by the scheme and the ideal waveform is evaluated using the root mean square error (RMSE). The study verifies that, in addition to the triangular pulse signal, the scheme can also generate a square pulse signal.

The temperature field distribution of germanium (Ge) core fiber in the process of CO2 laser annealing with different powers and different scanning speeds was simulated by COMSOL Multiphysics. The suitable laser annealing condition was obtained by analyzing the distribution and change of the temperature field in the laser annealing process. Combined with the Raman spectroscopy measurement of the fiber after laser annealing, the laser power of 2.153 W and scanning speed of 6 mm/s were proper for the Ge core fiber annealing when the outer diameter of the fiber was 190 μm, the inner diameter of the fiber was 28 μm. The simulation of the paper provided a reference for experiments to optimize the properties of Ge core fibers.

It is one of the most important and typical tasks for formation unmanned aerial vehicle (UAV) to round-up target UAV in multi-UAV battlefield operations. This study combines wireless ultraviolet (UV) communication technology with round-up algorithms and proposes a UV unmanned aerial vehicle alliance round-up algorithm collaborative formation. With the help of wireless UV assisted UAV formation, data confidentiality transmission, and nondirect-looking communication, the algorithm integrates alliance generation algorithm with the regional minimization strategy. The dynamic programming method is then used to solve the optimal alliance structure. Meanwhile, the area minimization strategy is employed to implement the target UAV aerial round-up, and the efficient UAV formation round-up multitarget task in complex scenarios is completed. The simulation comparison shows that the proposed UV collaborative formation UAV alliance round-up algorithm reduces both energy consumption by an average of 12.73% in the UAV formation multitarget round-up process and algorithm iterations by 27.49% than the regional minimization strategy. Therefore, this verifies the plausibility of algorithm performance with low energy consumption and high round-up efficiency.

Gaussian mixture model in machine learning estimates the Gaussian distribution parameters of all constellation points according to the received signal. Therefore, a Gaussian mixture model cluster demodulation method is proposed for the nonlinear discrete Fourier transform spread orthogonal frequency division multiplexing system in visible light communications. The Gaussian distribution probability of each received signal constellation point is calculated, and the corresponding constellation point to the maximum probability is selected as the decision result of the received signal for demodulation so that signal-to-noise (SNR) ratio gain can be obtained. The simulation results show that the Gaussian mixture model cluster demodulation method can obtain 0.6 dB-2.7 dB and 0.2 dB-1.7 dB SNR gain for 16 and 32 quadrature amplitude modulation, respectively, in LED nonlinear channel.

Aiming at the power supply problem in medium-distance and strong electromagnetic interference environments such as rocket ignition and wireless sensing, a visible light wireless energy transmission system is designed, which uses visible light to achieve wireless energy supply at a distance of several meters. The optical model of the visible light wireless energy transmission system was established by the optical simulation software, the influence of the axial defocus of the light source and the displacement of the plano-convex lens on the light energy utilization rate, the uniformity of the spot, and the photoelectric conversion efficiency were analyzed, and the experimental parameters of the system were determined, which provides a basis for the realization of higher-power, longer-distance, and higher-efficiency visible light wireless energy transmission and variable-distance transmission automatic devices. Experimental results show that the use of a combination of reflective and condensing lenses greatly reduces beam scattering and effectively improves the energy transmission efficiency of the visible light wireless energy transmission system. The system helps to cover the the meter-level blind area, and provide the power supply at a low cost for the low power devices in some extreme environments where battery replacement is inconvenient and electromagnetic interference is serious.

The combination of an optical cavity and a proportional-integral (PI) controller is commonly used in experimental quantum optical fields. In this study, an optimal PI controller for an optical cavity was designed based on the average-squared value of the error signal. The controller was implemented using a field-programmable gate array (FPGA) data acquisition board and LabVIEW software. The overall gain of the controller is optimized by adopting the cavity transmission as an optical power reference, such that the cavity locking performance does not degrade as the optical power varies.

Micro-irregular components manufactured via rolling, extrusion, and drawing have complex shapes with irregular processing sections. This structural element is widely utilized in devices such as high-end clocks, electronics, and medical appliances. Currently, the geometric dimension measurements of micro-irregular components are realized by using a microscope during the manufacturing process. However, this method is labor intensive with low production efficiency and unstable measurement accuracy. Therefore, a line-structured light based micro-irregular component geometric dimension measurement method is proposed in this study. First, the internal and external parameters as well as the distortion coefficients of the industrial camera are obtained by implementing the calibration method by Zhang Zhengyou, while the line-structured light plane is calibrated using the Steger thinning method and least squares method. Second, a micro-irregular component geometric dimension measurement program is developed using Microsoft Foundation Classes and OpenCV. Finally, the measurement accuracy and repeatability of the method are evaluated by using the standard gauge block and the geometric dimension measurement test of three kinds of micro-irregular component. The results reveal that the overall measurement errors of this method are less than 0.1 mm in both width and height, achieving high measurement accuracy to meet the needs of actual production.

The contact pressure distribution between components and polishing pads during the chemical mechanical polishing (CMP) of optical components is a critical factor that influences the polishing removal efficiency and polishing effect of components. However, it is difficult to obtain through simulations because the contact state between components, abrasives, and polishing pads is complex and changes continuously. In this study, a set of CMP surface-pressure distribution in-situ real-time detection devices is designed, and the thin-film piezoresistive sensors are arranged under the polishing pad in an array to detect the pressure distribution on the contact surface between the component and polishing pad in real time. Moreover, the theoretical model of the contact pressure distribution between the polishing pad and component surface is analyzed using simulations and compared with the experimental measurement results. Based on the experimental platform built independently, grinding experiments are conducted, and the surface shape of the polishing pad is measured using a Keyence CL-3000 laser displacement sensor. The experimental results show that with an increase in grinding time, the shape of the polishing pad surface gradually becomes flat and is close to the limit of the current grinding conditions. Its standard deviation decreases from 0.2079 to 0.1839 mm. The standard deviation of the regional pressure value measured using the pressure distribution detection device decreases by 8.2% and 0.2% in the first and second stages, respectively. The pressure distribution on the contact surface of the workpiece and polishing pad gradually become uniform, which corresponds to the trend of gradual flattening of the polishing pad surface. This study demonstrates that the proposed device can effectively detect pressure distribution and real-time changes during the polishing process.

At present, optical extensometers based on field-of-view splitting (FOV-splitting) technique can only improve the strain measurement accuracy in a single direction, but the measurement accuracy in the perpendicular direction is not high enough, that is, it cannot achieve biaxial high-precision strain measurement at the same time, which limits its application range. Therefore, a biaxial FOV-splitting technique is proposed, which is formed by rotating four identical rhombic prisms, and by combining with the telecentric lens, a biaxial high-precision optical extensometer was developed. The cyclic loading experiment of stainless steel specimen was carried out to verify the superiority of the above optical extensometers over ordinary optical extensometers. In addition, four uniaxial tensile experiments were carried out on stainless steel specimens, and the maximum errors of elastic modulus and Poisson's ratio obtained by the bidirectional optical extensometer and electrical measurement method were 0.62% and 2.86%, and the four average errors were 0.41% and 1.38%, respectively, indicating that this optical extensometer has high strain measurement accuracy.

As power generated using offshore wind turbines continues to increase, maintaining safe operating conditions with respect to the wind turbines becomes increasingly important. The traditional downtime inspection method is costly. This study proposes a novel method for inspecting wind-turbine blades based on thermoelastic stress analysis (TSA) that employs thermal detection of infrared radiation. The necessary condition for TSA is to achieve adiabatic conditions (high-frequency cyclic loadings). However, wind-turbine blades are subjected to cyclic loadings that do not attain high frequencies. To improve the accuracy of the thermal detection of infrared radiation under low-frequency loadings, the classical TSA theory was modified and the correctness of the modified model was verified via fatigue tests. The BLADED wind turbine simulation software was used to analyze the blade thrust, and the thrust force and thrust variation frequency of the blade in the three directions were calculated. The surface temperatures of the wind-turbine blade under low-frequency loadings were analyzed using the modified TSA model. The proposed model can be used to detect stress and damage related to the blade surfaces.

In order to accurately restore the single pulse laser paint removal process, a finite element model for single pulse laser paint removal was established and the temperature field and thermal stress field of laser paint removal were analyzed. The simulation and restoration of the paint layer morphology were realized through the birth and death unit technology, and the comparative verification of different power laser experiments was completed. The results show that the maximum ablation depth is determined by the temperature criterion, and the maximum ablation width is determined by the thermal stress criterion. The average fitting degree between the paint removal morphology obtained by the multi physical field analysis model and the test is 93.3%, which is 6.5% higher than that of traditional single temperature criterion. This research has good guidance and application value for the actual laser paint removal process.

In this study, we experimentally investigate high-power laser beam combining based on dichroic mirrors. Three-channel 4 kW nearly single mode fiber lasers with central wavelengths of 1059, 1075, and 1090 nm are combined to a single beam. The combined power reaches 11.34 kW with a combining efficiency of 95%. Compared with the sub beam, the beam quality of the combined laser shows gradual degradation as the output power increases and the surface temperature of the dichroic mirror rises. When the full power is reached, the beam quality degrades to M2x=2.941 and M2y=3.183 in both directions. The reasons that affect the combining efficiency and beam quality are analyzed. The effect of substrate thickness of the dichroic mirror on the degradation of beam quality is experimentally studied. This provides an important reference for further optimizing the combined beam quality.

In order to study the influence of oxide aperture diameter on the characteristics of 940 nm vertical cavity surface emitting laser (VCSEL), 940 nm VCSELs with varied oxide apertures were fabricated, and then tested for analyzing. The gain of the quantum wells with different candidate barrier materials was simulated by PICS3D software, and InGaAs/AlGaAs was selected because of the higher gain. Moreover, the gain-cavity mode detuning was introduced in the design. On the basis of optimization, 940 nm VCSELs with six oxide apertures were fabricated and their photoelectric output characteristics were tested. The results show that the VCSEL with 4 μm oxide aperture achieves a slope efficiency of 0.93 W/A at room temperature and a maximum power conversion efficiency of 40.1%. For VCSEL with 7 μm oxide aperture, the maximum output power reaches 12.24 mW at room temperature. The VCSEL with 2 μm oxide aperture can operate on the fundamental transverse mode condition with maximum output power of 2.67 mW at room temperature, and maintain the fundamental transverse mode with a side-mode suppression ratio greater than 45 dB at 2 mA continuous injection current, on the working temperature from 10 ℃ to 80 ℃.

Maintenance of aircraft skin with partially faded paint requires multipaint layer laser removal controllability. Based on the response surface analysis method, a mathematical model between laser parameters (spot lap rate, laser power, and number of scans) and the key indicators of controllable paint layer removal (paint layer removal thickness and surface roughness) is established, and the influence of laser multiparameter coupling on key indicators is analyzed. The results show that the influence of laser parameters on paint layer removal thickness is in the order of number of scans,laser power, and spot lap rate, wherein all are positively correlated. Meanwhile, surface roughness decreases with an increase in spot lap rate, increases with an increase in laser power, and has a peak effect with number of scans. Therefore, the response surface model provides a reference for laser controllable paint removal with the thickness accuracy of ±5 μm, providing method guidance and theoretical support for laser controllable aircraft skin paint layer removal.

A thin disk vortex laser end-pumped out-of-focus is presented. When the focus of the convergent pump beam is located in the thin Nd∶YAG disk, the laser operates in the fundamental mode. While the focus is moved out of the thin disk, the laser generates a vortex beam with an order of 1, and the handedness can be changed by finely tuning the tilt angle of the output mirror. A continuous wave output power of 0.57 W and a Q-switched pulse output power of 0.48 W, with the repetition rate of 10 kHz, pulse width of 35.2 ns, single pulse energy of 0.048 mJ, and peak power of 1.37 kW is experimentally demonstrated. This scheme of vortex laser is free of specially designed pump beams and laser resonators, and thus is compact in structure.

This paper proposes the use of double-concave waveguide layers for improving the radiative recombination characteristics of deep-ultraviolet (DUV) laser diodes (LDs). Simulation studies of four waveguide layer structures are performed using the Crosslight software. The results indicate that introducing a double-concave lower-waveguide layer improves the effective barrier height of the holes, effectively suppresses the leakage of holes from the multiple-quantum-well (MQW) region, and increases the concentration of carriers in the MQW region. The optimized structure enhances the radiative recombination rate and exhibits improved P-I characteristics and optical confinement factor, providing an effective solution for enhancing the performance of DUV LDs.

In this study, the frequency of the external cavity diode laser (ECDL) is locked to the hyperfine transition of 87Rb D2 line 52S1/2, F=2→52P3/2, F=3 using modulation transfer spectroscopy (MTS) frequency stabilization. The laser linewidth is narrowed from 382.18 kHz in the free-running mode to 37.94 kHz after frequency stabilization. The narrow linewidth laser after frequency stabilization can be utilized as the probe light for the integrating sphere cold atom clock. Thus, the contribution of the laser frequency noise to the short-term instability of the atomic clock could be smaller than 5.6×10-14 τ-1/2.

The research work of LD pumped Tm∶YAP laser is reported. Tm∶YAP laser is end pumped by LD with wavelength of 793 nm, and acoustooptic Q-switched operation in the cavity. When the laser repetition frequency is 300 Hz and the input pump power is 37.07 W, a 1936 nm laser output with a maximum single pulse energy of 17.06 mJ and a pulse width of 26.9 ns is obtained, and the corresponding peak power is 634.2 kW, which is higher than the reported peak power values of this crystal. At the maximum input pump power, the beam quality factors for horizontal and vertical directions were 1.41 and 1.34, respectively. In addition, under the continuous operation of the laser, a double Fabry-Perot etalon is used to adjust the laser wavelength, and the spectral tuning range is 1932.11-1942.07 nm.

In the industrial field, babbitt alloys prepared by casting often have defects. In order to reduce the defects in microstructure and properties of babbitt alloy, the microstructure and properties of Babbitt layer prepared on 20 steel substrate by traditional casting and cold metal transfer (CMT) surfacing are compared. In addition, laser remelting (LR) experiments were conducted on the Babbitt layer surface. The microstructure of casting, surfacing, and remelting Babbitt layers were, respectively, measured by metallographic microscope, scanning electron microscope, and energy dispersive spectrometer, while hardness was tested for all three using the Vickers hardness (HV). The results show that the CMT surfacing layer microstructure is finer than that of casting layers and metallurgical bonding with steel substrate is stronger. Meanwhile, LR can refine grain to eliminate coarse microstructure without segregation and porosity. Different laser powers have different effects on the microstructure and properties of Babbitt metal. At laser powers of 300 W and 500 W the hardness of remelting Babbitt layer surfacing and casting samples reach the maximum of 35.16 HV0.025 and 36.92 HV0.025,respectively. This means that the LR effect on Babbitt metal microstructure and properties has great engineering application value and development prospect for plain bearing research.

Semiconductor lasers are widely used for laser scanning; however, beam shaping is required because of the significant difference in their fast and slow axis divergence angles. In this study, a design scheme of the integrated lens array beam shaping system is proposed to improve the beam uniformity of the laser diode array and satisfy the miniaturization requirements of the small scanning imaging system. An integrated aspheric lens is used to shape the Gaussian beam. The fast axis is collimated, the slow axis is expanded, and a linear beam with a high aspect ratio and a uniform light intensity distribution can be obtained. Theoretically, the principle of collimation beam expansion of the integrated aspheric lens array is analyzed. The initial structural parameters of the system are determined according to Fermat principle. The system is simulated and optimized using optical design software, and a linear beam with a fast axis divergence angle of 2.8 mrad, slow axis divergence angle of 48.93° (aspect ratio of 325), energy utilization rate of 88.79%, and energy uniformity of 94.51% is obtained. The results show that the shaping effect of the proposed method is ideal. The proposed system has a simple structure and a small size, which is consistent with the development trend of miniaturization of beam shaping systems in the future.

The preparation of block glass with characteristics such as strong white emission photoluminescence, high stability, and low toxicity is of great significance to the progress of LED display technology. In this study, we prepared Al2O3-xSiO2 block xerogels of different components using the sol-gel method. During sintering at about 500 ℃, the glass exhibits a strong white visible photoluminescence wide peak due to the radical carbonyl-terminations defects from the pore surface, and the luminous intensity is obviously related with the concentration and luminous intensity of radical defects.

The structure, electronic and optical properties of inorganic perovskite materials CsBI3 (B= Pb, Sn, Ge) are analyzed based on the first principle by Siesta software. First, a stable material structure is obtained using the GGA-PBE and GGA-PBEsol methods. Then, the bandgap of the material is analyzed based on two density functional methods GGA-PBE and GGA-BLYP. This work simulates the material strain by changing the lattice constant of the material, showing that the bandgap increases with an increase in the lattice constant. Moreover, doping with Ge can decrease the bandgap of supercell CsPbI3. When doped with low-concentration Ge, the band gap of the material was found to reduce by 0.7% to 3.8%. Finally, from the absorption spectrum, it can be seen that the absorption coefficients of CsPbI3 and CsGeI3 are close to 6×105 cm-1, and the absorption peak of CsPbI3 is approximately 350 nm and that of CsGeI3 is approximately 410 nm. However, the absorption coefficient of CsSnI3 is close to 4.75×105 cm-1, and the absorption peak is approximately 350 nm.

Frozen-slurry-based laminated object manufacturing has potential for use in the field of 3D printing for porous ceramics. To study the laser cutting process of frozen ceramic slurry, the heat conduction mathematical model of a CO2 laser plane thermal source is established. COMSOL finite element simulation software is used to simulate the laser scan heating process. Considering pure ice as the ideal material, the mathematical model of the laser cutting depth is established by combining the experimental research. The results show that the laser cutting process of frozen ceramic slurry is similar to that of traditional non-metallic materials, and the depth of the "V"-shaped gasification cutting zone increases with the increase in the laser energy density. Because of the heat absorption and scattering of ceramic particles, a heat affected transition zone exists below the cutting area of frozen ceramic slurry. The actual cutting depth is different from the theoretical cutting depth of pure ice. If correction coefficients related to the material characteristics are introduced into the theoretical model, it can more effectively satisfy the actual laser cutting law. The results of this study can be used as a reference for parameter selection in the laser cutting process of frozen ceramic slurry.

This paper describes a terahertz metasurface biosensor with a graphene and metallic aluminum composite structure. The aluminum structure is designed to form an electromagnetically induced transparency-like resonance. A layer of wet graphene is transferred onto the structure. The Fermi energy level of the graphene is controlled by the incorporation of silk proteins into the graphene, which causes the amplitude of the sensor's transmission spectrum to change. The experiment reveals that the detection limit is 0.35 ng/mL. The sensor is analyzed using the electromagnetic wave regulation characteristics of the Dirac point of graphene, as well as the coupling model. This biosensor enables the highly sensitive detection of trace proteins in the biomedical field.

In this study, the propagation and control of Airy-Gaussian beams in Gaussian parity-time (PT) symmetric media are investigated numerically, by utilizing the nonlinear Schrödinger equation as a theoretical model. The impacts of the characteristic parameters of Gaussian PT symmetric media (modulation depth P, modulation factor ω, and gain/loss factor W0) and the characteristic parameters of Airy-Gaussian beams (truncation factor a, distribution factor χ0) on propagation characteristics of Airy-Gaussian beams are examined in detail. The results demonstrate that the Airy-Gaussian beams can produce oscillating solitons and transmit steadily in Gaussian PT symmetric media. The soliton strength increases with the increase of P, W0, and a, and decreases with the increase of ω. The oscillation period decreases with the increase of P and ω and increases with the increase of W0. When χ0 increases, when 0<χ0<0.55, the peak intensity of the soliton does not change obviously; when χ0>0.55, the peak intensity of the soliton decreases rapidly. This research can offer a theoretical foundation for the use of soliton transmission in complicated heterogeneous media and all-optical control.

To improve the brightness of semiconductor lasers as the pump sources of fiber lasers and solid lasers, based on the technologies such as beam collimation, spatial beam synthesis, synthesis of polarized light, and optical fiber coupling, a compact beam shaping system that uniforms beam quality of fast and slow axes of semiconductor lasers is proposed. Using similar stepped prisms and two 30° rectangular prisms to fill the dark region in fast axis direction and a polarization beam combiner to compress the slow axis beam width, a compact and high brightness fiber coupling system is designed. The system is composed of eight mini-bars, which are coupled into an optical fiber with a core diameter of 100 μm and a numerical aperture of 0.22. The output power is 272.4 W, the optical conversion efficiency is 85.1%, and the maximum brightness is 22.832 MW/(cm2·sr).

A comfortable and healthy lighting environment can improve people's work efficiency, and can avoid physical damages caused by an uncomfortable lighting environment. However, most offices still face problems with lighting-related energy saving and comfort. To resolve these problems, this study proposes a lighting control system that takes sunlight and occupancy as input and the dimming coefficient K (0≤K≤1) of lamps as output. The system establishes a linear mathematical model among sunlight, occupancy, the illuminance component of adjacent lamps, and the dimming coefficient through an algorithm and uses the Matlab least squares method to obtain the optimal dimming coefficient of each lamp. The lighting design software DIAlux was used to investigate the lighting environment under the control system. The results show that under the control of the system, the illuminance of the occupied and unoccupied working surfaces reaches 500 and 300 lx, respectively, and the uniformity of illuminance is greater than 0.7. Therefore, the control system solves the problem of low uniformity of illuminance in the daytime. In terms of satisfying the office lighting needs, the energy-saving efficiency of the control system in the daytime and nighttime reaches 66% and 14%, respectively.

To solve the problem of low segmentation accuracy of metal workpiece surface defects, we propose a workpiece surface defect segmentation model based on a U-net network combined with a multi-scale adaptive-pattern feature extraction and bottleneck attention module. First, we embed a multi-feature attention aggregation module in the network to improve the utilization of information and extract more relevant features, so as to extract defect targets with high accuracy. Then, the bottleneck attention modules are introduced into the network to increase the weight of defect targets, optimize the extraction of features, and obtain more feature information, thus obtaining better segmentation accuracy. The improved network mean pixel accuracy reaches 0.8749, which is 2.92% higher than the original network. The mean intersection over union reaches 0.8625, an increase of 3.72%. Compared to the original network, the improved network has better segmentation accuracy and segmentation results.

The step superlattice (SSL) electron blocking layer (EBL) and wedge-shaped (WS) hole blocking layer (HBL) are proposed to improve the carrier injection efficiency, and optimize the performance of the deep ultraviolet laser diodes (DUV LDs). The Crosslight software is used to simulate the DUV LDs with rectangular EBL and HBL, rectangular superlattice (RSL) EBL and tower-shaped (TS) HBL, and SSL EBL and WS HBL, respectively. The simulation results indicate that SSL EBL and WS HBL increase the carrier injection in the quantum wells (QWs), reduce the carrier leakage in the non-active regions, increase radiation recombination rate, reduce the threshold voltage and threshold current, and increase the output power and the electro-optical conversion efficiency of DUV LDs more effectively.

Ultra-high quality factor optical microcavities are key components for constructing various integrated photonic devices. Hybrid microcavities based on the photonic crystal microcavities provide a novel platform for realizing a strong light-matter interaction that possesses extensive application prospects in many fields, including cavity quantum electrodynamics, integrated single photon sources, and quantum computing. In this paper, we theoretically propose a novel photonic-plasmonic hybrid microcavity functioning in the visible light band based on the basic double heterostructure photonic crystal cavity with a gold bowtie plasmonic nanoantenna. Here, the structural parameters of the bowtie plasmonic nanostructures (i.e., gap, angle, length, thickness, and relative position) were adjusted to investigate the regulation effects on the quality factor Q, effective mode volume V, and figure of merit Q/V of the cavity using a three-dimensional finite-difference time-domain method. The simulation results reveal that the effective mode volume and the figure of merit of the hybrid microcavity are stable on the order of 10-6 (λ/n)3 and 108 (λ/n)-3, respectively. Moreover, we achieved the highest Q/V value of 5.730689×108 (λ/n)-3, depicting a value much better than that of other microcavities.

LED array light sources are widely used in medicine, micro-nano processing, optical imaging, and other fields due to their high brightness, long life, energy savings, and environmental protection. However, their homogenization system has issues such as difficult light collimation and small achievable illumination spot area, making them difficult to be widely used in the optical field that requires uniform illumination. To address this issue, this paper proposes a microlens array based large-area LED array light source homogenization method. First, the theoretical analysis is performed by matrix optics and near-axis optics theory, and then the system design and simulation experiments are conducted by using light tools software. Finally, a large-area of the uniform spot is achieved on the image surface.Compared with the previous homogenization system, which can achieve up to 50 mm×50 mm, the homogenization system can achieve a uniform spot of 104 mm×104 mm, and uniformity of 87.375% of the large-area rule. This method is of great significance systems that require large-area uniform illumination in the fields of medicine, infrared night vision, projection display, and aerial lighting.

With the rapid advancement of laser technology, ultrafast optics has become a very important frontier area in modern physics research. High-harmonic generation, a primary technique for generating ultrashort laser pulses, has progressed rapidly in the past decade. In this paper, the conservation of spin angular momentum and orbital angular momentum, the spin-orbit interaction, and other novel physical phenomena in the high-harmonic generation in the gas medium, are reviewed. In addition, gaps and challenges in existing research are summarized. The application of structured light field in high-harmonic generation significantly enhances investigations of light-matter interaction and creates new opportunities in light manipulation and strong-field physics fields.

In order to combine several segmented sub apertures into an equivalent large-aperture telescope according to the design goal, each sub aperture must be in optical co-phasing. In this paper, a co-phasing method based on a pyramid sensor is proposed. The sinusoidal relationship between the sensor signal and piston error is fitted through experimental calibration, and the piston error is inversely calculated. The experimental results show that the measured piston errors essentially conform to the linear relationship of the real values, the root mean square error is approximately 19.2 nm after fitting, and the measured value can objectively and accurately reflect the actual piston error. Based on this, the near co-phasing correction of a seven-aperture splicing mirror is conducted, and the resolution is improved by nearly six times after correction. Compared to traditional methods, the proposed method has the advantages of a simple structure, fast response speed, and high light energy utilization.

A novel colorimetric glucose biosensor based on graphene oxide (GO)-gold nanoparticles (AuNPs)-glucose oxidase (GOD) is fabricated using chemical cross-linking and electrostatic methods. GOD catalyzes the glucose oxidation to produce H2O2, which in turn shifts the local surface plasmon resonance (LSPR) band of GO-AuNPs to achieve glucose detection. GO improves the stability of composite particles, reduces metal particle biotoxicity, and enhances sensor response. The microstructure and optical properties of the composite particles are characterized using transmission electron microscope (TEM), Raman spectroscopy, and UV-Vis spectrophotometer. The optimal detection conditions of the sensor are systematically investigated, and the sensor exhibited high sensitivity and selectivity for tested glucose mass concentrations. The sensitivity of the sensor is 14 nm/(mg/mL) in the range of 0-1.6 mg/mL, which suggests that this sensor can be used for glucose detection in clinical settings. Our sensor combines the advantages of GO and AuNPs, and holds potential for simple, stable, and cost-effective use for glucose detection.

High-power narrow-linewidth continuous-wave fiber lasers have a wide range of application values in scientific research, industrial processing, and military defense. On the premise of ensuring the output quality, continuously improving the output power is one of the key goals of high-power lasers. This research focuses on the suppression of the stimulated Brillouin scattering effect, which is one of the key factors restricting the laser power improvement. Various methods of nonlinear effect suppression and the corresponding performances are introduced, especially the spectral broadening method. In addition, the current problems and the development prospects of this technology are analyzed.

With the rising and research deepening of new technologies such as laser radar, gravitational wave detection, and optical atomic clock, The breadth and depth of applications covered by optical precision measurement are expanding, the stability of the traditional free operation of the laser is difficult to meet the application requirements, ultra-narrow linewidth, low noise, and long-term stability of light source has become the urgent goal in this field. Fiber laser has the characteristics of compact structure, easy integration, and narrow limit line width. Through noise suppression and frequency stabilization technology, fiber laser can output ultra-high stability and ultra-narrow linewidth laser. In recent years, ultra-narrow line width fiber laser has gradually become a hot research direction. In this paper, starting from the theory of noise of fiber laser, the noise source, classification, and testing method of fiber laser are introduced, based on the theory of noise, the principle of different intensity and frequency noise suppression technology, development course, and the current progress of fiber laser are summarized, respectively, and the development tendency of narrow linewidth fiber laser is discussed.

As a core component of the acquisition tracking and pointing (ATP) system, the fast steering mirror (FSM) is widely used in satellite laser communication, laser weapons, adaptive optics imaging, high-precision laser aiming, and other applications because of its fast response, high accuracy, and high resolution. This paper presents the working principles of the FSM and ATP system. Various FSM devices of global research institutions are reviewed based on several parameters, such as driving mode, FSM figure, working bandwidth, range of scan angle, control precision, volume, weight, power consumption, and applications in satellite laser communication. Three main classes of FSMs [the voice coil motor, piezoelectric ceramics, and micro-electro-mechanical system (MEMS)] are elaborated. The operating mode and performance difference of FSMs with different driving structures are described, and the critical parameters for applying FSM in the ATP system are analyzed. The key technologies of FSM in laser communication are prospected. It is concluded that high precision, digitalization, and miniaturization are the future trends of FSM.

Lead selenide colloidal quantum dots (PbSe QDs) have huge application prospects in room temperature infrared optoelectronic devices due to their excellent properties such as enhanced multiple exciton generation, large exciton Bohr radius, wide range of the tunable wavelength, and high photoluminescence quantum yield. However, the problems of poor photoluminescence stability and low efficiency of PbSe QDs synthesized via the solution method further limit their development owing to the oxidation of quantum dot surfaces and poor carrier transport performance. Therefore, a systematic discussion of the effects of the surface modification engineering of PbSe QDs on its mobility, trap states, energy level shift, photoluminescence efficiency, and stability modification is presented in this paper. Additionally, a summary of the application of surface modification engineering in PbSe QDs solar cells, light-emitting diodes, and photodetectors is provided. Finally, the problems existing in the practical application of optoelectronic devices and future research directions are outlined.

Quantum precision measurements are crucial for basic research and original innovations. As a vital research topic, the interaction between a laser and thermal-alkali atomic ensemble is significant for the frontier investigations of physics and technical applications, being one of the frontiers of scientific research. Notably, studies and applications based on laser-atom interactions have facilitated breakthroughs in the principles and technologies for ultrahigh precision and miniaturization of an array of precision measurement sensors represented by spin exchange relaxation-free (SERF) atomic magnetometers, coherent population trapping (CPT) atomic clocks, and SERF atomic spin gyroscopes. This review analyzes the achievements and progress in the magnetic field, time, and inertial measurements in recent ten years, and these are summarized from the perspective of the principle and application of the interaction between a laser and thermal-alkali atomic ensemble. Furthermore, prospects for the future development of devices based on the interaction between a laser and thermal-alkali atomic ensemble are discussed.

Inverted perovskite solar cells (PSCs) have been attracted more and more attention thanks to its simple architecture, negligible hysteresis, and low manufacturing cost. Electron transport layer is an important component of perovskite solar cells, which is facilitate with electrons transfer and blocks holes. The modification of electron transport layer can effectively improve the roughness for surface, energy level, and electron mobility, so as to improve the photoelectric conversion efficiency. In this paper, the influence of ETL on the performance of inverted perovskite solar cells is reviewed from the selection of electron transport layer materials, interface modification and doping of electron transport layer and the modification, and the commercialization of inverted perovskite solar cells in the future is prospected.

Laser lithotripsy is one of the many fields in which laser has been used since its inception. The thulium-doped lithotripsy fiber laser has evolved in recent years and has gradually been proven to achieve faster lithotripsy rates with powdered lithotripsy, generate less lithotripsy counter-thrust, allow higher liquid irrigation rates, and other surgical advantages, while the whole system supports water-free operation, high electro-optical efficiency operation, efficient all-fiber coupling, and substantial volume reduction. Therefore the thulium-doped lithotripsy fiber laser has attracted increasing interest. In this paper, some important research progresses of thulium-doped fiber lasers are summarized in detail from three aspects: continuous-wave, quasi-continuous-wave, and nanosecond short-pulsed thulium-doped fiber lasers, and the applications in the field of lithotripsy are introduced. We present the advantages and principles of thulium-doped fiber laser for lithotripsy and look forward to the directions and challenges for future research.

Dye-sensitized solar cells (DSSC) are one of the ways to effectively utilize solar energy because of their characteristics of simple preparation process and low cost. The composition, structure and working principle of dye-sensitized solar cells are briefly introduced. The TiO2 photoanode material, as an important part of dye-sensitized solar cells, is introduced in detail. The current research results of TiO2 electrode are summarized, and the influence of TiO2 photoanode material modification on DSSC performance is analyzed. At the same time, the future development direction of TiO2 photoanode is prospected.

Petroleum oil products can produce three-dimensional fluorescence spectra with considerable intensity under certain excitation light, allowing the identification and analysis of petroleum pollutants. Because of the complex characteristics and huge data of the fluorescence spectrum of petroleum oil products, it is not easy to be described with a simple mathematical model, nor to rely on artificial observation and analysis. This paper presents a convolutional neural network (CNN) model constructed using raw fluorescence data of three petroleum products (gasoline, oil, diesel), which automatically learns features from training data and classifies petroleum pollutants in water, using its nonlinear computing ability and adaptive representation learning ability. Through various fluorescence spectrum experiments, training and validation spectral datasets of petroleum products are constructed, and the CNN model is established based on the deep learning framework Keras for Python. The CNN model is trained, validated, and tested on the spectral dataset, to classify and discriminate measured oil products. The experimental results show that the classification accuracy of the CNN fluorescence model on the training and validation sets of the three petroleum products is 99.76%, the classification accuracy in a comprehensive test is 82.65%, and the classification accuracy for a single substance is 100%. Additionally, the experimental results confirm the feasibility of combing three-dimensional fluorescence technology with a deep learning algorithm, to distinguish and classify petroleum products accurately and reliably. These results provide technical guidance for further research on creating intelligent identification models for environmental pollutants in water, as well as a new direction for environmental detection methods.

To investigate the differences of spectral features among typical features and to address the complicated preprocessing and low accuracy of traditional spectral classification methods, this study considers four features: soybean, corn, rice, and bare soil, as examples, comprehensively investigates the importance of variables in classification, and conducts a comparative analysis and validation of deep learning and traditional methods. First, we use the continuous projection algorithm (SPA) for the baseband screening and compare and analyze the classification accuracy of two deep learning models: the one-dimensional convolutional neural network (1DCNN) and the long short-term memory artificial neural network (LSTM), under the conditions of the original spectrum, the feature band, and the partial feature band, to evaluate the information-carrying capacity of the feature band to the original spectrum. Then, for the misclassification problem, we use the progressive band-screening method to train the misclassified samples again with a combination of basic variables until the classification accuracy does not increase significantly, and analyze the spectral characteristics and misclassification behavior of the misclassified samples. Finally, we compare the classification accuracy of different methods. The results show that the basic band screening can eliminate a large amount of redundant information in the spectral data, simplify the network structure, and improve the model efficiency. The advanced band-screening method can incrementally add effective spectral information for misclassified samples, which helps improve the classification accuracy of traditional methods. The deep learning method can also achieve high classification accuracy without preprocessing steps such as spectral transformation, which is significantly better than the traditional method. However, its training process is more complicated and less interpretable than that of the traditional method.

As the beginning of the plant life process, seed germination directly affects the final crop yield. Low-temperature frequently inhibit seed germination, posing a serious threat to food production safety. The effects of low-temperature on the germination of grain seeds (quinoa, highland barley, rice, and wheat) were investigated in this paper using Fourier transform infrared spectroscopy combined with curve-fitting. The results showed that the germination potential, germination rate, and germination index of the four grain seeds decreased as the temperature decreased, but the germination rate and germination index of highland barley seeds remained high at 4 ℃, indicating that highland barley seeds had stronger low-temperature tolerance. The results of infrared spectrum demonstrated that the original infrared spectra of grain seeds under low-temperature were similar, mainly composed of the characteristic absorption peaks of polysaccharide, fat, and protein. Under low-temperature stress, the curve fitting analysis for polysaccharide (1200-950 cm-1) and amide Ⅰ band (1700-1600 cm-1) in quinoa seeds revealed that polysaccharide content increased while protein content decreased. The polysaccharide and protein content of highland barley seeds increased at first, then decreased. The content of polysaccharide in rice seed decreased, while the content of protein increased. The polysaccharide content of wheat seeds increased first and then decreased, while the protein content decreased first and then increased. Furthermore, under low-temperature stress, different proportions of protein secondary structures in quinoa, highland barley, rice, and wheat seeds changed from disorder to order. As a result, Fourier transforms infrared spectroscopy combined with curve fitting is an efficient method for investigating the effect of low-temperature stress on seed germination.