Hybrid Graphene-Plasmonic-Based Single-Mode Metamaterial Perfect Absorber With an Ultra-Narrow Band for Hemoglobin Concentration Sensing

This paper proposes an ultra-narrow band singlemode metamaterial perfect absorber consisting of periodic square graphene split rings and gold (Au) strips at the top layer, an insulator interlayer of SiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>, and an Au base layer. The absorber designed in this paper incorporates the benefits of conventional graphene plasma and metal plasma and has two applications a perfect absorber and a refractive index sensor (RIS). The finite difference time domain method is used to study the absorption and sensing characteristics of the designed topology. The results show an absorption peak at 3.092 THz with an absorption coefficient of 97.45%, and an absorption bandwidth of 88.11 GHz is achieved. In addition, the generated narrow absorption peak can be flexibly tuned by varying the graphene layer's chemical potential. Also, high sensitivity and FoM values of 3040 GH/RIU and 34.5 RIU-1 are obtained for the proposed RIS, respectively. The performance of the suggested RIS is analyzed to measure the hemoglobin concentration in human blood. According to the results, the offered design can be a suitable option for future optical biosensors for biomedical applications.