Research On Beam Modulation Based On Optical Phased Array

With the improvement of computer storage capacity and the development of complex algorithms,intelligent unmanned systems based on sensor technology and embedded development have become a hot topic of research.As one of the representative products,lidar uses mechanical deflection technology to search for the target position.Due to high cost and large size,mechanical operation greatly limits the development of spatial information optics,and cannot meet the requirements of light and small space free communication.Optical phased array is a non-mechanical deflection technology in which the phase of the array is linearly distributed,which transforms traditional mechanical scanning into intelligent beam scanning.The optical coupling between adjacent elements of the phased array easily leads to poor far-field radiation effects,and corresponding beam modulation schemes need to be formulated to achieve beam deflection.The modulation circuit uses STM32 single-chip microcomputer as the core controller of the system,and realizes the compensation of phase error through reasonable deployment of internal integrated resources and peripheral function chips,and feedback optimization algorithms.Electrical compensation can break through the limitations of physical coupling effects,greatly reduce the spacing of the waveguide grating array and increase the scanning angle of the beam.Based on the full study of the intelligent optical beamforming launch technology and the design of ultra-large integrated circuits,this paper studies the beam modulation of the silicon-based optical phased array,and proposes an optical phased array chip combined with on-chip monitoring,and designs two beam modulation schemes,make the modulation circuit according to the phased array modulation requirement,and test the phased array chip.The main content of this article is as follows:1)The principle of optical phased array is analyzed in detail.The relationship between the beam exit angle and the phase difference between adjacent waveguides is deduced from the physical quantities of microwave and geometrical optics,that is,the principle of phase control beam scanning.Analyze the structure of the phased array chip to be tested,propose the host computer modulation scheme and the on-chip modulation scheme for the front and back ends of the phased array,introduce in detail the working principle,modulation system composition and modulation process of the two modulation schemes,and build an overall test system.2)Analyze the specific conditions and modulation requirements of the optical phased array chip to be tested,and design the overall implementation of the modulation circuit hardware based on this:The modulation circuit is divided into a phase control module,a current acquisition module,and a communication module.The phase control module can realize the thermal adjustment of the phased array waveguide,and the current acquisition module realizes the collection of the output photocurrent at the back end of the phased array and sends it to the single-chip microcomputer for processing,and establishes a communication protocol to complete the data exchange between the PC and the modulation circuit.The reliability design of the PCB hardware board ensures the stability of the phased array beam modulation process.3)Design the drive of the optical phased array modulation circuit.First,configure the software development environment,and then determine the overall architecture of the software system according to the phased array requirements,and separately design the upper computer program and the modulation circuit program in blocks.First,configure the serial port between the host computer and the modulation circuit,then call the subroutine in the main control program of the single-chip microcomputer to realize the two modulation schemes,and finally show the test results of the two modulation schemes of the phased array and analyze.