Diffractive Optical Element Design And Optimization Based On Hybrid Algorithm

With the growth of industries such as face recognition camera modules and dot matrix projectors,diffractive optical elements(DOEs)are becoming increasingly popular in modern optics due to their lightweight and integrated features.However,the design of diffractive optical elements with subwavelength feature sizes is not yet mature,and the existence of vector beam effect requires the use of rigorous electromagnetic calculation methods to optimize their phase structures.Compared to scalar approximation design,the optimization simulation method based on vector diffraction theory is less efficient and requires more computational resources.Therefore,in order to efficiently design subwavelength diffraction optical elements with higher performance,a new design requirement is proposed,which is to reduce the vector electromagnetic computation time and ensure the convergence of the optimization algorithm.In this paper,we propose a subwavelength diffractive optical element design scheme based on a hybrid algorithm combining prey-predator particle swarm optimization and simulated annealing,with the goal of designing a 5×5 beam splitter.In this scheme,the diffraction efficiency,uniformity error and figure of merit calculated by the finite difference time domain vector model were used as evaluation functions.The prey-predator particle swarm optimization algorithm was used to optimize the initial solution,and the simulated annealing algorithm was used for the second optimization.Compared with the traditional particle swarm optimization algorithm,the prey-predator system introduced in the hybrid algorithm can reduce the overall optimization time of the algorithm and greatly improve the optimization ability of the algorithm,and the simulated annealing algorithm can ensure the fast convergence of the algorithm.Through many numerical simulations and comparative analysis,the results show that the hybrid algorithm is robust and the optimization efficiency is improved.In addition,in order to verify the feasibility of the design scheme,we prepared several groups of diffraction optical element samples by micro-nano processing technology and nanoimprinting technology,and conducted light efficiency test and microscopic morphology analysis of the experimental samples by building an actual optical path and scanning electron microscopy.The experimental test data show that the correlation coefficient between the simulated design and the manufactured diffractive optical element is above 0.85,which has a strong correlation,and verifies the effective design and optimization ability of the design scheme for diffractive optical elements.Finally,the error analysis of the process defect is carried out,and the influence of the machining error on the device performance is discussed.