利用飞秒激光搭建的双光子聚合系统，成功制作出微纳长周期光纤光栅（MLPG）。该系统通过计算机控制三维位移平台完成结构的制作，可编程实现光栅的自动化制作，并全程监控光栅的制作过程。与传统制造方法相比，基于双光子聚合的制造方法，在光纤表面使光刻胶周期性的发生双光子聚合完成MLPG的制作。因此在形成光栅时不依赖光纤基底的变化，该长周期光栅（LPG）结构形成于光纤外表面，适用于不同种类光纤上的LPG制备。在直径为6.9 μm的微纳光纤上制造了8个周期为95 μm的光栅块，在1331 nm波长处观察到了13.5 dB的传输谱损耗峰。实验结果表明，MLPG的温度灵敏度与折射率灵敏度分别达到了1.39 nm/℃、2207.89 nm/RIU（RIU为单位折射率）。

为了提高葡萄糖传感器在人体环境(pH值为7.4)的检测灵敏度，提出了一种基于苯硼酸衍生物的长周期光纤光栅葡萄糖传感器，传感器将四乙烯基苯硼酸通过C=C双键重组的方式聚合在长周期光纤光栅表面，用于测量葡萄糖浓度。实验结果表明：该葡萄糖传感器在多次使用后中心波长仍可复位原点，在葡萄糖溶液pH值为 7.4、浓度为0.1~3 mg/mL范围内的灵敏度为0.34 nm/(mg?mL-1)。此外，该传感器在反复测定和长时间阶段测定仍然保持良好的一致性和稳定性。

This paper reviews a wide variety of fiber-optic microstructure (FOM) sensors, such as fiber Bragg grating (FBG) sensors, long-period fiber grating (LPFG) sensors, Fabry-Perot interferometer (FPI) sensors, Mach-Zehnder interferometer (MZI) sensors, Michelson interferometer (MI) sensors, and Sagnac interferometer (SI) sensors. Each FOM sensor has been introduced in the terms of structure types, fabrication methods, and their sensing applications. In addition, the sensing characteristics of different structures under the same type of FOM sensor are compared, and the sensing characteristics of the all FOM sensors, including advantages, disadvantages, and main sensing parameters, are summarized. We also discuss the future development of FOM sensors.

The proposed technique demonstrates a fiber ring resonator interrogated by an optical time domain reflectometer (OTDR), for intensity sensing. By using this methodology, a cavity round trip time of 2.85 μs was obtained. For a proof of concept, a long-period grating was inserted in the resonant cavity operating as a curvature sensing device. A novel signal processing approach was outlined, regarding to the logarithmic behavior of the OTDR. Through analyzing the experimental results, an increase in the measured sensitivities was obtained by increasing applied bending. With curvatures performed from 1.8 m^–1 to 4.5 m^–1, the sensitivity values ranged from 2.94 dB·km^–1 to 5.15 dB·km^–1. In its turn, the sensitivities obtained presented a linear behavior when studied as a function of the applied curvature, following a slope of 0.86×10^–3 dB. The advantages of applying this technique were also discussed, demonstrating two similar fiber rings multiplexed in a series of configurations.

本文在正六边形光子晶体光纤长周期光栅包层空气孔中选择性填充液体材料,设计并优化一种高灵敏度长周期光栅双谐振温度传感器。基于模式耦合理论建立光纤光栅传感模型,发现在包层空气孔填充特定折射率液体材料后,同一光栅周期下,模型分别在短波长、长波长处出现透射谐振峰,然后利用全矢量有限元法在完美匹配层边界条件下对模型的温度特性进行了数值分析。结果表明:当包层空气孔中填充磁流体时,随着温度的升高,左峰(短波长处)中心波长蓝移,右峰(长波长处)中心波长红移,且左、右峰间隔随温度变化曲线近似线性,其温度灵敏度为11.40 nm／℃;当第一层空气孔中填充折射率温度系数更高的乙醇,其他空气孔中填充磁流体时,左、右峰间隔的温度灵敏度为2.99 nm／℃。

聚合物光纤光栅不仅具有体积小、质量轻、柔软、成本低等诸多优点, 还因聚合物自身的特性而具有灵敏度高、响应范围宽、生物兼容性等优良特性。首先梳理了聚合物光纤的光敏性机理, 概述了聚合物光纤光栅制备的刻蚀光源和方法; 其次根据聚合物光纤的组成材料, 概述了多种聚合物光纤光栅的制备进展和性能指标, 包括聚甲基丙烯酸甲酯、环烯烃共聚物TOPAS、透明无定物氟聚合物CYTOP和聚碳酸酯。总之, 目前聚甲基丙烯酸甲酯聚合物光纤光栅的研究占主导, 而基于新型材料的聚合物光纤光栅因自身独特的优势也逐渐受到重视。

为了提高光纤传感器的性能和进一步缩小传感器的尺寸, 通过实验制备出一种基于光纤布拉格光栅(FBG)与长周期光栅(LPG)并联的新型集成光学传感器。该传感器中的FBG和LPG是利用飞秒激光直写技术直接在普通单模光纤中刻写的。FBG和LPG是并联关系, 因此很大程度地缩小了传感器的长度。外界的温度和折射率的变化会引起FBG和LPG的谐振峰波长位置发生变化, 据此对该集成传感器进行温度和折射率测量。实验结果表明: FBG谐振峰对折射率和温度的灵敏度分别为0 nm/RIU和1298 pm/℃, 而LPG在1 555 nm附近谐振峰对折射率和温度的灵敏度为19646 nm/RIU和1093 pm/℃。因此, 根据双参数传感矩阵, 该传感器可以对温度和外界折射率进行同时传感。

A fiber Bragg grating (FBG) pressure sensor with high sensitivity and resolution has been designed and demonstrated. The sensor is configured by firmly fixing the FBG with a metal bellows structure. The sensor works by means of measuring the Bragg wavelength shift of the FBG with respect to pressure change. From the experimental results, the pressure sensitivity of the sensor is found to be 90.6 pm/psi, which is approximately 4000 times as that of a bare fiber Bragg grating. A very good linearity of 99.86% is observed between the Bragg wavelength of the FBG and applied pressure. The designed sensor shows good repeatability with a negligible hysteresis error of ± 0.29 psi. A low-cost interrogation system that includes a long period grating (LPG) and a photodiode (PD) accompanied with simple electronic circuitry is demonstrated for the FBG sensor, which enables the sensor to attain high resolution of up to 0.025 psi. Thermal-strain cross sensitivity of the FBG pressure sensor is compensated using a reference FBG temperature sensor. The designed sensor can be used for liquid level, specific gravity, and static/dynamic low pressure measurement applications.