A reflective diffraction grating with a periodic square-wave profile will combine the effects of thin-film interference with conventional grating behavior when composed of features having a different refractive index than that of the substrate. A grating period of 700–1300 nm was modeled and compared for both silicon (Si) and silicon dioxide (SiO₂) to determine the behavior of light interaction with the structures. Finite element analysis was used to study nanostructures having a multirefractive index grating and a conventional single material grating. A multimaterial grating has the same diffraction efficiency as that of a grating formed in a single material, but had the advantage of having an ordered relationship between the grating dimensions (thickness and period) and the intensity of reflected and diffracted optical wavelengths. We demonstrate a color-selective feature of the modeled SiO₂ grating by fabricating samples with grating periods of 800 and 1000 nm, respectively. A high diffraction efficiency was measured for the green wavelength region as compared to other colors in the spectrum for 800 nm grating periodicity; whereas wavelengths within the red region of spectrum interfered constructively for the grating with 1000 nm periodicity resulting a higher efficiency for red color bandwidth. The results show that diffraction effects can be enhanced by the thin-film interference phenomenon to produce color selective optical devices.

中文翻译：

---

二氧化硅薄膜光栅的波长选择衍射

当由具有不同于衬底的折射率的特征构成时，具有周期性方波轮廓的反射型衍射光栅将薄膜干扰的影响与常规光栅的行为相结合。对700-1300 nm的光栅周期进行了建模，并对硅（Si）和二氧化硅（SiO ₂），以确定光线与结构相互作用的行为。有限元分析用于研究具有多折射率光栅和常规单一材料光栅的纳米结构。多材料光栅具有与由单一材料形成的光栅相同的衍射效率，但是具有在光栅尺寸（厚度和周期）与反射和衍射光波长的强度之间具有有序关系的优点。我们演示了模型化的SiO ₂的颜色选择功能通过分别制造具有800和1000 nm光栅周期的样品来实现光栅化。与800 nm光栅周期性光谱中的其他颜色相比，绿色波长区域的衍射效率高。而光谱红色区域内的波长对周期为1000 nm的光栅产生相长干涉，从而导致红色带宽的效率更高。结果表明，通过薄膜干涉现象可以增强衍射效应，从而生产出颜色选择光学器件。