Fig. 1. Schematic of refractive index sensing model of waveguide coupled grating containing porous silicon

Fig. 2. Diagram of optical path in waveguide coupled grating

Fig. 3. Diagram of Goos-Hänchen displacement

Fig. 4. Reflectance spectrum of waveguide coupled grating sensing structure

Fig. 5. Resonant wavelength shift of sensing units with different refractive indexes

Fig. 6. Resonant wavelength shift of HOCH2CH2OH solutions with different concentrations

Fig. 7. Linear fitting relationship between HOCH2CH2OH solution concentration and resonant wavelength