Study On Cavity Surface Thermal Effect Induced By Microdefects In Semiconductor Laser

In the process of laser production,it is inevitable to bring micro defects to the cavity surface,such as scratches,cracks and grooves.The existence of these micro-defects will induce the laser to produce modulation effect on the cavity surface,and the laser will be redistributed at the defect,and the reflection superposition and enhancement at the defect will form a strong focus,so that the temperature of the cavity surface will increase sharply at the defect,causing melting and gasification of the cavity surface,and finally causing laser ablation of the material.With the continuous operation of the laser,the damage caused by cavity surface gasification will be further extended.In this paper,the damage propagation of Ga As cavity surface induced by microdefects is studied by theoretical derivation,numerical simulation and experimental simulation.In this paper,based on the principle of heat conduction,the following related studies have been done:The temperature field model of gallium arsenide cavity surface was established based on the heat conduction model.By studying and summarizing the physical mechanism of the interaction between laser and gallium arsenide,the temperature field model of laser irradiation on gallium arsenide was established.The damage propagation induced by microdefects in gallium arsenide cavity surface was studied based on moving mesh technique.After the laser irradiates the gallium arsenide cavity surface with micro defects for a long time,the temperature of the cavity surface will rise rapidly at the defect,and the gallium arsenide cavity surface will melt and gasify,leading to the further expansion of the initial defects and the formation of damage propagation.The melting and gasification phenomenon produced in the process of temperature change is monitored by the principle of phase transition to realize the monitoring and research of damage propagation.To prepare for the simulation modeling and research of laser surface ablation of gallium arsenide.In order to analyze the influence of different initial defect sizes on damage propagation,the finite element simulation model of laser irradiation on Ga As cavity surface with micro defect was established by using COMSOL Multiphysics simulation modeling software.In the simulation modeling,the transient study was first selected to enter the modeling interface,the physical field was selected as "solid heat transfer",the relevant parameters of gallium arsenide were defined,the laser heat source was defined,the relevant intermediate variables and the applied dependent variables were defined,and the initial defects were set as conical,cylindrical and spherical,respectively.Finally,the established model is divided and analyzed.After the completion of the simulation modeling,the influence of initial defects of different sizes and different types of initial defects on damage propagation was quantitatively studied and analyzed by modifying the parameters of initial microdefects,such as width,depth and defect type.The results show that the depth of damage propagation is directly proportional to the depth of the initial defect,and inversely proportional to the width of the initial defect.At the same time,the larger the upper surface area of the initial microdefects,the greater the depth of damage propagation.In order to analyze the damage state of Ga As cavity before gasification,a multi-physical field coupling mechanism was established based on temperature field and stress field,and the thermal stress damage of Ga As cavity induced by defects was studied and analyzed.The thermal stress damage induced by the initial microdefects of different sizes and shapes was simulated.The results show that the maximum thermal stress and deformation of the cavity surface are located at the edge of the defect,but not at the center of the spot.Meanwhile,the shape variable caused by thermal stress is inversely proportional to the width,volume and spot radius of the initial defect,and is directly proportional to the depth of the initial defect and the laser power.