Experimental Measurement and Simple Analytical Estimation of Signal Gain in Yb-Doped Fiber

Fiber lasers intensively use the active medium to compensate for the cavity losses in order to achieve stable pulse generation. Here we propose the experimental scheme to measure the signal gain in a normal dispersion Yb-doped active fiber; also we propose the theoretical method to estimate the small signal gain and saturation power as a function of experimental setup characteristics; this method can be used in modeling and optimization of all-normal ultra-long fiber lasers and fiber lasers with distributed amplification.