Multilayer metamaterial graphene sensor with high sensitivity and independent on the incident angle

Abstract

A new metamaterial refractive index sensor in terahertz frequency band is proposed. The designed structure is multilayer and periodic. It consists of two SiO2 layers separated by an air gap. On the upper SiO2 layer, a unit cell of a graphene circular ring as well as four graphene elliptical half rings are placed while, a graphene circular disk is located on the lower SiO2 layer. By changing the Fermi level of graphene, selection of the optimized dimensions of the structure and the embedded air gap between the two SiO2 layers, a high sensitivity sensor by suitable figure of merit is provided. The maximum sensitivity of 36.7 μm/RIU and figure of merit of 6.43, with refractive index variations of the sensing environment from 1 to 2, is obtained. The symmetric sensor is independence from the incident wave polarization and angle. Electric field and surface current distribution of the structure is investigated and strong interaction of the incident wave with the graphene pattern is illustrated. The performance of the designed structure is compared with recent similar works and it is shown that sensitivity improvement is achieved. The proposed structure is suggested for biosensing applications.