Efficient blue upconversion emission due to confined radiative energy transfer in Tm3+:Nd3+ co-doped Ta2O5 waveguides under infrared-laser excitation

Lahoz, F., Shepherd, D.P., Wilkinson, J.S. and Hassan, M.A. (2008) Efficient blue upconversion emission due to confined radiative energy transfer in Tm³⁺:Nd³⁺ co-doped Ta₂O₅ waveguides under infrared-laser excitation. Optics Communications, 281 (14), 3691-3694. (doi:10.1016/j.optcom.2008.03.046).

Record type: Article

Abstract

Intense blue upconversion emission at 480nm has been obtained at room temperature in Tm³⁺:Nd³⁺ co-doped Ta₂O₅ channel waveguides fabricated on a Si substrate, when the sample is excited with an infrared laser at 793nm. The upconversion mechanism is based on the radiative relaxation of the Nd³⁺ ions (⁴F_3/2 to ⁴I_11/2) at about 1064nm followed by the absorption of the emitted photons by Tm³⁺ ions in the ³H₄ excited state. A coefficient of energy transfer rate as high as 3 × 10^-16 cm³/s has been deduced using a rate equation analysis, which is the highest reported for Tm-Nd co-doped systems. The confinement of the 1064nm emitted radiation in the waveguide structure is the main reason of the high energy transfer probability between Nd³⁺ and Tm³⁺ ions.