Q-switched fiber laser generation utilizing metal oxide-based saturable absorber in the region of 1.0 µm and 1.5 µm

In this study, we explored a saturable absorber (SA) using a metal oxide-biopolymer film, resulting in the generation of Q-switched fiber lasers at 1.0 µm and 1.5 µm wavelengths. A straightforward sonochemical technique was employed to synthesize a nickel oxide (NiO) film in cooperation with Chitosan as a host polymer. The fabricated NiO-Chitosan film exhibits nonlinear absorption properties with modulation depth of 32.20%, saturation intensity of 0.43 kW/cm2, and non-saturable loss of 7.80%. Upon integrating the NiO-Chitosan film into the cavities of Erbium-Doped Fiber Laser (EDFL) and Ytterbium-Doped Fiber Laser (YDFL), the emergence of stable self-starting Q-switched pulsed lasers were observed at 1040.86 nm and 1557.60 nm central wavelength, respectively. Notably, the shortest pulse widths of 0.73 µs and 2.44 µs were achieved, along with maximum repetition rates of 111.61 kHz and 61.73 kHz, respectively, at these wavelengths. Our investigation identifies an effective SA material with good nonlinear absorption properties for inducing Q-switching in the 1.0 µm and 1.5 µm regions. Significantly, the Chitosan properties, encompassing biocompatibility, non-toxicity, and high thermal resistance, combined with the uncomplicated NiO fabrication process and cost-effectiveness, hold promise for diverse applications.