How do fiber optic cables transmit?

Fiber optic cables transmit data by sending pulses of light down thin strands of glass or plastic fiber.

Here's a breakdown of the process:

• Light Source: The transmission begins with a light source, typically a laser or LED (Light Emitting Diode), which generates light pulses. Lasers are generally used for long-distance transmission due to their higher power and narrower beam, while LEDs are more cost-effective for shorter distances.

• Data Encoding: The data to be transmitted is encoded onto the light. This is done by modulating the light source – turning it on and off very rapidly, or varying its intensity. This modulation creates a digital signal (on/off represents 1s and 0s) that represents the data.

• Transmission Through the Fiber: The light pulses travel through the core of the fiber optic cable. The core is a very thin strand of glass or plastic. A crucial property that allows the light to travel efficiently is total internal reflection.

• Total Internal Reflection: The core is surrounded by a layer of cladding, which is also made of glass or plastic but has a slightly lower refractive index than the core. This difference in refractive index causes the light to reflect back into the core whenever it strikes the boundary between the core and the cladding at a sufficiently shallow angle. This phenomenon, called total internal reflection, ensures that the light stays within the core and travels along the length of the fiber with minimal loss.

• Reception and Decoding: At the receiving end, a photodetector converts the light pulses back into an electrical signal. This electrical signal is then decoded to retrieve the original data.

Here's a table summarizing the key components and their functions:

In essence, fiber optic cables use light to transmit information, leveraging total internal reflection to keep the light confined within the fiber's core, allowing for high-speed and long-distance data transfer with minimal signal loss.