Design Of Laser Shaping Optical System And Application In Optical Antenna

Laser diodes are compact,efficient,and reliable light sources in many scientific and engineering applications,however,the emitted beams of high-power semiconductor lasers usually have large divergence angles and astigmatism,and it needs to be equipped with a corresponding beam shaping system to obtain a laser beam with a circular spot,a suitable size,and a small divergence angle to meet the needs of long-distance optical communication.Among the commonly used reflective transceiver antennas,the Cassegrain antenna is widely used due to its simple structure,easy manufacture,large aperture,long-distance transmission,no dispersion,and wide band.However,the Cassegrain antenna has the problem of central energy loss caused by the occlusion of the secondary mirror,and the efficiency of transmitting solid beams is greatly reduced.Therefore,it is of great theoretical significance and practical value to design an optical shaping system that can simultaneously improve the transmission efficiency of antennas and the beam quality of semiconductor lasers.This thesis mainly studies the transmission characteristics of semiconductor laser beams,proposes a new design method of laser shaping optical system,which solves the problem of energy loss in the center of the secondary mirror of the Cassegrain transmit antenna.The main research contents include:(1)The research progress of optical antenna at home and abroad,the research status,and the development direction of semiconductor laser shaping technology are compared and analyzed.The transmission characteristics of the fundamental mode Gaussian beam output from a semiconductor laser are studied.The characteristics of the beam far-field intensity distribution and beam divergence angle of the single-emitter high-power semiconductor laser are analyzed.In addition,the evaluation method of the beam quality of the semiconductor laser beam is discussed.(2)The design method of laser shaping optical system based on aspheric cylindrical lens,radial gradient-index lens,and spherical gradient-index lens is studied,and the ray-tracing based on the above lens is simulated by Matlab,and the beam shaping method of the above lens is compared.In addition,a novel optical system that generates a hollow beam is designed and its performance is analyzed using optical simulation software.(3)In order to improve the transmission efficiency of the antenna and the beam quality of the semiconductor laser at the same time,a new laser shaping optical system(E-A shaping system,Beam shaping system from elliptical divergent beam with astigmatism to annular collimated beam)is designed,which can realize four functions of aberration correction,spot rounding,beam collimation,and hollow beam generation.The design and calculation of the structural parameters of the system are given,and the optical system is applied to the Cassegrain optical antenna.Various practical factors affecting the transmission efficiency of the antenna system are discussed,and the methods and steps for optimizing the system structure are given.At the wavelength of1550 nm,the transmission efficiency of the entire system can reach 93.91%.Considering material dispersion,the transmission efficiency can still be maintained at more than 90.00% in the wavelength range of 500?1647 nm.