A cobalt-doped transparent glass ceramic saturable absorber Q-switch for a LD pumped Yb3+/Er3+ glass microchip laser

We fabricate a transparent glass ceramic contains magnesium-aluminum spinel nanocrystallites doped with Co2+ ions. The ground-state and excited-state absorption cross section of this glass ceramic at 1.54 mu m are estimated to be (2.8 +/- 0.3) x 10(-19) cm(2) and (4.8 +/- 0.5) x 10(-20) cm(2), respectively. For the first time, the passively Q-swithched operation of LD pumped 1.54 mu m microchip Yb3+/Er3+ glass laser is realized with transparent glass ceramic as saturable absorber. The Q-switched pulses of 3.846 kHz in repetition rate, 6.2 ns in duration and 6.3 mu J in energy are obtained. At last, the dependences of pulse width and repetition rate on pump power are also investigated.