Precise selection and amplification of a single comb line from femtosecond mode-locked lasers

We propose and demonstrate a novel, to the best of our knowledge, scheme for extracting and amplifying a single comb line with a high signal-to-noise ratio (SNR) from a femtosecond mode-locked laser (FMLL). The scheme is realized based on the combination of pulse repetition-rate multiplication, optical injection locking, and the polarization-pulling-attributes of stimulated Brillouin scattering. The SNR of the selected and amplified comb line is more than 70 dB, and its frequency can be tuned at an arbitrary comb line position over the whole range of the FMML. The white frequency noise floor measured through a delayed self-heterodyne interferometry technique is around 80 Hz²/Hz. The scheme presented in this work has shown the potential for many applications such as ultra-precision metrology and spectroscopy.