The annealing depth increase s exponentially with annealing time at the first stage and then increases linearly with the square root of annealing time at the second stage of annealing.

• 退火可分为两个阶段, 波导深度的增加在第一阶段随退火时间成 指数关系, 第二阶段与退火时间的平方根成线性关系。