Abstract
This study explores the effect of sensor length on the strain sensitivity of a fiber Bragg grating system. The sensitive system, protection of the grating region, sensor pre-tensioning, adhesive, and choice of sensor length are the concerns which must be considered before/during the testing and installation of a fiber Bragg grating sensor. A simple experimental setup, including a detector and light source, may be utilized to obtain the wavelength shift and hence the strain measurements. The sensing principle is based on tracking the wavelength shift due to the change of the lateral stress that was applied by turning the screw gauge on the fiber grating bonded on a material. It is inferred from the results that if the effective gauge length is smaller, then the shift in the wavelength and strain is larger and vice versa. It has also been demonstrated that the fiber Bragg grating system is more sensitive to a smaller sensor length and less to a larger sensor length. The measured strain sensitivity of a 10 cm and a 15 cm sensor is 0.0011 nm/mu epsilon and 0.0016 nm/mu epsilon, respectively, under the same loading conditions. The experimental results also show the capability of the proposed system to perform strain measurements.