Perfect absorption in symmetrical single layer ultrathin metal grating with unilateral illumination

• Published in: Results in physics Vol. 18; p. 103232
• Main Authors: Li, Siren, Yang, Hanning, Shi, Hongyan, Jiang, Xiangqian, Sun, Xiudong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2020; Elsevier
• Subjects: Gratings; Perfect absorption; Surface plasmon; Surface plasmon; Gratings; Perfect absorption
• ISSN: 2211-3797; 2211-3797
• DOI: 10.1016/j.rinp.2020.103232

•We achieve perfect absorption in symmetrical ultrathin grating under unidirectional illumination.•The absorption rate can be greatly enhanced by the weak coupling of long-range surface plasmon and localized surface plasmon.•The absorption spectral of the grating we proposed is similar to the electromagnetic induced absorption line shape. In symmetric environment, as the tangential electric field is almost constant across the ultrathin film, the absorption rate of the film is up to 0.5 under single side illumination. In this letter, we propose a symmetrical single layer ultrathin metal grating structure where perfect absorption (up to 0.99) can be achieved with unilateral illumination. We consider that this phenomenon of extraordinary optical absorption is caused by the coupling of the localized surface plasmon resonance and the long range surface plasmon. In particular, the electromagnetic response of the metal grating we proposed greatly resembles the electromagnetic induced absorption (EIA) which shows a narrow absorption peak within a broad absorption profile.