Strontium ferrite nanoparticles based broadband nonlinear optical modulator for ultrafast pulse generation in fiber lasers

Nanomaterials exhibiting broadband nonlinear optical responses have garnered considerable interest in the field of ultrafast photonics. These materials have been extensively validated as effective saturable absorbers (SAs), demonstrating their capability to facilitate the generation of broadband optical pulses. In this study, strontium ferrite nanoparticles (SrFeO-NPs), were synthesized using the sol-gel method and were then employed as SA to initiate ultrafast pulse operation in fiber lasers. The prepared NPs exhibited excellent nonlinear absorption properties, enabling the measurement of modulation depth and saturation intensities across the 1–2 μm spectral range. The measured results showed that the SrFeO-NPs as SA in fiber lasers yielded pulse durations in the femtosecond (fs) domain in Yb, Er, and Tm-doped fiber lasers, with pulse durations of 801 fs, 857 fs, and 671 fs, respectively. The performance characteristics of the output pulses, containing wavelength, repetition rates, output power, pulse energy, and stability, were also examined and discussed in detail. This study paves the way for novel approaches in integrating diverse materials, thereby advancing the development of broadband laser systems utilizing nanomaterials for applications in the extended near to mid-infrared spectral region.