Fiber Bragg Grating (FBG) is a type of optical fiber that is used in telecommunications, sensing, and other applications. It consists of a section of optical fiber that has been modified to reflect light at a specific wavelength. The modification is achieved by creating a periodic variation in the refractive index of the fiber along its length.
FBGs are typically made by using a high-intensity ultraviolet laser to create a series of narrow, parallel lines along the length of the fiber. The spacing between the lines determines the reflected wavelength of the FBG. When light at the reflected wavelength is introduced into the fiber, it is reflected back by the grating and can be detected and analyzed.
FBGs have several important properties that make them useful in a variety of applications. For example:
- They are very precise and can be tuned to reflect light at a specific wavelength. This makes them useful for applications such as optical filters and wavelength-division multiplexing (WDM) in telecommunications.
- They are highly sensitive to changes in temperature and strain, which makes them useful for sensing applications. When an FBG is subjected to temperature or strain, the reflected wavelength changes, allowing the change to be measured.
- They are compact and can be easily integrated into optical fiber systems. This makes them useful for applications such as distributed temperature sensing, where multiple FBGs can be used to monitor temperature changes along the length of a fiber.
Overall, FBGs are a versatile and important tool in the field of optical fiber technology. They are used in a variety of applications, including telecommunications, sensing, and optical instrumentation.