We model CW operation of end-pumped four-level glass lasers to obtain expressions for threshold, slope efficiency, and figures of merit. Discussion of thermal effects ultimately limiting performance in these lasers is also given. Basic design considerations for optimum performance of an end-pumped CW Nd: glass laser intended for mode locking are presented. Based on these investigations we have built a CW Nd:glass laser containing a heavily-doped thin phosphate glass plate as the gain material. The plate was inserted into a folded cavity and pumped longitudinally by a Kr laser at 0.8 μm. With 2.5 percent output coupling the pump threshold and the slope efficiency well above threshold were measured to be 10.5 mW and 36 percent, respectively. These values agree reasonably with theoretical predictions. Experimental confirmation of the predicted thermal limiting effects are also obtained.
