Fig. 1. Schematic of experimental setup

Fig. 2. Schematic of vernier effect. (a) Spectrum of FSI; (b) spectrum of FPI; (c) spectrum of superposition

Fig. 3. Simulated output spectra of single structure and composite structure sensors. (a) Single structure; (b) composite structure

Fig. 4. Wavelength shift of single FPI and composite structure sensors. (a) Single FPI sensor; (b) composite structure sensor

Fig. 5. Output spectra of single structure and composite structure sensors. (a) Single structure; (b) composite structure

Fig. 6. Resonance wavelength shift of single FPI sensor and composite sensor and linear fitting of sensitivity. (a) Resonance wavelength shift of single FPI sensor; (b) resonance wavelength shift of composite structure sensor; (c) linear fitting of sensitivity