All-fiber multi-wavelength passive Q-switched Er/Yb fiber laser based on a Tm-doped fiber saturable absorber

We report on a ring cavity, multi-wavelength, passive Q-switched erbium-ytterbium double cladding fiber laser based on the use of an unpumped segment of Tm-doped fiber acting as a saturable absorber for passive Q-switched pulse generation and a wavelength filter for multi-wavelength laser generation. By performing pump power variations from 1.6 to 9.8 W, stable Q-switched laser pulses are observed in a repetition rate from 135.8 to 27.5 kHz at room temperature. With a maximal repetition rate of 135.8 kHz, the minimum pulse duration of 430 ns is obtained. The maximal average output power of 2.2 W is reached with a pump power of 9.8 W. The maximum pulse energy was 16.4 µJ and the average output power slope efficiency is ~24.8%. The obtained results demonstrate a laser performance with extended range of high repetition rate and improved stability.