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MXenes, a new class of 2D transition metal carbides, nitrides, and carbonitrides, have attracted much attention due to their outstanding properties. Here, we report the broadband spatial self‐phase modulation of Ti₂CT_xMXene nanosheets dispersed in deionized water in the visible to near‐infrared regime, highlighting the broadband nonlinear optical (NLO) response of Ti₂CT_xMXene. Using ultrafast pulsed laser excitation, the nonlinear refractive indexn₂and the third‐order nonlinear susceptibilityof Ti₂CT_xMXene were measured to be ∼10⁻¹³m²/W and ∼ 10⁻¹⁰esu, respectively. Leveraging the large optical nonlinearity of Ti₂CT_xMXene, an all‐optical modulator in the visible regime was fabricated based on the spatial cross‐phase modulation effect. This work suggests that 2D MXenes are ideal broadband NLO materials with excellent prospects in NLO applications.

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Abstract Pellet-based extrusion deposition of carbon fiber-reinforced composites at high material deposition rates has recently gained much attention due to its applications in large-scale additive manufacturing. The mechanical and physical properties of large-volume components largely depend on their reinforcing fiber length. However, very few studies have been done thus far to have a direct comparison of additively fabricated composites reinforced with different carbon fiber lengths. In this study, a new additive manufacturing (AM) approach to fabricate long fiber-reinforced polymer (LFRP) was first proposed. A pellet-based extrusion deposition method was implemented, which directly used thermoplastic pellets and continuous fiber tows as feedstock materials. Discontinuous long carbon fibers, with an average fiber length of 20.1 mm, were successfully incorporated into printed LFRP samples. The printed LFRP samples were compared with short fiber-reinforced polymer (SFRP) and continuous fiber-reinforced polymer (CFRP) counterparts through mechanical tests and microstructural analyses. The carbon fiber dispersion, distribution of carbon fiber length and orientation, and fiber wetting were studied. As expected, a steady increase in flexural strength was observed with increasing fiber length. The carbon fibers were highly oriented along the printing direction. A more uniformly distributed discontinuous fiber reinforcement was found within printed SFRP and LFRP samples. Due to decreased fiber impregnation time and lowered impregnation rate, the printed CFRP samples showed a lower degree of impregnation and worse fiber wetting conditions. The feasibility of the proposed AM methods was further demonstrated by fabricating large-volume components with complex geometries.