Effects of spatial hole burning in 888 nm pumped, passively mode-locked high-power Nd:YVO4 lasers

We report on an experimental study of 888 nm pumped, passively mode-locked, high-power Nd:YVO 4 lasers with an enhanced cavity design, involving spatial hole burning (SHB) in the active medium. We observed a significant pulse shortening due to the concept of “Gain-at-the end,” despite using long gain length up to 30 mm. A 31.6 W average output power TEM 00 Nd:YVO 4 oscillator, providing 16.2 ps pulses at an repetition rate of 96 MHz is presented. The pulse duration turns out to be primarily a function of the effective gain length, which can be explained by means of SHB. A further pulse shortening with decreasing gain length down to 9.5 ps at 11.1 W average output power is demonstrated.