Adjustable strong circular dichroism based on a tricircular arc metasurface

Area of Science:

• Metasurfaces
• Chirality
• Circular Dichroism

Background:

• Circular dichroism (CD) is crucial for applications in biology and chemistry.
• Achieving strong CD requires breaking structural symmetry to differentiate responses to circularly polarized waves.

Purpose of the Study:

• To propose and analyze a novel metasurface structure for enhanced circular dichroism.
• To investigate the influence of structural parameters and incorporate phase change materials for tunable CD.

Main Methods:

• Design of a metasurface combining split rings and three circular arcs with controlled asymmetry.
• Numerical simulations to analyze CD response and parameter influence.
• Integration of vanadium dioxide for dynamic modulation of CD.

Main Results:

• The proposed metasurface exhibits strong circular dichroism, with absorption up to 0.99 for left-handed circularly polarized waves at 5.095 THz.
• A maximum circular dichroism exceeding 0.93 was achieved.
• Incorporation of vanadium dioxide enabled flexible CD modulation with depths up to 98.6%.

Conclusions:

• The designed chiral metasurface demonstrates robust and tunable circular dichroism.
• The structure's angle independence and high modulation depth make it suitable for practical applications.