Ultra-narrow band perfect absorber for sensing applications in the visible region Ritika Ranga, Yogita Kalra, Kamal Kishor and Nishant Shankhwar Eur. Phys. J. D, 77 3 (2023) 42 Published online: 15 March 2023 DOI: 10.1140/epjd/s10053-023-00615-7