Nickel Nanoparticles Saturable Absorber for Multiwavelength Pulses Generation in Ytterbium-Doped Fiber Laser

We report on the generation of multiwavelength Q-switched pulses from a Ytterbium-doped fiber laser (YDFL) cavity by employing a nickel nanoparticle (Ni-NPs) thin film as an optical modulator. Owing to the high nonlinearity of Ni-NPs and the distinguished saturable absorption property, stable single-, dual-, triple-, or quadruple-line, Q-switched generation with a 0.7 nm channel spacing have been achieved by simply adjusting the 976 nm pump power to between 144-290 mW. At the maximum diode pump power, the output obtained from Ytterbium-doped fiber laser (YDFL) has a minimum pulse width of 138.7 ns, a maximum repetition rate of 82.4 kHz, a maximum pulse energy of 9.1 nJ and a maximum output power of 777.14 mu W.