Practical low-noise stretched-pulse Yb^3+-doped fiber laser

We report on the development of what we consider to be a practical and highly stable stretched-pulse laser based on ${\mathrm{Yb}}^{3+}$-doped silica fiber. The Fabry–Perot cavity uses nonlinear polarization rotation as the mode-locking mechanism, and a semiconductor saturable-absorber mirror to ensure robust self-starting and incorporates a diffraction grating pair to compensate for the normal dispersion of the fiber. Use of a single-mode grating-stabilized telecommunications-qualified pump laser diode ensures reliable, low-noise operation ($\sim 0.05\%$ amplitude fluctuations at 10-Hz measurement bandwidth). The laser generates high-quality, 60-pJ pulses of $<110‐\mathrm{fs}$ duration at a repetition rate of $\sim 54 \mathrm{MHz}$ (3-mW average power).