Self-referenced frequency comb from a polarization-maintaining Er: Fiber laser based nonlinear polarization evolution

To the best of our knowledge, this paper presents the first self-referenced polarization-maintaining (PM) Er: nonlinear polarization evolution-based fiber frequency comb. A short PM fiber section segment acts as an artificial saturable absorber and compensates for the group velocity mismatch. A conventional f-2f interferometer allows detecting carrier-envelope offsetting frequency (f_ceo) after an octave-spanning spectrum generation. A complete description of the PM Er: fiber comb combining a noise study of the repetition rate (f_r) and f_ceo is presented. Accordingly, the in-loop residual phase noise of f_ceo and f_r are 468 mrad and 0.336 mrad from 1 Hz to 3 MHz, respectively. Further, we verify the long-term performance of the comb system by recording the fluctuation of f_r and f_ceo for more than 10 h. We observed that combining fast actuators for phase noise suppression would potentially enable a compact and robust frequency comb system for a range of applications such as comb-based liars, optical clock, and gas sensing.