Impact of truncation on absorption spectra in a graphene-based random photonic crystal

Abstract

The present study investigates the influence of randomness on achieving multimode broadband and narrowband absorption of graphene-embedded photonic structures. In the first proposed photonic configuration, with a change in randomness parameter, it is possible to achieve single-mode and multimode broadband absorption up to 0.8. This value is further enhanced up to 0.99 by varying the Fermi level to −0.9 eV. The position of absorption peaks can be tuned by varying the thickness of the silicon carbide layer. Further, an investigation is carried out on the influence of adding a defective periodic photonic crystal to the first photonic configuration, which provides a multimode narrowband absorption with a value of up to 0.99, and the strength and location of absorption peaks can be altered to the desired value by changing the graphene Fermi level and the thickness of the silicon carbide layer. Finally, the authors also survey the influence of a magnetic field B on the absorption behaviour of left-handed circularly polarised (LCP) and right-handed circularly polarised (RCP) waves. The results indicate that the full width at half-maximum of absorption peaks expands with the application of a positive magnetic field for LCP waves, whereas it shrinks for RCP waves. This has applications in the design of tunable broadband and narrowband absorbers and sensors.