| In recent years,as a new energy transmission mode,laser wireless energy transmission has attracted much attention due to its good directivity,energy concentration and no interference with communication equipment.In particular,the receiving device has the characteristics of small size and light weight,and is generally considered to be the best choice for providing energy and increasing endurance for the micro aircraft.This paper intends to research into the shaping of semiconductor laser beam in laser wireless energy transmission system and the impact of beam intensity uniformity on the photocell conversion efficiency.First of all,based on a linear array semiconductor laser beam,using the method of numerical simulation and experimental measurement of the combination.Two sets of beam shaping optical system have been designed to obtain the intensity uniformity of different laser beam.Then the laser beam with different intensity uniformity was irradiated on the surface of GaAs cell respectively,and the variation law of GaAs cell conversion efficiency with different intensity uniformity was measured.Finally,the laser beam shaping and the conversion efficiency of the photocell are analyzed and summarized.So the main work includes:1.The working principle of photocell has been presented.The working principle of photcell has been revealed from the band structure,the stimulated absorption theory and the bandgap structure,and the structure of p-n junction in photoelectric pool has been analyzed in theory,The and the reasons of optimal response wavelength and cutoff wavelength has been pointed out.2.The performance and parameters of GaAs photocell has been introduced.The advantages of GaAs photocell have been showed through comparing performance parameters.By analyzing the equivalent model of GaAs photocell,the influence of GaAs photocell surface temperature on its physical characteristics has been revealed,and the influence of incident laser intensity uniformity on the conversion efficiency of GaAs photocell has been explained.3.The beam shaping system of linear array semiconductor laser diode has been researched and designed.Two sets of beam shaping systems have been established by numerical simulation for direct output and fiber output.One is wedge-mirror-prism array semiconductor laser beam shaping system,the other is non-spherical mirror beam shaping system.And the practical system has been measured to analyze the reason of the difference between the simulation system and the practical system.4.The effect of light intensity uniformity on the conversion efficiency of GaAs photocell has been studyed,Based on the working principle of GaAs photocell,we analyze the photoelectric conversion efficiency of GaAs photocell when the laser intensity is different by using the equivalent circuit,and study the conversion efficiency of GaAs photocell in different light intensity uniformity by experiments.Results show that the light intensity uniformity has a great influence on the photoelectric conversion efficiency of the GaAs photocell.In some extreme conditions,it may cause the hot spot effect and completely destroy the GaAs photocell.The results of this paper have theoretical significance and application value for improving the efficiency of laser wireless energy transmission. |
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