Designing multicolor patterns of inverse opals with photonic bandgap and surface plasmon resonance

Abstract

Structural colors are generated by light interaction with micro- or nanostructure such as interference and diffraction and can be potentially applied for various fields such as optical security, anti-counterfeiting materials and cosmetics. Photonic crystals are periodic optical nanostructure which inhibit certain wavelength of light and produce structural colors when photonic bandgap is placed in visible range. Surface plasmon resonance is the resonant oscillation of electrons at the interface between metal and dielectric stimulated by incident light and also can produce structural color. Here, dual-optical structure which utilizes both properties of photonic bandgap and surface plasmon resonance was fabricated using colloidal self-assembly and photolithography. Gold was deposited regio-selectively on the surface of inverse opal and the structure has both inverse opal color from photonic bandgap and plasmonic color of gold from surface plasmon resonance together. This structure is applicable for multi-structural color micro-patterning and have unique reflectance spectrum which enhances its capability for optical security and anti-counterfeiting applications. The combination of colors is controllable by changing particle diameter and reflectance spectra can be controlled by changing the ratio of gold-deposited area. Furthermore, by infiltrating fluids, both colors of photonic crystals and surface plasmon resonance changed corresponding to refractive indices of infiltrated fluids.