Theoretical study of amplified spontaneous emission using a model based on a geometrically dependent gain coefficient

Abstract

It is shown that a model based on a geometrically dependent gain coefficient (GDGC), which is characterized by gain parameters (m′, , b), introduces a powerful method to describe amplified spontaneous emission (ASE) intensity behavior and its bandwidth reduction when the ASE is propagating along the z-direction. The model also gives correct predictions for unsaturated and saturated gain coefficients and the frequency dependence of the ASE output intensity in a given laser system. For the calculation, the GDGC model in saturated and unsaturated conditions along with the intensity rate equation were applied, and for verification of the model the reported ASE intensity measurements and the measured bandwidth reduction in KrF lasers were utilized. The present model will have applications in any type of pulsed laser system of different active media and different dimensions without going through complicated analysis or utilizing heavy computer numerical computations. Details of the present approach will be given and the excellent agreement with the available and typical experimental measurements for KrF lasers confirms the validity of the proposed GDGC model.