熔石英损伤修复形貌对光场调制的标量衍射理论研究

Repaired Morphology Induced Optical Modulation in Fused Silica Based on Scalar Diffraction Theory

熔石英表面损伤对于传输光场以及光学系统有诸多不利影响,CO2激光修复技术可以提高损伤阈值,有效地消除或减轻损伤对光路的影响.本文利用数学仿真工具MATLAB和标量衍射理论针对大尺寸高斯以及圆锥类型修复形貌(非蒸发和蒸发修复)对光调制的影响进行相应的模拟仿真计算,获得修复形貌对传输光场的调制作用以及被调制光场在修复元件下游的衍射传输情况.本研究以355nm激光为激发波长进行相应的仿真计算,分别探讨了两种修复形貌对入射光场调制的异同以及该光场被调制后对下游光传输的影响.结果表明,CO2蒸发与非蒸发技术对损伤修复形貌的光场传输有着不同的影响,传输光场的调制度随着形貌的宽深比(半径R-深度L)不同而变化.因此,适当控制修复形貌及尺寸可在有效提高熔石英激光损伤阈值的同时避免调制光强过大对下游光学元件的再次损伤,以保证激光装置稳定运行.

Surface damage in fused silica is disadvantageous for the optical transmission and optical systems.The CO2 laser repair technology can improve the damage threshold and effectively eliminate or reduce the influence of damage on the light path.The optical modulations induced by the large size of Gaussian and cone repaired craters(non-evaporation and evaporation)are simulated by the mathematical tool MATLAB and the scalar diffraction theory to obtain the data of light field modulation in the repaired area and light transmission in the downstream components.355 nm ultraviolet laser is used for this simulation and the influence of two kinds of repaired morphology on the light modulation and transmission are comparably studied.The results show that CO2 laser evaporation and non-evaporation repair technologies are different for the tramsmission of light field.The modulation of light field changes with the width-depth(radium R to depth L)ratio of the repaired crater.Therefore,the reasonable morphology and size can not only improve the laser damage threshold of fused silica but also avoid the excessive light intensity modulation to damage the downstream optical components again,which ensures the stable operation of laser facilities.