Broadband Slow Light Metamaterial Based on a Double-Continuum Fano Resonance

We propose a concept of a low-symmetry three-dimensional metamaterial exhibiting a Double- Continuum Fano (DCF) optical resonance. Such metamaterial is described as a birefringent medium supporting a discrete "dark" electromagnetic state weakly coupled to the continua of two nondegen- erate "bright" bands of orthogonal polarizations. It is demonstrated that light propagation through such DCF metamaterial can be slowed down over a broad frequency range when the medium param- eters (e.g. frequency of the "dark" mode) are adiabatically changed along the optical path. Using a specific metamaterial implementation, we demonstrate that the DCF approach to slow light (SL) is superior to that of the EIT because it enables spectrally uniform group velocity and transmission coefficient.
Comment: 5 pages, 4 figures. Submitted to PRL