Work

Mid-infrared filters based on subwavelength grating structures supporting high-Q resonance modes

Year: 2025

Type: article

Abstract: We propose a notch filter based on a subwavelength grating structure, featuring ultra-narrowband suppression characteristics within the mid-infrared spectrum (3–5 μm). The device leverages Fano resonance generated by the coupling between Fabry–Pérot cavity modes and surface plasmon polaritons. By introducing controlled nanoscale perturbations within the unit cell, a high- Q resonant state is excited, resulting in a narrow linewidth of 1.08 nm in the transmission spectrum. The resonance depth can be freely adjusted via the grating duty cycle, while the quality factor increases with the degree of asymmetry, reaching up to 3900. The structure also exhibits a strong response to variations in the ambient refractive index while maintaining a high quality factor (>800), and demonstrates a high sensing sensitivity of 798 nm/RIU. This work establishes a versatile and robust platform for high-performance mid-infrared filtering and sensing applications, including refractive index detection, molecular spectroscopy, thermal imaging, and gas sensing.

Source: Physics Open

DOI: 10.1016/j.physo.2025.100366

Authors: Yuanhang Zhao, Zhihui Wei, Kai Wang, Bo Wang, Guiyan zhao, Yan Wang

Institutions: Chinese Academy of Sciences, Changchun Institute of Optics, Fine Mechanics and Physics, Beihua University

Language: English

Topic: Plasmonic and Surface Plasmon Research

Subfield: Biomedical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,700

Funders: Education Department of Jilin Province, Department of Science and Technology of Jilin Province