Facile fabrication of micro-grooves based photonic crystals towards anisotropic angle-independent structural colors and polarized multiple reflections.

In nature, many living organisms exhibit low-angle-dependent or even angle-independent structural colors for wide viewing angle, such as the blue skin of mandrill, feather of blue bird and shell of longhorn beetle, etc. To mimic these structural colors, based on periodic semicircular micro-grooved (PSMG) substrate, silica colloidal photonic crystals provide anisotropic angle-independent structural colors. The PSMG photonic crystals were fabricated by self-assembling monodispersed silica nanoparticles on a micro-grooved template, which can be easily prepared in large scale by a hot embossing method, and no additional materials are needed in the whole preparation process. The PSMG photonic crystals exhibit identical structural colors around the groove axis, whereas it is angle-dependent along the groove axis. In addition, this PSMG surface of photonic crystal also leads to color separation effect and monocolor polarization conversion. This system provides a facile and scalable means to prepare anisotropically angle-independent colloidal photonic crystal, which is considered important in applications in the field of anti-counterfeiting or the manufacture of monochromatic light reflector with wide viewing angles and other novel optical devices.