End-pumped, passively Q-switched Yb:YAG double-clad waveguide laser

We present a diode-pumped, double-clad Yb:YAG waveguide laser that contains an integrated section of Cr4+:YAG saturable absorber for passive Q switching. Using two 4-W polarization-coupled, broad-stripe diode-pumped lasers, we obtained 30-muJ pulses of 1.6-ns duration at repetition rates of as much as 77 kHz. The slope efficiency was similar to50% with respect to absorbed pump power, with a maximum output average power of 2.3 W and a peak power of similar to18 kW. The output beam was single lobed, with M-2 values as great as 1.5 X 1.3. We also demonstrate a passively Q-switched Nd:YAG waveguide laser of similar design, operating at 1.064 mum and 946 nm. (C) 2002 Optical Society of America.