What Are Optical Fibers?

Video Transcript

"Hi I'm Steve Jones and I'm going to explain what optical fibers are. First of all they are actually solid glass. People imagine and when you see drawings you think oh they are tubes but they are not, they are solid glass. Light that gets into them is reflected from within the solid glass and cannot get out until it reaches the other end. The glass therefore has to be very transparent because you can imagine what a two miter thick window would look like well such a fiber can travel, the light in it can travel for something like 15 kilometers without amplification so this is very important and what are they used for? Well the uses mainly are to transmit light pulses or light. In most uses like telephones and TV the pulses are in fact very small, very fast and it is a digital signal and you can send large amounts of information for telephones and for TV through these optical fibers. At the end of course it is transferred and turned into an electrical signal which feeds the television set. Another use and a particularly important one is a medical use where bundles of optical fibers are put together and end up in quite a flexible tube and this can be put down inside peoples' esophagus down into their stomach or into the lungs and so forth to look at the inside of the body and the way this is done is when you have got a huge number of fibers like this, some can carry light one way and others can carry a signal back the other way so you can create an image on the end of this and that image is brought back to the opposite end where it is reconstructed. You can see an image of the inside of the body. So this is a very very important use for doctors. They can actually look into somebody's stomach, see an ulcer forming and so forth. So basically what is an optical fiber? It is a solid piece of glass actually thinner than one of the hairs on your head, it is very transparent and it is light that is trapped inside it and it's light pulses that we send down it to transmit telephone and TV signals and other kinds of pictures so that is what optical fibers are."