3 GHz, fundamentally mode-locked, femtosecond Yb-fiber laser.

We demonstrate a fundamentally mode-locked Yb-fiber laser with 3 GHz repetition rate and ∼206  fs pulse duration. The laser incorporates two enabling technologies: a 1 cm heavily Yb-doped phosphate glass fiber as the gain medium and a high-dispersion (-1300  fs2) output coupler to manage cavity dispersion. The oscillator self-starts and generates up to 53 mW average power.