Tm3+-doped tellurite fiber weak signal amplifier at a wavelength of 2.27 µm

•Universal setup for gain measuring in the spectral range over 2.2 μm was proposed.•New double-clad Tm-doped tellurite glass fiber was used as an investigated medium.•The Tm-doped tellurite fiber gain coefficient was estimated as 0.11 m−1 without ASE and nonlinear effects.•Direct measurements of the gain in this material have not been carried out before. The amplification of a weak narrow-spectrum pulsed signal at a wavelength of 2.27 µm in Tm3+-doped tellurite fiber was demonstrated. The double-clad Tm3+-doped TeO2–ZnO–La2O3–Na2O glass fiber was used as an amplifier active medium. The pulsed seed signal was selected from the supercontinuum by the high reflective fiber Bragg grating. The experimental setup allowed us to obtain pure amplification data over 2.2 µm without amplified spontaneous emission and nonlinear effects contribution. The gain coefficient of Tm3+-doped tellurite fiber was estimated as 0.11 m−1.