Low threshold Q-switched pulses based on a WTe2-graphene saturable absorber

Abstract

Low-threshold and narrow-pulse-width Q-switched optical pulses are obtained using a tapered fiber-based WTe2-graphene saturable absorber (SA) in an erbium-doped fiber laser (EDFL) for the first time. Benefiting from the low unsaturated loss of graphene, the Q-switching threshold (25.8 mW) is an order of magnitude lower than that using SA with WTe2 only. Meanwhile, owing to the high carrier mobility of WTe2, the minimum pulse width (1.2 µs) is the narrowest among the graphene-based fiber lasers. The results indicate the potential of the WTe2-graphene SA in future application and development of laser pulses.