Passive Q-switching of an Er, Yb:glass laser with Co:Mg(Al,Ga)₂O₄-based glass-ceramics

Transparent glass-ceramics (GCs) containing Co:Mg(Al,Ga)₂O₄ nanocrystals (mean diameter of 7-9 nm) are synthesized by heat treatments at 850-950°C from magnesium aluminosilicate glass nucleated by TiO₂ and doped with Ga₂O₃ and CoO. The GCs exhibit a broadband A₂4(F4)→T₁4(F4) absorption due to the Co²⁺ ions, low saturation fluence (∼0.5  J/cm²), fast recovery time of initial absorption (∼300  ns), and high laser damage threshold (∼20  J/cm²). They are used for passive Q-switching of a diode side-pumped Er,Yb:glass laser generating 3.1 mJ/20 ns pulses (peak power, 155 kW) at 1535 nm with a TEM₀₀ output mode. The Q-switching performance of the Co:Mg(Al,Ga)₂O₄-based GCs is compared with that for various Co²⁺-doped GCs and Co:MgAl₂O₄ single crystal. The prepared GCs are promising for further applications in passively Q-switched Er:YAG and other Er crystalline (or ceramic) lasers.