Design and Analysis of 19 cell PCF for Robust Single Mode Operation usingAvoided-Crossing Modes Approach

Abstract

Double-cladding large mode area rod-type photonic crystal fibers have become a key component for power scaling in high power fiber laser systems to provide an ultra large effective area. By a careful design, the single-mode regime can be obtained insuch large core active fibers. In this paper, the 19-cell photonic crystal fibers with 3 rings in the fiber inner cladding have been investigated with the avoided-crossing approach, in order to find guidelines for the design of single-mode fibers. The air-hole diameter and the wavelength have been changed.In a certain point of air-holes diameter and the wavelength for 19cell PCF, the avoided crossing between HOMs has been occurred. In this point, the confinement loss of HOMs is increased which is more ensured for SM operation