LiNbO3: Yb3+/Er3+/Tm3+— power driven green to blue tunability

Triple-doped (Yb3+/Er3+/Tm3+) lithium niobate single crystals have been grown by the Czochralski method. Under selective Yb3+ excitation at 920 nm, bright visible up-converted luminescence is observed. It is found that the emission spectra of triple-doped system can be described as the superposition of Yb3+-to-Er3+ and Yb3+-to-Tm3+ energy transfer up-conversion, which exhibit differential power dependencies. As a consequence, the triple-doped system exhibits both power and concentration dependent emission spectra. It is possible to select the appropriate concentration of dopants in order to attain a very wide range of green to blue color tunability, within a single crystal, easily controlled by adjusting excitation power density.

► Main up-conversion emissions in LiNbO3:Yb3+/Er3+/Tm3+ are characterized.
► Total color hue depends on pump power.
► Wide color tunability from green to blue is demonstrated.
► Color tunability is linked to saturation effects in the up-conversion mechanisms.