Fig. 1. RIP of an MAF with a curved RIP and a trench in the cladding.

Fig. 2. (a) Uniform high-index layer MLCF with parameters Δ1=0.0021, a1=1  μm, and a2=1  μm. (b) An SIF with core radius 10 μm and Δ=0.00115. (c) A bending loss comparison between MLCF and SIF.

Fig. 3. (a) Uniform high-index layer MLCF with parameters Δ1=0.0021, a1=1  μm, and a2=1  μm. (b) A curved RIP MLCF obtained from Eq. (6) with Δ11=0.004. (c) A bending loss comparison between the MLCFs in (a) and (b).

Fig. 4. Bending loss evolution as a function of core-trench separation b with a bending radius of 10 mm at a wavelength of 1550 nm.

Fig. 5. (a) bA evolution as a function of the bending radius. (b) The bending loss evolution as a function of the bending radius, with different bA at 1550 nm [the r in the legend denotes the bending radius in (a)]. (c) The bA evolution as a function of the trench index for different widths.

Fig. 6. Bending loss comparison between the MLCF with a trench and the MLCF without a trench.

Fig. 7. RIP of the fabricated fibers. The inset is the micrograph of the MLCF.

Fig. 8. Measured dispersion of the fabricated MLCF and SMF-28.

Fig. 9. Spectral bending loss as a function of the bending radius and wavelength.

Fig. 10. Comparison of the bending losses between the fabricated MLCF and the SMF-28 fiber at 1310 and 1550 nm. The curves and markers represent the results of the simulation and the measurement, respectively.

Fig. 11. (a) Comparison of the measured and calculated bending loss as a function of the wavelength, with a bending radius of 5 and 10 mm.