Ultraviolet ultrashort pulses have important application value in the fields of ultrafast science and strong field physics due to their short wavelength,excellent focusing characteristics, and high peak power. Excimer laser gas as gain medium has unique advantages in amplifying ultraviolet ultrashort pulses, so using excimer lasers to amplify ultraviolet ultrashort pulses to obtain high-intensity laser output provides a new possibility for the application of ultraviolet lasers. This article introduces the features of excimer laser amplification briefly firstly, then describes the ultraviolet ultrashort excimer laser technology in units based on the amplification characteristics of excimer, and at last describes the measurement of deep ultraviolet ultrashort pulse duration as well.

There exists various defects during the growth of large-size YAG crystals, and dislocation is one of the main defects. Dislocation can cause stress birefringence, decrease the optical uniformity, increase optical losses, shorten the work life of the crystal and so on, therefore, it is very important to grow YAG crystal without dislocation or with low dislocation for the development of high-efficiency solid-state laser. This paper summarizes the research progress of dislocation in YAG crystal at home and abroad in the recent 40 years, including the research on dislocation in YAG crystal by chemical etching method, the decoration method, synchrotron radiation method, stress birefringence method, X-ray micro tomography and light scattering tomography, as well as the application examples of TEM and SEM, and also introduces the effect of crystal growth process on dislocation density and distribution in crystal. It provides a reference for the dislocation research and the growth of large-size and high-quality YAG laser crystals.

The absolute measurement device of high-precision bidirectional reflectance distribution function (BRDF) can be used to measure the BRDF of the diffuse reflectance reference body such as the calibration diffuse reflector on the satellite. The uncertainty of the rotation angle is one of the main uncertainties of the entire device. By calibrating the geometric position of each component, the angle of the measurement device can be better measured, which can effectively reduce the uncertainty of the absolute measurement of BRDF. In this work, a geometric position calibration method of each component for the absolute measurement device based on its characteristics is developed, where the tandem six-axis robot is used as the measuring tool and the light beam emitted from the integrating sphere light source fixed on the hollow index plate is used as an indicator. The mirror reflection experiment shows that the accuracy of the rotation angle is better than0.05°, which meets the application requirements. It is shown that the calibration method not only has high measurement accuracy, but also greatly simplifies the assembly and adjustment process,and realizes non-contact calibration, which provides a reference for the calibration of similar devices.

Aiming at the problem of real-time image edge extraction, a quantum LoG image edge detection algorithm based on classical Gauss-Laplacian operator (LoG operator) is designed. By simulating the quantumLoG algorithm with Matlab software on a classical computer, it is proved that the quantum LoG algorithm can quickly and effectively realize the recognition and extraction of image edges. In addition, the influence of two types of decoherence effects on the algorithm is also investigated. The calculation results show that compared with the existing corresponding quantum image edge detection algorithms, the quantum LoG algorithm has better anti-noise characteristics.

The properties of magnetopolaron in asymmetry quantum well is studied by Pekar variation method. The ground state energy of magnetopolaron is derivated theoretically, and the relationship between ground state energy of magnetopolaron and wave vector, well width, magnetic field cyclotron resonance frequency and well depth is discussed respectively. It is shown that the magnetopolaron ground state energy is an increasing function of the wave vector and the magnetic field cyclotron resonance frequency, but a decreasing function of the well width and well depth. Due to the inversion asymmetry of crystal structure and the effect of magnetic field, the polaron energy will undergo Rashba spin-orbit splitting and Zeeman splitting. The dominant position of Rashba effect and Zeeman effect under the strong and weak magnetic fields is discussed respectively. Since the existence of phonons reduces the total energy of polarons, the polaron state is more stable than the bare electron state, and its energy splitting is also more stable.

An electro-optic Q-switched Tm:YAG laser with high peak power and narrow pulse width side-pumped by laser diode (LD) array is introduced. Using LGS crystal as electro-optical Q-switch, the characteristics of the laser output are investigated when thewhite Sapphire and Glan prism are used as a polarizer respectively. The results show that when using Sapphire stack as a polarizer, there will be a tail pulse with the increase of pump energy, however, when using a Glan prism as a polarizer, there is no tail pulse. Using a Glan prism as the polarizer, the central wavelength of the laser output is 2.02 μm, and a laser output with a maximum single pulse output energy of 60 mJ, a pulse width of 65.6 ns, a peak power of 0.91 MW and a slope efficiency of 5.41% can be obtained at a repetition frequency of 10 Hz.

In order to explore the trapping properties of a focused twisted Hermite-Gaussian-Schell model beam on Rayleigh particles, based on the generalized Huygens-Fresnel principle and the Rayleigh scatteringtheory, the analytical expressions of light intensity and radiation force of a focused twisted Hermite-Gaussian-Schell model beam passing through a focused lens are derived, and then the effects of beam parameters such as beam order, twist factor and lens focal length on the radiation force of a focused twisted Hermite-Gaussian-Schell model beam are numerically simulated. The results show that the intensity distribution of a focused twisted Hermite-Gaussian-Schell model beam gradually splits and rotates around the transmission axis during the propagation, and the gradient force and trapping stable range of the beam increase with the beam order and twist factor. By selecting appropriate beam parameters and lens focal length, two types of Rayleigh particles with different refractive index can be stably trapped. The results are valuable for the application of focused twisted Hermite-Gaussian-Schell model beams in optical tweezers.

Halide perovskite possesses excellent photoelectric properties and can be prepared by low-temperature solution method. Photodetector arrays made of halide perovskite are highly required in the area of imaging, optical communication and other fields. However, halide perovskite can be easily dissolved by conventional solvents (including developer), which makes it incompatible with photolithography process. Herein, a novel method based on spin coating (the polar perovskite precursor solution only infiltratesthe hydrophilic pattern area) and low-temperature annealing has been proposed to prepare perovskite arrays, which can solve the problem of incompatibility between polar solvents and perovskite materials. The fabricated photodetector based on CH3NH3PbI3 thin film arrays exhibits good photoelectric performance, with a high detectivity of 4.7×1011Jones and the responsivity of 0.055 A/W under 530 nm light irradiation. This work provides a simple and effective strategy to prepare well-defined perovskite photodetector arrays based on thin film array.

Compared with linear Bell inequality, nonlinear Bell inequality provides a new method of verifying quantum correlations as a new type of criterion. It is practically important to study the properties of entanglement states by using nonlinear Bell inequality. Considering that the entanglement state with noise can simulate the actual quantum communication process, the optimal measurement operator of the corresponding state is found through numerical optimization based on Matlab, and the influence of noise parameters on the violation of nonlinear Bell inequality is studied. The results show that the entanglement state with noise can also violate the nonlinear Bell inequality in specific circumstances, and the more the number of measurements are, the more stringent the requirement of entanglement state will be. The results are important for the selection and preparation of states in actual experiments.

Based on the combination of GHZ particles and single photon, a quantum secure direct communication protocol is proposed. In this protocol, Alice encodes the information, and then divides all GHZ particles into three parts: S1, S2 and S3. Firstly,Alice sends S1 to Bob and detects the channel security. Secondly, mixes S2 with single photon SS and sends to Bob and detects the channel security after rearranging and adding decoy particles in order. Thirdly, mixes S3 with SSand repeats the previous operation. Finally, Bob measures the information and decodes it. This protocol can save the complex unitary operation, simplify the implementation process of the protocol, and at the same time, the combination of sequence rearrangement and decoy particles ensures the security of the protocol. In addition, the mixing of single photon and GHZ states makes it possible to load 4 bits classical information on a quantum state, which greatly increases the coding capacity and transmission efficiency.

Based on wavelength division multiplexed (WDM) technology, quantum and classical signals can be transmitted together in the same fiber. However, the noise caused by the nonlinear interaction between classical signals and optical fiber will reduce the signal-to-noise ratio of quantum key distribution (QKD), so measures need to be taken to reduce the influence of classical noise. Different from the previous methods focusing on QKD device, the background noise rate, secret key rate and maximum secure transmission distance of WDM-QKD for different kinds of fibers are analyzed and compared by establishing the classical noises, decoy-state and finite-key models from the perspective of optical fiber transmission in this work. The numerical simulation results show that G.655 fiber can reduce the background noise rate of WDM-QKD, G.654 fiber can increase the secure key rate and the maximum secure transmission distance, while the performance of WDM-QKD with the popular standard single-mode fiber G.652 is in the middle of the three cases.

To deal with the real time changing of atmospheric channel with meteorological conditions in space quantum communication system, a prediction method of atmospheric attenuation coefficient of quantum signals based on deep learning is proposed. The experiment is based on meteorological data set of Xi’an, and three neural network models, namely BPNN, LSTM and GRU, are built for analysis and comparison. The results show that all the three neural network models can accomplish prediction effectively with over 80% data fitting rate, among which LSTM and GUR have better performance. Meanwhile，three network models all produce large errors at the peak value. The prediction scheme provides a basis for further research in various compensation methods and intelligent parameter optimization for atmospheric channels in space quantum communication.

Multi-vortex-Gaussian beams with different numbers of vortices and topological charges have different light intensity and different phase distribution. When the number of vortices increases, the number of vortex singularities increases and the statistical beam width also increases. The propagation of multi-vortex-Gaussian beams in a non-local medium with negative refractive index is numerically simulated by the split-step Fourier method. It is found that the asymmetry of the vortex point about the origin or the unequal topological charges of each vortex point can result in the change of the transmission direction of the soliton, so the transmission direction of the beam can be controlled by changing the position of the vortex point and the number of topological charges. If the sign in front of the imaginary part of the vortex point changes, the rotation direction of the soliton will change. In addition, the critical power and orbital angular momentum of the soliton will increase with the increase of the topological charge. Therefore, the beam information can be encoded by the vortex point position, the number of vortex points, and the topological charge, so that the beam can carry more information when it is transmitted in the medium.

In order to monitor the change of solar spectral irradiance with high accuracy, a high accuracy solar spectral irradiance monitor is designed to obtain solar spectral irradiance data. The instrument has three independent optical paths. The main light path is used to measure solar spectral irradiance, the reference light path is used for spectral calibration, and the solar tracking light path is used for precision solar tracking outdoors. The design of the main light path is introduced in detail. Féryprism is used for dispersion and convergence in the main light path, and the entrance slit of the monitor is imaged to the focal plane of the Féry prism. Two photodiodes are used to detect the spectral irradiance from 380 nm to 2500 nm by rotating the prism. Through theoretical analysis and experimental verification, it is shown that the full width at half maximum of the monitor is less than 40 nm in the 380～2500 nm spectral range. Standard lamps are used to verify the spectral response range of the solar spectral irradiance monitor, and the experimental results show that the spectral range of the monitor meets the measurement requirements.