Generation of Dark Pulses in Mode-Locked Erbium-Doped Fiber Ring Laser Operating in L-Band Region Using Sc2O3 Absorber

Abstract

By incorporating scandium oxide (Sc₂O₃) powder into a PVA film, a Sc₂O₃ saturable absorber (SA) was successfully developed, boasting a modulation depth of 25%. When integrated into a ring erbium-doped fiber laser, the Sc₂O₃-SA facilitated the production of mode-locked dark pulses featuring multi-wavelength emission, leveraging its saturable absorbing ability along with the nonlinear properties inherent in the Sc₂O₃ thin film and the long erbium-doped fiber. Mode-locking operation was achieved within a pumping range of 209.3–239.8 mW, resulting in a peak pulse energy of 0.71 nJ. Operating at 1597.8 nm, the mode-locked laser demonstrated a repetition rate of 10.42 MHz and a pulse width of 23 ns. Domain-wall dark pulse operation was demonstrated in the L-band region, achieving a relative stability with a signal-to-noise ratio of 55.6 dB, utilizing a Sc₂O₃ thin film absorber and an 8-meter-long active fiber. These findings underscore the promising potential of Sc₂O₃ to be used in pulsed laser systems, particularly due to its exceptional nonlinear optical properties.