The Optic-therm-electrical Model Based On Multi-physics Coupling And Grids Optimization Of In_0.3Ga_0.7As Laser Power Converters

Laser power converters（LPCs）is an important part of laser wireless power transmission（LWPT）system,and its performance restricts the development and application of the LWPT system.In this paper,the factors affecting the efficiency of LPC under practical work are analyzed through theoretical modeling,numerical calculation and experimental analysis,and the methods to improve the performance of LPCs under high laser intensity are discussed.A two-dimensional optic-therm-electrical model of In_0.3Ga_0.7As LPC based on multi-physics coupling was established.The rationality and accuracy of the model were verified by experiments,and the accurate prediction of temperature,short circuit current,open circuit voltage and efficiency of LPCs was realized.It is also found that the temperature and laser intensity affect the conversion efficiency by affecting the open circuit voltage.Under a certain laser intensity,the temperature of LPC drops first and then rises with the increase of bias voltage.The series resistance of the LPC seriously restricts the maximum output power.About 0.26Ωof the series resistance could reduce the maximum output power of the LPC by 41.35%,and the increase in the series resistance of about 0.58Ωcould reduce the maximum output power by 45.54%.The influence of grids parameters,such as width,thickness and density,on the performance of LPCs was studied,and it was found that the efficiency of LPCs at a certain laser intensity increased rapidly and then decreased linearly with the increase of the grids width.The main factor affecting the efficiency at the rising section was the series resistance,and the decrease section was the shielding rate.The thickness of grids just affects the series resistance,without affecting the optimization law of other parameters of grids.The bigger the thickness of the grid,the smaller the optimal width,and the higher the processing accuracy required of the width.The higher the grids density,the more obvious improvement in efficiency,the smaller the corresponding optimal grids width,and the higher processing accuracy required of width.Under a certain grid width,the efficiency of LPCs first increases and then decreases with the increase of grid spacing,so the grid spacing also has an optimal value.According to the actual work of LPCs under different laser intensities,the necessity of grids optimization under different laser intensities is analyzed.It is found that under a certain grids density,the higher the laser intensity,the larger the optimal grids width,the lower the processing accuracy required of the width,and the more obvious the performance improvement.The maximum output power after optimization can be increased by 14.81%,absolute value 16.20 m W/cm².Meanwhile,the higher the laser intensity and the grids density,the more obvious improvement of the efficiency after optimization.When the grids density increased by 4 times,the maximum output power increased by 18.42%,absolute value 22.68 m W/cm².With a grid line width of 12μm,the higher the laser intensity,the smaller the optimal grids spacing,the more obvious the efficiency improvement after optimization,and the maximum output power is increased by 17.53%,absolute value 22.78m W/cm².The researches and conclusions of this paper can provide theoretical and experimental references for the structural design and the performance analysis of LPCs under different conditions,and provide solutions for the grids design and optimization of LPCs under different processing techniques and working environmental conditions.