Multiwavelength Q-switched erbium-doped fibre laser-based aluminum nanoparticles saturable absorber and sagnac loop filter

In this paper, we experimentally demonstrate a stable multiwavelength Q-switched erbium-doped fiber laser generation based on aluminum nanoparticles (AlNPs) as the saturable absorber (SA), with the aid of a Sagnac loop filter for the first time, to the best of author's knowledge. The fabricated AlNPs-SA has a modulation depth, a non-saturable loss and saturable intensity of 7%, 10% and 0.0015 MW cm−2, respectively. By carefully adjusting the polarization controller and progressively increasing the pump power, up to 11 lasing lines in the Q-switching regime are obtained with a channel spacing and an optical signal-to-noise ratio of 0.48 nm and 30 dB, respectively. Meanwhile, the Q-switched performance has a minimum pulse width of 2.36 µs and a maximum pulse repetition rate of 33.45 kHz by varying the pump power to 300 mW. The proposed laser may become valuable for numerous applications such as dense wavelength division multiplexing technology.