Single-Mode regime of large mode area double cladding photonic crystal fibers

In this work, carried out in the framework of the EU FP7 ALPINE project, the single-mode regime of 19-cell core DC-PCFs has been numerically analyzed by comparing different approaches. Besides the FSM, the effective index of the fundamental mode of the double cladding fiber without defect and of the first cladding mode [3] of the Yb-doped hexagonal core PCF, both computed with a full-vector modal solver based on the finite element method[4], whose magnetic field modulus distributions are shown in Fig. 1(a) and Fig 1(b) respectively, have been considered to calculate the cut-off condition of the first High-Order Mode (HOM).