Passive mode-locking by a Ti₂AlN saturable absorber in 1.5 µm region

We conducted an investigation on the saturable absorption properties of Ti₂AlN through both experimental material characterizations and a density functional theory energy band calculation. On the basis of the saturable absorption properties of the Ti₂AlN MAX phase that was observed in this investigation, a fiberized mode-locker operable in the 1.5-μm spectral region was fabricated with a side polished fiber platform. The modulation depth and saturation intensity of the mode-locker were measured as ~7% and ~91 MW/cm², respectively. By inserting the mode-locker into an Er³⁺ doped fiber ring cavity, conventional soliton pulses, which were stably mode-locked, could be generated at ~1557.6 nm.