Multi-pass traveling-wave amplifier based on an end-pumping Nd:glass slice

This paper describes a multi-pass traveling-wave amplification structure used to amplify 8×8 mm signal lasers with a 5-mm thick Nd:glass slice. The pumping source is a laser diode stack containing eight laser diode arrays. These arrays are carefully placed to maintain high coupling efficiency. Experimental results show that a 300-μJ signal laser can be amplified to 13 mJ with the first 12-pass structure of amplification, and to 246 mJ with its dual-pass feature. The method for solving the thermal problem of this structure is also calculated and analyzed. Results show that the cooling solution of a sapphire slice can effectively reduce the temperature of the pumping side of the Nd:glass slice.

► Hollow duct collects laser diode stack pumping energy and couples to Nd:glass slice.
► 300 μJ signal laser can be amplified to 13 mJ with 12-pass traveling-wave structure.
► Sapphire slice is tightly pressed onto Nd:glass to provide a good heat transmission.
► Distortion of the thermal characteristics in Nd:glass remains a serious problem.