Numerical simulation as a modeling and teaching tool of optical devices and systems

Abstract

This paper describes the development of numerical simulation models of an Er-doped waveguide laser and a mode-locked fiber soliton laser. The Er-doped waveguide laser model is a simple and straight-forward but powerful dynamic model using time domain algorithm. It is based on i) time dependent rate equations of a quasi-two-level-system for the population densities and ii) time-dependent traveling wave equations for the pump and signal power which are solved simultaneously in time-domain. The dynamic responses of population densities, pump and signal power are investigated. The model is used to study more sophisticated structure with cross-coupling from optical feedback of an etched grating. Another simulation model is developed to investigate the generation of sub-picosecond solitons in an active mode-locked fiber ring laser which consists of a polarization preserving Er-doped single mode fiber, an amplitude modulator and a phase modulator and has taken into account of dispersive spreading, self-phase modulation, finite amplification bandwidth, pump depletion, and Raman self-frequency shift. A newly developed numerical technique, Fourier Series Analysis Technique, is used to solve the non-linear Schrodinger equation of soliton propagation. Time trace of the soliton pulse propagation and its spectrum can be obtained under a wide range of operation conditions.