UV–visible broadband polarization-independent metamaterial absorber based on two-dimensional Au grating

•A simple broadband absorber consisting of 2D Au square grating on graphene-SiO2 film and Au substrate is proposed.•The absorber achieve nearly perfect absorption with absorption of exceeding 90 % spanning a broad range from100 nm to 700 nm).•The absorber is polarization and angle insensitive for incident light even at large angle.•The absorption are well explained by Rayleigh anomaly, cavity resonance, surface plasmon polaritons and magnetic polaritons. A broadband metamaterial absorber (BMA) based on a thin metamaterial nanostructure consisting of 2D Au square grating on graphene-SiO2 film and Au substrate is proposed and designed. The optimized structure can achieve nearly perfect absorption with absorption of exceeding 90 % spanning a broad range from deep UV light to visible light (100 nm−700 nm). The excitation of Rayleigh anomaly (RA), cavity resonance (CR), surface plasmon polaritons (SPPs) and magnetic polaritons (MPs) are responsible for nearly perfect broadband absorption, which have been analysed clearly by finite-difference time-domain (FDTD) method and the LC circuit model. Furthermore, the BMA is polarization and angle insensitive for incident light even at large angle. This proposed BMA not only has a simple geometry and ordinary metal-based material composition, but also shows a high performance in both bandwidth and absorptivity, suggesting that great potential in solar cell and photodetector applications.