Near-infrared perfect absorption achieved with graphene-LiF multilayer metamaterial

Area of Science:

• Photonics and Metamaterials
• Optoelectronics

Background:

• Perfect absorption of electromagnetic radiation is crucial for applications in the near-infrared (NIR) to short-wave infrared spectrum.
• Graphene-based systems offer tunable absorption, but achieving polarization-insensitivity and broadband response simultaneously remains challenging.

Purpose of the Study:

• To present a graphene-lithium fluoride (LiF) multilayer heterostructure for perfect absorption in the NIR spectrum.
• To demonstrate dual electrical and structural tunability for dynamic control of optical responses.

Main Methods:

• Fabrication of a graphene-LiF multilayer heterostructure.
• Utilizing the gate-tunable conductivity of graphene and low-loss properties of LiF.
• Investigating absorption through critical coupling and plasmonic modes.

Main Results:

• Achieved perfect absorption in the NIR wavelength range.
• Demonstrated polarization-insensitive absorption for both transverse magnetic (TM) and transverse electric (TE) polarizations across various incident angles.
• Observed broadening of absorption bandwidth and a blueshift with an increasing number of graphene layers (GLs).

Conclusions:

• The proposed graphene-LiF metamaterial enables broadband perfect absorption with dual tunability.
• This versatile platform allows for dynamic control over optical responses in NIR applications.
• The design addresses limitations of previous systems by offering polarization-insensitivity and broadband characteristics.