Ultra-narrowband perfect absorber based on polymer cylinder with cavity array structure for refractive index gas sensing

Area of Science:

• Metasurfaces
• Plasmonics
• Optical Engineering

Background:

• Perfect absorbers are crucial for various optical applications.
• Metasurfaces offer unique light-matter interaction capabilities.
• Polymer-based devices are desirable for cost-effectiveness and flexibility.

Purpose of the Study:

• To propose and analyze a novel polymer metasurface perfect absorber.
• To investigate its optical properties and potential for gas sensing.
• To provide a design scheme for narrowband polymer absorbers.

Main Methods:

• Numerical simulation of a polymer cylinder array with cavities.
• Excitation of toroidal dipole resonance with a linearly polarized plane wave.
• Analysis of absorption spectra, quality factor, and angular stability.
• Evaluation of sensing performance including sensitivity, FOM, and DL.

Main Results:

• Achieved a peak absorbance of 99.4% with an ultra-narrow FWHM of 0.18 nm.
• Obtained a high quality factor (Q) of 7571.
• Demonstrated excellent angular stability, maintaining >90% absorbance from 0° to 18°.
• Exhibited high gas sensitivity (1021.43 nm/RIU), FOM (5675 RIU⁻¹), and low DL (8.81 × 10⁻⁶ RIU).

Conclusions:

• The proposed polymer metasurface acts as a highly efficient narrowband perfect absorber.
• It shows significant potential for high-performance gas sensing and environmental monitoring.
• This work offers a valuable reference for designing polymer-based metasurface absorbers.