Cladding in optical fiber is a concentric layer surrounding the core that confines light within the core through total internal reflection. Composed of materials with a lower refractive index than the core, cladding prevents light from escaping the core and contributes to the waveguiding properties of the fiber. Step-index cladding has a uniform refractive index, while graded-index cladding has a gradually decreasing refractive index to reduce modal dispersion. Multilayer cladding utilizes multiple layers with alternating refractive indices to improve light confinement and reduce loss.
