Perfect absorber due to optical Tamm states based on α-MoO₃

Area of Science:

• Condensed Matter Physics
• Materials Science
• Optoelectronics

Background:

• Alpha-phase molybdenum trioxide (α-MoO3) is a biaxial van der Waals semiconductor.
• It exhibits anisotropic phonon polaritons with elliptical and hyperbolic dispersion.
• This enables strong mid-infrared (mid-IR) light absorption.

Purpose of the Study:

• To design a composite structure for perfect light absorption in the mid-IR range.
• To investigate the role of optical Tamm states (OTSs) in absorption enhancement.
• To provide theoretical guidance for α-MoO3-based optoelectronic devices.

Main Methods:

• Fabrication of a composite structure with α-MoO3 and two 1D photonic crystals (1DPCs).
• Utilized the transfer matrix method (TMM) for theoretical analysis.
• Performed electromagnetic field simulations to analyze absorption mechanisms.

Main Results:

• Achieved perfect absorption for both transverse electric (TE) and transverse magnetic (TM) polarized light.
• Absorption occurred at longitudinal and transverse optical phonon frequencies due to OTSs.
• Analyzed the influence of α-MoO3 thickness, 1DPC width, and polarization angles on absorption.

Conclusions:

• The composite structure effectively enhances mid-IR light absorption in α-MoO3.
• Optical Tamm states are crucial for achieving perfect absorption at specific frequencies.
• The findings offer valuable theoretical insights for developing novel mid-IR detectors and sensors.