Optical Magnetic Field Enhancement via Coupling Magnetic Plasmons to Optical Cavity Modes

The authors theoretically present a powerful method to enhance and modify the magnetic resonances in metamaterials by strongly coupling them to the optical modes of Fabry–Pérot (FP) cavities. Strong coupling between magnetic plasmons (MPs) and optical cavity modes is observed, manifested by the large anticrossing of the resonant positions in the reflection spectra. It results in two branches of hybridized MP modes with a Rabi-type splitting as large as 78 meV. The maximal magnetic field intensity achieved in the metamaterials with an FP cavity is enhanced greatly and an enhancement factor >3 is observed compared with that achieved by the bare metamaterials (without thin metallic mirror). This has the potential applications in the magnetic nonlinearity and magnetic sensors.