Multiwavelength Q-switched pulse operation with gold nanoparticles as saturable absorber

A multiwavelength Q-switched pulse operation obtained directly using a Tm-doped fiber laser and employing gold nanoparticles (GNPs) as a saturable absorber (SA material) is reported. The GNPs SA exhibits a modulation depth of 5.4% and a nonsaturable loss of 21.3%. Due to the saturable absorption and the high nonlinearity, dual-wavelength and triple-wavelength Q-switched pulse operations are obtained at pump power levels of 200 and 500 mW. To the best of our knowledge, this is the first ever reported use of GNPs as SA in multiwavelength Q-switched lasing generation.