Giant and controllable Goos-Hänchen shifts based on surface plasmon resonance with graphene-MoS2 heterostructure

Surface plasmon resonance (SPR) with two-dimensional (2D) materials has been proposed to enhance the sensitivity of biosensors. Here, we will apply SPR to greatly enhance and control the Goos-Hanchen (GH) shift. It is theoretically shown that the GH shifts can be significantly enhanced in the SPR structure coated with a graphene-MoS2 heterostructure. By changing the layer number of graphene or MoS2, the giant GH shifts can be obtained. Maximum GH shift (235.8λ) can be obtained when 2 layers of MoS2 and 3 layers of graphene are combined. Moreover, the GH shift can be positive or negative depending on the layer number of MoS2 and graphene. When the GH shift is used as the interrogation for the biosensor, it has a superior sensitivity. By comparing the sensitivity based on the SPR with only Au coating or Au-graphene coating, the sensitivity of the GH shift-interrogated biosensor can be enhanced by nearly 300 times, and hence paves the way for further applications in fundamental biological studies and environmental monitoring.