Controlled light energy and perfect absorption in twisted bilayer graphene

Area of Science:

• Condensed matter physics
• Materials science

Background:

• Bilayer graphene (BLG) exhibits unique electronic properties.
• Stacking order significantly influences BLG's behavior.

Purpose of the Study:

• To theoretically investigate the optical conductivity and dielectric response of BLG.
• To explore the impact of interlayer displacement and chemical potential on light-matter interactions in BLG-based devices.

Main Methods:

• Theoretical study of dynamical optical conductivity tensor.
• Calculation of dielectric response for arbitrary interlayer displacement (Δ) and chemical potential (µ).
• Modeling of a layered device incorporating an epsilon-near-zero (ENZ) insert.

Main Results:

• Deviations from standard stacking orders (AA, AB, AC) induce finite transverse conductivity.
• Interlayer displacement (Δ) and chemical potential (µ) tune light polarization, energy flow, and absorptivity.
• Near-perfect absorption and tunable dissipation are achievable by controlling Δ and µ.

Conclusions:

• Bilayer graphene's optical properties are highly tunable.
• Programmable optoelectronic devices can be designed using tailored BLG structures and ENZ materials.