Coherent perfect absorption in plasmonic planar metasurface

The coherent perfect absorption (CPA) for a planar resonator of silver has been elaborated here in numerical and analytical approaches. It is investigated numerically in different geometrical shapes and spectral regimes. The CPA mode is observed to be spectrally sensitive to the geometry of the resonator. The scattering matrix method is employed in theoretical analysis. The CPA conditions and output irradiance expressions are extracted. The mode is studied by the relative phase between two counter inputs of the resonator. The appearance of this mode is attributable to the dipole resonance effect. The way light is controlled in the required regime in perfect subwavelength structural geometry is obtained in this study. The nanostructure is functional in optical switching, modulation and terahertz sensor of photonics devices.    Key words:  Sensor, modulation, resonator, scattering and finite-difference time-domain (FDTD).