Fiber optic sensors in ocean observation: A comprehensive review

A survey of recent investigations on ocean sensors is carried out with a specific focus on fiber optic sensing methods, materials for fabricating sensor head and sensor performance. Four categories of fiber optic sensing structures, including interferometer, fiber grating, photonic crystal fiber, and surface plasmon resonance are reviewed. These techniques measure physical and chemical variations of sensitive optical fibers and reveal changes in properties of the optical signal when exposed to the ocean environment. Advantages and disadvantages of all the sensing schemes are discussed and compared. Hybrid sensors that combine different optical sensing techniques are also discussed.