Non-close packed colloidal crystals

Solid colloidal crystals (also known as opals) self assemble mostly in close packed structures. They can show full gaps for high values of the refractive index contrast. However, they are not the best topologies for photonic band gap applications. Recently, we have shown that non-close packed structures can improve photonic gap performance. Here we will discuss the possibilities of this new approach to the quest of new colloidal-based methods to achieve much better optical gaps in colloidal lattices. We will show that non-close packed opals would present a full gap when the connectivity of spheres in the planes perpendicular to the (I 11) direction is suppressed.