中文摘要：

基于长时期的纤维栅栏(LPFG ) 的双山峰回声，一个新奇电影传感器被介绍，在哪个对包围气体敏感的电影在反响的波长与这部电影改变的双山峰的纤维栅栏区域，和间隔的 cladding 上是涂的折射索引。根据夫妇模式理论，一个三元组穿着的数字模型被开发分析在敏感 S n 和薄电影之间的关系光参数(电影厚度 h 3 并且折射索引 n 3 )并且纤维栅栏参数(栅栏时期螞 和核心索引调整蟽)。由使用优化方法，最佳的电影光参数和栅栏结构参数被获得。到这些电影的折射索引的这个计划的敏感被预言到的数字模拟表演是超过 10 ? 7。理论上的分析为实际高度敏感的电影传感器提供直接基础。

英文摘要：

Based on the dual peak resonance of long-period fiber grating（LPFG）, a novel film sensor is presented, in which films sensitive to the surrounding gases are coated on the cladding of the fiber grating region, and the intervals of the dual peak resonant wavelengths change with the film refractive index. According to the coupled-mode theory, a triple-clad numerical model is developed to analyze the relation between the sensitivity Sn and the thin film optical parameters （the film thickness h3 and the refractive index n3） and the fiber grating parameters （the grating period A and the core index modulation σ）. By using optimization method, the optimal film optical parameters and the grating structure parameters are obtained. Numerical simulation shows that the sensitivity of this scheme to refractive index of the films is predicted to be more than 10-7. The theoretic analysis provides straightforward foundation for the actual highly sensitive film sensors.