  We investigate 1D aperiodic multilayer microstructures in order to achieve
near total absorption in preselected wavelengths in a graphene monolayer. Our
structures are designed by a genetic optimization algorithm coupled to a
transfer matrix code. Coupled mode theory (CMT) analysis, in accordance with
transfer matrix method (TMM) results, indicates the existence of a critical
coupling in a graphene monolayer for perfect absorptions. Our findings show
that the near-total-absorption peaks are highly tunable and can be controlled
simultaneously or independently in wide range of wavelengths in the
near-infrared and visible. Our proposed approach is metal free and does not
require surface texturing or patterning, and can be applied for other two
dimensional (2D) materials.

Optics