Simulation Study Of Laser Damage Characteristics Of Micro And Nano Structured Optical Surface

The optical properties of micro and nano-structured surfaces of optical components have long been a research hot topic for many scientists.Meanwhile,the requirement to improve the laser damage resistance of optical elements and make them work stably under the strong field environment of high-power lasers has also become a hot topic which has been focused by many researchers.Therefore,in this paper,we combine these two hot topics and research the laser damage resistance of micro and nano structured optical surfaces through simulations using the finite element simulation software COMSOL.Firstly,we use COMSOL simulation software to model three shapes of micro-nano structures on the surface of optical elements,and simulate laser irradiation at 1064 nm on the surface of micro-nano structured optical elements,and attain temperature field distribution and electric field distribution on the surface of three shapes of micro-nano structures(semi-cylinder,triangular prism,quadrangular).Then,we analyzed the electric field and temperature field distribution diagrams for the possibility of electric field damage and thermal melt damage of the optical element,and then determined the excellent laser damage resistance of the optical element.Comparing the three micro-nano shapes studied in this paper,the trigonal micro-nano optical elements have higher resistance to laser damage compared to the quadrilateral and semi-cylindrical micro-nano optical elements under the structural parameters of semi-cylindrical,trigonal and quadrilateral shapes with equal lengths of 400 nm on the bottom side and equal heights of 200 nm.Further,by changing and adjusting the microstructure parameters of the optical surface,the temperature and electric field distributions are compared and analyzed to obtain the optimal microstructure process parameters to achieve the best laser damage resistance of the optical element.The conclusions: the optimal structural size parameters of semi-cylindrical micro-nano structures are: semi-cylindrical radius in the range of 50-80 nm and 160-190 nm,in which the optical elements containing semi-cylindrical micro-nano structures have high resistance to laser damage.The optimal structural size parameters of the trigonal micro-nano structure are:trigonal height b0=100nm,200 nm,300nm,400 nm,bottom edge width a0 in the range of50-150 nm and trigonal height b0 of 200 nm,bottom edge width a0 in the range of 300-350 nm,in which optical elements containing trigonal micro-nano structure have high resistance to laser damage.The optimal dimensions of the quadrilateral micro-nano structure are quadrilateral height b0=300nm,bottom edge width a0 in the range of 250-320 nm,350-400 nm and quadrilateral height b0=200nm,400 nm,bottom edge width a0 in the range of 100-120 nm,in which optical elements containing quadrilateral micro-nano structure have high resistance to laser damage.The results of this thesis provide a theoretical basis and reference for changing of the shape of the surface micro-nano structure of the optical element to affect the laser damage resistance of the optical element,and optimizing the design and fabrication of the surface micro-nano structure parameters of the optical element,in order to improve the optical element's laser damage resistance.