Tunable triple-band graphene refractive index sensor with good angle-polarization tolerance

In this article, we design a triple-band graphene refractive index sensor with good angle-polarization tolerance, which is composed of graphene elliptic-circular nanodisk resonators periodically arranged on a dielectric substrate. The numerical results indicate that the resonant wavelengths of three modes of graphene resonators show consecutively linear tunability when the refractive index of the surrounding medium varies, and the sensitivity is up to 11.56 mu m/RIU. The sensing range can be further adjusted by controlling the doping level of graphene. In addition, the proposed graphene sensor maintains polarization insensitivity over a wide angular range (0-60 degrees), showing very good angle-polarization tolerance. This work enables us to achieve a tunable triple-band sensor and provides potential value for label-free biomedical sensing.