CW 1.06-μm pumped ytterbium-holmium co-doped all-fiber laser for 2.05 μm

An Ytterbium-Holmium co-doped all-fiber CW laser is reported. The fiber used in the laser setup has been fabricated through the conventional MCVD process in conjunction with the SD technique and finally drawn using a standard fiberdraw tower. The laser was built in a linear Fabry-Perot configuration in which two fiber Bragg gratings reflecting at 2.05 μm were used as the cavity couplers. Under 1.06-μm in-core pumping of the fiber, CW lasing at 2.05 μm was provided due to energy transfer Yb 3+ →Ho 3+ . The laser demonstrated low threshold (~0.8 W), moderate slope efficiency of lasing (~8.4% when measured vs. pump power launched into the active fiber), and high stability: during 6 hours its output power fluctuated within a 3% range. The laser spectrum width at a 3-dB level using an optical spectrum analyzer with a 37-pm resolution was measured to be ~70 pm.