<title>High-efficiency emission at 2950 nm in a holmium-doped fluoride fiber laser pumped with a fiber Raman laser at 1064 and 1175 nm</title>

Abstract

We have demonstrated laser emission at ~2950 nm when pumping a holmium-doped fluorozirconate fiber laser by a fiber Raman laser that emits at 1064 and 1175 nm. The optical-to-optical conversion efficiency was 31% and the maximum CW output power was 290 mW. To the best of our knowledge, this efficiency is the highest reported in the literature for this system. Beam characterizations revealed a uniform intensity profile (single-mode). When the fiber laser was held at a ~3 mm from a paper surface, it was possible to burn micro-holes. Since this wavelength coincides with the absorption peak of water at 2950 nm whose absorption coefficient is ~16 times the corresponding to 2712 nm (emission of Er³⁺:ZBLAN fiber lasers), the 290 mW obtained here might replace a high-power (~4.6 W) Er³⁺:ZBLAN fiber laser for cutting samples with high moisture content. Moreover, the low intensity guided in the fibers is important since these fibers melt at high intensities. The main advantage of this pumping scheme, compared to previous results is the non-simultaneous oscillation at 2100 nm. This laser has a great potential in micromachining and microsurgery applications.