Reconfigurable and spectrally switchable perfect absorber based on a phase-change material

Area of Science:

• Photonics and optical engineering
• Materials science
• Nanotechnology

Background:

• Perfect absorbers are crucial for optical sensing and communication.
• Tunable absorbers are highly desirable for flexible spectral control.
• Phase-change materials offer unique optical properties for dynamic devices.

Purpose of the Study:

• To propose and demonstrate a lithography-free, spectrally tunable perfect absorber.
• To utilize germanium-antimony-telluride (GST) phase-change material in an asymmetric Fabry-Perot cavity.
• To achieve dynamic spectral switching and reconfigurability for optical applications.

Main Methods:

• Fabrication of an asymmetric Fabry-Perot cavity with GST as the cavity layer.
• Investigation of optical absorption properties at different GST phases (amorphous and crystalline).
• Electrothermal cosimulations to verify phase change throughout the GST layer.

Main Results:

• Achieved maximum absorption of 99.7% at 1550 nm in the amorphous state.
• Demonstrated a spectral tuning range of 866 nm by switching GST phase.
• Maintained absorption above 99% across the entire tuning range.
• Confirmed reconfigurability by reamorphizing the GST layer.

Conclusions:

• The proposed device offers a viable path towards tunable perfect absorbers for 1550 nm and 2 µm optical communication windows.
• Lithography-free fabrication and dynamic spectral control using GST are key advantages.
• The reconfigurable nature of the absorber enhances its practical applicability.