Neodymium oxide saturable absorber for generating Q-switched and mode-locked pulses in 1.55-micron region

Exploring new saturable absorber (SA) materials is important for the advancement fibre laser technology especially in the improving the performance of Q-switched and mode-locked fiber lasers, which have tremendous applications in areas such as material processing, telecommunications, biomedical imaging, and scientific research. Here, we prepared a layer of Neodymium Oxide (Nd₂O₃) film as a nonlinear optical device to obtain the Q-switched and mode-locked pulses in the Erbium-doped fiber laser (EDFL) cavity. The developed Nd₂O₃ film recorded excellent optical properties with the saturable absorption of 2.8%, saturation intensity of 0.8 MW /cm² and non-saturable loss of 59.0%. By integrating the Nd₂O₃ film into a simple ring EDFL's cavity, a stable and robust Q-switched laser operating at 1558 nm was realized as the pump power is set between 45 and 92 mW. The average output power improved from 4.70 to 9.57 mW as the strength of the pumping was raised from 45 to 92 mW. The repetition rate and pulse width are tunable from 71 to 89 kHz and 3.48–2.56 µs, respectively as the pump power is escalated within the same range. The fundamental frequency of electrical signal exhibits signal-to-noise ratio (SNR) of 62 dB and this signifies the excellent stability of the Q-switching operation. In an extended EDFL cavity, the Nd₂O₃SA can produce a mode-locked soliton pulse operating at 1559.29 nm. The laser run at repetition rate of 1.89 MHz and pulse duration of 3.73 ps while recorded the highest peak power of 1.7 kW at pump power of 97.62 mW.