Linearly polarized single-stage 10 W erbium–ytterbium-doped fiber laser system for application to pumping Cr:ZnS

We report the development of a single-stage master oscillator power amplifier all-fiber laser system with a linearly polarized output power above 10 W at a central wavelength of 1560 nm with a narrow bandwidth of 35 pm and a polarization extinction ratio of 23 dB using an erbium–ytterbium-doped double-clad high-gain fiber. A nearly diffraction-limited beam profile with M 2 of 1.03 in the horizontal direction and 1.08 in the vertical direction makes this single-mode fiber laser system a suitable pump source for the development of Cr:ZnS lasers requiring a tight mode matching between the pump spot and the laser mode. As an example, we have obtained 1.3 W of continuous wave output power from a Cr:ZnS ring laser oscillator with superior stability thanks to the long-term polarization stability of the pump fiber laser. Further power scalability of the ring laser oscillator is limited by the crystal quality requiring an optimized doping concentration and crystal length in addition to an improved attachment technique to the heat sink.