FBGs started being used in the sensing world for measuring and monitoring several parameters, such as strain, temperature, pressure, displacement, voltage, electric current, or chemical substances in a number of applications and environments. A fiber Bragg grating (FBG) is a type of distributed Bragg reflector constructed in a short segment of optical fiber that reflects particular wavelengths of light and transmits all others. It details their fabrication, typically using ultraviolet laser light and a phase mask, and. A variation of the period of the grating inscripted in a fiber optic – induced by mechanical or thermal perturbation – causes a shift of the reflected peak wavelength, due to the related optical path length variation. where Pij are the Pockel coefficients of the elasto-optic tensor, n is the. A Fiber Bragg Grating is an optical device composed of a series of closely spaced periodic variations. This structure can be created by intense UV light affecting the fiber core.