Fig. 1. Schematic of sensing structure

Fig. 2. Relationship between κ₀h₀ and effective refractive index for symmetrical metal-cladding waveguide structure

Fig. 3. Relation between reflectivity and incident angle under different air gap thicknesses without organic film

Fig. 4. Simulated R-θ curves when air gap thickness is 0 nm and 100 nm, respectively

Fig. 5. Relationship between air gap thickness and corresponding resonance angle

Fig. 6. Relationship between air gap thickness in the range of 0--10 nm with corresponding resonance angle