阵列波导光栅中心波长的温度不稳定性成为限制其应用的主要原因。为了设计温度不敏感阵列波导光栅,结合弹性多层板热应力理论和应力集中效应给出掩埋波导芯层应力的解析解,利用等效折射率法计算阵列波导的有效折射率及其温度系数,考虑波导材料折射率和波导长度随温度的变化得到了硅基二氧化硅阵列波导光栅中心波长的温度系数。并研究了贴有应力板的阵列波导光栅中心波长的温度特性,结果表明在芯片底部贴有0.37 mm厚的铝板时,TE模和TM模中心波长的温度系数分别是5.9 pm/℃和8.0 pm/℃,下降到传统阵列波导光栅中心波长温度系数的一半。

The thermal instability is a big problem in arrayed-waveguide gratings (AWG). A general method to study the central wavelength temperature sensitivity is developed with theoretically considering thermo-optic effect, stress-optic effect, thermal expansion and stress-strain relation. By combination of elastic multilayer theory and stress concentration effect, analytical stress solutions in the core layer are obtained. Based on the results of asymmetrical anisotropy planar waveguides, the effective index and its temperature coefficient in buried channel waveguides are calculated by using the effective index method. And then, the solutions are used to estimate temperature sensitivity of AWG central wavelength. The temperature sensitivity controlled by the thermal stresses induced by attaching an aluminum plate is also discussed. The results show that the temperature sensitivity could be optimized after attaching an aluminum plate on the bottom of arrayed waveguides. For the TE mode, the temperature coefficient of central wavelength is reduced to 5.9 pm/℃, and for the TM mode, that is reduced to 8.0 pm/℃.