Er:YAG/Yb:YAG nanopowders‐derived Er/Yb co‐doped yttrium aluminosilicate (YAS) fibers fabricated by UV‐curable nanocomposites for 1.5‐µm single‐frequency fiber lasers

Abstract

The rare-earth (RE)-doped yttrium aluminosilicate (YAS) glass fibers have demonstrated their unique advantages in single-frequency lasers due to their high solubility of RE ions and high gain per unit length. However, the RE-doped YAS fiber is usually fabricated by RE:YAG crystal or ceramic rods and melting-intube method, which depend heavily on RE:YAG crystal or ceramic rods and, thus, cannot adjust the fiber compositions effectively; there is little research on the multiple RE ions co-doped YAS fiber deriving from RE:YAG crystal or ceramic rods. In present work, we developed a novel method to fabricate Er/Yb co-doped YAS fibers efficiently. The Er:YAG and Yb:YAG nanopowders were fabricated by the coprecipitation method, and then the nanopowders were dispersed into liquid organic resin to form a novel UV-curable nanocomposite, after curing, debinding, purifying, and drawing process, an Er/Yb co-doped YAS fibers was fabricated, the absorption coefficients of the fiber was measured to be 17 dB/cm at 976 nm ( 2 F 7/2 ground level to 2 F 5/2 level of Yb and 4 I 15/2 ground level to 4 I 11/2 level of Er) and 3.2 dB/cm at 1530 nm ( 4 I 15/2 ground level to the high states of 4 I 13/2 of Er). A 1.5-µm single-frequency laser was constructed with the 2-cm Er/Yb codoped YAS fiber. The longitudinal mode spacing was calculated to be 2.2 GHz with an effective cavity length of 4.5 cm, and the spectral signal-to-noise ratio was higher than 60 dB. To the best of our knowledge, it is the first time that Er/Yb co-doped YAS fibers are fabricated using the UV-curable nanocomposites. It indicates that this proposed technology is critical for the fabrication of various types of RE ions co-doped YAS fibers and their applications in single-frequency fiber lasers.