Design and fabrication of a novel side-leakage photonic crystal fiber and its propagation properties

Abstract

A novel side-leakage photonic crystal fiber (SLPCF) is proposed and fabricated by introducing a central elliptical Ge-doped core and side-leakage channel. The propagation properties of the ideal and actual structure are modeled by using full-vectorial finite element method for the rebuilt structure. This SLPCF exhibits good compatibility with the standard single mode fiber (SMF) due to its modal diameter of 9.275 μm which is very close to that of SMF at a wavelength of 1550 nm. Modal birefringence of 0.837× 10-4 and the group birefringence of 1.508× 10-4 are obtained at a wavelength of 1550 nm. Based on the side-leakage PCF, a Sagnac interferometer is constituted for evaluating the properties of the actual SLPCF. Experimental results demonstrate that the second order mode can be efficiently confined and thus single mode operation can be realized in a wavelength range from 1450 nm to 1750 nm when this fiber reaches a certain length. In addition, the average measuring value of group birefringence accords with the numerical result. The proposed SLPCF has a number of potential applications in fiber sensor and fiber components with high performance since the introduction of the side-leakage channel enhances its sensitivity, the environmental parameters such as torsion, curve and strain and so on.