Strong upconversion luminescence in Er^(3+)/Yb^(3+) doped halide modified tellur

Upconversion luminescence of Er^(3+)/Yb^(3+)-doped halide tellurite glass is investigated experimentally upon 976-nm excitation. Three intense emissions centered at 525, 545 and 655 nm owing to the transitions (2)^H_(11/2) → (4)^I_(15/2), (4)^S_(3/2) → (4)^I_(15/2) and (4)^F_(9/2) → (4)^I_(15/2), re