Optical absorption in bilayer graphene superlattices

A periodic statistical potential applied in each layer of bilayer graphene can change it to a superlattice, enabling its application as a flexible light absorber. In this work, the effect of structural parameters on the optical absorption and bandgap of such a bilayer graphene superlattice is studied theoretically in detail. The bilayer graphene superlattice consists of two single layers of graphene with different patterns of static periodic potential applied. The role of the unit cell length, different ratios between the width of each region, and the magnitude of the applied potential in the optical absorption is analyzed in detail. The results reveal that the optical absorption can be enhanced by increasing the magnitude of the square static periodic potential applied to each single layer of graphene. The effect of light polarization is also addressed. It is observed that different ratios of the widths of periodic regions do not change the absorption, while the configuration and value of the square static periodic potential applied plays a crucial role in the absorption spectrum.