Versatile and widely tunable mid-infrared erbium doped ZBLAN fiber laser.

We report on a long wavelength emitting rare earth doped fiber laser with the emission centered at 3.5 μm and tunable across 450 nm. The longest wavelength emission was 3.78 μm which is the longest emission from a fiber laser operating at room temperature. In a simple optical arrangement employing dielectric mirrors for feedback, the laser was capable of emitting 1.45 W of near diffraction limited output power at 3.47 μm. These emission characteristics complement the emissions from quantum cascade lasers and demonstrate how all infrared dual wavelength pumping can be used to access high lying rare earth ion transitions that have previously relied on visible wavelength pumping.