Optical fiber tweezers have a simple structure, operate flexibly and are small in size, and are widely used in biochemical analysis, life science and other fields. The optical fiber probe with hetero-core structure has natural advantages in near-field evanescent wave optical trapping, core beam coupling transmission, and cross-synergistic applications of microfluidic technology. It can realize cell and subcellular particle collection and transportation and can significantly improve the three-dimensional capture ability and dynamic manipulation level of particles. In this paper, the structural characteristics and application technology research progress of fiber optical tweezers with different core structures are reviewed. Their key technologies such as probe preparation, laser source and coupling mode are listed and compared. The role and development of hetero-core fibers with different structures in fiber optical tweezers are summarized and predicted.

For data communication between single wavelength laser communication terminals, good isolation between signal transmission and reception is the key to establish duplex bidirectional laser communication.In this paper, aiming at the transmission and reception scheme of a single laser wavelength laser communication terminal and the overall communication performance of the laser communication terminal, the influence of the surface roughness and contamination level of key components on the isolation performance of the laser communication terminal is analyzed.The model parameters are derived from Harvey model and ABg model, and the designed scheme is analyzed using TracePro software.When the surface roughness or contamination level of λ/2 wave plate, λ/4 wave plate and optical antenna structure in the signal transmission channel increases,the backscattering caused by the elements will reduce the isolation performance in the signal transmission channel.At the same time, the measurement result of laser communication terminal isolation is 77.86dB, which is basically consistent with the software simulation result of 78.35dB. This result can be applied in laser communication system communication.

In order to realize the real-time measurement of the boresight vibration of the dual line array surveying and mapping camera, a measurement model of the optical axis of the aerospace line array surveying and mapping camera is established. First, by setting up laser transceivers at both ends of the focal plane of the camera, through the central prism correlation, the angle parameter change measurement model between the two cameras is constructed. And proposes an optical axis measurement method for multi-line array cameras based on the dual-vector attitude determination principle. The calculation expression is given; the algorithm error is analyzed, and verified by simulation. In addition, the residuals of two algorithms are simulated, and the results show that the simplified algorithm is only in good agreement with the dual vector algorithm in a small measurement range, but when the detection range is expanded to 2 second, the algorithm in this article can be used to obtain 0.1 arc-second results. Finally, it was tested and verified in a thermal vacuum environment. It was verified that the calibration accuracy of the internal and external parameters of the camera using this algorithm reached 0.1 arc-second. The results showed that the angle parameters of the two cameras exhibited the periodicity of the orbit, which provided good conditions for the subsequent development of stereo surveying and mapping tasks.

The motion of objects is everywhere in nature. With the development of smart vehicle and 6G mobile communications, the demand for highly integrated integrated sensing and communication (ISAC) devices withcommunication and motion sensing is increasing. Based on the coexistence of luminescence and detection characteristics of GaN multiple quantum wells, an optoelectronic chip based on GaN on sapphire substrate is proposed in this paper. This chip has sensitive motion detection function and visible light communication function.The transmitter of the chip emits visible light in blue band to the moving target object. The visible light signal modulated by the motion of the target object is reflected back to the receiver of the chip to stimulate the changing photocurrent. By analyzing the changing photocurrent, the motion of the target object rotating at different speeds can be detected. The change period of the photocurrent curve is consistent with the rotation period of the target object. This paper also studies the visible light communication performance of the optoelectronic chip. The optoelectronic chip can be used as a visible light communication transceiver terminal, can also process and transmit the motion detection signals collected by the chip. The optoelectronic chip based on GaN multi-quantum wells provides a promising way in the field of low-cost, low-power, highly integrated optical motion sensing applications. It is a highly integrated ISAC terminal device with significant value.

Miniature head-mounted single-photon fluorescence microscopy is a breakthrough approach for neuroscience research that has emerged in recent years. It can image the neural activity of freely moving vivo animals in real time, providing an unprecedented way to access neural signals and rapidly enhancing the understanding of how the brain works. Driven by the needs of brain science research, there have been many types of miniature head-mounted single-photon fluorescence microscopes, such as high-resolution imaging, wireless recording, 3D imaging, two-region imaging and two-color imaging. In order to have a more comprehensive understanding of this new optical neuroimaging technology, this paper will classify its technologies according to the imaging field of view, introduce the characteristics of different types of micro-head-mounted single-photon fluorescence microscopes reported so far, and focus on the optical system scheme and optical performance parameters used. The advantages and disadvantages of different schemes are analyzed and compared and the future direction of development is described to provide reference for the practical application of brain science researchers.

This paper develops a fiber Bragg grating accelerometer based on bearing and flexure hinge for the measurement of medium-high frequency vibration signals. The mathematical model between its natural frequency and sensitivity and structural parameters is derived based on the mechanical model. Moreover, the structural design is optimized based on the theoretical analysis results, then the sensor was fabricated. Ultimately, its dynamic characteristics are validated using finite element simulation and vibration experiment. The results show that both its operating frequency range and acceleration sensitivity are 10−1200 Hz and 17.25 pm/g. In addition, this proposed sensor has some extinguished advantages such as an error of less than 0.3 g, a good linearity of greater than 0.99, a repeatability error of 2.33%, and free of temperature.

In order to solve some problems of the traditional analytical theory design scheme, such as high computational complexity, limited analytical solution, and time-consuming, based on the design of traditional optical device, a scheme for designing an optical power splitter with adjustable split ratio according to the reverse design method is proposed. In a compact region of 1.92 μm×1.92 μm, Ge₂Sb₂Se₄Te₁(GSST) is introduced to change the refractive index distribution of the device. The direct binary search algorithm is utilized to search the optimal state distribution of GSST in crystalline and amorphous states. And a T-shaped optical power splitter with adjustable split ratio is designed and implemented for the same device structure. The initial structure, split ratio, phase change material region state distribution, manufacturing tolerance, and light field distribution of the device are simulated and analyzed. The result shows the minimum relative errors of the designed optical power splitters with three splitting ratios of 1∶1, 1.5∶1 and 2∶1 between wavelengths 1530 nm and 1560 nm are 0.004%, 0.14% and 0.22%, respectively. The maximum fluctuations of the transmission curve in the manufacturing tolerance range are 0.95 dB, 1.21 dB and 1.18 dB, respectively. The splitter has a compact structure and has great potential for applications in optical communication and information processing.

The resolution of optical imaging is limited by diffraction limit, system detector size and many other factors. In order to obtain images with richer details and clearer textures, a multi-scale feature attention fusion residual network was proposed. First, shallow features of the image were extracted using a layer of convolution, and then the multi-scale features are extracted by a cascade of multi-scale feature extraction units. The local channel attention module is introduced in the multi-scale feature extraction unit to adaptively correct the weights of feature channels and improve the attention to high frequency information. The shallow features and the output of each multi-scale feature extraction unit were used as hierarchical features for global feature fusion reconstruction. Finally, the high resolution image was reconstructed by introducing shallow features and multi-level image features using the residual branch. The algorithm uses Charbonnier loss to make the training more stable and converge faster. Comparative experiments on the international benchmark datasets show that the model outperforms most state-of-the-art methods on objective metrics. Especially on the Set5 data set, the PSNR index of the 4× reconstruction result is increased by 0.39dB, and the SSIM index is increased to 0.8992, and the subjective visual effect of the algorithm is better.

Ammonia emission will cause harm to the environment and human health. It is particularly important to monitor the ammonia concentration with high precision. Off-axis integrating cavity output spectroscopy (OA-ICOS), which has the advantages of high sensitivity and high response speed, is used in this paper and has been designed to a high-precision ammonia detection device. The gas absorption cell is composed of two high reflection mirrors with a reflectivity of 99.99%, and the base length of the optical resonator is 30 cm. Finally, the optical path of nearly 3000 m was realized. The distributed feedback laser (DFB) with a central wavelength of 1528 nm which is tuned to 6548.611 cm⁻¹ and 6548.798 cm⁻¹. The concentration of NH₃ is changed from 10 ppm to 50 ppm and is detected under the atmospheric pressure of 140 torr at room temperature. The measurement results show that the linear fit R² between NH₃ concentration and signal amplitude can reach 0.99979. The Allan variance is used to analyze the experimental data, and the minimum detection limit of the system can reach 7 ppb at 103 s. The experimental results show that the detection device has good stability and high sensitivity, meets the demand for high-precision detection of ammonia gas, and also provides technical experience for domestic independent research and development of high-precision detection equipment for trace gases.

Vehicle infrared image target detection is an important way of road environment perception for autonomous driving. However, existing vehicle infrared image target detection algorithms have defects, such as low memory utilization, complex calculation and low detection accuracy. In order to solve the above problems, an improved YOLOv5s lightweight target detection algorithm is proposed. Firstly, the C3Ghost and Ghost modules are introduced into the YOLOv5s detection network to reduce network complexity. Secondly, the αIoU loss function is introduced to improve the positioning accuracy of the target and training efficiency. Then, the subsampling rate of the network structure is reduced, and the KMeans clustering algorithm is used to optimize the prior anchor size to improve the detection ability of small targets. Finally, coordinate attention and spatial depth convolution modules are introduced into the Backbone and Neck respectively to further optimize the model and improve the feature extraction ability of the model. The experimental results show that compared with the original algorithm YOLOv5s, the improved algorithm can compress the model size by 78.1%, reduce the number of params and Giga Floating-point Operations Per Second by 84.5% and 40.5% respectively, and improve the mean average precision and detection speed by 4.2% and 10.9% respectively.

In order to clarify the cavity design methods of thin-disk multi-pass amplifiers, this paper summarizes the different types of thin-disk multi-pass amplifiers and concludes that there are four fundamental design concepts: (1) 4f relay imaging, (2) resonant cavity design/optical Fourier transform, (3) near-collimated beam transmission, and (4) others. Each amplifier design method is described and the current status of its research is listed in as much detail as possible. By comparing the four types of disk multipass amplifiers, it is found that the varying methods have distinct advantages and disadvantages. 4f relay imaging requires a vacuum environment to avoid gas ionization at the focal point, making the mechanics and adjustment more difficult; the resonant cavity design/optical Fourier transform concept multi-pass amplifier has a small spot at the mirrors, making it more suitable for lower energy multi-pass amplifiers; The near collimated beam transmission method has great development potential because it does not require a vacuum environment, but accurately controlling the surface shape of the thin-disk is difficult while the laser is operating. Therefore, from the perspective of laser design, it is necessary to continue to optimize the design of the thin-disk multi-pass amplifier to increase its breadth of applications and realize the sustainable expansion of output energy.

In order to better preserve high-frequency information in demosaicing multispectral images, this paper proposes a new demosaicing method for multispectral images based on an improved guided filter. This method first models the strong correlation between adjacent pixels based on the autoregressive model, gradually estimates the model parameters at each pixel, obtains the optimal estimation value by minimizing the estimation error in the local window, interpolates the sampling dense band G, and generates high-quality guide images. The windowed intrinsic variation coefficient is then introduced into the penalty factor to obtain a weighted guide filter with edge sensing ability and to reconstruct the remaining sparse sampling bands. Finally, the CAVE dataset and the TokyoTech dataset are used for simulation. The experimental results show that compared with the five mainstream band multispectral image demosaicing methods, the peak signal-to-noise ratio and structure similarity of the reconstructed image in the CAVE dataset and the TokyoTech dataset are improved by 3.40%, 2.02%, 1.34% and 0.30%; and 6.11%, 5.95%, 2.28% and 1.42%, respectively. The local structure and color information of the original image are also better preserved, and the edge artifacts and noise are reduced.

The concentrating solar simulator can obtain high-power convergence of solar radiation spots, which has important applications in the fields of solar thermal power generation and thermochemical research. To obtain uniform solar radiation spots, a free-form condenser design method based on non-imaging optics is proposed, and its design principle and specific method are described. A freeform condenser is designed in comparison to a non-coaxial ellipsoidal condenser with the same containment angle, and the correctness of its method of design is verified by simulation analysis. The simulation results show that when a xenon lamp with a rated power of 6 kW is used as the light source, the single-lamp solar simulator composed of a freeform condenser can produce a spot with an average irradiance of 274.4 kW/m² in the target and a diameter of 60mm. The spot’s unevenness decreases from 18.28% to 5.69% compared with that of a non-coaxial ellipsoidal solar simulator. The seven-lamp solar simulator can produce a spot with an average irradiance of 1.65 MW/m², with a spot unevenness that decreases from 13.19% to 5.49%.

Optical path absorption spectroscopy is an important branch of absorption spectroscopy. In recent years, there has been a proliferation of optical path absorption spectroscopy techniques based on different light source technologies, absorption cavity technologies, and detection methods. As the demands on detection sensitivity and absorption optical path length increased, optical path absorption spectroscopy techniques based on the principle of enhanced absorption emerged, including integrated cavity spectroscopy (ICOS), cavity-enhanced absorption spectroscopy (CEAS) and cavity ring-down spectroscopy (CRDS). Enhanced absorption spectroscopy is advantageous for its high spectral resolution, high sensitivity, fast response time, and portability, but it presently lacks a unified concept and clear classification criteria. This paper compares the development history of absorption spectroscopy techniques and clarifies the concept of their multi-optical path. Based on whether resonant absorption occurs in the absorption cavity, the concept of absorption spectroscopy techniques based on resonance is proposed, and the current research status of resonant absorption spectroscopy techniques is analyzed and summarized, and the applications of this technique in various fields are outlined. Finally, the future development of key technologies in resonance absorption spectroscopy is envisioned.

Underwater polarized light with certain distribution characteristics is formed when sunlight is scattered by the atmosphere and refracted by the surface of the water. The resulting underwater polarization distribution pattern can be used in navigation. In this paper, an air-water model is proposed to calculate the polarization pattern of sky light under varying wave conditions and simulate the underwater polarization distribution pattern under the influence of wave refraction. Distribution images are simulated for underwater polarization’s degree and angle in conditions with calm water, sinusoidal waves and random waves with different solar altitude angles. The results are verified using underwater experiments. The comparison of the polarization distribution pattern under the waves and that under the calm water show that the proposed model can accurately characterize the characteristics of the polarization distribution pattern under typical wave surfaces, providing a theoretical basis for improving the environmental adaptability of underwater polarization navigation under fluctuating water surface conditions.

To solve the frequent problem of false alarms caused by complex background clutters in infrared small-target detection, a novel detection method based on \begin{document}${L_{1 - 2}}$\end{document} spatial-temporal total variation regularization is proposed. First, the input infrared image sequence is transformed into a spatial-temporal infrared patch-tensor (STIPT) structure. This step can associate the spatial and temporal information by using the high dimensional data structures in the tensor domain. Then, weighted Schatten p-norm and \begin{document}${L_{1 - 2}}$\end{document} spatial-temporal total variation regularization are incorporated to recover the low-rank background component to preserve the strong edges and corners, which can improve the accuracy of sparse target component recovery. Finally, the STIPT structure can be transformed into an infrared image sequence by the inverse operator, and an adaptive threshold segmentation is used to obtain the real target. The method is verified using a contrast test that incorporates five methods, and the experimental results show that the false alarm rate by this method decreases to 71.4%, 71.7%, 68.5%, 74.3% and 20.47% compared with the Maxemeidan, Tophat, LIRDNet, DNANet and WSNMSTIPT algorithms. The time cost also decreased to 42.4%, 82.9% and 28.7% of that of the Maxemeidan, DNANet and WSNMSTIPT. The extensive experimental results demonstrate the superiority of this method in detection performance, which can greatly improve the accuracy and efficiency of target detection with complex background clutters.

In the positioning process of aerial cameras with large inclination angles, the influence of height error in the earth ellipsoid model can be effectively solved with the help of a digital elevation model. This is very important for obtaining accurate ground coordinates, especially elevation. Firstly, the orientation of the line-of-sight angle of geographical coordinates in the geographic coordinate system is solved by transforming homogeneous coordinates according to the position and attitude information of the carrier aircraft and the frame angle information of the aerial camera, and then the longitude and latitude of the target point are determined by a digital elevation model. To overcome the tedious nature of calculating target elevation and the non-convergence in the imaging process, a fast iterative method is proposed to iterate over the target elevation’s value. The difference between the light elevation of the visual axis and the ground elevation is calculated by halving the target elevation. The median elevation difference is calculated iteratively until it is less than a certain threshold. Finally, Monte Carlo analysis was used to analyze the error terms in the whole imaging process. When the convergence threshold is 1/10 DEM in grid accuracy, the iteration efficiency increases by 50% and the convergence speed is greatly improved. Through the calculation of the digital elevation model, when the flight height is 15,409 meters and the camera frame’s angle is greater than 74°, a mountainous area’s target circular error probability is less than 200 m which meets the real engineering needs.

In gravitational wave interferometric detection, the problem of stray light has received long-term attention. In the spaceborne gravitational wave detection program, the laser light emitted by the local interferometer produces backward coherent stray light when passing the telescope while the radiation from space that is incident to the spacecraft produces forward incoherent stray light. Forward incoherent stray light has received less attention at this point, but it is a necessary factor of gravitational-wave telescope design. Therefore, this paper studies stray light produced by space gravitational wave telescopes in orbit. First, the annual solar angle is calculated according to the orbital data of the three-star satellite formation of the Taiji Project, and the solar radiation around the 1064 nm band is evaluated. The baffle shadowing function is derived, which satisfies the requirement for the baffle design. The telescope is then modeled optically and mechanically and scatter measurements are conducted for critical optical components. Finally, the stray light reaching the pupil of the telescope is determined based on the energy of the incident sunlight. The results show that when the angle between the incident light and the optical axis is 60°, the stray radiation at the exit pupil is 4.27×10⁻¹³ W, and the corresponding point source transmittance is 8.7×10⁻⁹ which meets the requirement for space gravitational waves to detect extremely low levels of stray light.

In order to improve the traditional attitude measurement accuracy of star sensors, interference angle measuring technology can be combined with a traditional star sensor. Based on the centroid positioning technology of traditional star sensors, the light intensity information of star image points is subdivided to break through the accuracy limitation of centroid positioning and form a highly precise interferometric star sensor with a large field of view. In this paper, the factors that restrict the Angle measurement accuracy of interferometer sensors are deeply studied with particular interest given to the influence of interference fringe segmentation error on angle measurement accuracy. Through research and analysis, we conclude that the asymmetry error is not the main factor affecting the angle measurement accuracy of interferometric sensors. When the mismatch error between the Mohr fringe period and the overall optical dimension of the optical wedge array is less than 1%, the single-factor angle measurement error is less than 0.01". For non-orthogonal error between Mohr fringe orientation and an optical wedge’s array arrangement direction, the accuracy error of single-factor angle measurement is sure to be less than 0.01 when the fringe rotation angle is less than 0.1°. Therefore, the above two main errors should be suppressed in the production and assembly so that the measurement accuracy of the interferometer sensor is closer to the high-precision theoretical value.

The Taiji program is a key task for China's space gravitational wave detection, and as an important part of space gravitational wave detection, the telescope's performance will directly affect the accuracy of gravitational wave detection. The existing typical space gravitational wave telescope structure has high secondary mirror sensitivity, which is difficult to meet the manufacturing and adjustment tolerance requirements of larger aperture space gravitational wave telescopes, especially the tolerance requirements for in-orbit stability. In order to solve the above problems, firstly, a new optical system structure of space gravitational wave telescope with intermediate image plane set between three and four mirrors is proposed to reduce the sensitivity of the secondary mirror. Combined with the theoretical method of Gaussian optics, the initial parameters of the structure of the new telescope are theoretically analyzed and calculated. Secondly, through the optimization design, a telescope optical system with a pupil diameter of 400mm, a magnification of 80 times, a scientific field of view of ± 8μrad, and a wavefront error RMS value of better than 0.0063λ was obtained. Finally, the sensitivity evaluation tolerance allocation table of the telescope system is established, and the tolerance of the existing telescope structure and the new telescope structure are compared and analyzed. Compared with the existing telescope structure, the sensitivity of the new telescope structure is reduced by 30.4%. The results show that the new telescope structure has the advantage of low sensitivity, which provides an optimal scheme for the design of space gravitational wave telescopes.

In this paper, an image super-resolution reconstruction algorithm SMRAN based on residual attention network is proposed to solve the problems of low resolution, less texture information and blurred details of colorectal endoscopic images. Images in the colorectal polyp endoscope image dataset PolypsSet are selected as raw data for experiments. A convolutional network is built to extract the shallow features of the low-resolution image and a Res-Sobel block is designed to enhance the edge features of the image. The multi-scale feature fusion block MEB is designed by introducing convolution kernels of different sizes to adaptively extract image features of different scales to obtain effective image information. The Res-Sobel block and multi-scale feature fusion module block MEB are connected through the residual attention network. Finally, the high-resolution image is reconstructed by the sub-pixel convolution layer. When the amplification factor is ×4, the performance of the proposed algorithm on the test set are as follows: the peak signal-to-noise ratio PSNR is 34.25dB and the structural similarity SSIM is 0.8675. Comparing with the traditional bicubic interpolation algorithm and commonly used deep learning algorithms such as SRCNN and RCAN, the proposed algorithm SMRAN shows better super-resolution reconstruction results on colorectal endoscopic images.

In the space gravitational wave detection Taiji mission, a heterodyne laser interferometer is used to detect gravitational wave signals in the middle and low frequency bands. In the Taiji mission, the laser interferometry system is composed of multi-channel interferometers, which involves the phase acquisition and readout of multiple sets of the interference signals. Therefore, the multi-channel phase measurement system is one of the key core technologies of the space laser interferometry. In this paper, a multi-channel phase measurement system is proposed, designed and tested based on the requirements of the Taiji mission and its ground-based laser interferometry experiments. First, the hardware and software design of the multi-channel phase measurement system is given, including hardware architecture design, phase measurement algorithm based on digital phase-locked loop and its implementation on FPGA, software architecture design, etc. Second, a time-domain functional tests of the multi-channel phasemeter are performed, which includes the phase accuracy and linearity. The results show that the dynamic and static phase linearity and accuracy of the multi-channel phase measurement system under different working conditions are good. Finally, the frequency domain noise tests of different channels, different frequencies and different amplitudes are carried out on the multi-channel phasemeter. The results show that the phase noise level of the multi-channel phase meter designed in this paper is better than \begin{document}$ 2{\text{π}} \mu rad/\sqrt{H\textit{z}} $\end{document} in the frequency band of 0.1 mHz−1 Hz. There is good consistency between different channels, and the phase noise introduced by channel differences or ADC chip differences is negligible in the target frequency band; for any interference signal with a frequency between 5−25 MHz, the phasemeter can be in the target frequency band meet the requirements within. Therefore, the multi-channel phase measurement system meets the requirements of space gravitational wave detection and ground-based interference experiments. At the same time, the research results of this paper also provide an experimental basis for expanding the phase measurement system with more channels in the future.

Wet transfering two-dimension (2D) material to semiconductor substrate is a common method to prepare hetero-junction photodetector. In the process of wet transfer preparation of hetero-junction, different preparation details have significant effects on the properties of the hetero-junction formed by 2D materials and semiconductors. In this paper, a series of identical Gr/Si hetero-junction devices were prepared by wet transfer method, the relationship between its preparation technology and the voltage-current characteristics was studied in detail. The experimental results show that the gradient drying process can significantly reduce the dark current of the Gr/Si hetero-junction photodetector, the optimal drying temperature peak is 170 °C, and the leakage current basically no longer changes above 170 °C. The surface impurities and residual water in the inter-layer of Gr/Si van der Waals hetero-junction has a significant effect on the leakage current of the hetero-junction. The selective etching and annealing process of Gr/Si van der Waals hetero-junction can also reduce the leakage current greatly . Therefore, suitable drying process, selective etching process and annealing process are necessary in the preparation of Gr/Si hetero-junction photodetector. These results can give reference for the fabrication of two-dimensional material hetero-junction devices by wet transfer method.

The polarization-multiplexing of a laser based on a medium with a large gain bandwidth and a high thermal conductivity can benefit dual-frequency and dual-comb lasers’ spectral bandwidth and power. This paper presents a demonstration of the polarization-multiplexing of a laser based on a bulk Yb:CALGO crystal. The polarization-multiplexing is realized by sandwiching the gain crystal within two 45˚-cut birefringent crystals, forming two orthogonally polarized beams with spatial separation inside and allowing the system to pump the laser at the waist of the cavity mode for more efficient pumping. The laser outputs watt-level power with a slope efficiency exceeding 30%. A dual-frequency operation with terahertz frequency separation is realized by inserting an etalon into the cavity.

The Taiji Project is a space gravitational wave detection mission proposed by the Chinese Academy of Sciences, which uses the method of laser differential interference to detect pm-level displacement fluctuations caused by gravitational waves between satellites. In order to eliminate the phase measurement error caused by the dissynchronization of the clock between satellites, Taiji Project intends to use the sideband multiplication transfer scheme to measure and eliminate the inter-satellite clock noise. This paper discusses the requirements, principles, and methods of inter-satellite clock noise transmission of the Taiji project, and designs experiments for principle verification. By building an electronics experiment, the limit value of the clock noise of the two systems was tested, the relevant parameters of the experiment were determined, and the principle of the sideband multiplication transfer scheme was verified by further optical experiments. The experimental results show that the clock noise cancellation scheme and related parameters proposed in this paper are reasonable and feasible, and are suitable for the needs of Taiji project. Moreover, in the 0.05 Hz-1 Hz frequency band, the suppression effect of inter-satellite clock noise is better than 2π×10^-5 rad/Hz^1/2, which meets the noise requirements of Taiji pathfinder and lays an experimental and theoretical foundation for the design of clock noise transmission scheme and parameter of future Taiji Project.

Flow cytomicrographic analysis is an important development in the automatic identification of planktonic algae in the water column, where the deformation of microscopic images under rapid injection conditions affects the accuracy of automatic identification of planktonic algae. Based on a microfluidic-microscopic imaging system for planktonic algae, the effect of flow rate on the deformation of microscopic images was investigated by analysing the deformation of algal cells and image clarity at different injection flow rates.Based on the principle of deformation caused by a rolling shutter photographing a moving object, a method of image deformation correction with unidirectional offset pixels is proposed and analysed in comparison with images acquired under static conditions of algal cells.The experimental results showed that the average values of aspect ratio and sharpness of L. oocystis cell images under static conditions were 1.16 and 116.53 respectively; during the dynamic injection process, the deformation (aspect ratio) of cell images gradually increased and the sharpness decreased as the flow rate increased; the average values of aspect ratio before and after correction were 1.35 and 1.26 respectively at 95 µL/min injection flow rate, and the dispersion of deformation decreased from 0.33 before correction to 0.1. The mean value of aspect ratio before and after correction was 1.35 and 1.26 respectively at 95 µL flow rate.The results provide a method for improving the accuracy of automatic identification of planktonic algal cells in the water column.

We propose cosh-Pearcey-Gauss beams with uniform polarization, which are mainly modulated by a hyperbolic cosine function (n, Ω) and the angles related to uniform polarization (α, δ). Based on angular spectrum representation and the stationary phase method, the Poynting vector, spin and orbital angular momentum in the far zone are studied. The results show that a larger n or Ω in the hyperbolic cosine function can partition the longitudinal Poynting vectors, SAMs and OAMs into more multi-lobed parabolic structures. Different polarizations described by (α, δ) can distinguish their Poynting vectors and angular momentums between the TE and TM terms, though this does not affect the patterns of the whole beam. Furthermore, the weight of the left and right sides of longitudinal Poynting vectors, SAMs and OAMs in TE and TM terms can be modulated by left-handed or right-handed elliptical polarization, respectively. The results in this paper may be useful for information storage and polarization imaging.

In order to realize tunable longwave infrared laser, this paper designs a ZGP temperature tuned longwave infrared optical parametric oscillator. Using a Ho:YAG laser with the center wavelength of 2097 nm to pump ZGP crystals with different phase matching angles, the laser with a segment continuously tunable range of 7.53−8.77 μm is realized in the temperature range of 15−30°C, with a total tuning range of 1.24 μm. The output power of ZGP - OPO is greater than 1.503 W over the entire tuning range. The output power is 1.503 W at the idler wavelength of 8.77 μm, and the corresponding slope efficiency and optical conversion efficiency are 12.19% and 6.53%, respectively. The experimental results show that temperature tuning of ZGP is an effective technical method to obtain continuously tunable long-wave infrared laser. The research of this experiment has potential application value in the field of engineering of tunable long-wave laser.

Optical encryption materials for pattern information have been widely used in anti-counterfeiting, information encryption and storage, and structural color metasurface based on anisotropic functional reuse has been developed. The optical encrypted metasurface based on one-dimensional grating diffraction requires the processing of mask or unit structure one by one, resulting in low limiting efficiency. The structure uniformity of traditional ablated LIPSS is poor, which affects the device performance. Based on the above problems, an optical metasurface machining method based on the modified structure of picosecond laser direct writing phase change material Ge₂Sb₂Te₅ is proposed. Firstly, the dispersion performance of the prepared GST modified gratings was characterized, and combined with the polarization dependence of the modified gratings, the angle-multiplexed information encryption metasurface was designed, and the metasurface prepared by the proposed method was further demonstrated. It realizes the performance of encryption under natural light, selective decryption reading and dynamic display under strong light. Compared with the traditional processing method, the proposed method can generate a series of grating structures in the form of simultaneous printing in a direct writing process, which improves the processing efficiency. At the same time, the grating structure obtained by processing is uniform and consistent, which improves the color rendering effect. The modified grating with 16° difference in orientation Angle realizes the selective information reading without crosstalk, and the obtained structure color is uniform and bright. The processing strategy proposed in this paper has a profound application prospect in the fields of anti-counterfeiting, information encryption storage and wearable flexible display devices. The processing strategy proposed in this paper has a profound application prospect in the fields of anti-counterfeiting information encryption storage and wearable flexible display devices.

In order to eliminate the uncertainty caused by the inclination of the beam, a dual polarization laser Doppler velocimetry system is established in this paper. The system uses a dual beam dual probe structure to detect the motion information of the object. Firstly, the included angle of the two beams is accurately obtained through the rotation experiment. For any beam inclination, the dual probe device is used to collect the scattered beam from the moving object surface, and the Doppler frequency shift of the two interference signals is obtained by combining the dual polarization optical path structure. Then, the refined framing algorithm is innovated to demodulate the two interference signals in real time, and the real speed of the object is obtained by synthesizing the two speed components. The experimental results show that the average error between the measured value and the theoretical value can reach 1% ~ 5% when the speed is within the range of 10 mm/min ~ 1500 mm/min. In the process of non-stationary motion, the RMSE average of V-T image corrected by thinning and framing algorithm is 1.19mm/min. The structure of the system meets the requirements of stability and reliability, high accuracy and strong anti-interference ability in speed measurement.

In this paper, a metamaterial Fano resonance design method based on deep learning is proposed to obtain high-quality factor (high-Q) resonances with desired characteristics, such as linewidth, amplitude, and spectral position.The deep neural network is used to establish the mapping between the structural parameters and the transmission spectrum curve, and the forward network is used to predict the transmission spectrum.The inverse network achieves the on-demand design of high Q resonance. The low mean square error ( MSE ) is achieved in the design process, and the mean square error of the training set is 0.007.The results indicate that compared with the traditional design process, using deep learning to guide the design can achieve faster, more accurate, and more convenient purposes.The design of Fano resonance can also be extended to the automatic inverse design of other types of metamaterials, significantly improving the feasibility of more complex metamaterial designs.

To improve the extinction ratio of a polarization beam splitter, we propose a dual-slot ultra-compact polarization splitter (PBS) consisting of a hybrid plasma horizontal slot waveguide (HSW) and a silicon nitride hybrid vertical slot waveguide (VSW). The coating material is silicon dioxide, which can prevent the oxidation of the mixed plasma and also facilitate integration with other devices. The mode characteristics of the HSW and VSW are simulated by using the finite element method (FEM). At suitable HSW and VSW widths, the TE polarization modes in HSW and VSW are phase-matched, while the TM polarization modes are phase mismatched. Therefore, the TE mode in an HSW waveguide is strongly coupled with a VSW waveguide by adopting a dual-slot, while the TM mode directly passes through the HSW waveguide. The results show that PBS achieves an extinction ratio (ER) of 35.1 dB and an insertion loss (IL) of 0.34 dB for the TE mode at 1.55 μm. For the TM mode, PBS reached 40.9 dB for ER and 2.65 dB for IL. The proposed PBS is designed for the 100 nm bandwidth, high ER, and low IL, which can be suitable for photonic integrated circuits (PICs).

The decoherence of temporal quantum correlation is explored in a voltage-controlled quantum dots molecule in a cavity. The temporal correlation in the hybrid system is studied by Leggett-Garg inequalities. The inequality violations can be interpreted as the existence of temporal quantum correlation during dynamical evolution. The temporal quantum correlation is enhanced by its electron tunnel’s strength and cavity frequency detuning. It is found that there is no temporal correlation in the regions where the values of spatial quantum correlation are zero and the maximal violations occur in conditions with high values of quantum coherence. In contrast, spatial coherence can persist at times when no violation is detected. The open quantum system approach is used to investigate the environmental effects on inequality violations. The temporal correlation is suppressed by the spontaneous decay of the quantum dots and cavity leakage. These results are serviceable in processing quantum information in hybrid quantum systems.

In order to improve the quality value (Q) to enhance the coupling between light and matter. In this paper, a dielectric metamaterial with simple structure, low fabrication requirements was proposed. It can excite symmetric protected bound states in the continuum (BICS). The dielectric metamaterial has a planar nanopore plate composed of tetrameric pores. By changing the position of the nanopores, the symmetrical protection BIC can be transformed into the symmetrical protection quasi BIC(QBIC), and then two high Q value Fano resonances can be induced. Through simulation calculation, the Fano resonance Q value can reach 1e⁶ when Δ=3 nm. Then, the far-field radiation of QBIC and Fano resonance is decomposed into the contributions of different multipole components. Based on the scattering power and electric field vector distribution, it can be found that the dielectric metamaterials λ₁ Fano resonance with high Q value is mainly due to magnetic quadrupole and toroidal dipole, while λ₂ Fano resonance has high Q value is mainly due to the toroidal dipole. Finally, the influence of nanopore side length and nanopore filling material on the two Fano resonances is analyzed and calculated. The research in this paper can provide theoretical guidance for the future research and preparation of high Q value optical response devices.

In this paper, the coplanar excitation of terahertz Spoof Surface Plasmon (SSP) realized by using a single-layer grating meta-surface coupling method is proposed, which overcomes the disadvantages such as the inconvenience of reflection measurement when applying the medium couplers. The periodic grating and terahertz SSP composite structure are simultaneously constructed on the monolayer metal structure. When the terahertz waves are incident vertically, the wavevector of grating structures and the wavevector of SSPs are matched, and the SSP mode can be excited. The high Q value resonant peaks can be generated in the transmission spectrum, and its factor Q can reach 1923. The effects of the structural parameters on the grating-coupled meta-surface transmission spectrum and dispersion characteristics are also analyzed. In addition, based on the high Q resonant peak in the transmission spectrum of the designed structure, the high sensing sensitivity is about 67 GHz/RIU at the resonant center frequency of 0.22 THz. The structure proposed in this paper, which realizes terahertz SSP excitation and high Q sensing by treating a single-layer meta-surface structure, exhibits great application potential in many practical applications.

In order to improve the stability of an electrowetting liquid lens’s zoom, based on the research of glass lenses, a statistical data-based index of liquid lens zoom stability and liquid lens repeated zoom accuracy is proposed. An experimental method is presented to optimize the structural parameters and materials of the liquid lens. Firstly, the main factors affecting the accuracy of a liquid lens’s repeat zoom were obtained through preliminary experimental research, including the polar solution volume, taper and non-polar solution viscosity. Secondly, taking the accuracy of the liquid lens’s repeat zoom and zoom range as evaluation indicators, it was found that the relationship between the accuracy of the liquid lens’s repeat zoom and the voltage is not monotonic, and that it rises first and then falls. On this basis, through the range analysis and comprehensive balance method, the primary and secondary factors and the optimal combination of parameters is obtained. After that, orthogonal experiments were used to optimize the design parameters. Finally, the effectiveness of this method was verified by experiments. The experimental results show that the repeat zoom accuracy of the optimized liquid lens is 0.2 m⁻¹, and the zoom range is −15.2−5.85 m⁻¹ over the voltage range of 0 to 230 V. It basically meets the requirements of stable and reliable liquid lens zoom, high precision, and large zoom range.

Polarization imaging, a novel photoelectric detection technology, can simultaneously acquire the contour information and polarization features of a scene. For specific application scenarios, polarization imaging has the excellent ability to distinguish different objects and highlight their outlines. Therefore, polarization imaging has been widely applied in the fields of object detection, underwater imaging, life science, environmental monitoring, 3D imaging, etc. Polarization splitting or the filtering device is the core element in a polarization imaging system. The traditional counterpart suffers from a bulky size, poor optical performance, and being sensitive to external disturbances, and can hardly meet the requirements of a highly integrated, highly functional, and highly stable polarization imaging system. A metasurface is a two-dimensional planar photonic device whose comprising units are arranged quasi-periodically at subwavelength intervals, and can finely regulate the amplitude and phase of the light field in different polarization directions. Polarization devices based on metasurface are featured with compactness, lightweight and multi-degree freedom, offering an original solution to ultracompact polarization imaging systems. Targeted at the field of polarization imaging, this paper illustrates the functional theory, developmental process and future tendency of related metasurfaces. We discuss the challenges and prospect on the future of imaging applications and systematic integrations with metasurfaces.

In order to overcome the adverse effects of near-ground turbulence on the imaging quality of the optical systems at imaging distances of tens to hundreds of meters, an optical imaging system based on a long focal length telescopic objective lens and an integrated adaptive module is designed. With a system center height of 1.9 m and the imaging distance of 50~200 m, the outdoor imaging experiment of a resolution plate is carried out. The experimental results show that the influence of turbulence on imaging quality is obvious at medium and long distances of 50~200 m near the ground. The experimental system can effectively overcome the influence of turbulence at different distances and improve the consistency of image resolution and clarity. As the imaging distance increases, the influence of turbulence increases, and the system’s correction ability and the imaging quality decrease. The imaging resolution of the system can reach 0.5 mm at an imaging distance of 100 m. Cracks on the surface of a concrete model are observed and corrected at a distance of 200 m. The experimental results show that the system can suppress the influence of turbulence and improve the clarity of the image, which verifies the practical application ability of the system.

Under conditions with large temperature differences in an infrared optical system, its imaging quality will deteriorate due to severe temperature changes. Large field-of-view medium-wave infrared cameras for airborne forest fire monitoring work in drastically changing environments. The system also has high requirements for stray radiation. In order to ensure that the optical system performs stably and with good imaging quality in the large field-of-view and the required large temperature range, a cooled medium-wave infrared optical system is designed based on athermalization and the comprehensive evaluation method of stray radiation based on noise equivalent temperature difference. The optical system consists of 6 lenses and 1 filter whose working wavelength is 3.7~4.8 μm; its F-number, focal length, and field of view are 2.5, 62.5 mm and 14.36°×10.87°, respectively. The pixel resolution of the medium-wave uncooled detector is 640×512. By using a combination of silicon and germanium materials and reasonably distributing the optical power, achromatic aberration and athermalization designs are realized. Through cold reflection optimization and cold aperture matching, stray radiation noise in the system is well-suppressed. By a bit of aspheric optimization, higher-order aberrations are corrected based on the requirements. The results show that the imaging quality of the optical system is stable and good in the temperature range of −55~+70 °C.

Multiple sub-aperture interference imaging enables the images formed by the sparse aperture imaging system to have a higher resolution after the cophasing error is corrected. In this paper, the MTF and surface target imaging of the system are analyzed with a Golay3 sparse aperture imaging system as the research object when there are different piston and tilt errors among the sub-apertures. A Golay3 sparse aperture imaging system was developed to carry out an imaging experiment with the USAF1951 resolving power test target as the area target. Three-aperture synthetic imaging is achieved by adjusting the position of the plane mirror in the light beam deflection and the adjustment module to correct the piston and tilt errors of the sub-apertures. The results of a theoretical analysis are then verified. According to calculations, the developed system’s angular resolution of 1.38 urad is close to the equivalent single-aperture imaging system’s theoretical resolution of 1.18 urad. The developed Golay3 sparse aperture imaging system can correct the cophasing errors and improve the imaging resolution.

In order to realize the non-contact high-precision measurement of high-temperature temperature fields such as the tail flame, combustion and explosion of aerospace engines, a static interferometric high-temperature temperature field imaging and detection method is studied. Firstly, a static interference high-temperature temperature field detection system is designed. Using a theoretical analysis of the measurement principle of high-temperature temperature fields, the relationship between the optical path difference and the temperature at the lowest point of high-temperature interference signal intensity is studied; Secondly, according to the response band of the visible light area array detector and the common temperature range, a static interferometric Savart prism is designed, and temperature field imaging is realized by using it for one-dimensional scanning; Finally, the optical system is designed and the corresponding relationship between the minimum optical path difference of the interference and the temperature is obtained by fitting. From this, the linear fitting formula is obtained. Simulations are conducted to verify the interference signal image where the temperature field after passing through the system reaches the area detector. The static interferometric high-temperature temperature field detection method can achieve the high-precision detection of 1000 K−3000 K temperatures. In the linear region, the temperature measurement resolution is 1.4 K and the temperature measurement relative error is better than 0.8%. This research lays the foundation for high-precision high-temperature temperature field imaging in the military and civilian fields.

In order to effectively suppress the interference of CO₂ radiation from 4.3 μm attachment on 3 μm−5 μm MWiR target signal, based on the Needle random intercalation optimization algorithm, an accurate inversion correction model for the growth error of multi-layer ultra-thick Ge/Al₂O₃ films under quartz crystal monitoring is established by the electron beam evaporation method, thus realizing the design, the accurate inversion and the accurate preparation of MWiR notch filter; in order to solve the problem that the surface profile of the MWiR notch filter changes greatly, the preset substrate surface method is used to realize the low surface profile regulation of MWiR notch filter. The results show that the high refractive index Ge film has good deposition stability with the increase of coating time, while the deposition scale factor of low refractive index Al₂O₃ thin film changes up to 11.9% in a regular gradual trend. For the prepared MWiR notch filter, the average cut-off transmittance is <0.3% at 4.2 μm−4.5 μm, and the average transmittances are >95% at 3.5 μm−4.05 μm and 4.7 μm−5.0 μm. The surface profile of the substrate after coating can be effectively controlled in a small range. The film has good adaptability to complex environment, and has successfully passed the environmental test of firmness, high temperature, low temperature and damp heat specified in GJB 2485-95.

A novel photonic quasi-crystal fiber (PQF) sensor based on surface plasmon resonance (SPR) is designed for simultaneous detection of methane and hydrogen. In the sensor, Pd-WO₃ and cryptophane E doped polysiloxane films deposited on silver films are the hydrogen and methane sensing materials, respectively. The PQF-SPR sensor is analyzed numerically by the full-vector finite element method and excellent sensing performance is demonstrated. The maximum and average hydrogen sensitivities are 0.8 nm/% and 0.65 nm/% in the concentration range of 0% to 3.5% and the maximum and average methane sensitivities are 10 nm/% and 8.81 nm/% in the range between 0% and 3.5%. The sensor provides the capability of detecting multiple gases and has large potential in device miniaturization and remote monitoring.

The machining quality and detection accuracy of aero-engine blades have a very important influence on the service life of blades. Aiming at the problem of improving the accuracy of blade detection, a high-precision scanning viewpoint planning method based on structured light was proposed in this paper. Firstly, the coarse model data were obtained by coarse scanning under the overall size of the blade, and the field of view was determined according to the camera resolution and acquisition accuracy. Secondly, the improved Angle Criterion algorithm was used to extract the boundary, and the boundary segmentation points were determined according to the boundary coordinates and the range of visual field. The coarse model was sliced by the section line method of surface, and the internal segmentation points were determined according to the slice results, so as to complete the uniform segmentation of point clouds. Then, a directed bounding box was established for the segmented point cloud data to obtain the coordinates of the center point, and the normal vector was statistically analyzed to determine the orientation of the main normal, so as to generate the viewpoint coordinates of high-precision scanning. Finally, the surface morphology of the blade was tested and verified. The experimental results show that the average standard deviation of the proposed method is reduced by 0.0054mm and the collected viewpoint is reduced by 1/3 compared with the viewpoint acquisition result of the supervoxel segmentation, which has a good application prospect in machining inspection of thin-walled blades.

A filterless microwave photonic phase shifter (MPPS) with a tunable frequency multiplication factor (FMF) and a full 360-deg tunable range is theoretically analyzed and verified by simulation. In the scheme, two parallel Mach-Zehnder modulators (MZM), cascaded with two dual-parallel integrated Mach-Zehnder modulators (DPMZM) by a 2×2 optical coupler (OC), are used to generate the ±1st- to 4th-order sidebands adjustably, and a phase modulator (PM) is used to phase shift one of the two lightwaves. After photodetection, the 2nd- to 8th- order harmonics with a continuously tunable phase shift from 0 to 360-deg can be generated by adjusting the RF driving signal and the DC bias voltage of the DPMZM, and the DC voltage of the PM. Simulation results demonstrate that both 360-deg continuously tunable phase shift and frequency multiplication can be implemented. Large Optical Sideband Suppression Ratio (OSSR) and Electrical Spurious Suppression Ratio (ESSR) of around 20 dB can be obtained. The phase shifter wavelength insensitive performance has been also evaluated by simulation.