非绝热近场光学诱导平滑硅表面微结构的电场模拟

如何进一步降低超光滑光学元件表面缺陷是现代超精密光学元件制作技术研究的热点之一。在传统抛光方法的基础上，引入非绝热近场光学诱导平滑硅表面微结构这一新型方法，进一步去除超光滑抛光表面残留的纳米级表面微缺陷，降低表面粗糙度。通过建立超光滑硅表面的微结构几何模型，采用时域有限差分法对表面微结构凸起在532 nm 激光作用下的局域电场增强进行数值模拟。对比不同尺度的微结构所激发的最大电场强度表明，在基底峰谷值小于25.5 nm 时，随微结构尺度递增，所激发的局域电场强度最大值约呈线性增长；随微结构倾斜率的逐渐递增，电场强度最大值也呈递增趋势。通过对激光诱导表面微结构调制电场的数值模拟，构建了硅表面微结构诱导平滑的物理图像，为描绘激光辐照下非绝热近场光学诱导平滑表面微结构的物理过程提供了有力的理论支持。

Simulation of electric field modulated by silicon-microstructure during non-adiabatic near-field optical etching process

How to reduce the micro-defects of supersmooth optical surface is one of the research hotspots of manufacturing technology of ultra-precision optical element. A kind of novel precision optical fabrication method called non-adiabatic near-field optical induced smoothing surface microstructure was introduced to remove the surface scratches and digs after conventional polishing process. After establishing the geometry models of microstructures on supersmooth surfaces of silicon, the electric field excited by microstructure under the irradiation of 532 nm laser was numerical simulated by finite difference time domain (FDTD). From the comparison of the maximum intensity of the electric field excited by the microstructure with different sizes, it can be seen that the maximum of local electric field intensity approximately increase linearly with the scale of the microstructure increase. It also shows an increasing trend with gradient of microstructure increase while the peak value is less than 25.5 nm. The physics map of the smoothing of microstructure on silicon surface is described by the numerical simulation of electric field modulated by microstructure under laser irradiation, which gives a way to explain the non-adiabatic near-field optical etching process.