Narrow linewidth, 100 W cw Yb3+-doped silica fiber laser with a point-by-point Bragg grating inscribed directly into the active core

We report on the power scaling to 103 W of a 1.1 μm continuous-wave Yb⁸⁺-doped silica fiber laser incorporating a point-by-point (PbP) fiber-Bragg grating inscribed directly into the active core using 800 nm femtosecond laser pulses. The spectrum of the laser exhibited a narrow linewidth that broadened to 260 pm at 103 W. The output was frequency doubled using an 11mm long periodically poled MgOiLiNbO₃ crystal to generate 2.1W of green with an internal conversion efficiency of 10% at high power and 0.81%/W at low power.