A long-term frequency-stabilized erbium-fiber-laser-based optical frequency comb with an intra-cavity electro-optic modulator

We demonstrate an optical frequency comb based on an erbium-doped-fiber femtosecond laser with the nonlinear polarization evolution scheme.The repetition rate of the laser is about 209 MHz.By controlling an intra-cavity electrooptic modulator and a piezo-transducer,the repetition rate can be stabilized with a high-bandwidth servo in a frequency range of 3 k Hz,enabling long-term repetition rate phase-locking.The in-loop frequency stability of repetition rate is about1.6×10-13 in an integration time of 1 s,limited by the measurement system;and it is inversely proportional to integration time in the short term.Furthermore,using a common path f –2 f interferometer,the carrier envelope offset frequency of the comb is obtained with a signal-to-noise ratio of 40 d B in a 3-MHz resolution bandwidth.Stabilized carrier envelope offset frequency exhibits a deviation of 0.6 m Hz in an integration time of 1 s.