Polarization-independent Enhanced and Tunable Goos-Hänchen Shift in a Metal-Dielectric Grating Structure with Monolayer Graphene

The sensitivity of Goos-Hänchen (GH) shifts on the geometric parameters of the structures suggest their great application prospects in sensing and detection. However, most of the enhanced GH shifts are achieved under either the transverse electric (TE) wave or transverse magnetic (TM) polarized wave. Here, we theoretically demonstrate that the well-designed metal-dielectric grating structure with monolayer graphene has the potential for realizing the enhanced GH shifts under both the TE and TM polarized waves at the same specific wavelength, which is dramatically different from the previous works and suggests that the enhancement of the GH shift is polarization independent. In particular, the enhancement of the GH shift obtained in this structure under the TE polarized wave is caused by the excited guided mode resonance in the dielectric layers of the grating strip. Moreover, the enhancement of the GH shift under the TM polarized wave is mainly due to the excited surface plasmon polariton at the interface between the dielectric layer and the metal layer in the top of grating strip. We also find that the size and sign of the GH shift can be controlled by the chemical potential of monolayer graphene and the geometric parameters of this structure. The highly controllable and polarization independent GH shift in the metal-dielectric grating structure with monolayer graphene paves the way for the future applications in the polarization independent devices, such as, optical sensors, optical switches and so on.