In this report, modeling and experimental results are presented for three fiber Bragg gratings that were fabricated in Newport F-SMF-28 fiber with the direct-write method. The model is based on coupled-mode theory assuming weakly guiding fibers. Details on qualitative investigations that drove the. Fiber Bragg grating (FBG) sensors have emerged as advanced tools for monitoring a wide range of physical parameters in various fields, including structural health, aerospace, biochemical, and environmental applications. This review provides a comprehensive overview of FBG sensor technology.