Huge local magnetic field enhancement at optical frequencies in metamaterials through coupling with photonic band gap

We theoretically study the coupling of magnetic plasmon polaritons (MPPs) with photonic band gap (PBG) in a system composed of a one-dimensional (1D) silver nanowire pair array lying on a one-dimensional photonic crystal (1D PC). The near-field plasmon interactions in individual silver nanowire pairs induce MPPs. The 1D PC consisting of dielectric multilayer stacks with alternating refractive indices forms a PBG in the reflection spectrum. When the position of the PBG of the 1D PC is tuned to be close to the MPPs, the MPPs and the PBG can couple together to lead to a hybrid mode within the PBG. At the hybrid mode resonance, the magnetic fields in the center of Ag nanowire pairs are enhanced to nearly 4.3 times larger than those in the nanowire pair array directly lying on a substrate. Our numerical results hold important applications in magnetic sensors and magnetic nonlinearity.