  The optical properties of photonic structures made with more than two
materials are very interesting for optical filtering and lighting applications.
Herein, we compared the transmission properties of one-dimensional photonic
crystals made with three, four and five materials, showing that, with a
photonic crystal made of t different materials, the band gap splits in t-1
bands. The same optical thickness for the different materials layers results in
split photonic band gaps with the same intensity. Photonic crystals with more
than two materials result in a simple structure that could be used for
multi-feature optical filters, or that could provide feedback for
multi-emission distributed feedback lasers. Furthermore, we analyzed the
transmission properties of ternary and quaternary random photonic structures.
These materials could very interesting for light trapping in photovoltaic
devices.
