164 fs mode-locked erbium-doped fiber laser based on tungsten ditelluride

In recent years, the diversity of transition metal dichalcogenides (TMDs) has made them occupy the essential status in the exploration of saturable absorbing materials. WTe2, also an important member of TMDs not only exhibits narrower band gap than MoS2 or WS2, but also has fast relaxation time, thus it has advantages in the realization of broadband absorption and ultrashort pulses. In this work, a WTe2 saturable absorber (SA) fabricated by magnetron sputtering technology features nonlinear absorption coefficient of −3.78 × 10−5 cm/W and modulation depth of 37.95%. After integrating this WTe2 SA into the ring cavity, a 164 fs mode-locked laser is achieved at 1557.71 nm. The laser remains stable about 8 h with an output power of 36.7 mW. The results show the favorable saturable absorption properties of WTe2, and further demonstrate the potential of WTe2 in the realization of ultrashort pulses, which indicates that WTe2 can be regarded as a possible candidate for future ultrafast lasers.