Lattice induced strong coupling and line narrowing of split resonances in metamaterials

Abstract

Strongly coupled metamaterial resonances typically undergo mode-splitting by which there is an exchange of energy between matter excitations and photons. Here, we report a strong coupling of the lattice mode with the structural eigen-resonances of an asymmetric split-ring metamaterial associated with mode-splitting and resonance line-narrowing that gives rise to high quality factor (Q-factor) resonances. We demonstrate selective control of the resonance strength, line-width, and Q-factor of individual split-ring modes by tailoring the coupling of the fundamental lattice mode to each of the hybridized resonances. A three-coupled-oscillator model shows lattice-mediated strong coupling in the form of an anti-crossing behavior between the hybridized metamaterial resonances. Such schemes of strong coupling between the lattice and the hybrid modes of the metamaterial unit cell offer an avenue to invoke lattice induced transparency, high-Q resonances and strong field confinement, which could find applications in designing slow light devices, ultrasensitive sensors, and multiband narrow filters.