A broadband and ultra-thin absorber for solar cell application is designed.The absorber consists of three layers,and the difference is that the four split ring resonators made of metal gold are encrusted in the gallium arsenide (GaAs) plane in the top layer.The simulated results show that a perfect absorption in the region from 481.2 to 684.0 THz can be obtained for either transverse electric or magnetic polarization wave due to the coupling effect between the material of GaAs and gold.The metamaterial is ultra-thin,having the total thickness of 56 nm,which is less than one-tenth resonance wavelength,and the absorption coeNcients at the three resonance wavelengths are above 90％.Moreover,the effective medium theory,electric field and surface current distributions are adopted to explain the physical mechanism of the absorption,and the permittivity sensing applications are also discussed.As a result,the proposed structure can be used in many areas,such as solar cell,sensors,and integrated photodetectors.