Blue Upconversion Emission in Er3+-Doped Fluoride Fiber

Abstract The blue upconversion emission in Er 3+ -doped ZBLA fiber has been studied by means of 632-nm and dual wavelength (632-nm + IR) excitation. Measurements reveal that the previous assignment of the blue emission to the 2 H 9/2 state de-excitation is not exactly verified. Instead we identify the excitation process as an energy transfer between the 4 S 3/2 and 4 F 9/2 states with the de-excitation of 2 P 3/2 state giving rise to 402- and 470-nm emission. The implication of this statement on the realization of a compact blue Er 3+ -doped ZBLA fiber emitter is discussed.