Fine tuning of the repetition rate and stabilization of harmonically mode-locked fiber laser with CW component in the spectrum

Harmonically mode-locked (HML) fiber lasers delivering pulses with pulse repetition rate (PRR) in the GHz range have become a valuable alternative to semiconductor and solid-state lasers ensuring high beam quality, reliability, userfriendly light output, inherent to laser configurations in all-fiber format. The main drawback of HML laser technology is the noise-induced irregularities of the time interval between pulses known as the HML timing jitter. Ensuring low-level supermode noise and precise pulse repetition rate tuneability in all-fiber-integrated harmonically mode-locked laser sources establishes a new level of their versatility and extends areas of their applications. We report on new techniques enabling both the mitigation of supermode laser noise and highly precise setting of the PRR in a soliton fiber laser harmonically mode-locked by nonlinear polarization evolution. The principle of operation relies on resonant interaction between the soliton pulses and a narrow-band continuous wave (CW) component cooperatively generated within the same laser cavity.