Industry News

How Fiber Optic Lighting Works

Fiber-optic lighting uses optical fiber as a “light pipe,” transmitting light from a source through the fiber to a remote location. The light may be emitted from the end of the fiber creating a small spotlight effect (also called “end glow”) or emitted from the outside of the fiber along its length, looking like a neon or fluorescent tube (also called “side glow”).

The light source is usually called a “fiber optic illuminator” and consists of a bright light source and often some optics to efficiently focus light into the fiber. Sources must be bright, so quartz halogen or xenon metal halide lights are commonly used. Smaller fibers may also use LEDs which very efficiently couple light into fibers but do not achieve the light levels of the other lamps.

Optical fibers used for lighting are similar to fibers used in communications, but optimized for transmitting light not high speed signals. The fibers consist of a core that transmits the light and an optical cladding that traps the light in the core of the fiber. Unlike communications fibers that use small cores to maximize bandwidth, lighting fibers use large cores with thin claddings to maximize coupling of the light from the illuminator into the fiber. Side-emitting fibers have a rough interface between the core and the cladding to scatter some of the light out of the core along the length of the fiber to create a consistent lighted look similar to neon light tubes.

Lighting fibers can be made of glass, just like communications fibers, or plastic. If the fibers are glass, they are usually very small diameter and many are bundled together in one jacketed cable to provide enough light transmission. Larger diameter plastic fibers are  also used, perhaps more commonly, because they are inexpensive and easier to install, but they have higher light loss and cannot withstand as hot a temperature, sometimes limiting the light input from a source.