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In this study, sodium silicate (Na2SiO3) was used as the precursor of SiO2 to prepare Cr2O3/SiO2 composite pigments. First, using cetyltrimethylammonium bromide to surface modification of the chromium oxide green pigment to make the surface of the particles positively charged. The negatively charged SiO2 sol coats the surface of the pigment particles through electrostatic attraction. Then use HCl solution acid to precipitate SiO2, and finally get Cr2O3/SiO2 composite pigment. The structure of the modified pigment was analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), particle size distribution analysis, and X‐ray diffraction (XRD) characterization. The influence of silica coating on the tinting strength, dispersibility of pigment in water, and hiding power of the chromium oxide green pigment were further investigated. The results demonstrate that SEM, TEM, and particle size analysis shows that this experimental method can obtain a good silica coating. When the coating quantity is 30%, the full coating of chromium oxide green by silica is achieved. According to the XRD analysis before and after the chromium oxide green coating, as the reaction temperature increases, the intensity of the SiO2 diffraction peak becomes larger and the crystallization effect becomes better. In the test of pigment performance, it can be concluded that the coloring power, hiding power, and dispersibility of Cr2O3/SiO2 composite pigments are better than those of uncoated chromium oxide green pigments. [ABSTRACT FROM AUTHOR]

MXenes, as an emerging group of two-dimensional materials, have attracted significant interest for diverse photoelectric applications by virtue of their tunable terminated surface, excellent electrical conductivity, and strong nonlinear optical response. They are usually synthesized via strategies involving hydrofluoric acid, which may result in oxygenic and hydrophilic termination groups on the MXene surface and thus decrease their stability in air. Herein, a mild synthesis method based on electrochemical exfoliation is proposed to prepare Ti3C2Tx MXene quantum dots (QDs), which are highly fluorinated to enhance stability. The open-aperture Z-scan system was employed to measure the nonlinear transmittance of the MXene QDs and proves their broadband saturable absorption from 540 to 1550 nm. By integrating the MXene QD saturable absorber into an ytterbium-doped fiber laser, a set of highly stable 357 ps mode-locked pulses centered at 1069.17 nm was achieved under a low threshold power of 54 mW. In addition, tunable mode-locked optical spectra could be observed in the cavity when switching the polarization state. This work provides an environmentally friendly approach to synthesize stable MXene QDs and opens an avenue for the realization of low-threshold and tunable photonics applications based on MXene QDs. [ABSTRACT FROM AUTHOR]

The effect of the Al2O3 dust environment on the crack propagation behaviour of 2524‐T3 Al alloy was investigated. The results show that the Al2O3 dust environment reduces the fatigue crack growth rate (FCGR) of alloy especially at low ΔK. Many Al2O3 particles are deposited and stuck in the crack during fatigue loading which promotes crack closure, while this effect is gradually weakened with the increase of ΔK. The deposited Al2O3 particles induce the disorderly arranged slip bands (SBs) ahead of the crack tip which deflects the crack path making it more tortuous in the Al2O3 dust. [ABSTRACT FROM AUTHOR]

Germanium phosphide (GeP), a rising star of novel two-dimensional (2D) material composed of Group IV–V elements, has been extensively studied and applied in photonics thanks to its broadband optical absorption, strong light–matter interaction and flexible bandgap structure. Here, we show the strong nonlinear optical (NLO) properties of 2D GeP nanoflakes in the broadband range with open-aperture Z-scan technique to explore the performance of 2D GeP microfiber photonic devices (GMPDs) in near-infrared (near-IR) and mid-infrared (mid-IR) ultrafast photonics. Our results suggest that employing the GMPD as an optical device in an erbium-doped fiber laser (EDFL) system results in ultrashort pulses and rogue waves (RWs) at 1.55 μm. Likewise, by the incorporation of GMPD into a thulium-doped fiber laser (TDFL) system, stable ultrashort pulse operation is also achieved at 2.0 μm. We expect these findings to be an excellent GMPD that can be applied in mode-locked fiber lasers to open up new avenues for its development and application in ultrafast photonics. [ABSTRACT FROM AUTHOR]

MXene is a promising two-dimensional (2D) material that is widely used in electro-photonic devices due to its unique properties. In this contribution, V2CTx, a novel MXene, was employed as a saturable absorber (SA) for hybrid passively mode-locked fiber lasers. An ultra-stable and self-starting mode-locked laser system with low threshold can be achieved using V2CTx nanosheets and nonlinear polarization evolution (NPE). Signal to noise ratio increased 13 dB compared with using only NPE SA. A 72 fs pulse duration is easily achieved from this hybrid mode-locked fiber laser system. To the best of our knowledge, this is the shortest pulse duration generated from the Yb-doped mode-locked fiber lasers using a hybrid or 2D SAs. This study proves that MXene V2CTx nanosheets can be developed as suitable SAs and served as potential advanced ultrafast photonic devices in the future. [ABSTRACT FROM AUTHOR]

Optical modulation technique plays a crucial role in photonics technologies, and there is an ever-increasing demand for broadband and ultrafast optical modulation in the era of artificial intelligence. All-optical modulation is known to be able to operate in an ultrafast way and has a broadband response, showing great potential in applications for ultrafast information processing and photonic computing. Two-dimensional (2D) materials with exotic optoelectronic properties bring tremendous new opportunities for all-optical modulators with excellent performance, which have attracted lots of attention recently. In this review, we cover the state-of-art all-optical modulation based on 2D materials, including graphene, transitional metal dichalcogenides, phosphorus, and other novel 2D materials. We present the operations mechanism of different types of all-optical modulators with various configurations, such as fiber-integrated and free-space ones. We also discuss the challenges and opportunities faced by all-optical modulation, as well as offer some future perspectives for the development of all-optical modulation based on 2D materials. [ABSTRACT FROM AUTHOR]

We report on the experimental observation of dual-wavelength dissipative soliton operation of a fiber laser with net anomalous cavity dispersion. Different from the dual- or multi-wavelength soliton operation of fiber lasers where mode locking is used to initiate soliton formation, no mode locking occurs in our fiber laser. Instead, soliton formation is through the dissipative mechanism caused by the effective gain bandwidth limitation. Either dual-wavelength scalar, or vector, or induced dissipative solitons are experimentally obtained. Their robustness is experimentally confirmed. [ABSTRACT FROM AUTHOR]

Due to the low density and high fatigue strength, Al-Cu-Mg alloy has become an attractive material for aerospace and navigation applications. However, the relatively high residual stress and low micro-yield strength after the fabrication process restrict its further application in the field of inertial instruments. The objective of this work is to investigate the effect of Ni plating on the residual stress and micro-yield strength in an Al-Cu-Mg alloy under different diffusion treatments. Compared with properties of the alloy without diffusion treatment, the micro-yield strength of the alloy after diffusion treatment increases 9.5%, and the corresponding residual stress decreases > 70%. This can be attributed to the increase of diffusion layer thickness and release of elastic energy. [ABSTRACT FROM AUTHOR]