Efficient self-seeding of a pulsed Ti^3+:Al_2O_3 laser

We describe the design considerations and operating characteristics of a compact, widely tunable, narrow-linewidth, megawatt-class pulsed laser system based on ${\mathrm{Ti}}^{3+}:{\mathrm{Al}}_2{\mathrm{O}}_3$ (Ti:sapphire) pumped by the second harmonic of a $1.06‐\mathit{\mu }\mathrm{m}$ Nd:YAG laser. The system delivers 10 mJ in a 5-ns near-transform-limited single-longitudinal-mode (SLM) pulse with a threshold of 20 mJ and a slope efficiency greater than 40%. By the technique of self-seeding, in which a portion of the gain medium’s spontaneous fluorescence is coupled back to the laser cavity, SLM operation may be obtained across the entire gain profile of Ti:sapphire with a minimum number of optical components and without external seeding.