Enhanced conversion efficiency of Cr⁴⁺ion in Cr: YAG transparent ceramic by optimizing the annealing process and doping concentration

Transparent chromium doped Y₃Al₅O₁₂ceramics with excellent optical qualities were successfully fabricated by solid state reaction sintering using divalent dopants (CaO and MgO) as sintering aids, and the conversion efficiency of Cr⁴⁺ion in Cr: YAG ceramic was effectively regulated by various approaches. All samples were fully transparent after vacuum sintered at 1820 °C for 8 h. It was found that under fixed amount of divalent dopants, the conversion efficiency of Cr⁴⁺ion in Cr: YAG ceramics was significantly increased by increasing Cr doping concentration, elevating annealing temperature, prolonging annealing soaking time or adopting oxygen annealing atmosphere. The absorption coefficient of as fabricated 0.1 at.% Cr: YAG ceramics at 1030 nm reached up to 5.2 cm⁻¹after annealed at 1300 °C for 30 h under an oxygen atmosphere. It was much higher than that of corresponding single crystal fabricated by traditional Czochralski method.