硫化铅纳米粒子的三阶非线性光学特性研究

摘要

针对硫化铅(PbS)特殊的三阶非线性光学特性,本文在水溶液里合成了PbS纳米粒子.紫外-可见光谱显示,由于使用了封端剂,合成的样品更加稳定.用紫外-可见吸收光谱和X射线衍射斑研究了PbS纳米粒子的特性,结果表明,由于纳米粒子尺寸减小,其吸收光谱显示极大的蓝移.利用Seherre方程估计PbS粒子的平均粒径约为8.2 nm.最后,基于使用了632.8 nm He-Ne激光器的用单光束Z-扫描技术研究了所制备的纳米粒子的非线性光学特性.对3种具有不同摩尔数的样品的测试表明,计算所得的非线性折射率在-10-7(cm2/W)量级.%PbS is a direct bandgap IV-VI semiconductor with a bandgap of 0.41 eV and an exciton Bohr radius of 18 nm at room temperature.It has exceptional third-order nonlinear optical properties and applications for optical devices.In this paper,we synthesize PbS nanoparticles in aqueous solution using different capping agents.UV-Vis spectra show that the sample is much more stable.The nanoparticles are investigated by UV-Vis absorption spectrum and X-ray diffraction pattern.As a result of the nanoparticle size reduction,we observe a larger blue shift in absorption spectrum.Using the Scherre equation,the mean particle size is estimated about 8.2 nm.The Z-scan technique,which is a single beam method,is used to investigate the nonlinear optical properties of the as-prepared particles.We use a continues He-Ne laser with 632.8 nm wavelength in the set-up.The method is applied to three samples with different molarities and the nonlinear refractive index is calculated to be of the order of 10-7(cm2/W)with a negative sign.