Experimental and theorectical studies of diode-pumped Tb:NdYAP system are performed. A generalized model which governs system key parameters of spatial mode matching, beam divergence, reflectivity, cavity loss, slope efficiency and threshold power is presented and analytical results for the mode overlap function are calculated. Experiments are carried out in an end-pumped configuration, where a YAP rod is pumped in the a-axis direction. The output efficiency for emission at 1079 nm is measured. Applications provided by the aniso--tropic feature of the YAP rod are explored for various crystal orientations and the polarizations of the emission lines at 1064 nm and 1079 nm.