Dynamical controllable optical device designed by tunable graphene nanostructures in a PIT structure

Abstract

Plasmonically induced transparency (PIT) is the classical counterpart of the Electromagnetically induced transparency (EIT) as a quantum nonlinear phenomenon that is achievable in metamaterial structures. In recent years, considerable research has been dedicated to metamaterials for the realization of PIT. Graphene metamaterials have drawn significant attention as a research area due to their unique characteristics, such as surface conductivity tunability by gate electrical biasing. Unlike the EIT effect, the PIT phenomenon is usually achieved between two resonators via near-field coupling without applying any pump. The distance between the two resonators is a vital parameter in PIT. The variation in the coupling strength requires physical parameter reformation of the PIT structure or material change. Here, two bright and dark resonators are utilized. By engineering the electrical field pattern of the bright resonance mode, the coupling strength dynamically changes. For this purpose, three graphene nanostrips as an adjustable quantum structure are used to form a bright resonator, and the quantum confinement of the carriers controls the coupling strength. In addition, the PIT quality factor is engineered from 33.87 for the quantum barrier case to 69.9 for the quantum-well case. Therefore, the coupling strength between the bright and dark resonators can be managed without any geometrical or material changes.