Phase-change metasurface with tunable and switchable circular dichroism.

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Metasurfaces offer unique optical properties.
• Tunable circular dichroism (CD) is crucial for advanced photonic devices.
• Phase-change materials like Germanium-Antimony-Tellurium (GST) enable dynamic control.

Purpose of the Study:

• To propose and numerically demonstrate a novel metasurface absorber with tunable circular dichroism (CD).
• To investigate the reconfiguration of CD effects using phase-transition properties of GST resonators.
• To achieve reversible chirality for switching CD signals.

Main Methods:

• Numerical simulation of a metasurface absorber incorporating periodic GST resonators.
• Exploiting chiral plasmonic resonance for strong CD.
• Utilizing the phase transition of GST for CD strength modulation and reversible chirality control.

Main Results:

• Achieved a strong CD of approximately 0.75 due to chiral plasmonic resonance.
• Demonstrated quasi-linear modification of CD strength from 0.03 to 0.75 via GST phase transition.
• Realized reversible chirality by independently controlling GST resonator states, enabling on/off/reverse CD switching.

Conclusions:

• The proposed GST-based metasurface absorber offers dynamic and reconfigurable CD properties.
• The ability to tune CD strength and switch chirality opens possibilities for advanced optical applications.
• This work presents a promising platform for developing next-generation chiral photonic devices.