纳米结构对蓝宝石红外增透性能的影响研究

Influence of Nanostructure on the Antireflective Performance of Sapphire

目的 解决现有的红外增透膜只能在特定波长及特定角度下有效的问题。方法 通过FDTD方法,以蓝宝石为基础材料,设计了纳米凸起结构、纳米孔洞结构及纳米光栅结构三类五种仿生增透纳米光栅结构,实现在0.7～5μm近红外及中红外波段增透。以表面微结构单元的高度、宽度和间距为优化对象,通过调节微结构阵列的单元几何参数以及单元排布,分析不同微结构的单元高度、宽度和间距对蓝宝石透过率的影响规律。结果 仿真结果表明,在其他几何参数固定的情况下,三类结构的光透过性都随着单元高度的增加而增强,且逐渐趋于稳定。在单元高度处于最佳状态时,三类结构的光透过性都在底部宽度接近或稍微超过单元间距时达到最佳,超过这个范围,透过特性随单元宽度尺寸的增加而降低。故制造过程中应注意各单元结构的间隔,以达到良好的增透效果。结论 通过横向对比三类五种结构,在对等参数条件下,纳米光栅结构具备最优秀的增透特性。

Objective In order to solve the problem that infrared anti-reflection film is valid only on a certain wave length or angle. Methods Three kinds of structures, containing nanometer raised structure, nanometer pore structure and nanometer grat- ing structures, were designed based on sapphire material by FDTD method to realize transmission enhancement in 0.7-5 μm near-infrared and mid-infrared region. To optimize the height, width and spacing of the surface microstructure unit, their influ- ence on transmission was analyzed through adjusting geometric parameter and unit configuration. Results Simulation results showed that with the other geometric parameters fixed, all of the three kinds exhibited enhanced light transmission phenomenon with an increase in cell height and gradually trended to be stable as the height increases. With cell height in its best condition, the best transmission characteristics were obtained when the three structures were close to or slightly above the bottom of the cell gap width. Beyond this range, the transmission characteristic decreased with increasing cell width. Therefore, in order to achieve a good antireflection effect, attention should be paid to the structure of each unit interval during the manufacturing process. Conclusion By virtue of comparison among the three kinds of five nano-structures, it is indicated that nano-grating structures own the best transmission enhancement quality under equal parameter conditions.