Unified model for plasmon-induced transparency with direct and indirect coupling in borophene-integrated metamaterials.

We propose, both numerically and theoretically, a uniform model to investigate the plasmonically induced transparency effect in plasmonic metamaterial consisting of dual-layer spatially separated borophene nanoribbons array. The dynamic transfer properties of light between two borophene resonators can be effectively described by the proposed model, with which we can distinguish and connect the direct and indirect coupling schemes in the metamaterial system. By adjusting the electron density and separation of two borophene ribbons, the proposed metamaterials enable a narrow band in the near-infrared region to reach high transmission. It provides a new, to the best of our knowledge, platform for optoelectronic integrated high-performance devices in the communication band.

Tunable plasmonically induced transparency with giant group delay in gain-assisted graphene metamaterials.

We propose a graphene metamaterial consisting of several layers of longitudinally separated graphene nanoribbon array embedded into gain-assisted medium, demonstrating electromagnetically induced transparency-like spectra. Combined with finite-difference time-domain simulations, the transfer matrix method and temporal coupled-mode theory are adopted to quantitatively describe its transmission characteristics. These transmission characteristics can be tuned by altering the gain level in medium layer and the Fermi energy level in graphene. Additionally, it is the incorporation between gain medium and graphene nanoribbons with optimized geometrical parameters and Fermi energy level that the destructive interference between high order graphene plasmonic modes can be obtained, suggesting drastic phase transition with giant group delay and ultra-high group index up to 180 ps and 104, respectively. Our results can achieve efficient slow light effects for better optical buffers and other nonlinear applications.