Broadband polarization-insensitive absorption by metasurface with metallic pieces for energy harvesting application

Highlights: • Three layers absorber structure. • Absorb wavelengths from 300 nm to 2000 nm. • Electro-optic tunability. • Approaches the highest efficiency of multilayer absorbers. • Useful for energy harvesting, infrared detection, and imaging. -- Abstract: We present a broadband absorber in tri-layer plasmonic metamaterials with an electro-optic material as a substrate to fine tune the resonances. Broad resonant absorption peaks are achieved in a structure with metallic pieces. In the wavelength range from 300 nm to 2200 nm, the absorption spectral width is calculated to be 1078 nm, 566 nm, 282 nm, 119 nm, and 78 nm with absorption levels of 75%, 90%, 94.6%, 98.6%, and 99.4%, respectively. The total absorption efficiency, of the structure is evaluated to be 71.43%, which approaches to the absorption efficiency of a complex design with over 40-pair layers. The wide incident angle, polarization-insensitive, broadband absorption can be utilized for energy harvesting and solar thermals. Moreover, the use of electro-optic substrate has the advantage and potential to reduce the use of scaling structures and fabrication errors, and tune the resonant wavelengths to the desired range for imaging and infrared detection applications.