Theoretical discussion on gain guided and index antiguided fiber laser by variational gain saturation factor

The variational gain saturation factor was suggested for the theoretical model of side pumping gain guided and index antiguided fiber laser, because of the invalid definition of constant saturation power owing to the large scale core area on the cross section. The variational gain saturation factor was defined by an integral formula and obtained by a numerical method. By this approach, the theoretical model of the side pump gain guided and index antiguided fiber laser was analyzed as regards the influence of output laser power by the index step and gain coefficient.