Performance study of metallic clad planar waveguide sensors in presence of graphene layer

In this paper, the performance of two metal clad planer waveguide based sensor in presence of a graphene layer just before or after the guiding layer is studied and compared. The analyses of waveguides are performed by analytical approach based on transfer matrix theory. In TM mode analysis, the dispersion characteristics of proposed waveguides show both the SPR mode and the waveguide modes. The penetration depth of SPR mode is increased with the graphene layer thicknesses in one considered configuration of waveguide and decreased in other considered configuration of waveguide. However, comparisons in considered waveguides are made on the basis of their sensitivity, detection accuracy and quality factor through the waveguide modes. It is observed that all these parameters are highly depends on the graphene layer thickness near the cutoff film thickness of waveguide modes due to the high penetration depth of light in cover media. Away from cutoff region, the presence of graphene layers before or after the guiding layer provides almost similar results. Based on obtained results, it is easy to choose an appropriate position and thickness of graphene layer for the guided-wave and radiated-wave applications.