Ultraviolet upconversion luminescence of Gd3+ from Ho3+ and Gd3+ codoped oxide ceramic induced by 532-nm CW laser excitation

► Ultraviolet upconversion emission of Gd3+ in oxide host was never being observed before. ► It is the first time that Gd3+ ion was successfully sensitized by the excited Ho3+ ions. ► In order to measure the time-resolved fluorescence, the CW laser was modulated by an electro-optic modulator with square wave modulations.