Adaptive Adams-Bashforth method for modeling of highly doped fiber amplifiers and fiber lasers

We report the formulation of the adaptive variable coefficient predictor-corrector Adams-Bashforth scheme for modeling the population dynamics in erbium-doped fiber amplifiers and lasers based on highly doped fibers. A modified form of the scheme derived using a Lagrange polynomial is shown to result in 75% reduction of step-size as compared to a conventional adaptive Euler method. Our analysis shows that the second-order predictor and third-order corrector is most suitable for accurate modeling of the above problem. The model has been validated by regenerating the absorption and emission spectrum for doped fibers found in the literature. This modeling approach has been carried further to simulate a filterless fiber laser cavity, in which several gain and saturation dynamics are encountered. Spectral power evolution in the fiber is simulated by using the above method, and the steady-state lasing wavelength is evaluated as a function of cavity attenuation. The experimental results are found to match very well with the simulation. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).