Ultrafast PM fiber ring laser mode-locked by nonlinear polarization evolution with short NPE section segments.

We demonstrate a nonlinear polarization evolution (NPE) mode-locked polarization maintaining (PM) Yb-doped fiber laser with short NPE section segments by setting proper splicing angle. With a theoretical analysis, we propose that an appropriate deviation splicing angle exists to maximize the adjustable range of transmission modulation. The simulation results are highly consistent with theoretical conclusions. Experimentally, using the optimal splicing angle predicted by the theoretical calculation, we have achieved an environmentally stable mode-locking fiber laser at 111-MHz repetition rate with corresponding pulse energy of 0.47 nJ. Additionally, the noise performance of this PM fiber laser is characterized. The measured RMS timing jitter and amplitude noise are 6.41 fs and 0.0052% respectively (1 kHz-10 MHz), which are competitive to the low phase noise performance of the typical fiber laser.