Topological Corner State-Based Fano Resonances for Ultrasensitive Sensing

Topological photonic crystals (PCs) support robust and highly confined optical modes, making them ideal for various applications, including sensing and light manipulation. Herein, the topological corner state (TCS)-based Fano resonance for the robustness and highest sensing ability is investigated. TCSs are robust to disorder and defects, and Fano resonance is sensitive to the refractive index change. Accordingly, we combine the advantages of the two mechanisms to propose high-performance sensing based on the Fano resonance-based TCSs. Thus, it can potentially revolutionize the sensing field. Our new approach offers several advantages over previous approaches, including improved robustness, sensitivity (439.7 nm/RIU), high${Q}$factor (${>}{10}^{{6}} $), and high figure of merit (FOM) (${>}{10}^{{5}} \text {RIU}^{-{1}}$). Finally, this is a significant achievement, and it suggests that our sensors have the potential to outperform all other Fano resonance-based sensors in terms of overall performance. Our work could lead to new and improved sensing applications in various fields, including environmental monitoring, biomedical diagnostics, and industrial process control.