Experimental Research On Beam Combining And Steering Of Optical Fiber Phased Array

Because of good stability,strong dynamic focusing and defocusing capabilities,small size,light weight,good flexibility,and low power consumption,the optical phased array has huge de velopment prospects in laser radar and laser communication.Compared with other types of optical phased array technology,the optical fiber phased array has more suitable for lidar detection of long-range targets due to the advantages of small launch aperture,compact structure,large output power,and fast beam control speed.The time-varying random phase noises between the beams of the fiber phased array must be fixed to improve the quality of the synthesized output beam.Increasing the output power and spatial resolution capability requires increasing the number of array element beams,however,which will increase the difficulty of phase adjustment in beam synthesis and beam scanning.Therefore,for longdistance detection,it is of great significance and application value to carry out research on the synthesis and regulation of two-dimensional fiber phased array beams.Firstly this paper briefly summarizes the current research status of optical phased array technology around the world,analyzing and comparing the advantages of various optical phased arrays.Then introduces the basic composition and working principle of fiber phased arrays,and focuses on fiber laser coherence The key technology of synthetic phase control,based on the mathematical model of fiber phased array beam scanning,considers practical factors,and analyzes the impact of various error factors on beam synthesis and scanning;finally,the 64-channel fiber phased array designed and built is used In the experimental system,beam optimization and beam scanning experiments were carried out.The main work in the paper includes:1.Based on the composition of the fiber phased array,the mathematical expression of the intensity distribution of the far-field light field of the fiber phased array is given.The principle of two-dimensional beam scanning and the principle Beam characteristics;and for the light field distortion caused by random phase disturbances,the effectiveness of the phase compensation method based on SPGD algorithm is simulated and analyzed.2.For the beam phase control of two-dimensional fiber phased array,the actual error factors are analyzed,and the adverse effects of phase modulator and active phase control system errors on the synthetic scanning light field are analyzed.Tolerance range of mid-phase modulator and active phase control system.3.Designed and built a 8×8 1550nm band scale two-dimensional fiber phased array experimental system,carried out beam synthesis and phase adjustment experiments.The half-wave voltage of the phase modulator and the actual output noise of the active phase control system were measured.The SPGD optimization algorithm was used to perform active phase compensation to achieve the optimal control of the synthesized beam.The quality of the synthesized beam was significantly improved.The angular widths of the beams are close to the theoretical level;two-dimensional scanning experiments are carried out on the optimized multiple beams,and the scanning speed reaches the order of 100 kHz.Analysis and preliminary experimental results show that for larger-scale two-dimensional fiber phased arrays,the SPGD algorithm can be used to effectively optimize the light field synthesis;the "optimized scanning" scheme can achieve fast and accurate two-dimensional beams scanning.