Study On Key Technology And Imaging Application Of Optical Waveguide Phased Array

With the development of modern optics,lasers are receiving extensive attention in optical communication,bio-optics,laser weapons,and other fields,and researchers have an increasing demand for laser deflection control,and traditional mechanical laser deflection devices can no longer meet the application requirements.In recent years,optical phased arrays with miniaturization and high scanning accuracy have become the main representatives of this technology.Researchers have proposed various solutions,such as MEMS-based and LCD-based optical phased arrays.These novel optical phased arrays design solutions bring many possibilities and potential application scenarios for Li DAR technology: for example,vehicle or airborne Li DAR,interchip or space wireless communication fields,scanning imaging or point cloud target scene reconstruction,etc.These novel application requirements have further inspired researchers to explore more integrated,faster,and more stable optical phased array design solutions.Optical waveguide phased arrays have emerged and exploring the design principles,control methods,and imaging applications of such optical phased arrays will potentially open up new ideas for laser detection,LIDAR,and other application areas.In this thesis,in-depth theoretical and experimental studies are conducted on the key technologies such as structure optimization design,beam control,and imaging applications of optical waveguide phased arrays,which are mainly as follows.I.Key technologies in the design of optical waveguide phased arrays are studied.(i).In the optimization of optical waveguide phased array on-chip antenna structure: a novol Si N-Si hybrid integrated vertical asymmetric subwavelength surface grating antenna is proposed,and the simulation results show that the antenna has the advantages of large operating bandwidth and high efficiency,which can effectively solve the problems of high insertion loss and narrow operating bandwidth of existing SOI optical waveguide phased array,which is important for wavelength and phase co-modulated optical waveguide phased arrays.To solve the dilemma of Ga As/Al Ga As waveguide structure with small refractive index difference between the core layer and cladding layer,which leads to high processing accuracy of grating structure,it is difficulty to realize two-dimensional light steering control.Thus,a compact reflective antenna is proposed,and the simulation results show that the antenna has high emission efficiency,high stability,and compact structure.(ii).In the design and fabrication of optical waveguide phased arrays: Based on the simulation results of each on-chip component of the optical waveguide phased array,the main on-chip components were fabricated,and the performance of each component was tested.Based on this,the 4×4and 16×16 thermo-optical modulated silicon optical waveguide phased arrays were designed and fabricated.According to the existing processing conditions in China,a 1×15 vertically stacked electro-optically modulated Ga As/Al Ga As optical waveguide phased array chip was fabricated and its optoelectronic characteristics were tested.II.Key technologies in the beam control of optical waveguide phased arrays are studied.(i).In the output beam calibration control of optical waveguide phased arrays,the stochastic parallel gradient descent algorithm is combined with a specific experimental system to calibrate the output beam of the small-scale optical waveguide phased arrays(1×15 electrooptically modulated Ga As optical waveguide phased array and 4×4 thermo-optically modulated Si optical waveguide phased array),and the output beam control of the optical waveguide phased arrays is achieved in high agreement with the theoretical results.To address the limitations of the stochastic parallel gradient descent algorithm in the application of large-scale optical waveguide phased arrays output beam calibration system,the traditional algorithm is proposed to be improved by adding the evaluation function trend judgment condition and the forced reset module.The reliability and efficiency of the improved algorithm are verified by simulation analysis and 16×16 optical waveguide phased array output beam calibration experiment.(ii).In terms of optical waveguide phased output beam scanning control: the adaptive variable-step retrieval algorithm for moving target retrieval is proposed,which combines the adaptive contour retrieval algorithm with the spiral retrieval algorithm to fully exploit the advantages of inertia-free scanning of the optical waveguide phased array output beam.Simulation and experimental test results show that the method can track complex moving targets and reshape their motion trajectories under low sampling rate conditions.III.The key techniques for reconstructing target images by optical waveguide phased array ghost imaging is studied.(i).Combining ghost imaging theory with optical waveguide phased array,the feasibility of target image reconstruction based on optical waveguide phased array ghost imaging technology is discussed,and experimental verification is performed under different scenarios using 4×4 and 16×16 Si waveguide optical waveguide phased array chips.(ii).The characteristics of the optical waveguide phased array output periodic pseudo-thermal light field are studied theoretically and experimentally,and the dual-period pseudo-thermal light output from the optical waveguide phased array is used to reconstruct moving target images,and the application prospects of the periodic pseudothermal light field in realizing fast image reconstruction of moving targets with a large fieldof-view are analyzed.(iii).Based on the theory of compressed sensing technology,the optical waveguide phased array compressed sensing ghost imaging technology is studied,and a single-arm ghost imaging experimental system is used to achieve high-quality image reconstruction of static targets under low sampling conditions using a 16×16 optical waveguide phased array chip.IV.Based on the research results related to the control and imaging of optical waveguide phased array in the previous sections,an optical waveguide phased array moving target tracking and imaging system is proposed by combining the optical waveguide phased array beam scanning control and the optical waveguide phased array-ghost imaging technology.Using this system,image reconstruction of millimeter-scale moving targets at 20 m away is achieved based on the conventional optical waveguide phased array beam scanning algorithm and ghost imaging algorithm.Using the above system,combined with the proposed adaptive variable-step retrieval algorithm and optical waveguide phased array compressed sensing ghost imaging technology,the trajectory and image reconstruction of complex moving targets at low sampling rates are achieved.