High speed communications have become extremely important to
our
society. Transferring high quality voice, video, and data at high
speeds has become commonplace thanks to physicists. One of the
technologies that physicists have developed to transfer data is the use
of fiberoptic cables. When using fiberoptic cables we translate data
into pulses of light which we then allow to travel through the cable.
Fiberoptic cables are long strands of glass or plastic that allow light to travel through the material without letting it escape from the cable back into the air until they reach the end of the cable. They accomplish this by using the concept of total internal reflection.
Remember the rules of refraction. When light moves from a substance that is more optically dense to one that is less optically dense it speeds up. This is what happens when light moves from glass or plastic into air. When this happens, the angle of refraction gets larger.
Now, if you keep increasing the angle of incidence you will reach a point when the angle of refraction is 90 degrees. This means the light will not be seen on the other side. If you increase the angle of incidence past this point the light will reflect back into the substance. We can then make the light stay inside the fiberoptic cable until it reaches the other end. Look below for a series of pictures that show this.
