A diode-pumped highly efficient Cr<sup>4+</sup>:YAG passively <i>Q</i>-switched Nd:GdVO<sub>4</sub> laser formed by a plano–concave resonator has been demonstrated. At the highest attainable absorbed pump power of 11.4 W, 4.05 W of average output power, which was two thirds of the maximum corresponding cw output, was achieved with an optical conversion efficiency of 35.5%, and the slope efficiency was determined to be 46.8%, reaching 85% of the magnitude of its cw counterpart. The resulting shortest pulse duration, single-pulse energy, and peak power were found to be 13 ns, 90 μJ, and 7 kW, respectively, with a pulse repetition frequency (PRF) of 45 kHz. Two particularly modified resonator configurations were employed; the largest pulse energy and the highest peak power reached were, respectively, 154 μJ and 11.2 kW at 8.5 W of absorbed pump power. An analytical relation between the PRF and the absorbed pump power is given for a passively <i>Q</i>-switched laser, showing good consistency with experiment with a Nd:GdVO<sub>4</sub> laser. The dependence of the operational parameters on the pump power and on the output coupling was also investigated experimentally. Issues involving the criterion for passive <i>Q</i> switching are discussed in some detail for Cr<sup>4+</sup>:YAG passively <i>Q</i>-switched neodymium-doped vanadate lasers.
© 2003 Optical Society of America
(140.3410) Lasers and laser optics : Laser resonators
(140.3480) Lasers and laser optics : Lasers, diode-pumped
(140.3530) Lasers and laser optics : Lasers, neodymium
(140.3540) Lasers and laser optics : Lasers, Q-switched
(140.3580) Lasers and laser optics : Lasers, solid-state
Junhai Liu, Bernd Ozygus, Suhui Yang, Jürgen Erhard, Ute Seelig, Adalbert Ding, Horst Weber, Xianlin Meng, Li Zhu, Lianjie Qin, Chenlin Du, Xinguang Xu, and Zongshu Shao, "Efficient passive Q-switching operation of a diode-pumped Nd:GdVO4 laser with a Cr4+ : YAG saturable absorber," J. Opt. Soc. Am. B 20, 652-661 (2003)