Hexagonal Si3N4 Photonic Crystal Fibers Design and Analysis

Abstract

In this work, design, simulation and comparison are reported for hexagonal shaped silicon nitride (Si3N4) PCFs with 3-layer and 5-layer cladding structure. In this study, the number of air hole rings surrounding the fiber core will be varied in order to obtain the best optical properties (confinement loss, dispersion, nonlinear coefficient and effective mode area) of the proposed PCF structure. The proposed configurations are designed and analyzed by COMSOL Multiphysics based on the three dimensional (3D) finite element method (FEM) with a high accuracy solver for modal and dispersion analysis. The geometrical parameters, i.e., air hole diameter and pitch, are well optimized to obtain both a low confinement loss and a desired dispersion in a wide wavelength band. The performances of the 3-layer and 5-layer configurations are compared under the same conditions. Simulation results indicate that the 5-L design can greatly decreases confinement loss as compared to the 3-L design, and the 5-L design also provides a better dispersion management. But the 3-layer structure shows a larger effective mode area which can be useful for some high-power applications. Due to stronger mode confinement, the nonlinear coefficient is larger in the 5-layer structure. The relative results show a general comparison of the various PCF types and provide useful insight into their feasible application in optical communication, sensing and nonlinear optics. The work also confirms that Si3N4 is a good candidate for low- loss, high index material for photonic devices in near-infrared.