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 a Cr(4+): YAG saturable absorber for passive Q switching. Using two 4-W polarization-coupled, broad-striped diode-pumped lasers, we obtained 30-microJ pulses of 1.6-ns duration at repetition rates of as much as 77 kHz. The slope efficiency was ~50% with respect to absorbed pump power, with a maximum output average power of 2.3 W and a peak power of ~18 kW . The output beam was single lobed, with M(2) values as great as 1.5x1.3 . We also demonstrate a passively Q -switched Nd:YAG waveguide laser of similar design, operating at 1.064 microm and 946 nm.