Mode-locked, 194-μm, all-fiberized laser using WS_2-based evanescent field interaction

Abstract

We demonstrate the use of an all-fiberized, mode-locked 1.94 μm laser with a saturable absorption device based on a tungsten disulfide (WS2)-deposited side-polished fiber. The WS2 particles were prepared via liquid phase exfoliation (LPE) without centrifugation. A series of measurements including Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM) revealed that the prepared particles had thick nanostructures of more than 5 layers. The prepared saturable absorption device used the evanescent field interaction mechanism between the oscillating beam and WS2 particles and its modulation depth was measured to be ~10.9% at a wavelength of 1925 nm. Incorporating the WS2-based saturable absorption device into a thulium-holmium co-doped fiber ring cavity, stable mode-locked pulses with a temporal width of ~1.3 ps at a repetition rate of 34.8 MHz were readily obtained at a wavelength of 1941 nm. The results of this experiment confirm that WS2 can be used as an effective broadband saturable absorption material that is suitable to passively generate pulses at 2 μm wavelengths.

Large-area highly crystalline WSe_2 atomic layers for ultrafast pulsed lasers

“…Moreover, the modulation depth at 1864 nm is measured to be ~1.83% by using the similar method, as shown in Fig. 4(c), which is the same order magnitude as that of graphene, black phosphorus, WS 2 and MoSe 2 at that range [33][34][35][36]. Note that the modulation depth at 1.9 μm is much smaller than that at 1.5 μm, which is mainly limited by the high transmission loss (~90%) of microfiber at this region.…”

“…Worth noting that shorter pulse width can be realized by further optimizing the cavity length with approximate zero dispersion in cavity [39]. Recent demonstrations indicated that several kind of 2D materials, like graphene [33], black phosphorus [34], WS 2 [35], and MoSe 2 [36], show broadband nonlinear optical absorption, which have been used as SA for mode-locking operation. However, thus far, mode-locked laser at 2 μm region based on WSe 2 has not been fully investigated.…”

“…The mode-locked operations are realized at both 1.5 and 2.0 μm, and the ultrashort pulse duration is achieved up to hundreds of femtosecond. Compared to the extensively studied 2D materials SA such as graphene, black phosphorus, MoS 2 , and WS 2 [33][34][35][36][37][38][40][41][42][43][44][45], large-area WSe 2 has less been reported in ultrashort pulse generation. This contribution provides the compelling evidence of WSe 2 as excellent SAs for ultrafast photonic applications.…”

2D Saturable Absorbers for Fibre Lasers

“…The highest result to date has been 2.5 GHz, mode-locking up to the 369th harmonic of a ∼30 m cavity [46]. In terms of wavelength coverage, Yb:fibre lasers have been mode-locked using MoS 2 [33,44] [51]. Continuously tunable mode-locking in the erbium gain band has also been demonstrated with a single MoS 2 -PVA composite device [37].…”

Carbon Nanotube Mode-Locked Thulium Fiber Laser With 200 nm Tuning Range

“…Several techniques have been developed for generating ultrafast pulses including semiconductor saturable absorber mirrors (SESAMs)8, nonlinear polarization evolution (NPE)910 and nonlinear amplifying loop mirror (NALM)11. In recent years, low-dimensional carbon nanomaterials such as carbon nanotubes (CNTs)121314 and graphene1516 have been intensively investigated for ultrashort pulse generation at 2  μ m. This has further led to the investigations of other forms of novel materials such as topological insulators1718, transition-metal dichalcogenides1920 and black phosphorus2122.…”