  The technological requirements of low-power and high-fidelity color displays
have been instrumental in driving research into advanced coloration
technologies. At the forefront of these developments is the implementation of
dye-free coloration techniques, which overcome previous constraints related to
insufficient resolution and color fading. In this context, resonant dielectric
nanostructures have emerged as a promising paradigm, showing great potential
for high efficiency, remarkably high color saturation, wide gamut palette, and
realistic image reproduction. However, they still face limitations related to
color accuracy, purity, and simultaneous brightness tunability. Here, we
demonstrate an all-dielectric metasurface empowered by photonic bound states in
the continuum (BICs), which supports sharp resonances throughout the visible
spectral range, ideally suited for producing a wide range of structural colors.
The metasurface design consists of titanium dioxide (TiO2) ellipses with
carefully controlled sizes and geometrical asymmetry, allowing versatile and
on-demand variation of the brightness and hue of the output colors,
respectively.
