Lattice plasmon resonance in core-shell SiO₂/Au nanocylinder arrays

Core-shell SiO2/Au nanocylinder arrays (NCAs) are studied using finite-difference time-domain simulations. The increase of height induces new surface plasmon resonances along the nanocylinders, i.e., dipole and quadrupole modes. Orthogonal coupling between superstrate diffraction order and the height-induced dipole mode is observed, which could achieve a well-defined lattice plasmon mode even for smaller NCAs in asymmetric environments. Electromagnetic field distribution has been employed to determine the coupling origin. Radiative loss could also be effectively suppressed in these core-shell NCAs, indicating the possibility of future applications in fluorescence enhancement and nanolasers.