ANALYSIS OF ULTRA-SHORT PULSE PROPAGATION IN NONLINEAR OPTICAL FIBER

Abstract

Ultra-short pulse is a promising technology for achieving ultra-high data rate transmission which is required to follow the increased demand of data transport over an optical communication system. Therefore, the propagation of such type of pulses and the effects that it may suffer during its transmission through an optical waveguide have received a great deal of attention in the recent years. Our goal in this paper is to study the propagation characteristics of that pulse in a nonlinear optical fiber. In analyzing these characteristics, the nonlinear effects along with the dispersion are taking into account. Additionally, the considered nonlinear effects include self phase modulation (SPM) and stimulated Raman scattering (SRS). The problem to be processed is modeled using the finite difference time domain (FDTD) technique which represents an efficient tool in achieving the required purpose. Because of the symmetrical structure of the optical waveguide, the FDTD modeling of bodies of revolution (BOR) in cylindrical coordinates is the most preferable algorithm in analyzing our problem. The FDTD treatment of dispersion and nonlinearity of the optical waveguide is accomplished through the direct integration method. In addition, the Lorentzian model is chosen to represent the dielectric properties of the optical fiber. The azimuthal symmetry of optical fiber enables us to use a two-dimensional difference lattice through the projection of the three-dimensional coordinates (r, ϕ, z) into the (r, z) plane. Extensive numerical results have been obtained for various cavity structures.