How do optical fibers work?

I would love to help you explore how we use light to transmit everything from pet videos to financial data across the globe. Before we dive into the physics of how these incredible glass threads work, could you tell me a bit about your background with physics or technology, and what makes you curious about fiber optics?

I am a complete beginner, just curious how the internet works.

It is wonderful to have you here! Since you are curious about how the internet actually gets to your home, we have built a custom roadmap to take you from a complete beginner to someone who truly understands the magic of light transmission.

Your path

The Physics of Total Internal Reflection

Data Encoding: How Information Travels

Types of Optical Fibers

The Magic of Light Pipes

To understand how the internet travels across oceans in seconds, we first need to look at the core concept: is simply a way to transmit information using pulses of light instead of electrical signals. Instead of sending electricity down a copper wire, we send light down a tiny strand of glass.

A single beam of yellow light undergoes total internal reflection as it zig-zags through a transparent glass pipe, bouncing cleanly between its parallel horizontal walls.

Think of an optical fiber as a highly efficient "light pipe"—much like a water pipe guides water around bends and curves, this glass thread guides light. No matter how much the cable twists, the light remains trapped inside, traveling all the way to the other end to deliver your data.