Nanosecond Pulse Generation in the C-Band Region Using Silver Sulfide as a Saturable Absorber

Abstract

We successfully demonstrate the generation of nanosecond pulses in a passively Erbium-doped fiber laser (EDFL) by an Ag₂S-based saturable absorbeer (SA). A simple and low-cost liquid phase exfoliation (LPE) method is used to fabricate the SA. Through LPE, the SA element is coated onto a thin film of polyvinyl alcohol (PVA), which serves as the host material. The Ag₂S SA film exhibits good nonlinear absorption characteristics to give it strong potential as an ideal SA. It has a modulation depth of 25.3% and a saturation intensity of 1.11 MW/cm². The laser is able to generate a self-started mode-locked pulse at a threshold pump power of 145.83 mW with a fundamental repetition rate of 0.98 MHz and a pulse duration of 256 ns, respectively. At the maximum pump power, the laser delivers a pulse energy of 2.08 nJ and an output power of 2.11 mW. This demonstration suggests that Ag₂S SA has good capacity for generating nanosecond mode-locked lasers in the C-band region.