S-band Mode-locked Thulium-doped fluoride fiber laser using FePS3 as saturable absorber

Abstract

• erformance of FePS 3 as a saturable absorber was investigated. • Generation of mode-locked in Thulium-doped fluoride fiber laser at 1504.8 nm. • FePS 3 exhibits a modulation depth of 14.59 % at 1550 nm. • The pulse width generated was 3.90 ps with a peak power of 1.93 kW. A demonstration of iron phosphate trisulfide (FePS 3 ) as a saturable absorber (SA) for mode-locked pulse generation in a thulium-doped fluoride fiber (TDFF) laser was demonstrated in this work. An arc-shaped fiber was prepared using the polishing method, and the FePS 3 solution was then deposited via the drop-casting method. The SA shows a nonlinear optical absorption with a modulation depth of 14.59 % and a saturation intensity of 0.006 MW/cm 2 . Integration of the SA into the TDFF ring cavity resulted in mode-locked pulses with a central wavelength of 1504.8 nm, a 3 dB bandwidth of 0.704 nm, and a 3.90 ps pulse width. At the pump power of 280 mW, the generated pulses demonstrated a high signal-to-noise ratio (SNR) of 45 dB at a fundamental frequency of 400.6 kHz. At this maximum pump power, the maximum average output power produced was 3.01 mW, with maximum pulse energy and peak power of 7.51 nJ and 1.93 kW, respectively. A higher damage threshold can be achieved in this configuration due to the optical interaction between FePS 3 and the evanescent wave, thus providing a better laser performance. These findings can shed light on the applicability of a novel class of 2D material as a reliable SA for photonics applications.