Size-dependent third order nonlinearity as well as ultrafast carrier dynamics of BPs is studied, and used in a fiber laser.

No abstract

Broadband nonlinear optical properties from 500 to 1550 nm of ultrasmall black phosphorus quantum dots (BPQDs) have been extensively investigated by using the open-aperture Z-scan technique. Our results show that BPQDs exhibit significant nonlinear absorption in the visible range, but saturable absorption in the near-infrared range under femtosecond excitation. The calculated nonlinear absorption coefficients were found to be (7.49 ± 0.23) × 10−3, (1.68 ± 0.078) × 10−3 and (0.81 ± 0.03) × 10−3 cm/GW for 500, 700 and 900 nm, respectively. Femtosecond pump-probe measurements performed on BPQDs revealed that two-photon absorption is responsible for the observed nonlinear absorption. The saturable absorption behaviors observed at 1050, 1350 and 1550 nm are due to ground-state bleaching induced by photo-excitation. Our results suggest that BPQDs have great potential in applications as broadband optical limiters in the visible range or saturable absorbers in the near-infrared range for ultrafast laser pulses. These ultrasmall BPQDs are potentially useful as broadband optical elements in ultrafast photonics devices.

No abstract

In this study, graphene nanosheets decorated with ZnO nanoparticles (NZG) was prepared from graphene oxide by a facile solvothermal method. Simultaneously, NZG as a substitute of conventional ZnO was incorporated into rubber matrix. The NZG not only showed improved vulcanization efficiency but also could simultaneously play the roles of reinforcement for natural rubber (NR) nanocomposites. The results showed that the cure reaction of NR/NZG nanocomposites is significantly faster than that of neat NR. The dynamic and static mechanical properties and the gas barrier property of NR/NZG nanocomposites were systematically investigated at different NZG content. Compared with neat NR, the tensile strength, modulus at 300% strain and tear strength of NR/NZG-2.5 nanocomposite are dramatically enhanced by 67.8%, 188.6% and 74.1%, respectively, at only 2.5 phr NZG content. The permeability of NR/NZG-2.5 nanocomposite decreased by 53% compared to neat NR. The well dispersion of graphene, high vulcanization efficiency of ZnO nanoparticles, together with the enhanced interfacial interaction, is considered to be responsible for the significant synergetic effects in the improvement of the vulcanization characteristic, mechanical performance and the gas barrier property of the composites.