Comparison of laser models via laser dynamics: the example of the Nd3+:YVO4 laser

This study has recorded series of switch-on transients for 10 to 20 different final values corresponding to single longitudinal and transverse mode operation of a Nd³⁺:YVO₄ laser. During such transients, the laser exhibits first large spikes and then slowly decreasing relaxation oscillations, so that large domains of its phase space are explored. The genetic algorithm selects the values of the parameters that better fit globally the data. Contrary to previous works that fitted only part of the data, e.g. the relaxation oscillation frequencies, all the available information has been used to reduce any bias. Convergence may be accelerated in the last stages of the fit by combining this method with a least-square fit. The latter has also the advantage of providing correlation factors revealing the coupling between some parameter values. The models are eventually compared on the basis of the fitness parameter or the standard deviation of the fit.