Robust optical-frequency-comb based on the hybrid mode-locked Er:fiber femtosecond laser.

We demonstrate an optical frequency comb in which an Er:fiber-based femtosecond laser employs nonlinear amplifier loop mirror (NALM) and nonlinear polarization evolution (NPE) mode-locking mechanisms. The laser combines advantages of good robustness of NALM and low noise feature of NPE. Our experimental results show that the hybrid mode-locked laser has high power, low relative intensity noise and self-started property, enabling the construction of a robust optical frequency comb system. In-loop relative instabilities of both stabilized repetition rate and carrier-envelope-offset frequency are well below 1 × 10 at 1 second integration time.