Thulium-holmium doped fiber laser mode-locking with hafnium disulfide (HfS2) coated on D-shaped fiber

Abstract

The performance of hafnium disulfide (HfS2) was demonstrated in this study to generate a mode-locked pulse in a thulium-holmium doped fiber laser (THDFL). The drop-cast method was used to deposit HfS2 solution onto a D-shaped single-mode optical fiber. The fabricated D-shaped fiber had a modulation depth and saturation intensity of 12.3% and 7.53 MW/cm2, respectively, according to nonlinear optical absorption measurements. The evanescent wave interaction with the HfS2 based SA embedded on a D-shaped optical fiber resulted in a mode-locked pulse at a pump power of 208.6 mW with a central wavelength and pulse duration of 1916.29 nm and 1.509 ps, respectively. Meanwhile, raising the pump power to 208.6 mW results in a repetition rate of 11.10 MHz. The output shows a stable mode-locked THDFL pulse with a signal to noise ratio (SNR) of around 75.74 dB. Overall, this research focuses on the potential of HfS2 used as SA coated on a D-shaped optical fiber for the generation of short pulses in a 2 µm band region.