Trimeric metasurfaces for independent control of bright and dark modes of Fano resonances

In this paper, we present a simple trimeric metasurface consisting of three dipolar resonators in each unit cell, to achieve the independent controlling over both the broad bright mode and the sharp dark mode of Fano resonances. Through both the finite difference time domain simulation and microwave experiment, we find that spectral positions of the bright and dark modes are linearly dependent on, respectively, the global spacing between adjacent unit cells and the local spacing between adjacent dipoles within each unit cell. The dependence of the spectral position of bright (dark) mode on the global (local) spacing is independent without mutual influence, which provides a facile pathway to control the Fano resonance with large flexibility. Our proposed scheme to control Fano resonance is highly desired in various fields including lasing spaser and biosensing with improved performance. (C) 2016 AIP Publishing LLC.