An investigation of bonding-layer characteristics of substrate-bonded fiber Bragg grating
An investigation of bonding-layer characteristics of substrate-bonded fiber Bragg grating
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DOI：
10.1109/jlt.2005.856235
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发表时间：
2005-11-01
影响因子：
4.7
通讯作者：
Li, WY
中科院分区：
文献类型：
--
作者：
Cheng, CC;Lo, YL;Li, WY
建立了光纤布拉格光栅（FBG）粘接层的解析模型，用以预测当衬底受到外力作用时，从衬底到FBG的应变传递。该模型提供了一个指导，如何键合的光纤光栅在基板上作为应变传感器或作为啁啾光纤光栅光谱调谐设备中使用的电信。此外，逆方法的基础上的优化技术的发展，以调查沿着光纤光栅的应变分布的哪一部分引起边带和波纹时，光纤光栅被拉伸，成为啁啾光纤光栅（CFBG）使用衬底应变技术。结果表明，不合格的粘结层对应变从衬底到FBG的传递的主要影响是在FBG的两端附近，这会导致反射光谱中的边带。使用高剪切模量的胶水，可以增加粘结长度，减小粘结层厚度，有效提高粘结层的应变传递率。然而，如果应变从基板转移到FBG表现出波动，由于不适当的键合工艺或退化的键合层，波纹出现在相应的波长光谱。波纹的数量和幅度与FBG中的应变波动强烈相关。
An analytic model of a bonding layer for a fiber Bragg grating (FBG) bonded on a substrate was developed to predict the strain transfer from the substrate to the FBG when the substrate is subjected to external forces. This model provides a guide on how to bond an FBG on a substrate as a strain sensor or as a chirp FBG spectrum-tuning device used in telecommunications. In addition, an inverse approach based on an optimization technique was developed to investigate which part of the strain distribution along the FBG causes sidebands and ripples when an FBG is stretched to become a chirped FBG (CFBG) using the substrate-straining technique. Results show that the primary influence of an unacceptable bonding layer on the strain transfer from the substrate to the FBG is near the two ends of the FBG, which causes sidebands in the reflective spectrum. Using a glue with a high shear modulus, we can increase the bonding length and reduce the bonding-layer thickness to effectively improve the strain transmissibility of the bonding layer. However, if the strain transfer from the substrate to the FBG exhibits fluctuations due to an improper bonding process or a deteriorating bonding layer, ripples occur in the corresponding wavelength spectra. The number and amplitude of the ripples correlate strongly to those of strain fluctuations in the FBG.