Facile One-Step Synthesis and Enhanced Optical Nonlinearity of Graphene-γMnS

Synthesis and Third-Order Nonlinear Synergistic Effect of ZrO2/RGO Composites

Tuning the third-order nonlinear properties of graphene by hybrid method is of great significance in nonlinear optics research. ZrO2/reduced graphene oxide (RGO) composites with different ZrO2 concentrations were prepared by a simple hydrothermal method. The morphology and structure show that ZrO2 nanoparticles were uniformly dispersed on the surface of graphene nanosheets. The nonlinear optical (NLO) characteristics of composites with different ZrO2 concentrations were studied by the Z-scan technique of 532 nm picosecond pulsed laser. The results showed that ZrO2/RGO composites had saturated absorption and positive nonlinear refraction characteristics. Meanwhile, the third-order nonlinear susceptibility of the ZrO2/RGO composite with a 4:1 mass ratio of ZrO2 to graphene oxide could reach 23.23 × 10-12 esu, which increased tenfold compared to RGO, and the nonlinear modulation depth reached 11.22%. Therefore, the NLO characteristics could be effectively adjusted by controlling the concentration of ZrO2, which lays a foundation for further research on the application of ZrO2/RGO composites in NLO devices.

Regulation and enhancement of the nonlinear optical properties of reduced graphene oxide through Au nanospheres and Au@CdS core-shells

Regulating nonlinear optical (NLO) absorption and refraction properties of graphene is significant in nonlinear photonics. In this work, the functionalizing strategy of quantum dots (QDs) was used for the regulation of the NLO properties of reduced graphene oxide (rGO) with Au nanospheres and Au@CdS core-shells. The third-order NLO properties of rGO-Au and rGO-Au@CdS nanocomposites were investigated by Z-scan technique with 38 ps laser pulses at 532 nm wavelength. The saturation absorption (SA) of rGO was weakened when it was combined with Au nanospheres and switched to reverse saturation absorption (RSA) when combined with Au@CdS core-shells as irradiance intensity increased. The strength of RSA was tunable with the size of Au@CdS core-shells. Meanwhile, the nonlinear susceptibility of rGO was weakened with the complex Au but was tunable with the complex Au@CdS and realized two times enhancement. The effect of charge transfer mechanism was proposed to explain the regulated effect.

Tunable Nonlinear Optical Property of MnS Nanoparticles with Different Size and Crystal Form

It is significant to study the reason that semiconductor material has adjustable third-order optical nonlinearity through crystal form and dimensions are changed. αMnS nanoparticles with different crystal forms and sizes were successfully prepared by one-step hydrothermal synthesis method and their size-limited third-order nonlinear optical property was tested by Z-scan technique with 30 ps laser pulses at 532 nm wavelength. Nanoparticles of different crystal forms exhibited different NLO (nonlinear optical) responses. γMnS had stronger NLO response than αMnS because of higher fluorescence quantum yield. Two-photon absorption and the nonlinear refraction are enhanced as size of nanoparticlesreduced. The nanoparticles had maximum NLO susceptibility which was 3.09 × 10⁻¹² esu. Susceptibility of αMnS increased about nine times than that of largest nanoparticles. However, it was reduced when size was further decreased. This trend was explained by the effects of light induced dipole moments. And defects in αMnS nanoparticles also had effect on this nonlinear process. MnS nanoparticles had potential application value in optical limiting and optical modulation.