Q-switched neodymium-doped fiber laser with a gold nanoparticle saturable absorber

A gold nanoparticle saturable absorber (SA) was successfully employed in a Neodymium-doped fiber laser (NDFL) cavity for pulse generation via a Q-switching mechanism for the first time. The SA device made by mixing the gold nanoparticles into PVA solution before being dried onto a fiber ferrule was included in the NDFL cavity, which was optimized to obtain Q-switched pulses centered at 1089 nm wavelength. The pulse rate of the laser rose from 32.1 to 47.6 kHz while the pulse width fell from 8.7 to 5.8 µs as the 808 nm pump laser was varied from 67 to 114 mW. The output power also linearly improved from 4.16 to 5.07 mW as the pump strength boosted from 145.83 to 187.04 mW. The gold nanoparticles SA also offers excellent modulation depth of 5.6%, which is fit for SA purpose. The developed Q-switched laser has numerous applications including, material micromachining, communication, sensing, and so on.