Sensors and Actuators A: Physical ( IF 4.6 ) Pub Date : 2020-01-25 , DOI: 10.1016/j.sna.2020.111836 Saawan K. Bag , Meher Wan , Rajat K. Sinha , Shailendra K. Varshney
We report a simple and compact optical fiber sensor based on surface relief gratings in conventional graded-index multimode optical fiber (GIMMF) for refractive index sensing. Bragg gratings on MMF are less explored compare to its single mode counterpart, even though the MMF platform possesses several advantages such as robustness, enhanced light-matter interaction and easy light coupling. In this work, surface relief gratings are directly written on one side of the cladding etched MMF core surface by using focused ion beam milling (FIB). A detailed theoretical analysis of the structure and sensing principle is analysed. The device performance as a refractive index sensor has been investigated experimentally by immersing the device in different concentration of NaCl solution. Experimental results show a sensitivity of 70 nm/RIU for a refractive index range of 1.333 to 1.345. The device is easy to fabricate with high repeatability and low cost, compact in design and competent to be used in harsh environmental conditions. The surface grating on etched MMF provides a better interaction between the sensing region and the environment which makes it a potential candidate for various chemical and biological sensing applications.
中文翻译:
蚀刻多模光纤上用于折射率传感的表面起伏光栅的设计与表征
我们报告了一个简单而紧凑的光纤传感器,该传感器基于传统的渐变折射率多模光纤(GIMMF)中的表面起伏光栅,用于折射率传感。与MMF平台相比,MMF平台上的布拉格光栅探索较少,即使MMF平台具有坚固性,增强的光-物质相互作用和容易的光耦合等优点。在这项工作中,通过使用聚焦离子束铣削(FIB)将表面起伏光栅直接写入包层蚀刻的MMF芯表面的一侧。对结构和传感原理进行了详细的理论分析。通过将器件浸入不同浓度的NaCl溶液中,已通过实验研究了该器件作为折射率传感器的性能。实验结果表明,对于1.333至1.345的折射率范围,灵敏度为70 nm / RIU。该装置易于制造,重复性高,成本低,设计紧凑,能够在恶劣的环境条件下使用。蚀刻的MMF上的表面光栅在感应区域和环境之间提供了更好的交互作用,使其成为各种化学和生物感应应用的潜在候选者。