Modeling of Q-switched lasers with top-hat pump beam distribution

Abstract

For laser diode end-pumped solid-state lasers, the pump beam can be considered to be a Gaussian distribution or a top-hat distribution or between them. The rate equations for Q-switched lasers have been treated before, by considering the pump beam as a Gaussian distribution. This paper deals with the rate equations and the solutions for Q-switched lasers under a top-hat pump beam distribution. The normalized rate equation is obtained and solved numerically. A group of general curves are given and the comparison with the results under the Gaussian pump beam distribution and the plane-wave approximation is made. The results show that the solutions of the rate equations under a top-hat pump beam distribution are different from those under a Gaussian pump beam distribution, but the difference is very small. The solutions of the rate equations under both situations can give much more precise theoretical results than those under the plane-wave approximation.