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Mechanism of refractive index increase in silica glass for the development of fiber-optic photodevices

用于开发光纤光电器件的石英玻璃折射率增加机制

基本信息

批准号：
12450132
负责人：
OHKI Yoshimichi
金额：
$ 6.91万
依托单位：
Waseda University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

The refractive index change induced in a transparent material by UV photon or ion irradiation promises direct drawing of a waveguide that can be used as optical gratings. Structural changes in silica glass induced by ion microbeam were evaluated using microscopic photoluminescence and Raman scattering, and optical and atomic force microscopes (AFM) measurements. The AFM measurements on the microbeam irradiated area show the formation of a groove on the surface. In addtion, a cross sectional observation on the surface parallel to the incident plane reveals surface deformation along the ion tracks, which is deepest at the projected range of ions. Taking into account the possible structural changes of silica induced by energy deposition, the measured topological changes at the front and side surfaces result from internal compaction of silica glass. Refractive index changes were estimated from the Lorentz-Lorenz relationship using the distribution of the internal compaction estimated by the AFM measurements. A small refractive index change was observed along the ion tracks besides a much stronger index change at the projected range, suggesting that energy depositions by the ionization as well as by the atomic collision should be taken into account.It has also become clear that the refractive index change can be induced by UV photons from a KrF excimer laser in a-SiO_x N_y : H films prepared by PECVD. Fabrication of a diffraction grating was performed using a phase mask made of a high quality fused silica plate. The surface of the fabricated grating observed by scanning electron microscopy (SEM). A clear square-toothed pattern with periodicity of around 1 μm can be observed. Furthermore, from the Fraunhofer diffraction pattern, the periodicity of the grating pattern was estimated to be around 1 μm, which agrees with the SEM image. This simply demonstrates that a-SiO_xN_y : H can be processed by UV photon irradiation.

利用紫外光子或离子辐照在透明材料中引起的折射率变化，可以直接绘制出可用作光栅的波导。利用显微光致发光和拉曼散射、光学显微镜和原子力显微镜（AFM）测量了离子微束辐照石英玻璃后的结构变化。对微束辐照区域的AFM测量显示在表面上形成凹槽。另外，在平行于入射平面的表面上的横截面观察揭示了表面变形沿着离子轨道，这是最深的离子投影范围。考虑到能量沉积引起的二氧化硅可能的结构变化，在前表面和侧表面测量的拓扑结构变化的结果从内部压实的二氧化硅玻璃。折射率的变化估计从洛伦兹-洛伦兹关系使用的AFM测量估计的内部压实的分布。在PECVD制备的a-SiO_xN_y：H薄膜中，除了在投影范围内折射率变化很大外，还观察到沿离子径迹沿着方向折射率变化很小，这表明电离和原子碰撞引起的能量沉积都应考虑在内.使用由高质量熔融石英板制成的相位掩模进行衍射光栅的制造。利用扫描电子显微镜（SEM）对制作的光栅表面进行了观察。可以观察到周期约为1 μm的清晰的方齿图案。此外，从夫琅和费衍射图案，光栅图案的周期性估计为约1 μm，这与SEM图像一致。这简单地说明了a-SiO_xN_y：H可以通过紫外光子辐照进行加工。