Nanoparticle-tuned structural color from polymer opals

The production of high-quality low-defect single-domain flexible polymer opals which possess fundamental photonic bandgaps tuneable across the visible and near-infrared regions is demonstrated in an industrially-scalable process. Incorporating sub-50nm nanoparticles into the interstices of the fcc lattice dramatically changes the perceived color without affecting the lattice quality. Contrary to iridescence based on Bragg diffraction, color generation arises through spectrally-resonant scattering inside the 3D photonic crystal. Viewing angles widen beyond 40 degrees removing the strong dependence of the perceived color on the position of light sources, greatly enhancing the color appearance. This opens up a range of decorative, sensing, security and photonic applications, and suggests an origin for structural colors in Nature. (c) 2007 Optical Society of America.