This paper provides an overview of the different types of fiber optic sensors (FOS) that can be used with composite materials and also their compatibility with and suitability for embedding inside a composite material. An overview of the different types of FOS used for strain/temperature sensing in composite materials is presented. Recent trends, and future challenges for FOS technology for condition monitoring in smart composite materials are also discussed. This comprehensive review provides essential information for the smart materials industry in selecting of appropriate types of FOS in accordance with end-user requirements.

Fiber Bragg grating (FBG)-based acoustic emission (AE) detection and monitoring is considered as a potential and emerging technology for structural health monitoring (SHM) applications. In this paper, an overview of the FBG-based AE monitoring system is presented, and various technologies and methods used for FBG AE interrogation systems are reviewed and discussed. Various commercial FBG AE sensing systems, SHM applications of FBG AE monitoring, and market potential and recent trends are also discussed.

Singlemode polymer fiber Bragg gratings (FBGs) are etched down to a diameter of 30 $\mu{\rm m}$ to be used for high sensitivity tensile force measurements. The singlemode polymer fiber and the Bragg gratings are fabricated using the in-house fabrication facility. The fabricated cladding etched polymer FBGs are characterized for low value tensile force measurements and the sensitivity of the sensors is measured and compared with the theoretically estimated values. A sensitivity of 643 nm/N is obtained for the polymer Bragg grating with a diameter of 30 $\mu{\rm m}$. A pressure sensor based on a singlemode polymer fiber grating is also demonstrated. Low pressure in the range of 290–790 Pa is measured and the observed sensitivity of the pressure sensor is 1.32 pm/Pa. Given the bio-compatible nature of polymer fibers, such as high sensitivity force and pressure sensors can find applications in bio-medical field where high sensitivity low value force/pressure measurements are required.

A photonic crystal fibre interferometer that operates in reflection mode for humidity detection is presented for the first time, which has the advantage that it does not require the use of any hygroscopic material. The fabrication of the sensor head is therefore simple since it only involves cleaving and splicing. The all-silica nature of the device has potential for many applications.