Polarization dependent coupling of surface plasmon on a one-dimensional Ag grating with an InGaN∕GaN dual-quantum-well structure

The authors report the observation of a polarization-dependent surface plasmon (SP) feature on a one-dimensional Ag-grating structure through the SP coupling with an InGaN∕GaN dual-quantum-well structure closely below the metal grating. Polarized photon output is observed because only the momentum matching condition of the SP mode propagating in the direction perpendicular to the grating grooves can be reached through the diffraction of the fabricated grating and, thus, the SP radiation efficiency is significantly enhanced only in this polarization. The dispersion curve of the observed SP mode shows a group velocity of 2.4×108m∕s, which manifests the SP characteristics in the air/Ag∕GaN grating structure.