Fiber Optics Technology for Temperature and Humidity Sensor Development

This chapter reviews optical fiber sensors designed for measuring temperature and humidity, covering their fundamental principles, advanced architectures, and functionalized designs. The review discusses several sensor platforms, including those based on fiber Bragg gratings (FBGs), Long-Period gratings (LPGs), and Fabry–Perot interferometers (FPIs), as well as multimode interference (MMI) sensors, microstructured fibers, and distributed fiber sensors, describing the sensing mechanisms and the corresponding working principles. Additionally, the chapter presents strategies to enhance sensitivity and selectivity through microstructural modifications, material infiltration, and coating techniques with materials such as graphene oxide (GO) and polymers. This work demonstrates that fiber-based sensors offer high versatility for temperature and humidity monitoring, which is highly beneficial for industrial, environmental, and biomedical applications. This family of devices, hence, opens new avenues for sensitive, compact, and fast-response platforms capable of supporting the development of novel sensing technologies.