Heavily Tm^3+-doped silicate fiber with high gain per unit length

We present the experimental investigation of a single-mode double-clad Tm3+-doped silicate fiber with ion concentration of 7 wt.% (8.35 x 1020/cm3). A gain per unit length of 5.8 dB/cm at 1945 nm has been successfully achieved in a 3-cm Tm3+-doped silicate fiber amplifier, pumped with 647.6 mW at 1567 nm. To the best of our knowledge, this would be the highest gain per unit length reported for Tm3+-doped fibers. Furthermore, we experimentally demonstrate efficient cm-long fiber lasers and watt-level cladding pumped Tm3+-doped silicate fiber amplifiers.