Ultra-wideband graphene-based absorber in the terahertz regime based on elliptical slots and a complementary...

A graphene-based absorber is presented based on elliptical slots and a complementary sinusoidal-patterned dielectric layer. The proposed absorber structure includes upper dielectric and metal film layers resulting in a Fabry-Perot cavity. The produced cavity enhances the confinement of electromagnetic waves. The presented absorber yields an absolute bandwidth of 4.02 THz (0.51-4.53 THz) considering an 0.88 absorbance level together with normal incidence. The presented structure benefits from an almost insensitive ultra-wideband absorbing performance as θ varies up to 50°and 60° for TE and TM polarizations, respectively. Moreover, the considered symmetry in the design procedure results in an almost insensitive structure with respect to the φ incident angle. Finally, the obtained 160% fractional bandwidth is much greater compared to mentioned previous works in literature.