Fig. 1. (a) Whole spectrum of the ExTFG with a certain polarized light in the wavelength range of 1250 nm to 1650 nm, and (b) polarization dependence spectra for the zoomed peak ‘1’ between 1255 nm and 1275 nm, blue: TM polarization, red: TE polarization, black: equal polarization.

Fig. 2. (a) Size distribution and (b) absorption spectrum of the GNSs.

Fig. 3. Linking mechanism of the GNS-immobilized ExTFG.

Fig. 4. SEM images of the GNS-immobilized ExTFG: (a) 473×, (b) 1510×, (c) 5440×, and (d) 33910×.

Fig. 5. Experimental setup to monitor the spectra of the ExTFG or GNS-immobilized ExTFG.

Fig. 6. Spectral effect of GNSs immobilized on the ExTFG (a) in air and (b) in water.

Fig. 7. Spectral evolution in the SRI range of 1.3331–1.37935 for (a) the TM mode and (b) the TE mode of the bare ExTFG; (c) the TM mode and (d) the TE mode of the GNS-immobilized ExTFG.

Fig. 8. (a) Corresponding resonance wavelength shift of the bare ExTFG and the GNS-immobilized ExTFG, and (b) the normalized intensity variation of the GNS-immobilized ExTFG in the SRI range of 1.3331–1.37935.