Multi-mode fibers are described by their core and cladding diameters. Some vendors use violet to distinguish higher performance OM4 communications fiber from other types. The standard TIA-598C recommends, for non-military applications, the use of a yellow jacket for single-mode fiber, and orange or aqua for multi-mode fiber, depending on type. Jacket color is sometimes used to distinguish multi-mode cables from single-mode ones. Single-mode fibers are often used in high-precision scientific research because restricting the light to only one propagation mode allows it to be focused to an intense, diffraction-limited spot. Because of the modal dispersion, multi-mode fiber has higher pulse spreading rates than single mode fiber, limiting multi-mode fiber's information transmission capacity. In contrast, the lasers used to drive single-mode fibers produce coherent light of a single wavelength. This chromatic dispersion is another limit to the useful length for multi-mode fiber optic cable. The LED light sources sometimes used with multi-mode fiber produce a range of wavelengths and these each propagate at different speeds. Because multi-mode fiber has a larger core-size than single-mode fiber, it supports more than one propagation mode hence it is limited by modal dispersion, while single mode is not. However, compared to single-mode fibers, the multi-mode fiber bandwidth–distance product limit is lower. In practical terms, the larger core size simplifies connections and also allows the use of lower-cost electronics such as light-emitting diodes (LEDs) and vertical-cavity surface-emitting lasers (VCSELs) which operate at the 850 nm and 1300 nm wavelength (single-mode fibers used in telecommunications typically operate at 1310 or 1550 nm ). Because of the large core and also the possibility of large numerical aperture, multi-mode fiber has higher "light-gathering" capacity than single-mode fiber. The main difference between multi-mode and single-mode optical fiber is that the former has much larger core diameter, typically 50–100 micrometers much larger than the wavelength of the light carried in it. Multi-mode fiber is also used when high optical powers are to be carried through an optical fiber, such as in laser welding.Ĭomparison with single-mode fiber Īt fixed radius and refractive index, the number of modes allowed in an optical fiber depend on the wavelength used (showing only the energy distribution of the TE modes for simplicity). Multimode cocoa 6.8.0 portable#Multi-mode fiber is used for transporting light signals to and from miniature fiber optic spectroscopy equipment (spectrometers, sources, and sampling accessories) and was instrumental in the development of the first portable spectrometer. Standards-compliant architectures such as Centralized Cabling and fiber to the telecom enclosure offer users the ability to leverage the distance capabilities of fiber by centralizing electronics in telecommunications rooms, rather than having active electronics on each floor. An increasing number of users are taking the benefits of fiber closer to the user by running fiber to the desktop or to the zone. īecause of its high capacity and reliability, multi-mode optical fiber generally is used for backbone applications in buildings. Typical transmission speed and distance limits are 100 Mbit/s for distances up to 2 km ( 100BASE-FX), 1 Gbit/s up to 1000 m, and 10 Gbit/s up to 550 m. The equipment used for communications over multi-mode optical fiber is less expensive than that for single-mode optical fiber.
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