Analytical model for the design of fiber-coupled laser-diode end-pumped lasers

An analytical model has been developed for the optimization of fiber-coupled laser-diode pumped lasers by including the effect of pump beam quality into the analysis, Under the condition of minimum average pump spot size inside the active medium, simple analytical expressions for all of the key parameters of the optimum optical coupling system have been derived, These analytical functions depend on the laser-diode beam quality and properties of the active medium, With these expressions, we have derived the formula for the optimum mode size and the maximum output efficiency. In addition, the dependence of the maximum output efficiency on the pump beam quality has been studied, The present model provides a straightforward procedure to design the laser resonator and the optical coupling system for optimization, To illustrate the utility of the present model, a Nd:YAG laser pumped by fiber-coupled laser diodes is considered and optimized.