Fig. 1. (a) Cross section of the FM-MCF SPR biosensor; (b) cross section of the FM-MCF; (c) FEM mesh for calculation.

Fig. 2. The core-hole distance d variation during using hydrofluoric acid to fabricate the groove channel: (a) Cladding is tangent to the outermost air-holes; (b) air-holes are tangent to the cores; (c) fiber cores are also etched. The inserts below are zoom-in of red region.

Fig. 3. (a) Loss spectra of the core mode with different d when n_a = 1.33—1.36; (b) the effect of d on both resonance wavelength and sensitivity with various RI; (c) relations between d and FWHM as well as FOM of the sensor.

Fig. 4. Loss spectra of the core mode for different coating thickness (t): (a) Au; (b) Ag; (c) ITO.

Fig. 5. Loss spectra of the sensor with n_a increasing: (a) t_Au = 40 nm; (b) t_ITO = 100 nm.

Fig. 6. Relations between n_a and resonance wavelength for different t: (a) t_Au = 40 nm; (b) t_ITO = 100 nm.

Fig. 7. (a) Electric field distributions of LP_01x; (b) optical field distributions of LP_01x; (c) electric field distributions of LP_11ax; (d) optical field distributions of LP_11ax.

Fig. 8. (a) Loss spectra excited by LP_11ax mode; (b) relations between n_a and resonance wavelength at LP_11ax mode.

Fig. 9. The loss spectra of three bio-substances sensing: (a) Channel 1 for Au coating with n_a = 1.35; (b) channel 2 for Ag coating with n_a = 1.34; (c) channel 5 for ITO coating with n_a = 1.33. Insets are optical field distributions for three channels.

Fig. 10. Loss spectra for detecting one bio-substance simultaneously using multi-channel when n_a increases from 1.33 to 1.34: (a) Channel 1; (b)channel 2; (c) channel 5.