This Special Issue focuses on the innovative design of optical fiber sensor structures, including fiber Bragg gratings, long-period gratings, interferometric sensors, and advanced micro-structured fibers. Compared with conventional sensing technologies, FOS demonstrates superior capabilities in. Optical fiber sensors are renowned for their exceptional sensitivity, compactness, and ability to operate in harsh environments, making them essential in fields such as environmental monitoring, structural health diagnostics, biomedical applications, and industrial process control. Using fiber-integrated beam steering and shaping, individual sensors up to a diameter of 80 microns can be manufactured. In cooperation with our spin-off company Fionec GmbH. The optical fibre can be used as a distributed sensor by exploiting light scattering effects or as a quasi-distributed sensor network by functionalizing the fibre through Bragg gratings photo-inscription for instance. In this case, a laser is used for creating a periodic modulation of the fibre. This is the power of fiber optic sensing, a technology that transforms ordinary optical fibers into the digital world's sensory network. In 2023, researchers turned submarine cables into earthquake warning systems and gave electric vehicles “optical nerves” to prevent battery failures. From energy. Fiber-optic sensors are transforming industries by offering precision and reliability in measuring displacement, temperature, strain, and pressure. Tools like OpticStudio and Lumerical empower.