Glass-ceramics with Co2+:Mg(Al,Ga)2O4 nanocrystals: novel saturable absorber for compact erbium lasers

We report on the passive Q-switching of a compact diode-side-pumped Er,Yb:glass laser by a novel saturable absorber (SA) based on transparent glass-ceramics (GC) containing Co2+Mg(Al,Ga)2O4 nanocrystals. To prepare the GC, an initial magnesium aluminosilicate glass doped with Ga2O3 containing 0.1 mol% CoO was synthesized by a conventional melt-quenching technique and heat-treated at 850–950 °C. The X-ray diffraction analysis of the GC confirmed the precipitation of Co2+Mg(Al,Ga)2O4 crystals with spinel structure (6-7 nm in size). Depending on the heat-treatment temperature, the saturation intensity for the GC measured at 1540 nm was in the 0.5...0.7 J/cm2 range and the recovery time was in the 240...335 ns range. Using the SA based on GC prepared by the heat-treatment at 950 °C with an initial transmission of 84.7%, we generated stable Q-switched pulses 1.14 mJ in energy and 7.2 ns in duration. The peak power reached 160 kW, the repetition rate was 1 Hz and the laser wavelength was 1535 nm. The developed GCs are promising for Q-switching of erbium lasers emitting at 1.5-1.7 μm.

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