All-dielectric Schrödinger colours across the visible spectrum

Structural colours, which arise from nanostructures, are pervasive in nature and play a pivotal role in numerous modern applications. Traditional approaches usually deviate from the concept of Schrödinger's pixels and thus have restricted performance in colour gamut and chiaroscuro presentation. Here, we harness the interactions between optical modes to achieve an unprecedented structural colour using SiO₂-Si₃N₄ stacked metasurfaces. The mode interactions produce a high-reflection band formed by two Fano resonances with near-unity reflectance and sharp edges. The destructive interference between the tails of resonances and multiple reflections at the interfaces effectively suppresses the background reflection, creating an almost ideal stopband. Consequently, nearly perfect Schrödinger colours have been experimentally realized across almost the entire visible spectrum, setting a new colour gamut record of 1.06 times Rec.2020. By introducing local size deviation, higher-order diffraction emerges and the colour brightness has also been continuously adjusted for direct chiaroscuro presentation for the first time.