Ho-Yb fluoride glass fiber for green lasers

Abstract

Ho3+ upconversion emission at 543nm (5S2-5I8) is a potential candidate for realizing a red-diode pumped green laser. However, this emission is of three-level system, so that lower doping is needed to achieve lower lasing threshold. A long, low loss single mode fiber is usually adopted for this type of laser to obtain a sufficient pump absorption without much cavity loss [1]. To make a compact device, it is necessary to increase the pump absorption efficiency. Yb has been known as an effective sensitizer for Ho in many crystals when the diode emitting around 980nm is used for excitation [2]. We report effects of host glass composition and Yb sensitizer concentration on the Ho green upconversion emission and the pump power dependence of the excited population density for fiber lasers.