Tunable passively Q-switched ytterbium-doped fiber laser using MoWS2/rGO nanocomposite saturable absorber

Abstract

• Demonstration of a tunable Q-switched ytterbium fiber laser using MoWS 2 @rGO as SA. • SA have a modulation depth of 5.91% and a low saturation intensity of 0.003 MW/cm 2 . • The generated pulse possess a tunable bandwidth of 10 nm from 1028 nm to 1038 nm. • Pulse exhibits pulse repetition rate of 90.4 kHz, a pulse width of 1.22 μs. • Pulse exhibits output power of 0.193 mW and the highest pulse energy of 2.13 Nj. We demonstrated a tunable Q-switched ytterbium-doped fiber laser (YDFL) using MoWS 2 /rGO nanocomposite as passive saturable absorber. Further, the Mo 1−x W x S 2 /rGO nanosheets, with x proportion of 0.2, are synthesized using hydrothermal exfoliation technique. The proposed nanocomposite-PVA based thin film is fabricated by mixing the MoWS 2 /rGO nanosheets with polyvinyl alcohol (PVA). The fabricated thin film is sandwiched between two fiber ferrules to realize the proposed saturable absorber (SA). Further, the proposed MoWS 2 /rGO-PVA based thin film SA exhibits a fast relaxation time and a high damage threshold which are suitable to realize a Q-switched pulsed laser with a tunable wavelength range of 10 nm that extends from 1028 nm to 1038 nm. For the highest pump power of 267.4 mW, the generated Q-switched pulses exhibit a narrow pulse width of 1.22 μs, the pulse repetition rate of 90.4 kHz, the highest pulse energy of 2.13 nJ and its corresponding average power of 0.193 mW. To the best of author’s knowledge, this is the first realization of a tunable Q-switching fiber laser in a 1 μm wavelength using MoWS 2 /rGO nanocomposite saturable absorber.