47.

Strain-engineered widely-tunable perfect absorption angle in black phosphorus from first-principles: A multi-scale approach 

Mohammad Alidoust, Klaus Halterman, Douxing Pan, Morten Willatzen, and Jaakko Akola
Phys. Rev. B 102, 115307 (2020). [PDF]

Using the density functional theory of electronic structure, we compute the anisotropic dielectric response of black phosphorus, solve Maxwell’s equations, and study the electromagnetic response of a layered structure comprising a film of black phosphorus stacked on a metallic substrate. Our results reveal that a small compressive or tensile strain, ~ 4%, exerted either perpendicular or in the plane to the black phosphorus growth direction, efficiently controls the epsilon-near-zero response, and allows a perfect absorption tuning from low-angle of the incident beam θ = 0◦ to high values θ ≈ 90◦ while switching the energy flow direction. Incorporating spatially inhomogeneous strain model, we also find that for certain thicknesses of the black phosphorus, near-perfect absorption can be achieved through controlled variations of the in-plane strain. These findings can serve as guidelines for designing largely tunable perfect electromagnetic wave absorber devices.