Output spectrum of high-power CW fiber amplifier

A generation spectrum of a high-power Yb-doped fiber amplifier (YDFA) becomes broader with increasing power in the master oscillator power amplifier (MOPA) configuration, which degenerating the coherence of the laser. In this work, a spectral model had been proposed for the high-power YDFA in Continuous Wave (CW) region. A fiber amplifier was built at the 600W level and experiments were conducted for its output spectral characteristics based on this model. Through this model, the output spectrum of high-power YDFA in CW region could be calculated. Though the theoretical spectra were in little different from the measured ones, the predictions of the theory were still in excellent quantitative agreement with the experimental results.