Long wavelength operation of a dysprosium fiber laser for polymer processing

We demonstrate operation of a mid-infrared dysprosium-doped fiber laser with emission at 3388 nm, representing the longest wavelength yet achieved from this class of laser, to the best of our knowledge. Oscillation far removed from the Dy³⁺ gain peak around 3 µm is achieved through the design of a high feedback optical cavity employing a directly inscribed fiber Bragg grating as the output coupler. Laser performance is characterized by a slope efficiency with respect to injected pump power of 38% and maximum output power of 134 mW, an improvement of at least three orders of magnitude over prior attempts at long wavelength Dy³⁺ fiber laser operation. This wavelength coincides with a maximum in the absorption coefficient of PMMA, which we exploit for preliminary demonstration of the utility of this source in polymer processing.