Research On Silicon-based Large-angle Optical Phased Array

In recent years,with the rise of technologies such as unmanned driving and laser printing in military and civilian fields,high-precision imaging and target detection have also received widespread attention.Lidar has great potential for development in these fields for its extremely high resolution in the time domain,frequency domain and space domain.The traditional laser radar mostly uses mechanical controlling system,crystal material birefringence(electro-optic crystal,acousto-optic crystal)and other scanning methods for beam steering.Mechanical controlling system has disadvantages such as slow response speed and low control accuracy.While acousto-optic modulation and electro-optic modulation do not require mechanical motion for steering,the steering range is usually very small and can only be used in scenes where small beam steering are suitable.The optical phased array has the advantages of fast scanning speed,flexibility,high pointing accuracy,and has broad application prospects in beam scanning,and is an important direction for the development of laser radar.SOI-based optical waveguide phased arrays are the hotspots of optical phased arrays in recent years due to their fast response,low control voltage,large scan range,and high integration.This paper investigates the research progress of optical phased array at home and abroad,analyzes the unique advantages of optical waveguide phased arrays,analyzes the beam steering characteristics of one-dimensional and two-dimensional optical phased arrays in detail.The analysis of the scanning characteristics of the phased array of one-dimensional optical waveguide has been made.The steering range of the optical phased array can be increased by reducing the spacing of adjacent antenna,but the reduction in spacing can cause strong crosstalk in the array.In this paper,the basic principle and design idea of the superlattice waveguide array has been introduced.By changing the width of different waveguides in the waveguide array,a high-density waveguide array with a pitch of 0.9 ?m is designed,the crosstalk in the array has been strongly suppressed.A novel grating emitter array with small spacing and low coupling strength has been designed and simulatedby using superlattice waveguide array.This paper finally demonstrated a new type of superlattice optical phased array using the above mentioned grating emission arrays.The numerical simulation and analytical calculation methods has benn used.The simulation results show that the array can achieve a steering range of 106° with a SNR of-7 dB.At the same time,an SOI-based optical waveguide phased array device with an array number of 16 and a pitch of 3 ?m has been designed and fabricated.