InAs/GaSb superlattice SESAM mode-locked fluoride fiber laser at 2.8 µm

We demonstrate a mode-locked fluoride fiber laser operating at 2.8 µm using an InAs/GaSb superlattice (SL) semiconductor saturable absorber mirror (SESAM). Z-scan measurements show that the SL saturable absorber layer possesses off-bandgap nonlinearity near 2.8 µm, with a saturation fluence of 15.9 µJ/cm², a single-pass modulation depth of 2.4%, and a damage threshold of 10.4 mJ/cm². Using this high-damage-threshold SESAM, we achieved a maximum average output power of 1.16 W from the 2.8 µm mode-locked Er:ZBLAN fiber laser, with a pulse duration of 28.1 ps. Continuous mode-locking operation at an average power of 224 mW was sustained for 36 h without interruption, demonstrating the reliability of the InAs/GaSb SL SESAM for the development of mid-infrared mode-locked fluoride fiber lasers.