An Adaptive Mode-Division-Multiplexing Network for Quasi-Distributed Gas Sensing

多地点气体传感对于大量民用基础设施和环境应用至关重要，包括能源电网监测和对危险过程的监测，如碳封存或煤矿和垃圾填埋场等地区。对于这样的应用，通常涉及恶劣的传感环境和重大的安全问题，光纤气体传感通常是唯一的解决方案。这是因为光纤气体传感器消耗的能量很少，不需要电池或其他潜在的“不安全”电源。传统上，很难将大量的光纤气体传感器组合在一起进行多位置传感。该项目旨在通过开发自适应气体传感器网络来克服这一挑战，其中每个气体传感器的行为可以通过改变传感器网络中光信号的空间分布来单独调整。这使得10到100个气体传感器的大规模集成成为可能。因此，该项目有可能显著降低气体传感的每个传感器的成本，并影响涉及爆炸性或危险气体的无数工程应用。该项目还包括一项针对各级代表性不足群体的全面教育和推广计划。目前光纤气体传感方法依赖于使用单模光纤。本项目旨在颠覆这一传统范式，展示一种首创的基于少模光纤的自适应模分复用(MDM)气体传感器网络。在该方法中，单个气体传感器的传感特性可以通过自适应光学(AO)来控制询问信号的模式组成来动态调制。该传感器网络依靠最高阶光纤模式进行气体检测，利用最低阶光纤模式进行低损耗信号传输。这种独特的设计使人们能够解决高气体灵敏度和大规模多路复用之间的根本冲突，前者要求单个传感器的气体衰减较大，后者要求整个传感器网络的低损耗电力传输。具体地说，该项目旨在通过实验演示一个包含至少10个用于乙炔监测的气体传感器的AO-MDM传感器网络，并从理论上探索构建一个由100个甚至1000个气体传感器组成的高度多元化的传感器网络的可能性。

Multi-location gas sensing is critical for a large number of civil infrastructure and environmental applications, including energy grid monitoring and the surveillance of dangerous processes such as carbon sequestration or areas such as coal mines and landfills. For such applications, which generally involve a harsh sensing environment with significant safety concerns, fiber optic gas sensing is often the only solution. This is because fiber gas sensors consume little energy and have no need for batteries or other potentially "unsafe" electrical power supplies. Traditionally, it has been difficult to combine a large number of fiber gas sensors together for multi-location sensing. This project aims to overcome this challenge by developing an adaptive gas sensor network, where the behavior of each gas sensor can be individually tuned by changing the spatial profiles of optical signals within the sensor network. This makes large scale integration of 10 to 100 gas sensors possible. As a result, this project has the potential to significantly reduce per-sensor-cost for gas sensing and impact a myriad of engineering applications that involve explosive or dangerous gases. This project also includes a comprehensive education and outreach plan targeting underrepresented groups at all levels.Current approaches for fiber optic gas sensing rely on using single mode fibers. This project aims to overturn this conventional paradigm, and to demonstrate a first-of-its-kind adaptive mode-division-multiplexing (MDM) gas sensor network based on few mode fibers. In this approach, the sensing characteristics of individual gas sensors can be dynamically modulated by using adaptive optics (AO) to control the mode composition of interrogation signals. This sensor network relies on the highest order fiber mode for gas detection and utilizes the lowest order fiber mode for low loss signal transmission. This unique design allows one to resolve the fundamental conflict between high gas sensitivity, which requires large gas attenuation for individual sensors, and large scale multiplexing, which demands low-loss power transmission for the entire sensor network. Specifically, this project aims to experimentally demonstrate an AO-MDM sensor network that contains at least 10 gas sensors for acetylene monitoring, and theoretically explore the possibility of constructing a highly multiplexed sensor network with 100 or even 1000 gas sensors.