Fig. 1. Double-clad photonic crystal fiber structure

Fig. 2. Local structure of photonic crystal fiber

Fig. 3. Distribution of fiber mode field power along the radial axis of the fiber under different air hole diameters

Fig. 4. Six LP modes of PCF and their electric field distributions

Fig. 5. Power distribution of six linear polarization modes along radial axis of core radius

Fig. 6. λ=1.55 μm, n_eff and ∆n_eff change with core radius R_c

Fig. 7. Trend chart of effective mode field area and nonlinear coefficient of six modes changing with core radius R_c

Fig. 8. Mode fields of six linearly polarized modes in bend fiber

Fig. 9. Variation of bending loss with bending radius R_b

Fig. 10. Crosstalk loss trend of six modes with wavelength