An optical fiber grating is a small segment within an optical fiber altered to act as a selective filter for light. This treated area functions like a specialized mirror, reflecting a specific wavelength of light while allowing all other wavelengths to pass through. 1) At that time, the grating depended on interference between the forward-propagating wave inci-dent on. The principle behind this technology is both simple and powerful, enabling it to be applied in various industries, including telecommunications, sensing, and medical technologies. In this context, the discovery of photosensitivity in optical fibers led to the establishment of fiber Bragg gratings.