新型光子晶体光纤传感器的基础研究

Research on the Photonic Crystal Fiber-based Sensors

光子晶体光纤因其独特的光学特性、结构可灵活设计的优点以及对空气孔中填充的材料参量变化敏感的特点而成为近几年来传感领域的研究热点。该课题对填充金属纳米材料、气体、液体等材料的光子晶体光纤的光谱特性、温度传感特性及光子晶体光纤光栅的成栅机理进行了深入的研究,得到了一些很有价值的结论,为基于PCF的传感器的实现与应用及进一步拓宽光纤的原有领域奠定了良好的基础。(1)设计了一种有源PCF-SPR传感器,其特点是将有源内腔检测技术与表面等离子共振相结合,利用一根包层气孔充入金属纳米线溶液纤芯掺杂激活介质的光子晶体光纤实现探测激光产生、信息传感及光信号传输集一体的有源传感,并且由于纤芯的折射率可达到1.58,从而也拓宽了PCF-SPR传感器的探测范围。(2)针对在PCF气孔镀金属纳米膜的工艺较难的情况,实验上采用填充Ag纳米线悬浮液的方法实现了PCF-SPR温度传感,实验结果与仿真结果变化趋势一致,此方案可保持PCF用于表面等离子共振传感器的某些优点又简化了工艺操作。(3)设计了一种聚合物光子晶体光纤用于表面等离子共振传感器,这种光纤采用聚甲基丙烯酸甲酯制作,金属膜只需镀在光纤的外部,方便操作。仿真模拟结果表明,聚合物PCF半径、中心空气孔数量及空气孔的直径对波长灵敏度的影响很小,这样降低了对PCF制作的精密度的要求,有利于PCF的实际制作。(4)研究了一种基于混合液体填充的反射式光子晶体光纤温度传感探头,这种结构使得传感部分可以方便的伸入待测环境,相对于透射式传感装置而言,该种反射装置具有更为灵活实用的优点。实验结果表明,该种光子晶体光纤温度传感器可以在特定温度范围内呈现线性响应,其温度灵敏度约为1 d B/°C。此外,根据不同的溶液配比,该种传感器呈现可调谐的温度灵敏区间。(5)对由光子晶体光纤光栅组成的新型生物传感器特性进行了研究,重点对光纤结构参数(空气孔直径和孔间距)、光栅参数(光栅周期和周期个数)、塌缩程度和塌缩方式对谐振波长的影响进行了分析,研究结果表明,随着空气孔直径的增大、孔间距的减小、光栅周期的增大和塌缩程度的减小,其谐振波长向短波方向发生漂移,随着周期个数的增大,其谐振波长未发生明显漂移。

Photonic crystal fiber （PCF） has become the research focus in the field of sensors with the unique advantages of that it can be designed flexibly and exhibits a high sensitivity for the change of the filled gas, liquid, and metal-based nanomaterials. This subject has analyzed the spectral and temperature sensing characteristics of PCF with different materials by changing the structure parameters and the factors related to the surrounding environment. The results show that PCF based sensors is promising for related applications.（1）A surface plasmon resonance （SPR） refractive index （RI） sensor based on ytterbium-doped PCF filled with metal nanowires and analyte is proposed. With the proposed sensor, the output power of the ytterbium-doped PCF laser can be influenced obviously by a bit change of the refraction index of analyte in the air holes＆amp;nbsp;to achieve the intra-cavity fiber sensing. This PCF sensing system has great practical value and significance for their advantages of compact structure and high sensitivity.（2）A SPR temperature sensor based on PCF with silver nanowires is designed and investigated experimentally. The results show that the temperature sensitivity is as high as 3.5nm/℃ with the experiment, which can provide reference for the implementation and application of PCF-based SPR temperature sensor or other PCF-based SPR sensing.（3）An intra-cavity sensor based on a dual-wavelength Er-doped fiber laser is proposed and investigated experimentally. A measurement of the relative sensitivity enhancement of 158.5 is obtained.（4）A polymer PCF-SPR sensor is designed, in which a metal film can be deposited on the outer side of the fiber instead of coating in the holes of the conventional PCF. Numerical results show that excellent sensing characteristics of the structure can be achieved.（5） A kind of label-free refractive index biosensor based on long-period gratings （LPGs） inscribed in microstructured optical fibers （MOFs） is theoretically studied. Numerical results show that an ultrahigh refractive index sensitivity of approximately 397. 3nm/RIU over the refractive index range of 1.4~1.5 is achieved. Moreover, the sensitivity of the grapefruit MOF can be improved by reducing the periods of gratings. In addition, the shift of the resonant wavelength is linear to the analyte thickness with good sensitivity about 0.6nm/nm. It is expected to play a great role in theoretical guidance for further development of biosensors.