热光效应下的全内反射光束展宽规律以及应用

以热光型器件的热学模型和温度场解析表达式为基础，运用射线法．通过计算位于芯区不同子午面内的光线反射轨迹，对热光效应下光束经全内反射后展宽的原因和规律进行了分析，并且给出了具体光束展宽值的理论计算方法；设计了高反射率的全内反射型有机聚合物热光开关。在设计中应用所提出的规律，理论上计算出了具体的展宽波导宽度、芯区的掩埋深度、扩大的反射区宽度等结构参量。软件的模拟结果表明，该结构在反射态和直通态时的效率分别为82．6％和811．4％，串扰均大于30dB，并且对这些结构参量的模拟优化结果与理论计算结果基本一致。

Beam Expansion Law and Its Application in Total Internal Reflection Induced by Thermo-Optic Effect

Based on the thermal model of thermo-optic device and analytical expression of temperature distribution, by employing the ray optics, the beam expansion cause and law in thermo-optic-effect-induced total internal reflection (TIR) are analyzed by calculating the ray reflection trace in different meridan plane of the core, and a theoretical method to calculate the specific expanding value of beamwidth is given. A 2×2 polymer thermo-optic switch with high reflection coefficient is designed as an illustration of the law. Utilizing the law in authors′ design, the structure parameters of expansion waveguide width, buried depth of the core, and enlarged reflection area width are calculated. Simulation results show that the structure exhibits a reflection coefficient of 82.6 % at reflecting state, a cross coefficient of 84.4% at cross state, the cross talks are better than 30 dB. The simulation optimized result of these structure parameters agrees with theoretical calculation.