PMMA-gold metallodielectric photonic crystals and inverse opals: Preparation and optical properties

Bottom-up colloidal synthesis of photonic band gap (PBG) materials or photonic crystals (PC) has attracted considerable interest over the top-down approaches due to their simple processing steps and prospect of economic production of complex 3-dimensional structures. Here we report a template assisted bottom-up synthesis of long range order three-dimensional (3D) Poly (methyl methacrylate)-gold (PMMA-gold) metallodielectric PC structures and their robust inverse opals. PMMA opals prepared by dip coating of the PMMA particles, synthesized in our laboratory, onto indium tin oxide (ITO) substrates were used as templates into which gold metal was deposited by electrodeposition method and their inverse opals were prepared by a combination of chemical dissolution and controlled temperature treatment steps. The angle-resolved optical reflectance of these structures was measured using an optical bench set up. The spectrum obtained at an incident angle of 10° with respect to the normal show a broad band centered at 715 nm for the gold inverse opal, which show an almost non-dispersive character at all increasing incident angles. The paper presents the interesting spectral features of the opals and their inverse opal and their fabrication method in detail.