Light travels through fiber optic cables via a process called total internal reflection within strands of glass or plastic.
Fiber optic cables are designed to transmit data as pulses of light. These cables contain one or more optical fibers, which are thin strands of highly purified glass or plastic. The transmission occurs because of two key principles:
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Core and Cladding: Each optical fiber consists of a core (the central part that carries the light) and a surrounding layer called the cladding. The cladding has a lower refractive index than the core.
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Total Internal Reflection: When light traveling through the core strikes the boundary between the core and the cladding at a sufficiently shallow angle (greater than the critical angle), instead of refracting (bending) and passing into the cladding, it is completely reflected back into the core. This is total internal reflection.
Because of total internal reflection, the light bounces repeatedly along the length of the fiber, staying confined within the core. This allows the light signal to travel long distances with minimal loss of signal strength. The light pulses represent the data being transmitted.
Essentially, the fiber acts as a waveguide, guiding the light along its path. The purity of the glass and the design of the cable minimize signal degradation, allowing for high-bandwidth and long-distance communication.
