Generally, the data analysis of sensors based on spectral measurements, for instance, fiber Bragg gratings (FBG), long period fiber gratings (LPFG) is performed observing the shift or attenuation of a single wavelength. However, sometimes such spectrum variations are not evident or clearly perceptible; therefore, it becomes necessary to use other analysis techniques. One of them is principal components analysis (PCA) which allows to explore the behavior of the complete transmission spectrum pattern. In this work, we show the application of PCA to the response of fiber optical sensors for acetone detection. Two kinds of acetone sensors based upon single long period fiber gratings (LPFG) and Mach-Zehnder fiber interferometers (MZI), formed with a pair of cascaded LPFGs, coated with polydimethylsiloxane (PDMS) were developed. The sensor response was measured inside a Teflon chamber injecting a liquid acetone sample. The transmission spectrum variations at the devices output were measured with an optical spectrum analyzer, stored in a computer and analyzed by PCA. A comparison between the performance of both kinds of sensors was carried out and it was found that the sensitivity was increased up to 13 times (from 0.7 × 10⁻⁴ ppm⁻¹ to 9.4 × 10⁻⁴ ppm⁻¹) for the MZI sensors compared with that of single LPFG ones, which means, at best, a limit of detection (LOD) of 170 ppm.

通常，基于光谱测量的传感器数据分析，例如光纤布拉格光栅（FBG）、长周期光纤光栅（LPFG）是通过观察单个波长的偏移或衰减来进行的。然而，有时这种频谱变化并不明显或不明显；因此，有必要使用其他分析技术。其中之一是主成分分析 (PCA)，它允许探索完整传输频谱模式的行为。在这项工作中，我们展示了 PCA 在用于丙酮检测的光纤传感器响应中的应用。开发了两种基于单长周期光纤光栅 (LPFG) 和马赫-曾德光纤干涉仪 (MZI) 的丙酮传感器，它们由一对级联 LPFG 形成，并涂有聚二甲基硅氧烷 (PDMS)。传感器响应是在 Teflon 室内注射液体丙酮样品时测量的。用光谱分析仪测量器件输出端的透射光谱变化，存储在计算机中并通过 PCA 进行分析。对两种传感器的性能进行了比较，发现灵敏度提高了 13 倍（从 0.7 × 10^-4  ppm ^-1至 9.4 × 10 ^-4  ppm ^-1 ) 的 MZI 传感器与单个 LPFG 传感器相比，这意味着检测限 (LOD) 最多为 170 ppm。