Tuning photonic bandgap of 3D opal structures by utilizing polymer and silica hybrid colloids

Photonic crystals, which are the artificial multidimensional periodic structures, are attractive for ultra-compact optoelectronic devices. Various photonic crystals devices based on their photonic bandgap (PBG) have been reported. Recently, several methods have been developed for fabricating 3D photonic crystals. One of the simple methods is using colloidal spheres such as polystyrene or silica beads to form 3D face-centered cubic crystalline structures. An important issue for colloidal spheres based PBG devices is how to fabricate the devices with small bandgap-shift for optoelectronic device applications. Generally the colloidal spheres based PBG structures are formed by the monodispersed silica or polystyrene beads, and their bandgaps are decided by the refractive index and diameter of beads. In this paper, we demonstrate a simple method that can control the bandgap position by utilizing hybrid polymer and silica beads with large size-difference. The polystyrene (PS) beads with 750nm diameter and silica beads with 50nm diameter are mixed to form different PBG structures.