An optical fiber is a cylindrical ( waveguide) that transmits light along its axis through the process of total internal reflection. The fiber consists of a core surrounded by a layer, both of which are made of materials. To confine the optical signal in the core, the of the core must be greater than that of the cladding. The boundary between the core and cladding m. Diffraction is the deviation of from straight-line propagation without any change in their energy due to an obstacle or through an. Diffraction is the same physical effect as, but interference is typically applied to superposition of a few waves and the term diffraction is used when many waves are superposed. The term diffraction pattern is used to refer to an image or map of the different directions of th.