Synthesis And Nonlinear Optical Properties Of CdSe/ZnSe Nanoparticles And Nanocomposites Based On Reduced Graphene Oxide

Semiconductor nanoparticles have much larger third-order nonlinear susceptibilities than bulk semiconductors. With decreasing size, the third-order optical nonlinearity is strongly influenced by quantum comfinement. Because of the tunable optical properties, semiconductor nanoparticles have been attracting intensive research interest, and have significant potential in all-optical switching, optical storage media and optical limitter applications.Due to the unique thermal, electronic, optical and mechanical properties and potential widespread application value, graphene has attracted much attention of science researchers. In recent years, graphene has been studied as the purpose of making broad-hand optical limiters and photonic devices because of the ultrafast operation and low saturable absorption. At the same time, the special electronic propeties and structure of graphene make it an excellent scaffold for semiconductor nanoparticles and other nano material, and compared to the neat materials, the composite materials of the nanoparticles and graphene have showed improved nonlinear optical properties. The graphene can capture and transport electrons from the excited nanoparticles and effectively separate the electron-hole pair, thus,the graphene and semiconductor nanoparticles composites are regarded as a potential material for the optoelectronic and nonlinear optical devices.In this paper, CdSe and Zn Se nanoparticles were prepared and studied on their nonlinear optical properties. CdSe/ZnSe nanoparticles-reduced graphene oxide cmposites were also prepared and have showed enhanced third-order nonlinear optical properties. The main contents are as follows:1. CdSe and ZnSe nanoparticles were prepared by means of the injection of elenium powder in a hot mixture comtaining the metal cation precursor complexed by a carboxylic acid. The CdSe and ZnSe nanoparticles were characterized by transmission electron microscope, X-ray diffraction and UV/Vis spectra. The experimental results showed that the diameter of Cd Se and ZnSe nanoparticles were about 4nm, which is strong quantum confinement regime.2. The nonlinear optical properties of the nanoparticles were studied by the Z-scan technique with a Lazer of 30 ps pulses width at 532 nm, and the nonlinear refractive and nonlinear absorption were measured. The positive nonlinear refraction and reverse saturable absorption properties were observed upon CdSe and ZnSe nanoparticles, the third-order nonlinear refractive index was found to be 124.42 10 esu?? and 126.72 10 esu??, and the nonlinear absorption coefficient was 12 11.348 10 mW? ?? and 12 12.73 10 mW? ??,respectively.3. CdSe/ZnSe nanoparticles-reduced graphene oxide composites were fabricated by two phase process methods and phase-transfer methods. The structural characteristics studies of the synthesized composites were investigated by UV/Vis spectra, X-ray diffraction and transmission electron microscope.4. The nonlinear optical properties of the CdSe/ZnSe nanoparticles-reduced graphene oxide composites were measured. The Cd Se/ZnSe nanoparticles-reduced graphene oxide composites exhibits more enhanced nonlinear properties than pure reduced graphene oxide. The reverse saturable absorption properties of both composites were observed. The nonlinear absorption coefficient of CdSe nanoparticles-reduced graphene oxide composite was 10 11.83 10 mW? ??, and ZnSe nanoparticles-reduced graphene oxide composite was 10 11.34 10 mW? ??, both were higher than the nonlinear absorption coefficient of pure reduced graphene oxide, which was 10 11.12 10 mW? ??. Our results demonstrate that the CdSe/ZnSe nanoparticles-reduced graphene oxide composites are very promising for optical devices, such as optical limiters and optical switch.