Using fine-structured gratings to implement mid-infrared dual-band absorbers Xin He, Jinliang Jie, Junbo Yang, Yunxin Han and Sen Zhang Eur. Phys. J. Appl. Phys., 91 2 (2020) 20501 Published online: 18 August 2020 DOI: 10.1051/epjap/2020200087