A simple way to prepare Co:MgAl2O4 transparent ceramics for saturable absorber

Co-doped magnesium aluminate (Co:MgAl2O4) transparent ceramics were obtained by pre-sintering in air and hot isostatic pressing (HIP) with commercial spinel and CoO powders as raw materials. The influences of the pre-sintering temperature on the microstructure and optical quality of the 0.05 at% Co:MgAl2O4 ceramics were studied. It is found that the relative density of Co:MgAl2O4 ceramics increases from 96.8% at 1500 degrees C to 98.7% at 1600 degrees C and then decreases with further increasing the pre-sintering temperature. The average grain size of Co:MgAl2O4 ceramics increase from 4.6 mm to 19.2 mu m with the increase of pre-sintering temperature from 1500 to 1700 degrees C. For the sample pre-sintered at 1600 degrees C for 5 h and HIP post-treated at 1800 degrees C for 3 h, the average grain size is about 23.0 mm and the near in-line transmittance reaches 75% at the wavelength range of 1700-2400 nm. The ground state absorption cross section at 1540 nm of the optimal 0.05 at% Co:MgAl2O4 ceramics is calculated to be 2.9 x 10 x 19 cm(2). (C) 2019 Published by Elsevier B.V.