Color of anisotropic multilayers

This work proposes the use of anisotropic materials for the design of planar multilayer systems that produce polarization-dependent structural color, both by reflection and/or transmission. To obtain reflected colors, 1D perfectly periodic structures composed of anisotropic materials are used. For transmitted colors, we propose to assemble two identical photonic crystals comprising alternating layers of isotropic and anisotropic materials that differ in their definition of the unit cell. In such a system, a topological mode is generated at the interface between the two photonic crystals. These colors not only exhibit high brightness and purity, but can also be tuned by varying the layer thicknesses. Furthermore, their brightness can be controlled by changing the direction of the incident polarization. These systems are very promising for the design of materials with controllable color, for applications such as optical sensors and anticounterfeiting technologies.