Presentation Information
[10a-E201-6]RCD spectral evaluation and elucidation of resonance mechanisms of Al plasmonic chiral metasurfaces exhibiting broadband visible light circular dichroism.
〇Kotaro Ito1, Takeshi Kato2,3, Kazumasa Hiramatsu1, Atsushi Motogaito1 (1.Grad. Sch. Eng., Mie Univ., 2.IMaSS, Nagoya Univ., 3.Grad. Sch. Eng., Nagoya Univ.)
Keywords:
Chiral metasurface,Reflective circular dichroism,Plasmonic resonance mechanism
In this study, we investigate the spectral characteristics and resonance mechanisms of an aluminum (Al) plasmonic chiral metasurface exhibiting strong reflective circular dichroism (RCD) over a broad visible wavelength range. By replacing the conventional concave structure with a convex Z-shaped chiral structure, numerical simulations based on rigorous coupled-wave analysis (RCWA) demonstrated RCD values exceeding 0.4, reaching up to 0.6, in the wavelength range of 380–700 nm. Based on this design, samples were fabricated using electron-beam lithography and vacuum deposition, and their optical properties were evaluated via reflectance measurements. The fabricated metasurface exhibited a maximum RCD of 0.35 in the visible region from 400 to 700 nm. Furthermore, electromagnetic field analysis revealed that different resonance modes—radiative and non-radiative—are selectively excited depending on the handedness of incident circularly polarized light. The difference between these resonance processes is identified as the origin of the observed RCD. This study provides important insights into the design principles and underlying mechanisms of broadband chiral metasurfaces.