Robust all-polarization maintaining Yb fiber oscillator with a nonlinear optical loop mirror

We demonstrate an environmentally stable femtosecond Yb-doped all-polarizing maintained (PM) fiber laser with a nonlinear optical loop mirror (NOLM). While applying an unbalance coupling ratio coupler of 70/30 in a NOLM loop, the pulse spectral bandwidth was 20 nm with an output power of 8.95 mW at the repetition rate of 10.7 MHz. The recompressed pulse duration was 220 fs by using a pulse compressor based on pair of gratings. Due to the all-PM architecture, the root means square of output power fluctuation over 3 h was 0.4%. We expect that the developed all-PM Yb fiber oscillator will provide ultrafast broadband time-stretch spectroscopy in the future.