Optical fibers are transparent strands made by dielectric cylinder surrounded by another dielectric cylinder. It contains three parts, namely, core, cladding and jacket. Fiber-optic lines are pure glass strands which carries digital information. Light travels through the core as total internal reflection because of high refraction index material of core. Optical Communication System contains: 1) Transmitter: Generates light signals by receiving and directing the optical devices to turn light “on” and “off” in a sequence, 2) Optical Fiber, 3) Optical Regenerator: amplifies the incoming signals due to loss of signal during transmission and 4) Optical Receiver: decodes light signals and sends electric signals to user’s devices. Optical Fiber is less expensive, lightweight, flexible and degrades less signals and used in communication, medical, sensors, etc.