3. Optical networking Today, every major industrialized center is linked to the rest of the world with fiber-optic cable, and the result is high-quality and low-cost bandwidth. Fiber serves at the building level in commercial and industrial centers, freeing them from the restrictions of copper cable and enabling broadband communications that connects entities with high-speed pipelines.
5. Light Source Light Source LED Laser LEDs are typically used where the distance between the terminals is short; normally 10 km or less, and the bandwidth of the signal is lower than about 150 Mbps. LEDs are generally satisfactory for local networks.
6. LIGHTGUIDE CABLES A digital signal is applied to a lightguide by pulsing the light source on and off at the bit rate of the modulating signal and the pulses propagate to the receiver at slightly less than the speed of light. The lightguide has three parts: the inner core, the outer cladding, and a protective coating around the cladding.
7. 1 2 Single-mode fiber In single-mode fiber, light can take only a single path through a core that measures about 9 microns in diameter. Multimode fibers Multimode fibers have cores of 50 to 200 microns in diameter. Two types of optical fiber are manufactured:
9. OPTICAL NETWORKING APPLICATION ISSUES Lightwave communications systems have applications in both private and public communications systems. The primary LEC and IXC applications ride on SONET/SDH. For noncarrier applications SONET/SDH is also available, as are FDDI, fiber channel, and LAN protocols.
10. The following lists representative fiber applications: intercontinental and undersea transmission systems private campus backbones metropolitan area backbone systems trunking between local central offices digital loop carrier feeder systems cable television backbone transmission systems interconnection of PBXs with remote switch units Fibre Channel for high-speed computer communications local area networks
