Defect mode tunability based on the electro-optical characteristics of the one-dimensional graphene photonic crystals.

Abstract

New (to the best of our knowledge) photonic crystal optical filters with unique optical characteristics are theoretically introduced in this research. Here, our design is composed of a defect layer inside one-dimensional photonic crystals. The main idea of our study is dependent on the tunability of the permittivity of graphene by means of the electro-optical effect. The transfer matrix method and the electro-optical effect represent the cornerstone of our methodology to investigate the numerical results of this design. The numerical results are investigated for four different configurations of the defective one-dimensional photonic crystals for the electric polarization mode. The graphene as a defect layer is deposited on two different electro-optical materials (lithium niobate and polystyrene) to obtain the four different configurations. The electro-optical properties of graphene represent the main role of our numerical results. In the infrared wavelength range from 0.7 µm to 1.6 µm, the reflectance properties of the composite structures are numerically simulated by varying several parameters such as defect layer thickness, applied electrical field, and incident angle. The numerical results show that graphene could enhance the reflectance characteristics of the defect mode in comparison with the two electro-optical materials without graphene. In the presence of graphene with lithium niobate, the intensity of the defect mode increased by 5% beside the shift in its position with 41 nm. For the case of polystyrene, the intensity of the defect mode increased from 6.5% to 68.8%, and its position is shifted with 72 nm. Such a design could be of significant interest in the sensing and measuring of electric fields, as well as for filtering purposes.