An efficient Nd: A YAG single-frequency laser was demonstrated using a gradient-doped ceramic non-planar ring oscillator (NPRO). A thermal model of the gradient-doped ceramic NPRO was built to analyze the temperature field and thermal focal length. By employing a gradient-doped gain structure, the thermal distribution within the NPRO can be effectively smoothed to reduce thermal lensing effects. Up to 2.8 W of single-frequency output power at 1064 nm from the gradient-doped ceramic NPRO was obtained, with a slope efficiency of 38%.
