Tin diselenide (SnSe2) nanosheets as novel 2D layered materials have excellent optical properties with many promising application prospects, such as photoelectric detectors, nonlinear optics, infrared photoelectric devices, and ultrafast photonics. Among them, ultrafast photonics has attracted much attention due to its enormous advantages; for instance, extremely fast pulse, strong peak power, and narrow bandwidth. In this work, SnSe2 nanosheets are fabricated by using solvothermal treatment, and the characteristics of SnSe2 are systemically investigated. In addition, the solution of SnSe2 nanosheets is successfully prepared as a fiber‐based saturable absorber by utilizing the evanescent field effect, which can bear a high pump power. 31st‐order subpicosecond harmonic mode locking is generated in an Er‐doped fiber laser, corresponding to the maximum repetition rate of 257.3 MHz and pulse duration of 887 fs. The results show that SnSe2 can be used as an excellent nonlinear photonic device in many fields, such as frequency comb, lasers, photodetectors, etc.

The nonlinear optical properties of cuprous sulfide have been studied. The successful application in Er-doped fiber laser has proved cuprous sulfide as a novel, promising materials in the field of ultra-fast photonics.

Abstract MXene are a class of metal carbide and metal nitride materials with a two-dimensional layered structure. MXene Ti3C2Tx has the characteristics of good metal conductivity and adjustable chemical composition, which has attracted the attention of scientists. Recently, Mxene have shown strong nonlinear photonics and optoelectronic effect, which can be used to generate ultrashort pulsed laser. However, soliton molecules pulse in laser cavity based on Mxene have not been reported at present. In this article, MXene have been characterized systematically, and the nonlinear optical characters were measured. In addition, we combined MXene with taper fiber to make a saturable absorber device for an erbium-doped fiber laser. The modulation depth and saturation absorption intensity of MXene are 10.3% and 197.5 MW/cm2, respectively. Thanks to the outstanding character of MXene, a three-order soliton molecules pulse were generated in laser cavity. The center wavelength, pulse interval and spectral modulation period of soliton molecules are 1529.4 nm, 15.5 ps and 0.5 nm, respectively. The above experimental results show that MXene have broad application prospects in the fields of optical fiber communication, laser material processing and high-resolution optics.

Stannic sulfide (SnS2), a latterly developed two-dimensional (2D) material, has fascinated scientists because it can be widely applied to materials chemistry, biomedicine, photocatalysis, and so on. Especially, SnS2 has the advantages of adjustable band gap and good oxidation resistance, which indicates that this material has promising potential in nonlinear optics. However, the light interaction with SnS2 is rarely investigated. In this study, high-quality SnS2 nanosheets (Ns) developed through a liquid phase exfoliation approach have been applied in ultrafast photonics for nonlinear processes. This fabrication approach can greatly increase the damage threshold of the SnS2 saturable absorber (SA). Furthermore, the SnS2 SA device is applied to an erbium-doped fiber laser (EDFL) to obtain soliton molecules with different orders. Ultimately, eleventh-order soliton molecules, the highest order of soliton molecules through SnS2, are generated with a soliton separation of 8 ps and a spectral modulation period of around 1 nm. The above experimental results indicate that SnS2 has broad application prospects in the fields of mode-locked fiber laser and optical fiber communication.

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