Surface characteristics of SiO_2-TiO_2 strip fabricated by laser direct writing

SiO_2-TiO_2 sol-gel films are deposited on SiO_2/Si by dip-coating technique.The SiO_2-TiO_2 strips are fabricated by laser direct writing using an ytterbium fiber laser and followed by chemical etching.Surface structures,morphologies and roughness of the films and strips are characterized.The experimental results demonstrate that the SiO_2-TiO_2 sol-gel film is loose in structure and a shrinkage concave groove forms if the film is irradiated by laser beam.The surface roughness of both non-irradiated and laser irradiated areas increases with the chemical etching time.But the roughness of laser irradiated area increases more than that of non-irradiated area under the same etching time.After being etched for 28 s,the surface roughness value of the laser irradiated area increases from 0.3 nm to 3.1 nm.     

溶胶-凝胶法制备SiO2-TiO2平板光波导工艺研究

采用溶胶-凝胶法制备了SiO₂-TiO₂平板光波导,计算了平板光波导通光条件,分析了硅/钛溶胶-凝胶材料的热性能,观测了平板光波导的结构形貌,并测试了其通光损耗。结果表明：经过200℃,30 min干燥处理的凝胶薄膜呈疏松多孔状态,对于非对称平板波导,存在芯层通光截止厚度,而且当SiO₂-TiO₂芯层厚度为0.5 μm时,SiO₂下包层厚度至少有6 μm才能防止1550 nm波长光泄露入单晶硅衬底中。制备的光波导对于1550 nm波长光传输损耗最小值为0.34 dB/cm。     

启普发生器的改进和使用

普发生器是制取少量气体的玻璃仪器。它是荷兰化学家启普(P.J.Kipp,1806—1864)在1862年设计的。一百多年来,还没有更简便,更好使用的仪器可以代替它。这种仪器操作简便,透明直观,最适宜于教学使用。启普发生器如图1所示。它的组件现在都是由玻璃制成的,需用的固体反应物应为适当的块状,反应生成的气体不溶于水。例如用锌粒和盐酸反应制取氢气;大理石和盐酸反应制取二氧化碳;硫化亚铁和盐酸反应制取硫化氢等。