Reflective Color Filters with Enlarged Color Gamut Enabled by Stacking Silicon Nanowires on Thin-film Coatings

We present a method of spectral mixing, capable of addressing the current issues in structural color engineering, by stacking a vertical silicon nanowire array onto optical thin-film layers. These two photonic structures enable independent tuning the optical resonance of each structure, depending on geometrical parameters, such as the diameter of nanowires and thickness of absorbing medium. Successful fabrication/characterization results demonstrate that the proposed strategy can promote the color tunability and/or wide color gamut.