For example, fiber Bragg gratings (FBG) can be used for multi-functional sensory networks, like the acquisition of strain and temperature in real-time at different locations. For 3D shape sensing, FBGs in single-mode fibers are processed inside the fiber cladding in form of. The FiberLab group focuses on developing, optimizing, and processing of tailored fiber optical sensors for specific applications by using femtosecond laser technology for creating new material properties. In glass fibers, processed grating structures enable various applications. This is achieved by creating a periodic variation in the refractive index of the fiber core, which generates a. terest in 3-D photonic crystals. Most of the processing methods involve complex vapour deposition and various co-dopants, which have an advantage of overcoming the lack of finesse involved with general formation of glass structure through high temp rature processing and quenching. These microscopic structures within optical fibers have become the bedrock of cutting-edge sensor. Abstract: In this paper, the brief introduction of Fiber Bragg Grating, its significant applications, sensing principles, properties, fabrication and the basic designing of FBG have been discussed.