(a) The pulse train of ceramic Nd:YAG slab laser at PRF of 400 Hz and (b) extended profile of a single pulse with pulse width 160 μs

A high efficiency and high power laser diode (LD) face-pumped quasi-continuous-wave (QCW) ceramic Nd:YAG zigzag slab laser is demonstrated. The shape of the LD pump beam is optimized to ensure that the pump size is well matched with the ceramic slab and to improve the uniformity of the intensity distribution along the length and width direction of the ceramic slab. Meanwhile, an efficient cooling technique is adopted to obtain the uniform temperature distribution inside the ceramic slab. Under the LD pump power of 9.98 kW, a maximum average output power of 4.35 kW at 1064 nm is demonstrated at a pulse repetition frequency of 400 Hz, corresponding to an optical to optical conversion efficiency of 43.6%. To the best of our knowledge, this is the highest output power as well as the highest conversion efficiency reported for face-pumped QCW ceramic Nd:YAG single slab laser.

Optics & Laser Technology, 2014