The understanding of the nonlinear optical (NLO) properties of photonic materials is relevant and necessary for basic studies and technological developments. Among the materials with high optical nonlinearities, layered transition-metal dichalcogenides (LTMDs) have attracted considerable attention from the viewpoint of both synthesis as well as characterization and applications. We report here the third-order NLO properties of one LTMDthe metallic NbS2that was prepared by a modified redox exfoliated method, suspended in acetonitrile. The LTMD was morphologically and compositionally characterized using transmission electron microscopy, atomic force microscopy, X-ray diffraction, Raman scattering, and linear absorption. The Z-scan technique was employed to characterize the nonlinear refraction (NLR) and nonlinear absorption (NLA) behavior in the femtosecond regime. Metallic NbS2 presented a sign inversion of the nonlinear refractive index from negative (self-defocusing) to positive (self-focusing) with the increase of intensity up to 100 GW/cm2. Two distinct features characteristic of NLA, two-photon absorption and saturated absorption, were also observed for different intensity ranges, with the former evolving into the latter as the intensity increased in the same range as for the NLR measurements. The material’s band structure of NbS2 was calculated using the density functional theory, and the origin of the nonlinearities is discussed by comparison with the experimental data.

Zirconium telluride, a transition metal dichalcogenide, was synthesized by a redox exfoliated method to obtain a 2D monolayer semi-metal. After being characterized for compositional and optical analysis, its third-order nonlinear optical (NLO) properties were studied by the Z-scan technique in the femtosecond (100 fs) regime at 800 nm. Interestingly, in this spectro-temporal regime and in the intensity range exploited, the only third-order NLO effect observed was nonlinear refraction, giving rise to a positive value of the nonlinear refractive index coefficient, n2 = +(4.2 ± 0.3) × 10−16 cm2/W. Based on the calculated band structure and the excitation photon energies employed, the physical origin of the refractive nonlinearity is discussed.

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We report a new synthesis route to prepare YAB:Nd particles, on the basis of the urea precipitation method. The results confirmed the trigonal symmetry and the stimulated emission leading to random lasing in the powder.

Here we investigate the third-order Nonlinear Optical (NLO) properties of Layered Transition Metal Dichalcogenides (LTMDs), the metallic NbS2. The Z-scan technique was employed to characterize the nonlinear refraction (NLR) and nonlinear absorption (NLA) behavior in the picosecond regime.