Deep Subwavelength Wide-Angle Structural Colors at the Single Pixel Level

Structural colorations with artificially engineered nanostructures provide a dye-free mechanism for subdiffraction color generation with enhanced stability and environment friendliness. However, it remains elusive to create universally deep subwavelength pixels for arbitrary coloration at the single pixel level. The main obstacles are the unavoidable near-field coupling between neighboring pixels and the angular dependent hues associated with the scattering process. Here, a generic principle is proposed and developed to create deep subwavelength bright-field structural colors at the single pixel level by using alumina disk-on-film nanocavities. As a result of the gap-plasmon-induced perfect absorption, wide-angle complementary colors are achieved across the full visible spectrum where both the near-field coupling and angular dispersion are strongly suppressed. Deep subwavelength pixels down to 160 nm x 160 nm and green colors produced by composite pixels are experimentally demonstrated. The strategy represents a significant step toward practical application of structural colors at the single pixel level for nanoscale optical and optoelectronic devices.