So I have built a 3D structure and am shining a plane wave light source at one of the surfaces. Let’s just assume this surface looks like a square. The material used has n=1.4 and I would like to layer a material on top such that it is reflected back with almost 100 percent reflection for all wavelengths. How could I achieve this? I thought about layering on a material and just adjusting is k value but I’m not sure what the best way to do this as the k value is for absorbance.