Nonlinear light localization around the core of a `holey' fiber

TL;DR

This paper investigates localized surface modes in a nonlinear photonic crystal fiber with a defect, revealing stability conditions and the evolution of vortex excitations.

Contribution

It introduces a discrete model for analyzing surface modes in nonlinear photonic crystal fibers with defects and explores their stability and evolution.

Findings

Fundamental surface mode stability window identified.

Unstaggered ring-shaped mode is always unstable.

Vortex excitation can persist at low amplitudes before decaying.

Abstract

We examine localized surface modes in the core of a photonic crystal fiber composed of a finite nonlinear (Kerr) hexagonal waveguide array with a central defect. Using a discrete approach, we find the fundamental surface mode and its stability window. We also examine an unstaggered, ring-shaped surface mode and find that it is always unstable, decaying to the single-site fundamental surface mode. A continuous model computation reveals that an initial vortex excitation (S=1) of small amplitude around the central hole can survive for a relatively long evolution distance. At high amplitudes, however, it decays to a ring configuration with no well-defined phase structure.