Optical fibers are normally classified into two types, Single Mode Optical Fibers and Multi Mode Optical fibers, according to the number of modes the fiber carries. Further, Single mode optical fibers are classified into 3 categories by International Telecommunication Union (ITU). These fibers are differentiated by the Chromatic dispersion.

G.652 – Dispersion Un-shifted Single Mode Fiber.

G-653- Dispersion Shifted Single Mode Fiber.

G.655- Non-Zero Dispersion Shifted Single Mode Fiber.