Femtosecond pulse erbium-doped fiber laser by a few-layer MoS_2 saturable absorber

TLDR

We report generating femtosecond pulses in a fiber ring laser using a PVA‑based MoS₂ saturable absorber. The PVA‑based MoS₂ SA, with 34 MW cm⁻² saturable intensity and ~4.3 % modulation depth, was used as a mode locker in an erbium‑doped fiber ring laser. Mode‑locking was achieved at a 22 mW pump threshold, producing ~710 fs pulses at 1569.5 nm with a 12.09 MHz repetition rate, and varying cavity dispersion yielded pulses from 0.71 to 1.46 ps, demonstrating MoS₂’s broadband saturable absorption and suitability for ultrafast devices.

Abstract

We report on the generation of a femtosecond pulse in a fiber ring laser by using a polyvinyl alcohol (PVA)-based molybdenum disulfide (MoS2) saturable absorber (SA). With a saturable optical intensity of 34 MW/cm2 and a modulation depth of ∼4.3%, the PVA-based MoS2 SA had been employed with an erbium-doped fiber ring laser as a mode locker. The mode-locking operation could be achieved at a low pump threshold of 22 mW. A ∼710 fs pulse centered at 1569.5 nm wavelength with a repetition rate of 12.09 MHz had been achieved with proper cavity dispersion. With the variation of net cavity dispersion, output pulses with durations from 0.71 to 1.46 ps were obtained. The achievement of a femtosecond pulse at 1.55 μm waveband demonstrates the broadband saturable absorption of MoS2, and also indicates that the filmy PVA-based MoS2 SA is indeed a good candidate for an ultrafast saturable absorption device.