Modes in a long period grating fabricated on dispersion shifted fiber

Abstract

In this work we present the modal study of a dispersion shifted fiber (4 layers) and also in a fabricated long period grating in the same fiber type using the RSoft Software ®. For the grating analysis, the refraction index and the diameters were varied to simulate the changes due to the diameter increment provided by the electrical arc discharges effect. The structural optical fiber change, due to the periodic fattening induced by the electric arc, is added to the grating analysis as a sinusoidal type variation in each optical fiber layer. Several wavelengths are considered for the analysis and some of them are the ones commonly used by operational lasers and diodes launched in optical fibers. Results depicted the existence of many excited light modes when working with a wide spectrum white light source. When these modes satisfy the phase matching condition, they will couple in the LPFG providing it of particular filtering characteristics because of the fiber type and technique (fattening) of fabrication.