Fig. 1. The schematic structure of the MSC

Fig. 2. The effect of core spacing D and coupling distance L on coupling coefficient κ and coupled optical power P

Fig. 3. Design and actual refractive index profiles of ring-core FMF

Fig. 4. The variation of effective refractive index and effective refractive index difference with wavelength in ring core FMF

Fig. 5. The relationship between the mode effective refractive index and fiber radius

Fig. 6. Flow chart of MSC fabrication process

Fig. 7. Experimental setup for testing insertion loss of MSCs

Fig. 8. The characteristics of the LP₀₁-MSC at 1 480~1 630 nm band

Fig. 9. The characteristics of the LP₁₁-MSC at 1 480~1 630 nm band

Fig. 10. The characteristics of the LP₂₁-MSC at 1 480~1 630 nm band