Application of ferrocene-based polymers in optical fiber gas sensing

摘要

We have successfully evaluated and incorporated ferrocene-based polymers as sensing elements in a novel tapered optical fiber device. Preliminary studies have shown that certain gases can modify the refractive index of these polymers. We have used these polymers as cladding over a tapered region of single-mode fibers. The device behaves as a modal interferometer with a beat length that is controlled by the diameter of the tapered region and the refractive index of the cladding. We have shown that a small variation in the refractive index of the polymer has a direct influence on the transmission characteristic of the tapered region. The responses of several sensors to ammonia, carbon dioxide, and nitrous oxide have bene examined. we have fabricated several sensors with different sensitivities by tuning their beat length. Reusability and selectivity of severa lsensors have also been investigated. A novel, computer based, analysis has been developed to predict the behavior of these devices. A rasonable awgreement has been obtained between the experiments and the theory. These sensors can be fabricated inexpensively and operated in harsh environment. A few potnetial applications are pollution detection, hazardous waste analysis, exhaust analysis of internal combustion engines, and explosive gas monitoring.