Self-double solid-state NYAB laser: A theoretical model for coupling the nonlinear and rate equations in a double-pass cavity

In this study، the efficiency of a self-doubler NYAB laser، which is simultaneously an active and a nonlinear crystal، in a double-pass cavity is investigated. To this end، first، a model based on the coupling of five differential equations describing the interaction of pump beam of 807 nm، laser beam of 1060 nm، and second harmonic beam of 530 nm is presented. In this model، the conversion of pump beam to laser beam through the fluorescence process is described by the laser rate-equations. The generation of second harmonic beam is performed through the nonlinear processes. The model consists the linear and nonlinear interactions of light as well as the optical absorption. The results give the laser and second harmonic generation efficiencies against the pump powers.