Reflective color filters based on SiO2/Cu multilayer stacks

Abstract

Due to strong inter-band transitions, the optical response of copper exhibits a high light absorbance in the visible region of the spectrum, recovering blue wavelengths and reflecting a reddish color. In this contribution, copper is split into subwavelength thin films, which are separated by silicon dioxide dielectric layers to take advantage of photonic bandgaps, which subtract bands from the reflected light and, thus, give rise to a wide range of reflective colors, including blue. Using numerical simulations, we investigate the photonic bandgaps of SiO2/Cu stacks, enabled by Fabry–Pérot transmission resonances, which demonstrate the color tunability of these structures.