Visible frequency plasmonic perfect absorber made of a thin metal layer containing cylindrical grooves

In this communication, a visible frequency plasmonic perfect absorber (PPA) made of a thin metal layer (gold and aluminum) with an array of cylindrical grooves is demonstrated and studied numerically using the finite difference time domain solver. A novel design concept is used to achieve perfect absorption at tunable wavelengths between 400 and 1000 nm. The PPA unit cell is made of a cylindrical groove of appropriate depth, and the size of the groove is typically set to half the array period. By simply changing the array period, the perfect absorption (100%) spectral position is set to a desired wavelength. The PPA is observed to be very effective for wide incident angles and polarization states of input radiation. The study reports an attractive alternative way of designing all-metal-based PPA that may have potentials for various plasmonic and photonic applications.