Dielectric materials are used for anti-reflective coatings due to their high transparency and specific optical properties. Their thickness is crucial, as it influences wave reflection and interference, allowing for phase cancellation of reflected waves. These materials, typically insulators, do not have free conduction electrons, which minimizes reflection and allows for effective transmission of light. When the refractive index of the dielectric matches that of the surrounding materials, it creates a quarter-wave transformer that eliminates reflections at the interface. Using non-dielectric materials would result in light absorption, making them unsuitable for this application.
