According to the different transmission point moduli, optical fibers can be divided into single-mode fibers and multi-mode fibers. The so-called "mode" refers to a beam of light entering the optical fiber at a certain angular velocity. Single mode fiber uses a solid-state laser as the light source, while multimode fiber uses a light-emitting diode as the light source. multimode fiber allows multiple beams of light to propagate simultaneously in the fiber, resulting in mode dispersion (because each "mode" light enters the fiber at a different angle and reaches the other end at a different time, this feature is called mode dispersion). Mode dispersion technology limits the bandwidth and distance of multimode fiber. Therefore, the core wire of multimode fiber is thick, the transmission speed is low, the distance is short, and the overall transmission performance is poor, but its cost is relatively low. It is generally used in buildings or geographically adjacent environments. Single mode fiber can only allow one beam of light to propagate, so single-mode fiber does not have mode dispersion characteristics. Therefore, the core of single-mode fiber is relatively thin, with a wide transmission frequency band, large capacity, and long transmission distance. However, due to the need for a laser source, the cost is relatively high.
multimode fiber
Optical signals propagate through multiple paths in multimode fibers: it is generally recommended to apply them at distances of less than miles
The effective distance of multimode fiber from the transmitter to the receiver is approximately 5 miles, and the available tracking distance is also affected by the type and quality of the transmitting/receiving device; The stronger the light source, the more sensitive the receiver, and the farther the distance. Research has shown that the bandwidth of multimode fiber is approximately 4000Mb/s. The single-mode fiber is manufactured to eliminate pulse broadening, and due to the small core size (7-9 microns), it eliminates the jumping of light rays. Use focused laser sources at wavelengths of 1310 and 1550nm. These lasers directly shine into tiny fiber cores and propagate to the receiver without significant jumps.
single-mode fiber
The core of single-mode fiber is relatively thin, allowing light to be directly emitted to the center. Suggest using when the distance is long
In addition, the distance loss of single-mode signals is smaller than that of multi-mode signals. At a distance of the first 3000 feet, multimode fiber may lose 50% of its LED light signal intensity, while single-mode only loses 6.25% of its laser signal at the same distance.
The bandwidth potential of single-mode makes it the only choice for high-speed and long-distance data transmission. Recent tests have shown that a single-mode optical cable can transmit 64 channels of 40G Ethernet over a distance of up to 2840 miles.
The most common determining factor for choosing multi-mode or single-mode in secure applications is distance. If it is only a few miles, multi-mode is preferred because LED transmitters/receivers require much cheaper lasers than single-mode. If the distance is greater than 5 miles, single-mode fiber is optimal. Another issue to consider is bandwidth. If future applications may involve transmitting large bandwidth data signals, then single-mode will be the best choice.