Practical application of waveguide in wireless media
Guided-wave optics is a relatively new technology for transmitting light through dielectric conduits. Wave guides are used to transfer electromagnetic power from one point in space to another. The technology of guided-wave optics has been developed to provide long-distance light transmission without the use of relay lenses. In the concept of optical con_nement, a medium of one refractive index
is embedded in a medium of lower refractive index. The medium of high refractive index acts as a light \trap" by multiple total internal reection at the internal interfaces (boundaries). Light conduits are made based on this principle. An optical wave-guide is a light conduit consisting of a slab, strip or cylinder of dielectric material surrounded by another dielectric material of a lower refractive index. Light is transported through the inner medium without penetrating into the surrounding medium. The most commonly used of these wave-guides is the optical _bre, which is made of two concentric cylinders of low-loss dielectric material such as glass. Other examples of wave-guides include the typical coaxial cable, the two-wire and micro-strip transmission lines, and hollow conducting wave-guides. In practice, the choice of the structure of wave-guides is dictated by: 1. The desired operating frequency,
2. The amount of power to be transferred and
3. The amount of transmission losses that can be tolerated.
Below is a _gure showing some light conduits.