Broadband Fe3O4 nanoparticles saturable absorber for Q-switched fiber lasers

We demonstrated passively Q-switched 1-, 1.5-, and 2-mu m fiber lasers by exploiting fermferric-oxide nanoparticles (FONPs) as a broadband saturable absorber (SA). FONPs were prepared by a method of thermal decomposition, and then were mixed with sodium carboxymethylcelluose (NaCMC) to form a FONPs film. The FONPs film was sandwiched between two fiber ferrules to fabricate the FONPs SA, which had a broadband absorption from 800 to 2000 nm and nonlinear saturable absorption at 1-, 1.5-, and 2-mu m. By inserting the same FONPs SA into the ytterbium, erbium and thulium doped fiber laser cavities, the stable passively Q-switching operation at 1039, 1560 and 1982 nm was realized for a threshold pump power of similar to 82 mW, similar to 62 mW and similar to 830 mW, respectively. To the best of our knowledge, it is the first demonstration of the use of a single SA based on FONPs for wide-band Q-switching operation of fiber lasers from 1 to 2 mu m.

Automated summary

In this study, passively Q-switched fiber lasers operating at wavelengths of 1, 1.5, and 2 μm were demonstrated using FONPs as a broadband saturable absorber. This represents the first use of a single SA based on FONPs for wide-band Q-switching operation of fiber lasers from 1 to 2 μm.