Si基SiO2波导芯层热应力的理论研究

结合弹性多层板热应力理论和应力集中效应给出了Si基SiO2波导芯层热应力的解析解,推导了芯层应力差的解析表达式.说明对于传统阵列波导光栅,芯层应力差来源于初始翘曲和波导各层热膨胀系数差;系统分析了波导各层材料对芯层应力差的影响,指出调节衬底的热膨胀系数、上包层的热膨胀系数、衬底的厚度和下包层的厚度都可以消除芯层应力差,但改变衬底和上包层热膨胀系数是调节芯层应力差的主要手段;讨论了几种常见金属应力板对芯层应力差的影响.结果表明,在阵列波导底部高温粘贴适当厚度的金属板可消除芯层应力差.

Analytical Solutions for Thermal Stresses in the Core of Silica-on-Silicon Waveguide

Elastic multilayer theory and stress concentration in buried channel waveguides are combined to obtain analytical solutions for thermal stress in the core of silica-on-silicon waveguides.Then the closed-form expression of stress anisotropy is obtained.It is shown that the anisotropy of thermal stress in conventional AWG comes from the initial warp and the thermal-expansion mismatch between waveguide layers.A complete analysis shows that the stress anisotropy can be minimized by tuning one of four parameters,including the thermal expansion coefficients of the substrate and upper cladding,and the thicknesses of the substrate and lower cladding,or by attaching a metal plate with proper thickness on the bottom of the arrayed waveguide.