1. Field of the Invention
The present invention relates generally to the field of optical fiber waveguides, and more particularly to a means for determining when an optical fiber waveguide has been mishandled and potentially damaged.
2. Description of Related Art
With the demand for high speed, multi-media services constantly increasing, fiber optic technology is gaining increased attention as communication service providers design their networks to carry high bandwidth signals. Fiber optic technology is so attractive because of the tremendous bandwidth capability of light transmission. Light in the visible and near visible spectrum has characteristic frequencies exceeding hundreds of gigahertz (GHz) allowing information transmission at rates unattainable by traditional, twisted-pair technology.
In addition to their high bandwidth, optical fibers offer several advantages over copper-based transmission media: Fiber optic media have very low loss characteristics, particularly when compared to metallic media. Fiber optic cables are essentially immune to electromagnetic interference and do not generate any electromagnetic fields to interfere with other equipment. Inasmuch as fiber optic cables are nonconducting, they do not load electrical equipment--instead, the cables act as an optoisolator. Furthermore, fiber optic cables are small and lightweight and can be installed where twisted-pair copper wires will not fit. Lastly, optical fiber, despite its significant performance advantage, is price competitive with high-end twisted pair cable.
While these advantages are impressive, optical fibers do have some disadvantages. First, complex and oftentimes expensive interface equipment is generally required to convert between the electronic and optical domains for transfenring signals to the optical fiber and receiving signals from the optical fiber. As technology continues to advance, however, the disadvantage in terms of cost and complexity for optical interface equipment should be insignificant. Second, fiber optic cables must be treated with care during handling and installation to avoid damaging the waveguide. It has long been believed that the fiber itself is very fragile because it is made of glass. This belief, however, is false. Modern optical fibers have tensile strength ratings ranging from 600,000-800,000 pounds per square inch. Nevertheless, optical fibers are highly susceptible to damage when bent. Indeed, technicians or packaging personnel used to handling copper wire are often unaware or forgetful of the strict bending requirements that must be followed when working with fiber optic cables. For example, pulling wires around corners is acceptable for copper, but could severely damage fiber. Unfortunately, the damage caused by bending a fiber optic cable is essentially undetectable via visual inspection. It is not until the cable is installed or testing equipment is applied that the losses can be detected. Testing every cable or jumper before use is an expensive proposition in terms of both the equipment required and the technician's time involved.
Thus, what is sought is a cost effective mechanism for visually identifying when a fiber optic cable has been bent or handled roughly that would provide an early indication that the fiber may suffer from increased optical loss.