<title>Co-doped spinels: promising materials for solid state lasers</title>

Abstract

Optical absorption, luminescence, saturation of absorption and lifetime measurements have been carried out on Co-doped MgAl<SUB>2</SUB>O<SUB>4</SUB> and ZnGa<SUB>2</SUB>O<SUB>4</SUB>. The crystal field parameters are estimated for the tetrahedral Co<SUP>2+</SUP> ion. Three luminescence bands observed in the visible and near infrared are assigned to transitions from the <SUP>4</SUP>T<SUB>1</SUB>(<SUP>4</SUP>P) level to the lower levels <SUP>4</SUP>A<SUB>2</SUB>(<SUP>4</SUP>F), <SUP>4</SUP>T<SUB>2</SUB>(<SUP>4</SUP>F), and <SUP>4</SUP>T<SUB>1</SUB>(<SUP>4</SUP>F), respectively. Strong luminescence quenching due to nonradiative decay processes is observed MgAl<SUB>2</SUB>O<SUB>4</SUB>:Co. Saturation of Co<SUP>2+</SUP> absorption at 540 nm is measured and the absorption cross section is estimated to be 2.1 + 0.2 X 10<SUP>-19</SUP> cm<SUP>2</SUP> in MgAl<SUB>2</SUB>O<SUB>4</SUB>.