Reconfigurable wide-angle broadband terahertz wave antireflection using a non-volatile phase-change material

Area of Science:

• Optics and Photonics
• Materials Science
• Terahertz Technology

Background:

• Wide-angle broadband terahertz (THz) antireflection (AR) coatings are crucial for advanced THz components.
• Existing AR coatings often lack reconfigurability and flexibility.
• Phase change materials offer tunable optical properties.

Purpose of the Study:

• To develop a reconfigurable wide-angle broadband THz AR coating.
• To utilize the phase change material Germanium-Antimony-Tellurium (Ge$_{2}$Sb$_{2}$Te$_{5}$ or GST) for active AR functionality.
• To demonstrate improved performance of THz devices through suppressed reflections and eliminated interference.

Main Methods:

• Implementation of a GST film-based AR coating utilizing an impedance matching method.
• Thermal excitation to induce phase transitions in the GST film (amorphous to crystalline).
• Simulation and experimental validation of AR performance for varying incidence angles (0°–50°) and frequencies (0.1–3.0 THz).

Main Results:

• Complete suppression of THz-wave reflections achieved for angles from 0° to 50° within the 0.1–3.0 THz range.
• Effective elimination of Fabry-Perot interference caused by substrate reflections.
• Demonstrated active AR mechanism linked to GST's phase transition and conductivity modulation for impedance matching.

Conclusions:

• The GST-based AR coating offers flexible reconfigurability and broadband performance.
• Non-volatile properties of GST ensure long-term stability for impedance matching without continuous power.
• This work presents a promising approach for high-performance integrated THz components and systems.