An Optical Fiber Security System Utilizing Fiber Bragg Grating Sensors

In this study, we propose an optical fiber security system based on fiber Bragg grating (FBG) force-loading sensors embedded in the floor for security monitoring. FBG has the advantages of high sensitivity, small size, corrosion resistance, and resistance to electromagnetic interference. Therefore, FBG is very suitable for use as small, high-sensitivity sensors for security sensing applications. The system proposed here can monitor the different weights of passing pedestrians through different variations of strain. When thieves attempt a crime, the proposed optical fiber security system is capable of recognizing human body weight and triggering an alarm under the optical fiber security monitoring system. In this study, we utilized FBG sensors bonded to the bottom surface of a floor, and found that when there was a deformation of the floor structure, there was a linear relationship between the wavelength of the FBG sensor and the loading. Therefore, the force loading can be measured by observing the FBG wavelength. The loading sensitivity is about 0.000451 nm/N, and the R-squared value of the linear relationship reached up to 0.996. Thus, in this study, we establish an accurate and practical assessment technique for security monitoring via packaged FBG sensors that are surface-bonded to the bottom of a floor.