Ultrathin nano-ring metasurface absorber in visible regime based on circuit modelSeyedeh Leila Mortazavifar, Mohammad Reza Salehi and Mojtaba ShahrakiEur. Phys. J. Plus, 137 9 (2022) 1072DOI: https://doi.org/10.1140/epjp/s13360-022-03272-8