An actively Q-switched multi-wavelength ytterbium fiber laser with cascaded polarization-maintaining Bragg gratings

In this paper, we investigate the multi-wavelength lasing characteristics of an actively Q-switched ytterbium-doped fiber laser with two cascaded polarization maintaining fiber Bragg gratings (PM-FBGs). By properly adjusting the polarization states in the cavity, a total of 15 wavelength combinations, including single-, dual-, tri-, and quad-wavelength emission states, have been achieved. Stable Q-switched pulses with repetition rates ranging from 10 to 28 kHz are obtained. The influence of repetition rate and pump power upon the pulse width are also investigated. The high spectral stability in lasing operation indicates effectiveness of the proposed cascaded PM-FBGs in actively Q-switched multi-wavelength fiber laser configurations.