Nonlinear Saturable Absorption of Liquid‐Exfoliated Molybdenum/Tungsten Ditelluride Nanosheets

Abstract

Molybdenum disulfide (MoS2 ) and tungsten disulfide (WS2 ), two representative transition metal dichalcogenide materials, have captured tremendous interest for their unique electronic, optical, and chemical properties. Compared with MoS2 and WS2 , molybdenum ditelluride (MoTe2 ) and tungsten ditelluride (WTe2 ) possess similar lattice structures while having smaller bandgaps (less than 1 eV), which is particularly interesting for applications in the near-infrared wavelength regime. Here, few-layer MoTe2 /WTe2 nanosheets are fabricated by a liquid exfoliation method using sodium deoxycholate bile salt as surfactant, and the nonlinear optical properties of the nanosheets are investigated. The results demonstrate that MoTe2 /WTe2 nanosheets exhibit nonlinear saturable absorption property at 1.55 μm. Soliton mode-locking operations are realized separately in erbium-doped fiber lasers utilizing two types of MoTe2 /WTe2 -based saturable absorbers, one of which is prepared by depositing the nanosheets on side polished fibers, while the other is fabricated by mixing the nanosheets with polyvinyl alcohol and then evaporating them on substrates. Numerous applications may benefit from the nonlinear saturable absorption features of MoTe2 /WTe2 nanosheets, such as visible/near-infrared pulsed laser, materials processing, optical sensors, and modulators.

Simulations and experiments showing the origin of multiwavelength mode locking in femtosecond, Yb-fiber lasers

“…As well as traditional mechanisms based on nonlinear polarisation evolution (NPE) arising from the Kerr effect in the fibers [2] various external materials have been harnessed to create the required fast switches in such cavities, such as semiconductor saturable absorber mirrors (SESAMs [3,4] or, more recently, saturable absorbers based on two dimensional materials suchg as MoS 2 and graphene [5][6][7][8][9][10]). While some recent research has focussed on polarisation-maintaining (PM) fiber cavities [11], a large number of cavities have continued to use non-PM fibers and with NPE as a fast saturable absorber, either in combination with a SESAM or, as here, acting in tandem with a spectral filter.…”

Orthogonally dual-polarization passively mode-locking operation of Nd:La0.25Gd0.75VO4 crystal

“…For the saturable absorbers, at present carbon nanotube and some new two-dimensional materials such as graphene, MoS 2 and WS 2 were attracted more and more attentions and lots of work have been reported [20][21][22][23][24][25]. These materials are low cost, easy fabrication and has saturable absorption over a broad spectral range from near-infrared to mid-infrared.…”

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

“…Recent reports have demonstrated that the energy band structures of the semiconducting TMDs show a unique transition from indirect to direct band gap as the thickness is reduced to monolayer [5][6][7]. These monolayer TMDs with direct band gap can offer exciting opportunities for potential applications in both electronic and optoelectronic devices [4, [8][9][10][11][12][13][14][15][16][17]. Among all TMD materials, WSe 2 has recently received huge interest due to their distinctive electro-optical properties and remarkable electronic characteristics [18][19][20][21][22][23][24].…”