In environmental or safety monitoring, continuous on-line systems are generally desired and fiber optic sensor (FOS) networks are well-suited for this purpose, with capability for large area coverage. The advantages of FOS are freedom from electromagnetic interference, wide bandwidth, compactness, and geometric versatility. Deployment of distributed and array sensors covering extensive structures and geographical locations is also feasible. This is particularly true when Bragg grating based fiber sensors is considered in view of their highly favorable characteristics. The basic principle of operation commonly used in a FBG based sensor system is to monitor the shift in wavelength of the reflected “Bragg” signal, λ B , with the changes in the environment, e.g. strain, temperature. Most of the FBG-based sensors reported in the literature are designed for strain and temperature measurements [1,2,3]. These sensors are designed for distributed embedded structural strain sensing in bridges, roads, ships and buildings, etc. Chemical fiber optic sensors are also extensively developed [4].