Using the observations made by the hyperspectral infrared atmospheric sounder (HIRAS) carried on the FY-3E polar orbiting meteorological satellite, the back propagation neural network (BPNN) method is employed to conduct research on the inversion of atmospheric temperature and relative humidity vertical profiles in the East China region. An atmospheric temperature and humidity inversion model is constructed, and the parameters are optimized to obtain a network model configuration with high inversion accuracy, resulting in all-weather, high-precision atmospheric temperature and relative humidity profile. According to the results, the following conclusions can be drawn. 1) Temperature inversion results of the model have a mean error (ME) between -1.00 K and 1.00 K at each pressure layer, except that the absolute value of ME in the lower layer of the cloudy sky is greater than 1.00 K. The validation experiment conducts on ERA5 data has root mean square error (RMSE) between 0 K and 2.00 K for most pressure layers, except for ~2.50 K at the 925?950 hPa layer, the minimum RMSE corresponds to the 200?500 hPa, indicating higher temperature inversion accuracy in the upper atmosphere. 2) For the inversion of atmospheric relative humidity, the ME of the lower and upper atmosphere is larger, whereas that of the middle atmosphere is smaller; RMSE is larger in the middle layers and smaller in the lower and upper layers. 3) Compared to clear sky condition, the accuracy of temperature and relative humidity inversion models under cloudy sky condition is slightly lower. 4) The deviation of the temperature and relative humidity inversion results from the sounding data is slightly greater than the deviation from the ERA5 data although the trend of error with height variation is similar. The HIRAS data generally performs well in inverting the temperature and relative humidity of clear and cloudy skies, with high inversion accuracy. Therefore, this study has important reference value for inversion methods and techniques of atmospheric temperature and relative humidity, providing useful insights for future related research.

Gallium oxide (Ga2O3) materials possess excellent optoelectronic properties in the ultraviolet region and are widely used in blind detection. In this study, a metal-semiconductor-metal geometric model commonly used in Ga2O3 detectors is constructed based on the Monte Carlo method using the Geant4 software. The effects of Ga2O3 thickness and other parameters on the detection efficiency are analyzed. Based on the simulation results, a Ga2O3 ultraviolet detector prototype is designed, and experimental verification is conducted subsequently. The designed detector has a responsivity of 4.545 mA/W at zero bias voltage under 254 nm ultraviolet light with an intensity of 110 μW/cm2, and a detection rate of 2.54×1012 cm·Hz1/2/W. These results indicate that the detector can effectively detect weak ultraviolet signals.

To obtain high-quality plane waves, an diaphragm is designed to reduce the stray light caused by reflection or scattering from the tube wall of the collimator. First, a transmission model is established for the collimator, and the spots are simulated at different positions. Second, the diaphragm is simulated to analyze the influence of diaphragm thickness and cone angle on the stray light, thereby determining the appropriate parameters. Finally, the diaphragm is placed inside the collimator, and the light spot is compared with no diaphragm installed. Results indicate that without the diaphragm there is significant stray light, which overlaps the parallel light at a distance of 400 mm. After installing the diaphragm, stray light is not observed around the parallel beam, and a high-quality plane wave is obtained at 200 mm. Results indicate that stray light is effectively suppressed using the designed diaphragm. This study provides a reference scheme for suppressing stray light of the collimator during the calibration of Hartmann detectors.

In this study, the simulation analysis and optimization of stray radiation in deep cryogenic Dewar components were conducted using a multiwave common optical path Dewar infrared system. The thermal radiation effects on the detector from key surfaces at different temperatures were analyzed using temperature field and dichroic surface simulations. Suitable cold transmission materials were selected, and Kovar was used for the cold platform, cold screen, and dichroic holder of the Dewar system. The effects of different blade levels and surface treatments of the cold screen on the point source transmittance were also evaluated. Based on these findings, the following optimization scheme was proposed: an elevated cold screen to block most of the radiation emitted or reflected by the window cap, adopting two levels of blades for the cold screen, and spraying graphene on the inner surface of the cold screen to improve the suppression of stray radiation. This scheme provides both theoretical and practical value for the design and application of low-temperature Dewar modules.

Solar-blind deep ultraviolet photodetectors demonstrate exceptional thermal stability and reliability, have been widely applied in areas such as ozone hole monitoring, flame detection, and space communications. However, the absorption rate of conventional solar-blind photodetectors is limited by material absorption, posing challenges for further improvement. This paper introduces a multilayer solar-blind photodetector structure that integrates a metasurface, a gallium oxide layer, a silicon oxide insulating layer, and a metal layer. Numerical simulations of its absorption performance reveal that by incorporating the metasurface structure, the structure achieves an absorption rate exceeding 92% across the entire solar-blind band of 200?280 nm. Additionally, the proposed structure exhibits polarization insensitivity and incident angle insensitivity, highlighting its strong practical application potential. This work serves as a valuable reference for advancing the performance and miniaturization of solar-blind photodetectors.

Currently, the detection of blind pixel in infrared detectors is typically conducted using the national standard method, Measuring Methods for Parameters of Infrared Focal Plane Arrays (GB/T 17444—2013). However, this method may result in inaccuracies in identifying blind pixels. To enhance the accuracy of blind pixels detection in infrared detectors, a blind pixel detection method based on the surface difference value and noise is proposed based on the national standard method. First, the causes of misjudgment associated with the national standard method are examined. Next, two surfaces are approximately fitted using effective pixel data, and the difference between these surfaces is used to establish specific dead pixel judgment criteria for individual pixels, enabling precise selection of dead pixels. Furthermore, by analyzing noise within infrared images, overheated pixels are also detected. The combined results of detected dead and overheated pixels provide the total number of blind pixels. Finally, comparative experiments involving various blind pixel detection methods demonstrate that the proposed method achieves a higher detection accuracy than the national standard method.

A side alignment technique for polarization-maintaining fibers using the forward scattering pattern of a narrow-linewidth helium-neon laser is proposed. By rotating the fiber axis and observing changes in the scattering pattern, the fast and slow axes of the polarization-maintaining fiber can be precisely positioned. This technology addresses the inefficiencies and inaccuracies of traditional methods in measuring bow-tie or small-diameter polarization-maintaining fibers, providing essential support for their application in communication and sensing fields. Through experiments, the relationship between the rotation angle of the polarization-maintaining fiber and the intensity of the scattering pattern is examined.Results reveal that rotation alters the azimuth angle of the fast and slow axes, leading to corresponding changes in the scattering pattern's position. The analysis of the relationship between the rotation angle and scattering pattern reveal that the broad peak characteristic value is a more accurate and reliable metric for positioning the fast and slow axes of polarization-maintaining fibers. In addition, the effects of laser and fiber positioning on scattering patterns are examined. The Y-axis position offsets are particularly sensitive to the scattering patterns, whereas the fiber-to-light-screen distance significantly influences the spacing between scattering patterns. An experimental platform is constructed to validate the universality and practicality of broad peak characteristic values for fast and slow axis positioning in polarization-maintaining fibers.

In Φ-OTDR distributed fiber-optic intrusion detection system, it is essential to obtain sensing results to propose the solution strategy, reduce staff casualties, and property loss in time. Simultaneously, the data-driven deep learning signal classification method has the features of high accuracy and robustness. However, a large number of training samples are required to achieve a better result. To solve this problem, we initially propose a data enhancement method based on noise fusion, which extends the original unbalanced small-sample data into a model-satisfying dataset by designing a spatial correlation noise fusion enhancement (SCNFE). Then, for the signaling network inputs with different time scale, an improved Gramian angular field (GAF) image transformation method is proposed to obtain the samples that satisfy the input scale of the network by introducing the image transformation in the Gram's angle field. Finally, to satisfy the real-time intrusion signal classification of the network on distributed acoustic sensing (DAS) devices, a MobileNetV3-DAS classification network is proposed by combining the efficient channel attention (ECA) attention mechanism. Experiments demonstrate that the spatial correlation noise fusion method proposed in this study can reduce non-equilibrium rate to 1.09. Compared with MobileNetV3, the improved method reduces the model weight and inference time by 29.80% and 10.26%.

Uric acid is the final oxide of purine metabolism in the body and is one of the serum markers of inflammation. Persistent elevation of uric acid levels in serum can cause a series of diseases in the human body. Conventional methods for detecting uric acid have the disadvantages of expensive analytical reagents, and cumbersome and complicated chemical analysis. Detection based on terahertz metamaterial sensors is label-free and nondestructive, requires only a minute amount of reagents, does not damage analytes, and offers a high detection speed. A double-F multifrequency resonant metamaterial sensor with a maximum sensitivity of 160 GHz/RIU (RIU is a unit of refractive index) is proposed, which can be applied to high-sensitivity detection of uric acid. Different concentrations of uric acid solutions can be detected using this sensor. Results show that the lowest detection limit of the proposed sensor for uric acid solution is 0.001 g/L, which is lower than the lowest level of uric acid in a healthy human body. Thus, it is expected to be used in the detection of diseases.

In response to the high-precision measurement requirements of laser tracking measurement systems, this study analyzed their kinematic model and investigated a calibration method for the control field network. Based on the uncertainty propagation law of the implicit function model of the objective function, a structural error calibration evaluation model was developed. The influence of the number of transfer stations and the layout of calibration points on the calibration effect of structural errors was simulated and analyzed. Furthermore, a calibration and evaluation field was constructed for experimental verification. Experimental results demonstrate that the calibration accuracy of structural error parameters under different layouts aligns with the measurement accuracy of the evaluation field coordinates. When the dimensionless mean of the uncertainty of the structural error parameter calibration calculated using the structural error calibration evaluation model increases from 21.90 to 410.96, the root mean square error of the evaluation field coordinates increases from 0.2910 to 2.2365 mm. These findings confirm that the proposed method effectively evaluates the calibration effect of the structural error network in laser tracking measurement systems.

This study addresses the challenges of measuring inner hole parameters in workpieces with large depth-to-diameter ratios by proposing a rotating measurement method based on spectral confocal principles. First, a measuring system tailored for inner hole parameters with a large depth-to-diameter ratio is designed and constructed. An optical confocal probe that allows for non-contact measurements is next mounted at the front end of a hollow, long, straight guide rod. This guide rod is driven by an X-RXmotion module that facilitates the rotation of the optical confocal probe in the direction of the hole's depth. Then, 10 groups of experiments are conducted at various speeds to collect inner diameter data from the spectral confocal probe, which rotates forward and reversely alternately three times each within an inner hole workpiece characterized by a depth-to-diameter ratio of 12.52 and depth of 222 mm. Finally, algorithms are developed to calculate the diameter, center coordinates, and perpendicularity of the inner hole by fitting the contour of the inner hole workpiece using the inverse least squares method. The analysis also considered the effects of moving speed on the measurement accuracy of the inner hole parameters. It is verified by comparison experiment that the system has high measuring accuracy. The measuring value of hole inner diameter fluctuates within ±2 μm and the perpendicularity within 50 μm under low speed, while those are within ±7 μm and 80 μm under high speed. The results align closely with the calibration values for large deep-diameter workpieces, thus demonstrating the effectiveness of the proposed method and system.

Based on the demand of ocean detection LiDAR to improve the depth of ocean detection, this study combines a 532 nm single longitudinal mode laser pumped KTP-OPO with seed injection technology to design an optical parametric oscillator that can output 972 nm single longitudinal mode laser, high peak power 486 nm blue laser is obtained through external cavity doubling. When the energy of 532 nm laser is 25 mJ and the repetition rate is 100 Hz, the single pulse energy of 972 nm can reach 6.6 mJ, and the maximum conversion efficiency is 26.4%. After frequency doubling, a 486 nm blue laser pulse with a maximum single pulse energy of 1.58 mJ can be obtained, the maximum doubling frequency efficiency of 23.9%, the corresponding pulse width is 4.5 ns, the peak power can reach 351 kW, the beam quality factors Mx2=3.1 and My2=3.3, and the laser is expected to become the new light source of ocean detection LiDAR.

To improve the wear resistance and corrosion performance of a heat-exchanger tube assembly for solar thermal-power generation, the surface of 321 austenitic stainless steel, which is widely used in heat-exchanger components, is strengthened in this study to address the issue of component failure caused by severe wear and corrosion. First, a Ni60/WC alloy coating is prepared on a 321 stainless-steel substrate via high-speed laser cladding. Based on the laser power, scanning speed, and powder feed rate as influencing factors in addition to the hardness and dilution rate as characteristic variables, the process parameters are optimized via a single-factor test. Subsequently, the phase composition of the coating is analyzed based on the X-ray diffraction (XRD) pattern, whereas the morphology and elemental distribution of the coating are analyzed using scanning electron microscopy (SEM). Finally, a set of optimal process parameters is obtained by analyzing the macroscopic morphology, XRD pattern, and SEM results The optimal process parameters are as follows: laser power is 1000 W, scanning speed is 10 mm/s, and powder feed rate is 3.5 g·min-1. The coating phase primarily comprises a solid solution (γ-Fe, Ni) as well as carbides M7C3 and M23C6. The wear resistance of the coating improves significantly and the average friction coefficient of the cladding layer is approximately 0.4, which is lower than that of the matrix (0.8). The wear of the coating is 2.75 mg, which is approximately 65% of the substrate wear (i.e., 4.24 mg). The self-corrosion potential of the coating is -0.674 V, which is higher than that of the matrix (i.e., -0.754 V). The arc radius of the coating is larger than that of the substrate, indicating that the coating can reduce the corrosion rate of the substrate. The highest hardness value of the coating is 608 HV0.2, which is approximately 1.91 times that of the matrix, indicating the high corrosion resistance of the Ni60/WC alloy coating. In summary, the Ni60/WC alloy coating significantly improves the wear resistance and corrosion properties of 321 stainless-steel surface.

Traditional top-emitting vertical-cavity surface-emitting lasers (VCSELs) exhibit a long distance between the source region and heat sink, and internal heat conduction of the device is difficult, resulting in limited output power of both single-tube and array devices. To address these limitations, this study proposes a top-emitting VCSEL with a heat dissipation hole on the substrate. This hole is located directly below the countertop and is filled with high-thermal-conductivity materials, enabling rapid heat transfer from within the device. This design ensures mechanical support for the entire structure while improving the heat dissipation capacity. Simulation results indicate that the thermal flip power of the VCSEL device with a heat dissipation hole is 9.54 mW, representing a 36.4% increase compared to VCSEL devices without a heat dissipation hole. VCSEL devices with an oxidation aperture of 12 μm are prepared and tested under a duty cycle of 0.6%. The peak power of the VCSEL with a heat dissipation hole reaches 9.59 mW, which is 31% higher than that of the VCSEL without a heat dissipation hole.

Using yttrium vanadate (YVO4) and barium wolframate (BaWO4) Raman crystals together in the same Stokes wave cavity, a dual-wavelength extracavity Raman laser with wavelengths of 1176 nm and 1181 nm and a frequency difference of about 1 THz is achieved based on their Raman shifts of 891 cm-1 and 926 cm-1, respectively, under pulsed 1064 nm fundamental wave pumping. With incident fundamental laser pulse repetition frequency being 10 kHz and the average power being 10.7 W, the average output power of the dual-wavelength Raman Stokes wave reaches 3.78 W, with corresponding optical efficiency being 35.3%. The pulse width and the peak power are 11 ns and about 34 kW, respectively. The intensities and the temporal behavior of the two wavelengths components in Stokes output are generally consistent. The beam quality factor M2 is no more than 1.2. The results show that the dual-crystal Raman laser can be an effective method for generating dual-wavelength laser output. The various Raman crystals with numerous Raman lines also provide potential choices for dual-wavelength laser output with flexible frequency difference.

This study simulated spent fuel assemblies using alumina ceramic core rods and 304 stainless steel cladding and investigated the effects of various laser cutting process parameters on cutting quality. Based on cutting seam width, cutting surface roughness, and slag hanging length, a fiber laser with a maximum power of 12 kW was used to assess the cutting performance. The effects of various parameters on cutting quality were systematically analyzed under different laser powers, cutting speeds, defocus amounts, and cutting auxiliary air pressure conditions. Results indicated that the best cutting performance was achieved with a laser power of 9.6 kW, cutting speed of 0.7 m/min, defocus distance of -10 mm, and cutting auxiliary air pressure of 15 bar. The cutting width, slag hanging length, and section roughness were 1.89 mm, 1.2 mm, and 27.4 μm, respectively. This study provides valuable experimental data and technical insights for optimizing spent fuel laser disintegration technology.

To clarify the control mechanism of scanning spacing on forming quality in selective laser melting (SLM), multiphysics numerical simulation combined with experiments is performed to investigate the mechanism underlying the effect of scanning spacing on the thermodynamic behavior of adjacent melting overlap process. Results show that the preheating effect of the previous scan channel can increase the base temperature and peak temperature of the subsequent scan channel, although this effect weakens as the scanning spacing increases. When the scanning spacing is extremely small (≤50 μm), the temperature of the first zone reaches 1168 K and remelting occurs during the second scanning channel, whereas a larger scanning spacing (≥90 μm) increases the temperature gradient of the fuse and reduces the cooling rate of the scan channel. During weld bonding, the flow rate of the molten pool near the sintered side is sufficient and the melt velocity distribution is uniform, whereas the opposite is observed for the molten pool near the unsintered side. When the scanning spacing is 70 μm, the melt flow velocity difference between the two sides of the molten pool is the smallest, which is more conducive to the stability of the molten pool and the construction quality of SLM, and the relative density and Vickers hardness are 98% and 131.3 HV, respectively. The sweep-spacing parameter should be coordinated with other process parameters to improve the forming quality while ensuring the overlap rate.

In this study, Cu doped Zn-In-S/ZnS core/shell quantum dots are prepared by one-pot non-injection synthesis method, and the influence of the shell thickness of the quantum dots on luminescent properties is studied. In measuring the absorption and emission spectra of Cu∶Zn-In-S/ZnS core/shell quantum dots, as the Zn/In molar ratio increases, both absorption and emission spectra are found to undergo a red shift regardless of whether the shell is thin or thick. In the case of different shell thicknesses, the absorption spectrum of Cu∶Zn-In-S/ZnS core/shell quantum dots (QDs) with thick shell is red shifted, and the emission spectrum is blue shifted. This is primarily attributed to the quantum size effect and the adjustment of the band structure by the shell thickness. The fluorescence lifetime of Cu: Zn-In-S/ZnS core/shell QDs with a thick shell is longer than that of a thin shell. In addition, with change of temperature, the luminescent stability of Cu∶Zn-In-S/ZnS core/shell QDs with a thick shell is better than that of Cu∶Zn-In-S/ZnS core/shell QDs with a thin shell.

Utilizing both analytical and numerical methods, this study examine unconventional photon blockade in a second-order nonlinear system influenced by two-photon absorption environment. First, we derive the optimal conditions necessary for achieving unconventional photon blockade through analytical methods. The numerical results for the equal-time second-order correlation function are then presented. Results indicate that unconventional photon blockade is present in the second-order nonlinear system affected by two-photon absorption environment, with the analytical optimal conditions aligning closely with the numerical results. Finally, an analytical expression for the equal-time second-order correlation function is provided and compared with the numerical results. The comparison reveals that the theoretical predictions for the equal-time second-order correlation function are largely consistent with the numerical results, and in regions of discrepancy, the theoretical values tend to be lower than the numerical ones. This inconsistency arises because the analytical calculations truncate the system's Hilbert space to two-photon excitation. In addition, the width of the photon blockade window increases with stronger external driving forces, whereas it decreases with greater second-order nonlinear interaction strength. These findings offer valuable theoretical guidance for the experimental observation and practical application of photon blockade in this system.

The trace CO concentration detection system based on tunable diode laser absorption spectroscopy (TDLAS) technology presents low detection accuracy owing to interference from various environmental factors. Temperature fluctuations affect the responsivity and dark current of the photodetector, thus causing a drift in the detector's output signal, which consequently affects the accuracy of CO detection. Hence, a high-precision constant-temperature control system with a wide temperature range is designed in this study. The effect of temperature on the photodetector's output signal is analyzed based on both the responsivity and dark current of the photodetector. Subsequently, a high-precision constant-temperature control drive module is designed using a relay feedback self-tuning proportional-integral-derivative adjustment algorithm, dual-channel voltage acquisition, and an improved comprehensive Kalman filter algorithm. Experimental results show that this high-precision constant-temperature control system can achieve a temperature-control accuracy of ±0.005 °C in both high- and low-temperature environments.

This study analyzes a national fitness gym to incorporate a light-guiding system that uses natural light, supplemented with artificial lighting, to meet predefined standards. First, Ecotect software is used to simulate the lighting conditions at the gym's geographical location. Subsequently, an appropriate optical lighting system is selected, and the light distribution curve is modeled using TracePro software. Based on the site conditions, the required quantity and arrangement of the lighting system are calculated. In addition, indoor illumination variations under different outdoor lighting scenarios are simulated using DIAlux. To optimize the integration of natural and artificial lighting, the lamps' positioning is analyzed as a key influencing factor. Combined with the whale optimization algorithm, a response surface model is used to enhance the natural light compensation. Results indicate that this hybrid lighting approach satisfies horizontal illumination requirements while improving uniformity. Specifically, when the outdoor illumination reaches 19500 lx, four lamps can be eliminated; at 39500 lx, eight lamps can be removed; and at 49000 lx, artificial lighting becomes unnecessary.

As a key technology in the fields of future mobile communications and antenna systems, electromagnetic wave polarization based on metasurfaces has attracted widespread interest. However, in the current realm of polarization conversion metasurfaces, existing research still encounters challenges such as low operating frequencies, limited bandwidth, low conversion efficiency, and limited functionality. This paper presents the design of two types of reflective metasurface structures: a broadband electromagnetic wave polarization conversion metasurface and a beam steering metasurface. Specifically, by integrating anisotropic principles, we design a polarization conversion metasurface unit composed of a central "C"-shaped metallic aperture and diagonal "L"-shaped metallic strips that can achieve broadband linear polarization conversion from 22.5 to 48.5 GHz. Building upon this structure, the beam steering metasurface incorporates phase modulation principles; through the altering of the opening angle and rotation angle of the aperture rings, specific phase gradients between units can be achieved, thereby enabling beam steering functionality at 30 GHz based on the generalized Snell's law. Simulation results closely align with theoretical expectations, thoroughly validating the functionalities of the designed metasurfaces in polarization conversion and beam steering. This approach effectively addresses the limitations of existing studies and demonstrates promising application prospects in future communication systems and antenna technologies.

Conformal vibration polishing is an effective mid-spatial frequency (MSF) error smoothing process method for complex surfaces, and it has broad application prospects in the processing of optical elements in many major optical engineering projects. In this study, a finite element based simulation method is proposed to address the issues of unclear polishing mechanism and unclear process rules in vibration polishing of viscoelastic tools. Furthermore, the influence mechanism of flexible layer material properties, polishing pressure, and vibration frequency on mid-spatial frequency error smoothing in vibration polishing is examined. Additionally, the influence law on the mid-spatial frequency error smoothing ability is obtained. Through simulation analysis and experimental verification, the following conclusions are drawn: the mid-spatial frequency error smoothing ability of conformal vibration polishing initially increases and then decreases with the increase in the elastic modulus of the viscoelastic material, increases with the increase in polishing pressure, and initially stabilizes and then increases with the increase in vibration frequency. When the maximum elastic modulus of the viscoelastic body is within 9?12 MPa, the polishing pressure is between 800?1100 Pa, and the vibration frequency is between 20?30 Hz. Furthermore, the mid-spatial frequency error smoothing effect of vibration polishing is optimal, and it also has exhibits low-spatial frequency conformal ability.

Metasurfaces offer unique advantages for controlling incident electromagnetic waves. However, the design of a complete metalens involves extensive modeling and analysis of numerous unit structures. This process is both time-consuming and challenging, particularly when aligning phase distributions with desired outcomes, which poses significant limitations to simulation efficiency. In this study, we propose a deep learning-based super-resolution reconstruction model that exploits a generative adversarial network for metasurface design. The proposed model enables rapid and precise upscaling of phase-geometric arrays, generating unit structures with higher data density in the output phase. By training on 9000 sample sets, the proposed model achieves a prediction accuracy of 95.17% when upscaling a 60 pixel × 60 pixel phase-geometric array to 120 pixel × 120 pixel. To validate its feasibility, we design a visible-light achromatic metalens using the predicted phase-geometric array of typical achromatic metalens unit structures. This design is verified by simulation. The results demonstrate that the proposed deep learning model significantly reduces simulation time and enhances accuracy compared to traditional simulation and interpolation methods. The proposed model also offers an efficient approach for the initial design and selection of metasurface units, providing a scalable solution for accelerated computation and data expansion in electromagnetic wave control based on a generative adversarial network.

This paper presents a substrate integrated waveguide (SIW) cavity-backed slot antenna for dual-band operation. By etching a pair of triangular complementary ring slots in the antenna's back cavity for radiation, these slots can effectively excite narrow-gap hybrid modes inside the SIW cavity. One of the modes is shifted upward in the lowest mode (TE120 or TE210 mode) and the other is shifted downward in the highest mode (TE320 or TE230 mode). The two modes appear paired together, which significantly improves antenna performance. The prototype of this antenna is fabricated on a low-cost substrate via printed-circuit-board technology. Simulation results show that the antenna operates in two frequency bands of 11.80?12.50 GHz (0.70 GHz) and 14.50?15.00 GHz (0.50 GHz). It resonates at frequencies of 12.00 GHz and 14.80 GHz, with peak gains of 6.40 dBi and 4.90 dBi, respectively. Additionally, this antenna features a high gain and a stable unidirectional radiation pattern.

Phototransistor Organic Field-Effect Transistors (POFETs) are a class of optoelectronic devices that are based on organic semiconductor materials and combine the electrical modulation of field-effect transistors with photoresponse functionality. When exposed to light, the organic semiconductor materials absorb the energy, generating photo-generated carriers, which in turn modulate source-drain current. This enables the conversion of optical signals into electrical signals. POFETs offer high sensitivity, flexibility, and low cost, making them suitable for applications in optical sensors, flexible displays, and biomedical sensors, with vast application potential in other fields as well. In this thesis, two models for estimating the photo-generated carrier concentration based on drain current and photocurrent in POFETs are proposed. To validate the accuracy of these models, six types of POFET devices are fabricated, including those based on lead phthalocyanine (PbPc) and erbium phthalocyanine (ErPc2) single layers, and CuPc/ErPc2, pentacene/ErPc2, C60/PbPc, and pentacene/PbPc/C60 planar heterojunctions. The optoelectronic parameters of these devices are measured. Using the two estimation models, the photo-generated carrier concentrations of different POFET devices are calculated, and the results are comparatively analyzed. This study provides an effective approach for estimating the photogenerated carrier concentration in POFETs.

To obtain high-resolution electron bombarded complementary metal oxide semiconductor (EBCMOS) imaging devices, the influence of spatial resolution for EBCMOS proximity region is studied. The theoretical calculation model for spatial resolution in EBCMOS devices proximity region is established according to the principle of Fourier transform and electromagnetic fields. Effects of illumination, proximity distance, and proximity voltage on resolution are studied. The diffusion diameter of photoelectrons reaching the back-side bombarded CMOS (BSB-CMOS) surface can be reduced by reducing the proximity distance and increasing the proximity voltage, which will result in higher spatial frequency. The electron focusing and resolution will not varied when the magnitude of illumination is changed. When the proximity distance is 100 μm and proximity voltage is 3000 V, the electron beam diffusion diameter can be reduced to 10 μm, and the limit resolution can be increased to 127.27 lp/mm. This structure can effectively improve the resolution of the EBCMOS proximity region. Therefore, the research on the influence of spatial resolution in EBCMOS proximity region will provide a theoretical support for optimizing proximity structures and improving EBCMOS resolution.

Non-Hermitian systems are garnering attention in optics, electricity, acoustics, and other fields owing to their distinctive physical phenomena and promising applications. We explores the higher-order singularities in three-dimensional non-Hermitian systems. We also analyze the effects of these singularities on the energy response of the systems. We design and build a three-dimensional resonator array circuit, simulating its gain and loss by incorporating positive and negative resistances to establish a system constructed from repeated minimal unit cells. Through an analysis of the eigenvalues of the Hamiltonian operator and phase diagrams in the parameter space, the generation mechanism and evolution behavior of singularities in the system are elucidated. LTspice simulation results indicate that higher-order singularities significantly enhance the energy (voltage) response of the system, particularly when the circuit contains a specific number of unit cells, which can markedly increase the response speed. This finding provides new directions for optimizing sensor design and highlights the important application potential of higher-order singularities in non-Hermitian systems for improving the system performance.

In this study, the radially polarized partially coherent Gaussian vortex array (RPPCGVA) beam is constructed by introducing the multiple off-axis vortex phase into the center of each sub-lobe of partially coherent Gaussian array beam, and the focusing properties of the beam through a thin lens are investigated. The experimental results show that the RPPCGVA beams with different numbers of vortex arrays will gradually merge from the initial array beam into a single beam in the focus process due to its spatial correlation between the sub-beams, and present polygonal hollow, flat-top, and Gaussian-like distributions in the focal plane, respectively. In addition, the polarization state of the beam is gradually transformed from the initial radial polarization into an inverted triangle, oblique square, pentagon, etc. elliptical polarization distribution due to the effect of multiple off-axis vortex phases. However, the beam's intensity degrades to Gaussian distribution, and its polarization state degrades to an elliptical polarization distribution with circular symmetry when the coherence is very low. In addition, the beam still has strong self-healing ability when one of the sub-beams is partially blocked by a sectoral obstacle, but it will be destroyed for completely blocking, resulting in a distortion for the intensity and its state of polarization.

In recent years, special optical fields, especially vortex beams, have attracted widespread attention for their unique phase, polarization, and amplitude characteristics, which show great potential for applications in optical information transmission, rotational speed measurement, and quantum optics. Using the grating diffraction method, firstly, the generation of two types of dual-mode vortex beams, namely vortex beam superposition states and polarization vortex beams are explored in this study. The comparison shows that the structural similarity (SSIM) of the experimental and simulated optical fields of the vortex beam superposition state decreases gradually as the orbital angular momentum (OAM) mode increases. The SSIM of l=±5 is 7.78% lower than that of l=±1. Secondly, the study explores the effect of the center offset between the Gaussian beam and spatial light modulator on distortion of the optical field. As offset increases, the correlation coefficient of the light intensity of different OAM modes gradually decreases. The light intensity correlation coefficient of D=0.5 w is 13.91% lower than that of D=0.1 w (w is waist radius). Finally, by adjusting the parameters of two pure phase gratings with orthogonal modulation directions, we generate polarization vortex beams with adjustable topological charges, polarization orders, and diffraction orders in simulations. The polarization analysis shows that the number of spots detected by the polaroid is twice that of the polarization order. Our research has important theoretical and practical value in expanding the application of vortex beams in optical field regulation.

The wing panel has numerous structural features and the distribution of scanning path points is complex, complicating scanning planning. Therefore, a line laser scanning planning method based on clustering features and path splicing is proposed. First, the features to be scanned are extracted and discretized to generate scanning viewpoints and execution path points. These viewpoints are then grouped using density-based spatial clustering of applications with noise (DBSCAN), to reduce the complexity and scale of the scanning path. Second, the improved black kite optimization algorithm (BKA) is used to plan and splice the grouped paths, to ensure scanning continuity and reduce redundant paths. Finally, an improved Hippo optimization (HO) algorithm with self-adjusting weights is used to solve the joint angles, along with a particle swarm optimization (PSO) algorithm to comprehensively optimize joint speed, acceleration, and time. The results show that the proposed method can meet the scanning planning requirements of multiple structural panel features.

Micro-nano optical devices can realize multi-dimensional accurate manipulation of spatial light fields. Their advantages such as high resolution, small volume, short operating distance, and high integration overcome the limitations of traditional optical refractor devices, which have broad application prospects. However, with the continuous improvement of market demand indicators, the manufacturing contradiction between the micro-/nano-level feature size becomes more prominent, especially when the size of micro-nano optical devices is extended to exceed the millimeter level. This necessitates more stringent large-area and high-precision requirements for micro-nano fabrication technologies. In response to this challenge, this paper introduces in detail the application of lithography to micro-nano optical device fabrication and reviews the development history of different lithography technologies including ultraviolet projection, proximity, holographic mask, nanoimprint, laser direct writing, electron beam direct writing, and focused ion beam direct writing. The principles of the writing and technological evolution process are subsequently described. Additionally, the advantages and disadvantages of various lithography technologies and key technical problems are discussed. The prospect of using lithography technology to optimize the preparation of large-sized micro-nano optical devices with extreme precision requirements will further be explored in the future.

New psychoactive substances (NPSs) are a new type of drugs characterized by their strong addictive nature and harmfulness. Due to their variety and the rapid creation of new derivatives, they have become key priorities for public security agencies in terms of prevention and enforcement. This has highlighted the need for rapid, sensitive, and selective detection methods. Fluorescent sensors have emerged as a promising solution for NPS detection due to their convenience, low cost, high sensitivity, and excellent selectivity. This paper provides an overview of recent research advancements in fluorescent sensor technology for NPS detection. It introduces organic small molecule fluorescent sensors and fluorescent nanosensors for NPS detection. The paper also highlights the development trends in the field, providing a reference for further development of fluorescent sensors for NPS detection with high targeting efficiency and low background interference.

Transition metal dichalcogenides (TMDs) and their heterostructures exhibit excellent optoelectronic properties, thus rendering them promising candidates for next-generation electronic and optoelectronic devices. Investigating the ultrafast carrier dynamics in these materials not only allows for the exploration of ultrafast optoelectronic conversion processes within new materials but also provides a theoretical foundation for the development of high-speed optoelectronic devices. This review focuses on the latest advancements in carrier-dynamics behavior in TMDs and their heterojunctions. An optical pump-terahertz probe (OPTP) system and optimization methods were introduced to achieve OPTP signals with large signal-to-noise ratios in nanomaterials. Based on analysis using the OPTP, we summarized the different physical processes involved in the relaxation of TMDs, including exciton dynamics, phonon-assisted recombination, Auger recombination, and defect-induced relaxation processes. Aditionally, we discussed charge transfer via the OPTP in TMD heterostructures tuned by the pump wavelengths and stacking orders. This review summarized the recent progress of ultrafast dynamics in TMDs based on an OPTP and indentified some potential directions in condensed matter physics.

The challenges in public safety and criminal justice are becoming increasingly complex, underscoring the growing importance of forensic evidence identification. This is particularly relevant for rapid and precise recognition of chemical toxicants, biological toxins, and explosive residues. Ultraviolet Raman spectroscopy, with its distinct advantages, is emerging as an indispensable tool in forensic science. This paper introduces the fundamental principles of ultraviolet Raman spectroscopy, elaborates on its advantages, and uses bibliometric analysis to examine its current applications. It focuses on research achievements in identifying chemical agents, biological toxins, and explosive residues, providing crucial technical support for case investigations and public safety. Furthermore, the paper explores future trends in the forensic application of ultraviolet Raman spectroscopy, including advancements in technical research, equipment portability, and development of spectral databases. By offering a comprehensive and cutting-edge reference, this paper aims to foster the broader and more in-depth application of ultraviolet Raman spectroscopy in forensic science.

With the rapid advancements in fields such as high-performance computing, artificial intelligence, and intelligent vehicles, the demand for high-resolution graphical technology and contactless processing has increased. Advanced laser ablation for substrate patterning has gradually become an important method for achieving miniaturization and high integration of electronic devices. This paper introduces the research progress on processing different materials, such as organic and inorganic substrates, using advanced laser patterning technology. It specifically discusses the effects of different lasers on various substrate materials. Further, it reviews the application methods and effects of advanced laser patterning technology in areas such as through glass via advanced packaging technology, flexible sensors, microfluidic devices, and micro-nano optics and resonant devices. Finally, the future potential of advanced laser patterning technology is discussed, offering valuable insights for researchers working in related fields.

As instruments for accurately measuring magnetic fields, atomic magnetometers play a significant role in various fields, including fundamental physics, earth sciences, biomedicine, and national defense. This study presents a comprehensive review of the technical development of atomic magnetometers, covering their major categories and basic features, while providing a detailed discussion of the current research status and development trends of alkali metal optical pumping magnetometers, coherent population trapping atomic magnetometers, spin exchange relaxation-free atomic magnetometers, and nonlinear magneto-optical rotation atomic magnetometers. The study first classifies magnetometers based on classical physics principles and quantum effects. This is followed by an in-depth discussion of the working principles, sensitivity, dynamic range, bandwidth, and other key performance indicators of the four types of quantum-effect atomic magnetometers. The study then describes their advantages and challenges under various application scenarios. Finally, future developmental directions for magnetometer technologies are considered. These include miniaturization, integration, enhancement of vector magnetic field measurement capabilities, and potential applications in biomedical imaging and geophysical exploration.

The quasi-distributed fiber Bragg grating (FBG) shape sensor measures the position and shape of an object connected to an optical fiber by combining multiple FBGs using wavelength division multiplexing technology. Characterized by immunity to electromagnetic interference, ease of integration, corrosion resistance, and strong wavelength selectivity, FBG has high sensitivity to the three-dimensional (3D) shape changes of beams, panels, and skins. Thus, it is reliable for monitoring the health of critical structures in aerospace and healthcare fields. In this study, the domestic and international research progress on 3D shape reconstruction algorithms based on quasi-distributed FBG is reviewed. The influence of FBG layout density and temperature on the reconstruction effect of four algorithms is discussed. The advantages and disadvantages of each algorithm as well as the suitable reconstruction objects are summarized, and future directions of improvement are outlined.

Cavity phase matching (CPM) is a method of compensating for phase mismatch based on reflection phase shifts in resonant microcavities and can ensure efficient optical frequency conversion in nonlinear media within one coherent length. Compared with an optical parametric oscillator (OPO) based on birefringent phase matching and quasi-phase matching, a microcavity optical parametric oscillator (MOPO) based on CPM is compact, simple, flexible, and applicable to various nonlinear crystals, in addition to exhibiting unique spectral properties. Recently, MOPO theory and technology have been continuously developing. High-efficiency MOPO devices with different operation modes that can generate widely tunable or broadband laser outputs have been developed. Simulation results indicate that this technology can potentially generate monochromatic terahertz waves. Thus, MOPO devices are promising, novel light sources for integrated optics and micro-opto-electro-mechanical systems. This study introduces the basic principle of CPM, analyzes the operating characteristics of an MOPO, summarizes the developments, and outlines the prospects such type of device.

To disclose the gemological characteristics of the increasingly numerous dyed Hongjiaohua crystals in the market, natural and dyed Hongjiaohua crystal samples are observed and tested using gemological microscope, ultraviolet-visible spectrophotometer, photoluminescence spectrometer, and Raman spectrometer. The results indicate that the inclusion morphological characteristics of natural and dyed Hongjiaohua crystals exhibit significant discrepancies. Inclusions within natural Hongjiaohua crystals exhibit moss, film, nodular, speckled, cloudy, and gauzy forms. While the inclusions within dyed Hongjiaohua crystals may be in the form of colloidal contraction or condensation cracking of organic matter, with pigment colloids often in granular form. Additionally, a difference exists in their ultraviolet-visible diffuse reflectance spectra. Natural samples display an absorption band approximately at 410 nm and a notable deceleration in the slope of the spectrum around 666 nm. Both of these phenomena are ascribed to the transition of Fe3+ within hematite and goethite. However, dyed Hongjiaohua crystals lack this characteristic. The first derivative spectra of the diffuse reflectance spectra for natural samples indicate the presence of hematite, and some samples exhibit the characteristic peak of goethite. A difference of luminescence is also obvious between natural and dyed samples. Natural specimens exhibit no distinct spectral peaks in their photoluminescence spectra, whereas dyed samples present characteristic peaks that are indicative of the presence of dyes. Raman spectroscopy is employed to analyze the surface inclusions of natural Hongjiaohua crystals, thereby confirming that the primary component of these inclusions is hematite.

Pigments are essential materials that make cultural relics vivid and visually striking, with their varied colors reflecting the characteristics of different historical periods. Various nondestructive testing (NDT) methods have been used to analyze pigment composition in cultural relics. Among these methods, terahertz waves, which have been introduced over the past three decades, have emerged as a valuable tool for NDT. The application of terahertz technology in pigment research is of enormous importance. Traditional terahertz time-domain spectroscopy systems operate within a spectral range of 0.25?3 THz. In this study, a broad-spectrum terahertz time-domain spectroscopy system was developed to investigate six commonly used pigments for cultural relic protection. The transmission spectra of these pigments were measured over an extended range of 0.25?7 THz, and their refractive index and absorption coefficients were calculated. The experimental results were compared with those obtained using Fourier transform infrared spectroscopy, thereby confirming the reliability of the terahertz experimental results.

To address the necessity for rapid identification of pollutants in abrupt water-pollution incidents, a lightweight neural network algorithm suitable for portable devices is proposed. By obtaining surface-enhanced Raman spectroscopy (SERS) data of five common water pollutants and performing preprocessing, a two-dimensional Morlet wavelet transform is applied to separate high- and low-frequency signals, thus enhancing feature representation. To improve the model's feature-extraction capability, a multipooling strategy is introduced, and the efficient channel attention (ECA) mechanism is modified to develop a multipooling attention ECA (MP~~ECA) module. This module is integrated with the MobileNetV2 network to construct the MobileNetV2~~MP~~ECA model for wavelet image classification and recognition. The gradient-weighted class activation mapping (Grad-CAM) technique is utilized to generate heatmaps, which further verifies the effectiveness of wavelet transform in enhancing feature extraction and classification accuracy. Experimental results show that the proposed model achieves a classification accuracy of 97.83%, thus outperforming other attention mechanism models, conventional convolutional neural networks, and common machine-learning methods. Additionally, the model size of proposed model is only 6.11 MB and incurs a floating-point computation of 230.20 MFLOPs, thus rendering it suitable for resource-constrained mobile-device applications. This study provides a novel strategy and approach for efficiently detecting pollutants in real-world abrupt water-pollution scenarios.

In view of the problem of pigment selection in the restoration of cultural relics such as murals and painted sculptures, terahertz time-domain spectroscopy is used to distinguish the common heritage pigments. First, the time-domain spectra, frequency-domain spectra, transmission spectra, absorption spectra, and refractive index of six pigments with very different colors (garcinia, loess, laterite, lapis lazuli, calcite, and mineral green) are analyzed and studied in the range of 0.2?1.5 THz. Then, to further demonstrate the applicability of terahertz time-domain spectroscopy, the terahertz spectra of garcinia and orpiment and those of laterite and sinopis, which have very similar colors, are analyzed. Finally, the experimental results show that the spectra of the pigments have evident differences in the spectral characteristics of pigments with the same main ingredients, which are manifested by the shift, increase, and decrease of absorption peaks. Based on these characteristics, the pigments with the same main composition can be accurately identified. The results indicate that the proposed terahertz measurement techniques can provide accurate reference for the restoration of color of cultural relics.