研究目的
To propose and design a highly sensitive refractive index sensor based on conjugated bilayer-shaped chiral metamaterials with giant circular dichroism effect enabled by conductive coupling.
研究成果
The conjugated bilayer-shaped chiral metamaterial exhibits giant circular dichroism effects up to 93.8% and 96.2% at specific frequencies, enabled by conductive coupling. It achieves high sensitivities of 1.065 Thz/RIU and 1.777 Thz/RIU for refractive index sensing, outperforming other reported sensors. Key parameters affecting performance include the height h, with sensitivity decreasing as h increases. The structure shows promise for low detection-limit sensing applications in physical and biochemical fields, but further experimental validation is needed.
研究不足
The study is based on simulations, not experimental validation, which may not account for real-world fabrication imperfections or environmental factors. The sensitivity decreases with increasing refractive index and height parameter h, potentially limiting performance in certain applications. The structure's complexity might pose challenges in practical fabrication using photolithography and deep-dry etching.
1：Experimental Design and Method Selection:
The study uses finite difference time domain (FDTD) method simulations to investigate the optical properties of the proposed chiral metamaterial. The design rationale is based on enhancing circular dichroism through conductive coupling between two-shaped structures connected by a microstrip line.
2：Sample Selection and Data Sources:
The metamaterial structure is simulated as an infinite array using a unit cell with periodic boundary conditions in x and y directions, and open in z direction in free space. The dielectric substrate is polyimide with a dielectric constant of
3：67, and metallic parts are gold described by the Drude model. List of Experimental Equipment and Materials:
Simulations are performed using CST software (brand: CST Studio Suite). Materials include gold (thickness 2 μm, plasma frequency ωp =
4：37 × 10^16 s^-1, scattering frequency γ = 04 × 10^14 s^-1) and polyimide substrate. Experimental Procedures and Operational Workflow:
The simulation setup involves defining the unit cell geometry (arm lengths d1=22 μm, d2=22 μm, d3=26 μm, periods Px=60 μm, Py=60 μm, height h=
5：2 μm), applying periodic boundaries, and using the frequency domain solver to calculate absorption and circular dichroism under left and right circularly polarized light illumination. Data Analysis Methods:
Data analysis includes plotting absorption and CD spectra, calculating sensitivity as shift in resonance frequency per unit refractive index change, and determining figure of merit (FOM) based on peak shift and full width at half maximum (FWHM).
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