Here we report on different approaches to the fabrication of inverse opals. We start from silica opal templates with sphere size in the range between 200 nm and 1300 nm. The opal porous lattice is fully (above 90 % of the opal void volume) infiltrated with semiconductors (CdS, Ge) as well as polymers by several methods. Afterwards, the template is removed, from the composite, by a soft chemical etching method. Thus, and inverse opal is obtained. The periodicity of the template can be chosen to guarantee that photonic gaps or pseudogaps are in the transparency region of the bulk infiltrated material.
Optical properties of CdS, Ge, and polymer inverse opals, as well as the comparison with a theoretical calculations of the transmission and reflectance are reported. Ge inverse opal has a huge refractive index contrast (4) well above the onset value to present a sizeable full band gap.