Light Confinement in an Ordered and Disordered Superlattice Structure

Stacking of two or more different photonic crystal (PC) structures in a periodic arrangement leads to formation of an optical superlattice structure. In a superlattice, each constituent PC is called a subcell, whereas the repeating unit is termed a supercell. The presence of randomness in a superlattice structure can significantly alter its pass and stop-bands and eventually its transmission and reflection behaviour. In this work, we investigate the propagation of electromagnetic (EM) waves through a superlattice structure and its constituent one-dimensional (1D) PCs having different strengths of randomness. We observe that the transmittance and as well as light decay length are affected by the alteration of the photonic stop-bands due to the randomness of the structures which can generate resonance modes at new frequencies and on averaging, the reflection spectrum resembles to that of a broadband mirror at higher randomness values.