Hartman N F, Gaylord T K
Appl Opt. 1988 Sep 1;27(17):3738-43. doi: 10.1364/AO.27.003738.
A systematic procedure using the effective index method and impedance matching has recently been developed Appl. Opt. 26, 3123 (1987)] for the design of antireflection high-spatial-frequency rectangulargroove gratings on lossy materials including high conductivity metals. The design procedure in turn can be used as a starting point to design antireflection metallic gratings with lower spatial frequencies using rigorous coupled-wave analysis. These lower spatial-frequency gratings have the advantage of being easier to fabricate. In the present work, a particular antireflection gold grating design (having a period of 1.0 microm, a filling factor of 50%, and a groove depth of 147.5 nm for use at a freespace wavelength of 500 nm, normal incidence, and polarization parallel to the grooves) was fabricated and its diffraction characteristics experimentally measured. The grating indeed showed very nearly zero specular reflection in the blue region of the spectrum. Unlike previously reported antireflection anomalies, the effect is broadband occurring over a broad range of wavelengths and angles of incidence, and for both orthogonal polarizations. This work clearly shows that the systematic design of zero specular reflection grating surfaces is possible.
最近开发了一种使用有效折射率方法和阻抗匹配的系统程序[《应用光学》26, 3123 (1987)]，用于在包括高电导率金属在内的有损材料上设计抗反射高空间频率矩形凹槽光栅。反过来，该设计程序可以用作使用严格耦合波分析来设计具有较低空间频率的抗反射金属光栅的起点。这些较低空间频率的光栅具有更易于制造的优点。在当前工作中，制造了一种特定的抗反射金光栅设计（周期为1.0微米，填充因子为50%，在自由空间波长500纳米、垂直入射且偏振平行于凹槽的情况下凹槽深度为147.5纳米），并通过实验测量了其衍射特性。该光栅在光谱的蓝色区域确实显示出几乎为零的镜面反射。与先前报道的抗反射异常不同，这种效应是宽带的，在很宽的波长和入射角范围内都存在，并且对于两种正交偏振都如此。这项工作清楚地表明，系统设计零镜面反射光栅表面是可行的。
