Third-Order Nonlinearity Of Pb Or Sb Nanoparticles Doped Sodium Borosilicate Glass

Glass doped with nanoparticles shows excellent third-order optical nonlinearities, which has a great potential for application in nonlinear devices, such as optical switches, optical waveguides and optical limiting, ect Therefore, this paper takes the Pb, Sb nanoparticles doped sodium borosilicate glasses prepared by sol-gel method as the research subjects. Using a variety of means to characterize the micro-structure of the nanocrystals formed in the glasses. Femtosecond Z-scan technology are employed to characterize the third-order nonlinear optical properties of the glasses. The main findings are as follows:1. The structural variation regularity of sodium borosilicate xerogels along with sintering temperature, namely, the formation mechanism of sodium borosilicate glass is studied by the means of thermogravimetric-differential scanning calorimetry, Fourier-infrared spectroscopy, solid-state nuclear magnetic resonance technology. Tetraethyl orthosilicate polymerized by hydrolysis, dehydration, dealcoholization for composing-O-Si-O-bonds at room temperature. And boric acid dehydrated to form-O-B-O-bonds. As the temperature increasing, B will be integrated into the silicon-oxygen network to form-O-Si-B-bonds. Na2O provide bridging oxygen to BO3making it convert into tetrahedral BO4units. At400℃～500℃, xerogels exsit as a loose and porous structure. Around550℃, the gel start to turn into a glassy state. Up to600℃, a large number of tetrahedral BO4and SiO4units are formed in the glass, resulting in a high densification glass.2. Pb or Sb nanoparticles doped sodium borosilicate glass have been prepared by sol-gel method Moreover, the micro structure of nanocrystals and the third-order nonlinearity of the glass is manly studied. The results of X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy show that Pb, Sb nanocrystalline uniformly embedded in the sodium borosilicate glass in the form of small spherical particles, and the size distribution located in ten to several tens nanometers. The third-order nonlinear optical properties of the samples are tested by Z-scan technology. A Ti:sapphire laser with pulse duration of200fs at76MHz repetition rate is used as excitation source, and the operating wavelength λ is set at800nm. The third-order nonlinear optical susceptibilities χ(3) are calculated as in the order of10-11esu for both of them, indicating that they have a better third-order nonlinear optical performance. The mechanism for the enhanced nonlinearity is mainly attributed to the local field effect results from nanocrystals and the thermal effect caused by nonlinear test...