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

Weien Lai , Hanguang Gou , Ding Huang

Optics Letters +

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November 1, 2024

View abstract on PubMed

Summary

This study introduces a reconfigurable terahertz (THz) antireflection (AR) coating using a phase change material. The novel GST-based coating actively suppresses THz reflections across wide angles and frequencies, enhancing device performance.

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.