Theoretical modeling of a diode-pumped Nd:YAG laser with a solid nonfocusing pump light collector

We report theoretical modeling for a diode-side-pumped Nd:YAG laser in which the laser rod is fixed in a solid nonfocusing (prismatic) light collector. The geometry provides for pumping the rod from four sides, which gives a relatively uniform gain profile across the transverse section of the rod and enables a high tolerance of the laser output to resonator and pump diode misalignment. The numerical model is developed to illustrate how the pumping uniformity and the transfer efficiency are affected when changes in the collector and lasing materials are made. We use small-signal gain measurements to test the predictions of the model and to examine the extent to which surface scattering from the rough rod barrel further spatially averages the deposited pump energy. The effects of the different refractive indices of the rod, collector, and fixant and the absorption properties of the laser material on optical transfer efficiencies are discussed.