How It Works: Optical Fiber | Glass Optical Fiber | Corning

When we make a quick phone call, check a website, or download a video in today’s highly connected world, it’s all made possible by beams of light constantly bouncing through hair-thin strands of optical fiber.

The innovation emerged as one of Corning’s greatest success stories when scientists, in 1970, developed a way to transmit light through fiber without losing much of it along the way.

While many features of the fiber have improved enormously in the 50 years since then, the basic principles of data transmission remain the same.

So, how does fiber actually work? Let’s take a look.

When a device like your computer has information to send, that data starts out as electrical energy. A laser in the computer converts the signals to photons – tiny particles of electromagnetic energy, otherwise known as light – and sends them in rapid succession down the core of the hair-thin fiber.

Photons travel in waves through the inner core of the fiber. Because this core region has higher refractive index (i.e. light travels more slowly) than does the fiber’s outer cladding, the light signal is focused within the core and prevented from radiating out of the fiber. In addition, fiber cores are made from very high purity materials (typically Silica and Germania) to assure that the light energy is not absorbed or scattered by impurities. Radiation, absorption, and scattering are all forms of energy loss, also known as attenuation. By keeping such losses as low as possible, fiber allows light and the information it carries to travel great distances from the original source.

But if the core were the only component of the fiber, the light energy would eventually leak out, weakening the signal in a process known as attenuation. So optical fiber also includes an outer layer, or cladding, made from a different glass composition. The cladding material has a low refractive index designed to reflect light back into the core without allowing it to escape.

When the photons reach their destination, a photocell-equipped optical receiver decodes the digital light signals and converts them back into electricity, displaying the data on the other user’s computer, television, or other device.

Different types of communication signals require different kinds of fiber for efficient transmission. That’s why Corning offers both single-mode and multimode fibers.
 

• Single-mode fiber –the most common in worldwide telecommunications networks – is designed to carry light energy on one path, over long distances. Its core is miniscule – as small as 8 microns in diameter. It’s most frequently used for long-haul networks. Because it accommodates only one path of light, there’s less probability for overlapping signals and distortion.

• Multimode fiber, on the other hand, has a larger core measuring up to 62.5 microns in diameter. It’s built for light signals that must travel down many different paths simultaneously – usually over distances of less than a mile. Data centers and some connected-home networks, for example, prefer multimode fiber since it can handle very large amounts of data in a cost- and space-efficient manner.

Even as wireless communications and cloud computing have expanded the communications world, the majority of voice, video, and data signals still travel along fiber optic networks.

And Corning’s innovations in glass science are yielding new generations of high-speed, high-capacity fiber to meet the demands of today’s network applications. Optical fiber has always been physically strong. Under tensions, it is stronger than both high-tensile steel and titanium. Now, the ability of fibers to work in tough implementations is just as strong. New designs allow fibers to be bent around tight corners or stapled onto wall studs without affecting the light signal.

Capacity is also remarkable. A single strand can support up to 10 million simultaneous high-definition video streams. And in the home, new fiber innovations are enabling high-speed optical connections between computers, operating systems, gaming consoles, tablets, and more.

“Our scientists’ fundamental understanding of glass enable ongoing product and process innovations,” said Dr. Merrion Edwards, director of market and technology development for Corning Optical Fiber and Cable. “Those innovations continue to generate lower attenuation and thus improved capacity and speed.”

“Optical fiber is one of our iconic innovations, and we continue to be energized by what the future generations of fiber can do.”