Regular mode-hopping dynamics in Erbium-doped ring fiber laser with saturable absorber

We report on transition from single longitudinal mode operation to regular mode-hopping dynamics in Erbium-doped ring fiber laser with a saturable absorber. The laser can be switched from wavelength stabilization (with stability time of up to tens of seconds) to a wavelength self-sweeping regime (in the range of about 20 pm near 1560 nm) with an increase of the pump power and with elongation of the absorbing fiber length. The observed effect is associated with an interplay of amplitude and phase dynamic gratings. Additionally, a continuous wave single-frequency self-sweeping operation in an Erbium-doped fiber laser is demonstrated for the first time. The results are useful both for single-frequency and self-sweeping laser development.