M.I. Molina and Francis H Bennet
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B 29 (2012)
We examine localized surface modes in the core of a photonic crystal fiber composed of a finite nonlinear (Kerr) hexagonal waveguide array containing a topological defect in the form of a central void. Using the coupled-modes approach, we find the fundamental surface mode and the staggered and unstaggered ring-shaped modes, and their linear stability windows, for two void diameters. We find that for a small void diameter, the unstable unstaggered ring mode of the system always requires less power and its instability gain at low powers is smaller, than in the case without the void. Also, for
the small void case, the unstaggered ring mode does not require a minimum power threshold, in sharp contrast with the case
without the void. For a larger void, most of these observations hold as well. We follow numerically the dynamical evolution of these ring modes to reveal their decay channels at long propagation distances.