Tungsten disulfide saturable absorbers for 67 fs mode-locked erbium-doped fiber lasers

TLDR

The study demonstrates 67‑fs pulse generation in an erbium‑doped fiber laser using a tungsten disulfide saturable absorber. WS2 is deposited by pulsed laser deposition onto a tapered fiber to form a saturable absorber with large modulation depth, enabling ultrashort pulse generation. The resulting pulses are 67 fs, the shortest achieved with 2D material saturable absorbers, and the WS2 device outperforms graphene, topological insulators, and other TMDs in modulation depth and pulse duration.

Abstract

In this paper, we demonstrate 67 fs pulse emitting with tungsten disulfide (WS2) in mode-locked erbium-doped fiber (EDF) lasers. Using the pulsed laser deposition method, WS2 is deposited on the surface of the tapered fiber to form the evanescent field. The fiber-taper WS2 saturable absorber (SA) with the large modulation depth is fabricated to support the ultrashort pulse generation. The influences of the WS2 SA are analyzed through contrastive experiments on fiber lasers with or without the WS2 SA. The pulse duration is measured to be 67 fs, which is the shortest pulse duration obtained in the mode-locked fiber lasers with two dimensional (2D) material SAs. Compared to graphene, topological insulator, and other transition metal dichalcogenides (TMDs) SAs, results in this paper indicate that the fiber-taper WS2 SA with large modulation depth is a more promising photonic device in mode-locked fiber lasers with the wide spectrum and ultrashort pulse duration.