STTR Phase II: Chiral Long Period Grating Fiber Sensors

这个小型企业技术转移（STTR）二期项目将开发一种新型光纤传感器，可在恶劣环境中测量温度、压力、拉伸、轴向扭转和各种环境因素，包括液位。光纤传感器不会受到电磁干扰，也不会有点燃可燃燃料的危险，能够远程监测750°C及以上的温度，并能承受高辐射水平。由于印迹周期结构的脆弱性，传统的长周期光栅光纤（LPGs）是通过将光敏掺杂光纤暴露在图案紫外光照射下形成的。相比之下，双捻手性光纤传感器（CFS）中的玻璃纤维不必是光敏的，并将选择其鲁棒性。CFS的手性长周期光栅（CLPG）结构将在玻璃成形过程中产生，在该过程中，信号光纤和脚手架光纤在通过微型烤箱时缠绕在一起，在信号光纤中形成螺旋。由于手性光栅在核心和周围玻璃包层之间的光耦合以及它们随环境因素的位移引起的透射倾角将使用越来越复杂的微扰理论序列进行测量和计算。基于双捻CLPG结构的CFS克服了LPG和单双折射光纤加捻CFS的缺点。如果成功，它非常适合要求苛刻的应用，如核反应堆、外层空间和油井，以及医疗诊断和治疗以及汽车和航空航天工业。因此，粮安委可能成为现代技术和日常生活中无处不在的一部分，它越来越依赖于传感和自动决策。通过大幅度提高光纤传感器的工作温度，可以实现大量的节约。传统的发电机可以在更高的温度下运行，从而大大提高效率，并且可以大大提高油藏的采收率。在核电站中使用高温和抗辐射的CFSs可以使这些设施更加高效和安全。与传统的电子和光学传感器相比，CFS可以在更广泛的条件下工作，这将对整个经济产生影响，并将使CFS成为数十亿美元传感器市场中快速增长的一部分。新的玻璃成形制造方法和计算方法可用于光子学、微流体和医学诊断等多个领域。

This Small Business Technology Transfer (STTR) Phase II project will develop a novel optical fiber sensor of temperature, pressure, extension, axial twist and various environmental factors, including liquid level, in harsh environments. The optical fiber sensor will be free of electromagnetic interference and of the hazard of igniting combustible fuels and will be capable of remotely monitoring temperatures up to and beyond 750 °C and of tolerating high-radiation levels. Conventional long period gratings fiber (LPGs) formed by exposing photosensitive doped optical fibers to patterned ultraviolet illumination cannot operate in harsh environments because of the fragility of the imprinted periodic structure. In contrast, the glass fiber in the dual-twist chiral fiber sensor (CFS) need not be photosensitive and will be chosen for its robustness. The chiral long-period grating (CLPG) structure of the CFS will be created in a glass-forming process in which signal and scaffolding optical fibers are twisted together to form a helix in the signal fiber as the fibers pass through a miniature oven. Transmission dips due to coupling of the light between the core and surrounding glass cladding by the chiral grating and their shift with environmental factors will be measured and calculated using an increasingly sophisticated sequence of perturbation theories. The CFS based on the dual-twist CLPG structure overcomes the disadvantages of the LPG and of the CFS based on twisting single birefringent fibers. If successful it is ideally suited for demanding applications such as found in nuclear reactors, outer space, and oil wells, as well as in medical diagnostics and treatment and in the automotive and aerospace industries. The CFS may therefore become a pervasive part of modern technology and everyday life which relies increasingly on sensing and automated decision making. By substantially raising the operation temperature of optical fiber sensors, substantial savings can be realized. Conventional power generators could run at higher temperatures where they are substantially more efficient and the recovery rate in oil reservoirs can be increased considerably. The use of high-temperature and radiation-resistant CFSs in nuclear power plants can make these facilities more efficient and safe. The enhanced range of conditions in which the CFS can function relative to conventional electrical and optical sensors will have an impact across the economy and will make the CFS a rapidly growing segment of the multi-billion dollar sensor market. The novel glass forming fabrication methods and computational approaches may find use in diverse fields including photonics, microfluidics and medical diagnostics.