Design and performance of a high-average-power flashlamp-pumped Ti:sapphire laser and amplifier

Design, performance and characterization of a high average-power flashlamp-pumped Ti:sapphire oscillator and amplifier are presented. The extensive design study, which covers the whole excitation process of the laser, focused on efficient laser operation at high average powers but also took into consideration the practicability of the laser device. For the first time, pumplight-induced absorptions in Ti:sapphire and their avoidance by appropriate filtering were investigated. The laser performance could be improved, firstly, due to the proper design of the discharge circuit, which resulted in an increased spectral overlap of the flashlamp-emission with the Ti:sapphire absorption. Secondly, the insight into the consequences of the flashlamp plasma reabsorption in conjunction with a small-spectral-band-transmitting pump-light filter led to a simple, experimentally confirmed transfer-efficiency reflector model and, based on this, to an improved reflector shape. As a result of the study, average powers of up to 220 W at a total laser efficiency of 2.25% have been achieved, Also, a single-pass small-signal gain of 3.1 and a total stored energy in the laser rod of 690 mJ at 100-Hz repetition rate could be demonstrated. This significant improvement over former flashlamp-pumped Ti:sapphire lasers and amplifiers for the first time opens up the possibility of femtosecond-pulse amplification to high average powers at 100 Hz repetition rate.