According to HowStuffWorks, optical cables work by lining the inside of a wire with thin strands of glass and coating those strands of glass with two layers of plastic. The plastic creates a mirror-like effect around the glass that allows for internal reflection to help light travel through the optic strands.
An optic cable has the capability to carry a signal nearly 60 miles. When dealing with long-distance lines, equipment huts are needed at least every 60 miles to pick up and retransmit the signal. Failure to retransmit the signal results in a loss in signal strength or a distortion of the information being carried by the cable.
Creating optical fibers inside optical cables requires heating manufactured glass to between 3,000 and 4,000 degrees Fahrenheit. Once the glass is heated, it is drawn out in strands at a rate of nearly 66 feet per second. To ensure that no breaks form while the strand is being drawn out, it has to be constantly monitored by a laser micrometer. This laser also makes sure that the optical fiber is the same diameter from start to finish. If the optical fiber changes in diameter, the reflective properties do not work correctly, rendering the cable unable to carry signals correctly.