Optical FiberCable is a unique transmission medium. It has some unique advantages over conventional communication media such as copper wire, microwave or co-axial cables. The major advantages is its high transmission capacity. Fiber Optics is the least expensive, most reliable method for high speed and / or long distance communications. The medium used in Fiber optic transmission is glass or plastic. Optical fiber can seen as dielectric circular medium with a core and cladding. The core has a slightly higer index of refraction and light is guided by total internal reflection at the boundry between core and cladding.