Graphene based nonlinear multimode interference waveguide for refractive index sensing

Abstract

In this paper, a nonlinear optical refractive index sensor is proposed by adopting a thin, local and isotropic multilayer graphene into a multimode interference (MMI) waveguide. The self-imaging characteristics of the proposed MMI waveguide is simulated using the Beam Propagation Method (BPM) in three different wavelengths in the visible spectrum. BPM considers monochromatic signals and is related to solving the Helmholtz equation. The output intensity is found to show correspondence to field change in different wavelengths by varying the refractive index of the surrounding layer. The results showed that graphene is able to guide the electromagnetic field in the MMI region as the potential difference applied on graphene tuned its conductivity. The correlation integral between the input field and the propagating field of the waveguide is numerically analysed. This design is a high precision optical refractive index sensor that is suitable to be employed as real-time environmental monitoring device.In this paper, a nonlinear optical refractive index sensor is proposed by adopting a thin, local and isotropic multilayer graphene into a multimode interference (MMI) waveguide. The self-imaging characteristics of the proposed MMI waveguide is simulated using the Beam Propagation Method (BPM) in three different wavelengths in the visible spectrum. BPM considers monochromatic signals and is related to solving the Helmholtz equation. The output intensity is found to show correspondence to field change in different wavelengths by varying the refractive index of the surrounding layer. The results showed that graphene is able to guide the electromagnetic field in the MMI region as the potential difference applied on graphene tuned its conductivity. The correlation integral between the input field and the propagating field of the waveguide is numerically analysed. This design is a high precision optical refractive index sensor that is suitable to be employed as real-time environmental monitoring device.