The Monte Carlo model of laser scattering in turbid media was established with the help of scattering angle from the cumulative probability density interpolating of the Mie scattering phase function. With the model， the laser multiple scattering in uniform monodisperse polystyrene turbid medium was studied， the influence of turbid media with different optical depths and scattering phase function on laser multiple scattering was explored. By controlling the concentration of 5 μm and 10 μm size polystyrene particles， changing the optical depths of the turbid medium as 2， 5 and 8， the theoretical simulation and experimental side scattering images were obtained and compared. The percentage difference of scattering light intensity attenuation between the simulation and experiment is measured less than 16% under the same medium condition， and the trend of them is basically the same. The simulation can also provide the distribution of light intensity of different scattering orders， and accurately analyze the influence of multiple scattering.

A ground-based Multi-Axis Differential Optical Absorption Spectroscopy （MAX-DOAS） with the characteristics of simple operation， wide range and high sensitivity was constructed， and the time series of HCHO in Huaibei area from October 2019 to May 2020 were obtained continuously. In order to reduce the interference of other gases， different bands are used to retrieve the differential slant column density of HCHO. Through comparison， it was found that when the band of 324~342 nm was selected， the inversion error fluctuation is the minimum， and the concentration of HCHO gas can be obtained precisely. According to the results of HCHO monthly mean values， compared with the before and after COVIN-9 epidemic ，the concentration of HCHO in the COVIN-9 epidemic were decreased by 35% and 23% respectively. The results of daily and weekly variations respectively showed that HCHO concentration in Huaibei area have daily variation characteristics of high in the morning and evening and low in noon， and there is no obvious weekend effect. Combined with Hysplit wind field backward trajectory model， the wind field of high value weather was studied. It was found that during January 12~14 and 18~21， 2020， under the influence of northwest wind field， the pollution transport from Dangshan and other places in Huaibei area will be affected， which will lead to the increase of HCHO concentration. The result of MAX-DOAS measurement of HCHO vertical column density were compared with the OMI satellite data， and it was found that the two methods had good consistency （R2 = 0.87）.

A optical fiber sensor based on modular interference is proposed to measure temperature， refractive index and axial strain. Waist-enlarged taper is formed at the splice point of a single-mode fiber and a double-cladding fiber， which is then cascaded with two long-period fiber gratings with different periods. Due to the mismatch of the mode fields， the higher-order cladding modes are excited，three resonance peaks are formed， which have different sensitivity responses to different parameters. Therefore， by demodulating the wavelength shift of the three resonance peaks and using the coefficient sensitivity matrix， temperature， refractive index and axial strain can be measured.The experimental results show that the sensitivity is 60.07 pm/℃， 6.47 pm/℃ and 103.83 pm/℃ in the temperature range of 25℃~75℃， the refractive index is in the range of 1.335 5~1.359 5， and the sensitivity is -56.64 nm/RIU， 34.02 nm/RIU and -214.84nm/RIU， the axial strain is in the range of 200~1 400 με， the sensitivity is -2.14 pm/με， -3.61 pm/με and -2.59 pm/με.The resolution is 1.29℃， 0.000 42 RIU and 21.42 με respectively. The sensor has high sensitivity， good linearity and other advantages， can be widely used in the field of multi-parameter measurement.

For the space applications of fiber amplifier， the radiation performance of fiber amplifier in radiation environment was investigated experimentally. The evolution laws of output power and spectral character are investigated experimentally by irradiating the gain fiber of an erbium-ytterbium co-doped fiber amplifier with gamma rays. The investigation of the noise characteristics of erbium-ytterbium co-doped fiber amplifier has been carried out by means of frequency spectrum measurement. In the on-line irradiation experiments， with a total radiation dose of 50 krad， it is found that the laser output power， the power of peak wavelength and optical noise decrease with the increment of radiation dose. The noise characteristics of the fiber amplifier are analyzed by the optical noise model after irradiation. Compared with the results before irradiation， the coefficients of relative intensity noise of relaxation oscillation noise and the intermediate frequency part are increased by 1.625×10-4 nW·mW-2·Hz-1 and 3.122×10-4 pW·mW-2·Hz-1， respectively， while the coefficients of shot noise are reduced by 0.900 pW·mW-1·Hz-1 and 0.035 pW·mW-1·Hz-1， respectively. Therefore， it is necessary to pay attention to the suppression of the relative intensity noise for the practical application of fiber amplifier in space.

From the perspective of micro-nano optical fiber coupling， an optical fiber sensor is designed by using single mode optical fiber 2×2 coupling. By changing the tapering parameters of optical fiber coupler， the over-coupling state is reached. At this time， the over-coupling structure of optical fiber itself is affected by the environment， so that the wavelength of light has a higher response to the change of external temperature and strain， realizing the measurement of temperature and strain. In the experiment， optical fiber over-couplers with overcoupling length of 22 000 μm and 22 500 μm are tapered， and their transmission spectra were compared. The temperature and strain sensing tests results show that the lowest wavelength response to temperature is about 104 pm/°C， and the lowest wavelength response to strain is about -21 pm/με.

In order to improve the detection rate， detection speed and scene adaptability of detection methods based on human visual system， a multi-scene infrared dim target dataset is constructed， and an infrared dim target detection algorithm based on visual attention mechanism is proposed. From the bottom-up perspective， the multi-scale gray and variance estimation is proposed to calculate the saliency map and estimate the optimal target size fastly. Then， the candidate targets are extracted using Features from Accelerated Segment Test（FAST） corner detection algorithm， and non-maximum suppression is introduced to reduce redundancy. From the top-down perspective， based on the theory of biological lateral inhibition and cosine similarity， a soft fuzzy adaptive resonance theory network is proposed， and a dim target feature set is constructed to train it. Finally， the candidate target is recognized by the well-trained model. The experimental results show that the proposed method has higher detection rate， faster detection speed and more stable performance in different scenes than five representative methods based on human visual system.

The collaborative application of point cloud data and optical remote sensing image has been widely concerned in the field of remote sensing. In order to accurately register two kind of data and better integrate their advantages， an automatic registration method of point cloud and optical remote sensing image in urban scene is proposed. Firstly， the depth image is generated from point cloud data， that is， 3D data is converted into 2D image. Secondly， the Unet model is used to train the depth image and the optical remote sensing image respectively and get building segmentations. Thirdly， the minimum circumscribed rectangles of buildings are constructed based on the contour set of building segmentation， and the length-width ratio of rectangle is taken as the constraint condition to find Corresponding Points（CPs）. Then， we use the similar triangle principle to find CPs of the rectangle’s center point. Finally， the coordinate of the CPs are substituted into the transformation model to calculate the model parameters， thus the registration is achieved. The experimental results show that the proposed method can achieve better registration effect when it is difficult to match with traditional point feature method， and it is resistant to image translation， rotation and scaling.

The relative radiation correction method for large field of view polarization imaging instrument was discussed. According to the inversion order of the physical quantity of the incident light restored by the detection signal， the relative radiation correction method of the large field polarization imaging instrument based on single pixel radiation response model is proposed. The detector correction， spatial stray light correction， polarization correction and optical system relative transmittance correction are carried out in turn. During the on orbit test， a fast validation method of multi angle observation data based on desert field reflectance method is designed to meet the detection requirements of large field of view polarization imager. The experimental data show that the difference of single point radiation response is less than 4%， and the relative radiometric correction method is reasonable and effective， which provides data basis for on orbit radiometric correction using large amount of statistical method. The method of relative radiometric correction and on orbit fast test provide effective reference for the follwing polarization imaging instruments with large field of view.

In order to solve the problems of low accuracy and long time of pixel matching in online three-dimension（3D） measurement， a pixel matching algorithm based on improved grid motion statistics features is presented. In this method， only one frame of sinusoidal grating is projected onto the measured object， five frames of deformed patterns caused by the moving object with equal displacement are captured by camera， and the corresponding background light field is extracted. Then， the matching pairs of feature points are extracted by fast rotation invariant feature algorithm， and then the mismatching pairs are eliminated by using the improved grid motion statistical feature algorithm. Finally， according to the characteristics of high precision in online 3D measurement， five equivalent phase-shifting deformed patterns are obtained by taking the value of the highest frequency of the statistical displacement， and then the 3D shape of online moving object is reconstructed by using equal step phase-shifting algorithm. Large numbers of experiments verify the effectiveness and feasibility of the proposed method， and compared with the traditional and online FTP algorithm， the proposed method is more robust and can reconstruct the 3D shape with higher accuracy.

Through the analysis of imaging principle， simulation of optical model and construction of the principle prototype， the main factors affecting the calibration accuracy of the autocollimation calibration system in the experimental environment are discussed， and the main issues of the calibration system are put forward， which should be noticed in the design and work， including pixel size selection， image point location algorithm， focus amount calculation and system installation error. According to the analysis results， the calibration error of the principle prototype is corrected. Finally， the calibration accuracy of the principle prototype is less than 0.4 mm， and the calibration accuracy of the rotation in X， Y and Z directions are less than 0.6"， 0.6" and 12" respectively. The relative error of accuracy is better than 0.2%.

To solve the problem of the limited sensitivity， which is due to the poor interaction between the analytes and the localized enhanced electromagnetic field， the terahertz microfluidic sensor based on a metamaterial absorber with the enhanced electromagnetic field interaction is proposed by introducing the microfluidics technology. Owing to the interaction of the sensor and terahertz waves， the magnetic dipole resonances are excited and two significant absorption peaks with the absorption rates over 98% are formed in the range of 0.4~1.4 THz. Meanwhile， with integrating the microfluidic channel， the interaction between the analytes and the localized enhanced electromagnetic field located in the Fabry-Pérot cavity is dramatically enhanced， and the sensor can reach the high sensitivity of 537 GHz/RIU. In addition， the unit cell is designed as the four-fold rotational symmetrical structure， so that the polarization-insensitivitive and the wide range of incident-angle-insensitive properties of the sensor are obtained. The results indicate that the proposed sensor has the characteristics of high sensitivity and polarization-independent， and it exhibits a promising application prospect in the field of label-free trace detection.

In order to realize the free manipulation of terahertz beams， a multi-layer C-type unit structure is proposed to realize the phase control of the transmissionterahertz waves from 0 to 2π at the target frequency based on the Pancharatnam-Berry geometric phase theory. Based on the generalized Snell's law， 2-bit and 3-bit coding metasurfaces are constructed. The scattering angle of the transmissive terahertz beam can be controlled with the incidence of circular polarization wave. By using the Fourier convolution operation in the digital signal processing theory， the four-bit encoding convolution operation is performed on the coding metasurfaces of different periodic sequences to obtain a new coding sequence and realize the free adjustment of the transmission angle of the terahertz wave. The multi-layer C-encoded metasurface unit structure is used to perform rotary encoding to realize the 1st and 2nd order vortex phase plates and generate different orders of terahertz wave vortex beams.

Based on the process of combining atomic layer deposition and focused ion beam cutting and polishing， a multi-layer film-type wave zone plate preparation technology was proposed. Firstly， using the coupled wave theory， it is calculated that the outermost ring width of Al2O3/HfO2， Al2O3/SiO2， Al2O3/Ir and Al2O3/Ta2O5 four material combinations of multi-layer film band plates with X-ray energy of 8 keV and the theoretical diffraction efficiency of the Fresnel zone plate at 15 keV. The influence of the width of the outermost ring and the height of the zone plate on the diffraction efficiency was discussed， and Al2O3/HfO2 was selected as the subsequent laminate preparation. The growth characteristics of Al2O3 and HfO2 films prepared by atomic layer deposition were studied， and the feasibility of preparing single-layer film thickness of 10 nm by atomic layer deposition technology was verified. The experimental results showed that the preparation of Al2O3 and HfO2 films by atomic layer deposition technology was rough The degree of control is 1 nm， the uniformity is better than 1.5%， and the thickness error of the single stack is only 0.416 nm. At the same time， a high-resolution X-ray Fresnel zone plate with an outermost ring width of 10 nm and an aspect ratio of 200 was obtained using focused ion beam cutting and polishing technology.

A silicon based optical waveguide with 1.5% refractive index difference is used for data center interconnect on wavelength-division multiplexing chip. A 4-channel chip with same side， small size and low loss is designed and fabricated for data center transmitter. The size of the chip is 6.6 mm×2.2 mm， the minimum insertion loss is less than 2.33 dB， the 1 dB bandwidth is more than 11.35 nm， the polarization dependent loss is less than 0.14 dB， and the wavelength accuracy deviation is less than 0.38 nm. The optical performance can meet the wavelength-division multiplexing commercial specifications of the data center optical interconnect.

Organic inorganic hybrid perovskite material （CH3NH3PbX3） has been widely used in solar cells， photodetectors， light-emitting diodes and lasers due to its excellent photoelectric properties， such as high carrier mobility， direct band gap coefficient and high photoelectric conversion efficiency. However， the stability of organic-inorganic hybrid perovskite materials is a difficult problem for its practical application. In this paper， we discuss the influence of external environmental factors （water and oxygen， temperature， light， etc.） on the stability of organic-inorganic hybrid perovskite materials systemically. And the main research approaches to improve and enhance the stability of perovskite materials at this stage are summarized， such as improving synthesis methods， ion doping， device packaging and other means， and also the effect on the performance of photodetector. Finally， the challenges and development strategies of the neighborhood are proposed.

Firstly， the electronic structure control methods of photocatalysts based on two dimensional （2D） materials are briefly reviewed， including thickness control， element doping， defect engineering and heterojunction design， etc. Secondly， it is mainly introduced that the research progress of heterogeneous junctions composed of 2D materials and other semiconductor interfaces with different dimensions due to the unique advantages of heterogeneous junctions in reducing the rate of photoelectron hole recombination. Then the applications of new 2D photocatalytic materials in hydrogen evolution， CO2 reduction， nitrogen fixation and pollutant degradation are introduced. It is shown that， compared with bulk materials， 2D materials have higher specific surface area， a large number of active sites on the surface， more effective separation of carriers in the catalyst， appropriate energy band structure， and adjustable light absorption zone， etc. At last the current research status and challenges are briefly summarized， and the prospect of application of 2D materials in photocatalysis is prospected .

In order to study the infrared stealth effect of photonic crystal films in practical application scenarios， photonic crystal films and low emissivity films with mid- and far-infrared stealth performance were selected， and the engine compartment of a Jeep was taken as the object of study to analyze the effects of self-radiation and radiation from the reflected environment on the stealth effect. A photonic crystal film with mid- and far-infrared stealth effects was designed and fabricated， and then the effects of the films on the stealth effect of the engine compartment were tested during daytime and nighttime， respectively. The results show that solar radiation has less influence on the mid- and far-infrared stealth effect of photonic crystal films， and that photonic crystal films can better achieve object and background fusion. The work demonstrates that photonic crystals are better than low emissivity films in mid- and far-infrared stealth.

At room temperature， CuO nanowires were prepared on Cu substrate by solution method. Subsequently ZnO nanoparticles were grown on the surface of the CuO nanowires by solvothermal method to construct CuO/ZnO composite nanowires heterostructures. The morphology， structure and element composition of samples were characterized by using scanning electron microscope， transmission electron microscope， X-ray diffractometer and X-ray photoelectron spectroscopy. The results show that CuO/ZnO composite nanowires are composed of ZnO nanoparticles and CuO nanowires. Under simulated sunlight， the photocatalytic performances of the samples were studied by using Methylene Blue （MB） solution as the simulated pollutant. As a result， compared with pure CuO nanowires， CuO/ZnO composite nanowires can make the photodegradation efficiency of MB solution up to 40%， and display better photocatalytic activity. The research on photocatalytic mechanism indicates that the enhancement of the photocatalytic activity of CuO/ZnO nanocomposites is mainly due to the p-n heterojunction formed by the combination of CuO and ZnO， which effectively promotes the separation of photogenerated carriers..

Attosecond pulse light source， born at the turn of 21st centruy， is a fully coherent light source with attosecond-temporal and nano-spatial resolution， leading to the remarkable progress and breakthroughs in attosecond science in the past two decades. New research methods and important innovation opportunities in physics， chemistry， biology， materials， information and other fields have emerged with the advent of attoseond pulse. This review surveys the important efforts aimed at developing attosecond pulses， mainly summarizes the key technologies and status of high-order harmonics， attosecond pulse generation and attosecond pulse measurement， and presents the development prospects of attosecond pulse research in the end.