Perfect optical absorption in a single array of folded graphene ribbons

Area of Science:

• Optoelectronics
• Materials Science
• Photonics

Background:

• Graphene's atomic thinness presents challenges for optical absorption (OA).
• Existing methods for perfect OA (POA) often rely on complex patterned structures.
• Free-standing folded graphene ribbons (FGRs) offer a new approach to enhance OA.

Purpose of the Study:

• To propose and investigate a novel scenario for achieving perfect optical absorption (POA) in graphene.
• To explore the optical properties of free-standing folded graphene ribbons (FGRs).
• To demonstrate tunable optical absorption through structural and electrical means.

Main Methods:

• Utilizing free-standing folded graphene ribbons (FGRs) to create local resonances.
• Analyzing optical absorption spectra at normal and oblique incidence angles.
• Investigating the tunability of absorption via electrostatic gating and Fermi level changes.

Main Results:

• Achieved efficient OA through dipole (Mode-I) and bound-state-in-continuum (BIC, Mode-II) resonances.
• Demonstrated ~50% absorptance at normal incidence and ~98% at oblique incidence (φ≈40°).
• Observed asymmetric OA spectra and tunable absorption with electrostatic gating, including Fano coupling effects.

Conclusions:

• FGRs provide a remarkable and tunable platform for achieving POA in graphene.
• This approach significantly enhances light-matter interaction for 2D materials.
• The folding mechanism offers a new degree of freedom for optoelectronic device applications.