Intracavity filtering effect in a dual-output linear-cavity all-PM fiber laser mode-locked by NPE

We have demonstrated a stable and low-noise all-polarization-maintaining (PM) ultrafast erbium-doped fiber laser mode-locked via nonlinear polarization evolution (NPE) in a linear cavity with dual outputs. A detailed design strategy is presented. The all-PM configuration enhances the capability of resistance to environmental fluctuations. Self-starting mode-locking is realized by using a non-reciprocal phase shifter. The dual-output structure offers the intracavity filtering effect, where the reflective port serves as a bandpass spectral filter, significantly improving the transmissive-port optical properties. The laser directly generates ultrashort pulses with a pulse duration of 129 fs operating at a fundamental repetition rate of 105.8 MHz. The integrated root-mean-square (RMS) relative intensity noise from 10 Hz to 10 MHz is ∼0.008%, and the integrated RMS timing jitter from 5 kHz to 10 MHz is ∼36fs. Long-term stability is confirmed in 25 h with a RMS power fluctuation of ∼0.10%. Our high-performance fiber laser is a prospective candidate for low-noise applications.