Design Of Optical Phased Array Chip For Space Optical Communication

At present,the electromagnetic spectrum has been depleted due to the development of radio frequency communication,so there is an urgent need to explore new frequency bands.As a new communication mode,laser has been widely used in space laser communication because of its short wavelength,high brightness and strong directional characteristics.Compared with the traditional microwave communication system,the space laser communication has the following advantages: First,the space laser communication system has a huge capacity;Secondly,the space laser communication system is small in volume and light in weight;Finally,the space laser communication system has high confidentiality and anti-jamming,which is especially suitable for special environment.Therefore,the optical communication system based on laser radar has been paid more and more attention.At present,there are mainly two types of lidar:mechanical type and all-solid-state type.The mechanical scanning system is too large and the cost is relatively high.All-solid-state lidar based on optical phased array technology has become a research hotspot in recent years because of its high integration and low cost.The commonly used materials of optical phased array chips include lithium niobate,liquid crystal,piezoelectric ceramics and insulating silicon.The optical phased array device based on lithium niobate material has high scanning accuracy,but the scanning power loss is large due to the high operating voltage,and the scanning Angle is relatively small.Optical phased array devices based on liquid crystal materials have long durability,wide scanning range,low power consumption but slow response speed,need to work in a specific environment,and easy to be affected by temperature.Optical phased array devices based on piezoelectric ceramic materials have low consumption,wide transmission spectrum,but high production price,and need very high voltage environment to be used normally.Optical phased array devices based on silicon materials can carry out high speed and high efficiency scanning,and their high integration and mature manufacturing technology are favored by the majority of researchers at home and abroad.The main working principle of silicon-based optical phased array is to change the refractive index of the material by changing the applied voltage or temperature of the dielectric material,resulting in the beam deflection of the light passing through the dielectric material and realizing the scanning function.This paper mainly analyzes and designs silicon-based optical phased array structure,which is divided into the following work:First of all,this paper introduces the development history of space optical communication,which is mainly divided into two directions: long-distance space optical communication and indoor visible light communication.Then,this paper introduces the development history of silicon-based optoelectronic integrated optical phased array,which is mainly divided into one-dimensional optical phased array and two-dimensional scanning optical phased array.Secondly,the basic principle of the optical phased array based on thermal-optical effect and the main parameters affecting the far-field beam are introduced.Matlab is used to simulate which factors will affect the far-field beam in the equal-spacing optical phased array,and the scanning pattern of the optical screen and the far-field intensity are simulated.In this paper,an optical phased array layout based on the elementary function placement strategy is designed,and the inhibiting effect of the placement strategy on the gate is analyzed,and the placement strategy of the optical phased array waveguide is designed by genetic algorithm.Then,in order to facilitate the future design of optical phased array engineering of optical waveguide,the effective refractive index of optical waveguide is obtained by simulating the values of the effective refractive index of optical waveguide under different conditions.According to the data,the fitting function is designed.The parameter model is taken as the height of the waveguide is 0.21?m and the width of the waveguide varies from 0.30?m to 0.75?m.Verification is performed using validation functions and variance,root mean square and deterministic coefficients.The results show that the fitting results of the verification function are in good agreement with the simulation results of MATLAB.Finally,MATLAB is used for mathematical simulation,and the functional relationship between the grating period and the effective refractive index and the emission Angle of the optical waveguide is obtained.Based on the simulation data,the fitting function of the relationship between the value of the effective refractive index of the optical waveguide and the width and height of the waveguide is designed,and the functional relationship between the period length of the grating and the effective refractive index of the optical waveguide in the equal-spacing optical phased array is summarized.In the future,the grating period structure can be rapidly designed to meet the purpose requirements.