二氧化硅胶体球自组装光子晶体的研究

Microstructure and optical properties of colloidal crystals based on self-assembly of monodispersed SiO_2 microspheres

光子晶体由于具有光子带隙和光子局域等一系列优异的光学特性而受到了人们广泛的关注。由于采用胶体颗粒自组装法制备光子晶体制备工艺简单,所需要的费用也较低,因此已成为制备可见光至红外波段三维光子晶体的一种简便有效的方法。采用垂直沉积法制得了三维光子晶体薄膜,并用扫描电子显微镜和紫外-可见光-近红外分光光度计对其显微结构和光学特性进行了详细的研究。结果表明,自组装薄膜在三维方向上都具有有序结构,其密排面平行于载波片的表面。制备的光子晶体薄膜具有明显的光子带隙特性,带隙中心波长为956nm。研究了带隙中心波长同入射线与密排面法线夹角之间的变化关系,其结果与理论值吻合得很好。

Photonic crystals have an attraction due to their prominent optical properties such as photonic band gap and photonic localization. The self-assembly of colloidal microspheres into ordered three-dimensional （3D） structures with photonic band gap located in the visible or infrared bands has been a convenient and effective method because of its simple preparation process and low cost. The vertical deposition method is used to prepare 3D photonic crystals films, whose microstructure and optical properties are determined using scanning electron microscopy （SEM） and UV-visible-IR spectrometer. The SEM results show that the self-assembly films have ordered structures in the 3D with the packed plane parallel to the solid substrates. The transmittance spectra reveal that photonic crystals films possess obvious photonic band gap properties and central wavelengths of the stopgap locate at 956nm. The diffracted peak widths narrow and the peak depths increase as increasing volume fractions of SiO2 microspheres in colloidal solution, which mean better photonic band gap properties. Furthermore, the dependence of the central wavelengths on the angle between the incident light and the normal vector of the substrates is also measured, and the result is good agreement with the theoretical prediction.