183-W, M-2 = 2.4 Yb : YAG Q-switched laser

We have fabricated a diode-array end-pumped Yb:YAG rod laser with output po wers greater than 200 W cw and 195 W Q-switched at 5 kHz. At an output powe r of 183 W and a repetition rate of 5 kHz, the beam quality was measured to be M-2 = 2.4. The laser design incorporates a hollow lens duct to concentr ate the diode pump light for delivery to the end of the laser rod while mai ntaining access to the laser beam. This configuration provides increased fl exibility for the resonator design and permits the use of birefringence com pensation in the cavity to yield polarized output with increased efficiency . Using the recently described birefringence compensation method of Clarkso n ct al. [in Conference on Lasers and Electro-Optics (Optical Society of Am erica, Washington, D.C., 1998), paper CTuI3], we obtained 112 W of cw power with a polarized beam of M-2 = 3.2. (C) 1999 Optical Society of America.