How Corning Invented Modern Fiber Optic Cables

A 1970 method for creating glass fibers that carry light over long distances by layering glass inside a tube and drawing it into a thin, solid strand.

What it covers

The patent describes a process for manufacturing optical waveguides by depositing a thin film of glass with a specific refractive index onto the inner surface of a glass tube. This tube, which has a different refractive index, acts as the cladding. The combined structure is then heated and drawn, causing the tube to collapse inward and form a solid, thin fiber. This creates a core of high-purity glass surrounded by a cladding layer, which is the essential structure required to keep light trapped inside the fiber via total internal reflection.

What it doesn't cover

• —Does not cover the chemical vapor deposition processes (like MCVD) that later became the industry standard for mass production.
• —Does not cover the use of plastic or polymer-based optical fibers.
• —Does not cover the specific electronic hardware used to transmit or receive the light signals.
• —Does not cover fiber optic cables that do not use a core-cladding structure with differing refractive indices.

The clever bit

The innovation was the realization that you could create a solid fiber by collapsing a tube, ensuring the core and cladding were perfectly aligned and fused during the drawing process.

Why it matters

This patent represents the birth of the modern telecommunications backbone. By demonstrating a viable way to produce low-loss glass fibers, it enabled the transition from copper wires to light-based data transmission, which now carries the vast majority of global internet traffic.

Real-world examples

• 1.Undersea transoceanic internet cables
• 2.Fiber-to-the-home (FTTH) broadband connections
• 3.High-speed enterprise data center networking