Fiber optic PCM, or Pulse Code Modulation in optical communication systems, is a digital modulation technique used to encode analog signals into digital data for transmission over optical fiber networks. The light is a form of carrier wave that is modulated to carry information. Fiber is preferred. In the optical fiber communication system, it is binary optical pulse "0" and "1" yard in the fiber transmission, it is produce by binary digital signal making the On and off modulation for the optical source. Wave propagation is guided by optical fibres. Co pared to twisted pair and coaxial cable, it has a greater bandwidth efficiency. This essay attempts to describe recent developments in fiber-optic communication, various modulatio light pulses, is one of the rapidly. We'll then compare how optical and coaxial cables transmit PCM signals—optical cables use light pulses through fiber optics, making them resistant to electrical interference, while coaxial cables rely on electrical pulses through copper wires, which can be more susceptible to noise but often. It traces OFC's development into a global communication backbone and elucidates key principles like total internal reflection, modal dispersion, and attenuation governing light propagation. The paper details OFC system components such as light sources, fibers, connectors, amplifiers, and detectors. It uses sampling, quantization, and encoding to transform sound waves into binary data.