Multimode fiber has higher "light-gathering" capacity than single-mode optical fiber. 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 wavelength (single-mode fibers used in telecommunications operate at 1310 or 1550 nm and require more expensive laser sources. Single mode fibers exist for nearly all visible wavelengths of light).[1] However, compared to single-mode fibers, the limit on speed times distance is lower. 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. Also, because of their larger core size, multi-mode fibers have higher numerical apertures which means they are better at collecting light than single-mode fibers. Due to the modal dispersion in the fiber, multi-mode fiber has higher pulse spreading rates than single mode fiber, limiting multi-mode fiber’s information transmission capacity.
Single-mode fibers are most often used in high-precision scientific research because the allowance of only one propagation mode of the light makes the light easier to focus properly.
Jacket color is sometimes used to distinguish multi-mode cables from single-mode, with the former being orange and the latter yellow. A wide range of colors are commonly seen, however, so jacket color cannot always be relied upon to distinguish types of cable
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