Mode-locked Tm-doped fiber laser induced by ferroferric-oxide nanoparticles and a D-shaped fiber

Abstract

• We demonstrate a passively mode-locked laser operating at 2 um region based on a saturable absorber (SA) of FONPs deposited on the D-shaped fiber (DF). This is the first use of FONPs to achieve mode-locking at 2um. • The mode-locking operates in 1931 nm, the 3 dB bandwidth is 5.9 nm, the repetition frequency is 24 MHz, and the pulse width is 1.29 ps. In addition, the signal-to-noise ratio is ∼67 dB, indicating the stability of the output spectrum. As a unique type of transition metal oxides, ferroferric-oxide nanoparticles (FONPs) have attracted much attention due to their outstanding physical and chemical properties. In this paper, we demonstrate a passively mode-locked laser operating at 2 um region based on a saturable absorber (SA) of FONPs deposited on the D-shaped fiber (DF). FONPs were deposited on DF to form FONP-DF SA devices. As inserted into the thulium-doped fiber laser (TDFL), a mode-locked pulse was realized at 1931 nm. For all we know, this is the first demonstration of FONP-DF SA in fiber lasers at 2 um region. This work fills the gap of FNOP in the realization of 2 um mode-locking and lays the foundation for us to use FNOP-DF for magnetic field sensing in the future.