A diode pumped 1.1 W cw Er: YLF laser at 2.8 μm

Due to the strong water absorption, 2.8μm-Er3+-lasers have interesting applications in the medical field. So far diode pumped cw Er3+-lasers at 2.8 μm have been reported in the power range below 100 mW in YLF [1] and about 500 mW for different garnets [2, 3], In this paper we report for the first time on 970 nm diode pumping of Er3+-doped fluoride hosts YLF (YLiF4), KYF (KYF4), and GLF (GdLiF4). For comparison we also measured Er:GGG, which is one of the best performing cw 3 μm Er3+-lasers based on garnets. With Er:YLF, we achieved the highest cw output power of 1.1 W.