What is Multi-Mode Fiber Cables?

What is Multi-Mode Fiber Cables?
:Multi-mode fiber allows many "modes", or paths, of light to propagate through the fiber optic cable. The relatively large core of a multi-mode fiber allows good coupling from inexpensive LEDs light sources and the use of inexpensive couplers and connectors. Multi-mode fiber typically has a core diameter of 50 to 100 microns. Two types of multi-mode fiber exist with a refractive index that may be "graded" or "stepped". With graded index fiber the index of be "graded" or "stepped". With graded index fiber the index of refraction of the core is lower toward the outside of the core and progressively increases toward the center of the core, thereby reducing modal dispersion of the signal. With stepped index fiber the core is of uniform refractive index with a sharp decrease in the index of refraction at the core-cladding interface. Stepped index multi-mode fibers generally have lower bandwidths than graded index multi-mode fibers. The most popular fiber for networking is the 62.5/125 micron multi-mode fiber. These numbers mean that the core diameter is 62.5 microns and the cladding is 125 microns. Other common sizes are 50/125 and 100/140. The primary advantage of multi-mode fiber over twisted pair cabling is that it supports longer segment lengths. Multi-mode fiber can support segment lengths as long as 2000 meters for 10 and 100 Mbps Ethernet, and 550 meters for 1 Gbps Ethernet. The industry recommends fiber optic cable be considered for distances greater than 295 feet, when electromagnetic interference is a problem or when transmissions bit rates exceed 350 MHz.