Stretched pulse Yb^3+:silica fiber laser

We report what we believe to be the first results on short-pulse generation in ${\mathrm{Yb}}^{3+}$:silica fiber. By applying the stretched pulse technique in a unidirectional, polarization-switch ${\mathrm{Yb}}^{3+}$ fiber laser incorporating a prism-based dispersive delay line, we obtain self-start mode locking and 100-pJ pulses that can be compressed to give clean chirp-free $<100$-fs pulses. We believe such sources to have great potential for use not only in all-solid-state, high-power femtosecond pulse systems based on ${\mathrm{Yb}}^{3+}$:silica glass but also as seeds for conventional ${\mathrm{Nd}}^{3+}$:glass amplifier chains.