The Optical Properties of Aperiodic Thin-Layer Structures: The Effective Optical Thickness

Simple analytical relationships between the geometry of aperiodic thin-layer structures and the phase component of the reflection coefficient were deduced and investigated. The effective optical thickness of an aperiodic structure was introduced as a new parameter and then was analytically defined. The two-layer thin-layer model was proposed to describe wave properties of aperiodic thin layer structures with a weak spatial heterogeneity of the refractive index. This model significantly simplifies the relations that are used to analyze wave properties of this class of multilayer structures. The validity of the analytical results was proved by corresponding numerical calculations.