The different amount of rare earth ions doped zinc tungsten tellurite glasses with the compositions (70-x-y-z)TeO2 – 20ZnO – 10WO3 – xEr2O3 – yTm2O3 – zYb2O3 (x = 0.3, 0.5; y = 0.3, 0.5; z = 3) have been synthesized using melt quenching technique. Blue, green, red and infrared luminescence via energy transfer and frequency upconversion mechanisms in Tm3+/Er3+/Yb3+ triply-doped zinc tungsten tellurite glasses were investigated under single 975 nm diode laser excitation. Intense blue (Tm3+: 1D2→3F4, 1G4→3H6; 477 nm), green (2H11/2, 4S3/2→4I15/2 ; 525 nm and 549 nm), red (Er3+: 4F9/2→4I15/2, Tm3+: 1G4→3F4; 659 nm) and infrared (Tm3+: 1G4→3H5, 3H4→3H6 ; 807 nm) emissions were observed simultaneously at room temperature. Intense white light emission from all samples was observed with CCT values higher than 6500 K and CRI values lower than 80. The CIE coordinates of the emitted white light were found to shift to yellowish-greenish region with increasing pumping power. The possible energy transfer and upconversion mechanisms are discussed and plausible explanations are made.
Tellurite glasses, White light; Rare earth ions; Upconversion