Research On Beam Control Of Liquid Crystal Optical Phased Array

Liquid crystal optical phased array(LCOPA)technology is an advanced beam scanning technology.It has many advantages,such as low driving voltage,low SWaP,fast response and so on.It is widely used in the fields of adaptive optics,laser radar and space optical communication.LCOPA can achieve high accuracy beam deflection(beam pointing)through the precise modulation of the beam phase.Due to limited by the level of liquid crystal processing technic,the actual deflection efficiency of liquid crystal optical phased array is far below the theoretical level,but the defects of processing technic can only depend on the improvement of production level.Therefore,Improving the beam deflection efficiency from the perspective of wave control algorithm has practical application value.This paper focuses on the optimization of the deflection efficiency of liquid crystal optical phased array:First,the basic properties of liquid crystal materials are introduced in this paper,the distribution of liquid crystal director is solved based on the principle of minimum energy,and the voltage-phase shift characteristic of liquid crystal is analyzed.Based on this,the basic principle of phase modulation of liquid crystal phase shifter is given.Secondly,on the basis of comparing the principle of discrete phased array and continuous phased array wave control,combined with the properties of liquid crystal materials,two kinds of liquid crystal phased array beam control models are given,which provides theoretical support for the research of the next optimization algorithm.Thirdly,the factors that affect the deflection efficiency of the liquid crystal phased array are modeled and analyzed,which provides theoretical basis for further understanding the influence of process restriction of liquid crystal processing on the emergent wavefront.Then,the optimization method of the beam control efficiency of the periodic blazed grating model based on the pattern search algorithm is studied.According to the inferiority of slow iterative speed of the pattern search algorithm,the beam control efficiency optimization method based on the Rosenbrock algorithm is given.The simulation shows that the iterative speed of the Rosenbrock algorithm is obviously faster than the pattern search method on the premise of equal convergence efficiency.Finally,the optimization method of the beam control efficiency of the aperiodic blazed grating model based on the particle swarm optimization is proposed,according to the inferiority of slow iterative speed of the pattern search algorithm.Aiming at the inferiority that PSO is easy to fall into local optimum,the optimization method of the beam control efficiency of the aperiodic blazed grating model based on the bat algorithm is proposed,the simulation results show that the iterative speed is increased by 44%,the deflection efficiency is increased by 6.02%,and the array element voltage distribution is more extensive when comparing with the particle swarm optimization algorithm.