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Analysis: How to correctly select single-mode fiber and multimode fiber

With the high-speed development of information network, people’s requirements for data transmission are getting higher and higher, and fiber optic with its advantages of fast transmission speed, long distance, safety and stability, anti-interference, easy expansion, etc. is becoming more and more people’s first choice in cabling construction. As we all know, optical fiber is widely used in integrated cabling scenarios, and many people will encounter the selection problem of single-mode fiber and multimode fiber, and today we will learn about the selection problem of single-mode fiber and multimode fiber.

Classification of optical fiber

Optical fibers can be classified into single-mode and multimode according to the mode of transmission of light in them.

Multimode fiber: When the geometry of the fiber (mainly the core diameter d1) is much larger than the wavelength of the light wave (about 1 μm), there are dozens or even hundreds of propagation modes in the fiber. Different propagation modes have different propagation speeds and phases, resulting in time delays and broadening of the optical pulse after long distance transmission. This phenomenon is called mode dispersion in optical fibers. Mode dispersion narrows the bandwidth of multimode fibers and reduces their transmission capacity, so multimode fibers are only suitable for smaller capacity fiber optic communications. Multimode fibers have a core diameter of 50 or 62.5 μm and a cladding outer diameter of 125 μm, denoted as 50/125 μm or 62.5/125 μm.

Single-mode fiber: When the geometry of the fiber (mainly the core diameter) can be similar to the optical wavelength, such as the core diameter d1 in the range of 5 to 10 μm, the fiber allows only one mode (fundamental mode HE11) to propagate in it, and the rest of the higher secondary modes all cut off, so the fiber is called single-mode fiber, single-mode fiber core diameter of 8.3 μm, cladding outer diameter 125 μm, expressed as 8.3/125 μm.

Transmission distance of single-mode fiber and multimode fiber:

Single-mode fiber: According to the above single-mode fiber core diameter and outer packet diameter and single-mode optical module operating wavelength of 1310nm, 1550nm. single-mode fiber can support longer transmission distance than multimode fiber, in 100Mbps Ethernet to 1G Gigabit network, single-mode fiber can support transmission distance of more than 5000m.

Multimode fiber: Compared with twisted pair, multimode fiber can support longer transmission distance; in 10mbps and 100mbps Ethernet, multimode fiber can support up to 2000m transmission distance; in 1GbpS Gigabit network, multimode fiber can support up to 550m transmission distance; in 10Gbps 10 Gigabit network, multimode fiber OM3 can reach 300m, OM4 can reach 500 meters

Optical fiber working wavelengths are short wavelength 850nm, long wavelength 1310nm and 1550nm. fiber loss is generally decreases with wavelength lengthening, 850nm loss is 2.5dB/km, multimode fiber working at this wavelength, the loss is too large. 1310nm loss is 0.35dB/km, 1550nm loss is 0.20dB/km, single-mode fiber working wavelength, but also the lowest loss of the fiber. Therefore, combining various factors, the transmission distance of single-mode fiber is better than that of multimode fiber.

Application of single – mode and multi – mode fiber

Single-mode fiber can make the fiber directly to the center, generally used for long-distance data transmission;Multimode fiber is often used for short distance data transmission because the optical signal propagates through multiple paths.

Single-mode optical module is often used in MAN with long distance and relatively high transmission rate.Multimode optical modules are used for short distance transmission.

Selection of single-mode and multimode fibers

In addition to fiber core number, fiber type and transmission distance, the selection of optical fiber also needs to be based on the use of optical fiber scene and fiber structure and outer sheath.

1. When outdoor optical fiber and cable are directly buried, it is appropriate to choose loose armored optical cable.When overhead, loose cable with black PE outer sheath with two or more reinforcing bars can be selected.

2, the building used in the selection of optical cable should be used in the tight set of optical fiber cable and pay attention to its flame retardant, toxic and smoke characteristics.Generally in the pipeline or forced ventilation can choose flame retardant but smoke type (PLENUM) or combustible non-toxic type (LSZH), exposed environment should choose flame retardant, non-toxic and smokeless type (RISER).

3, the building vertical or horizontal cable distribution, and the building can be used in the general tightly set of fiber optic cable, wiring fiber optic cable or branch fiber optic cable.

4. Select single-mode fiber and multi-mode fiber according to network application and fiber application parameters. Usually, indoor and short-distance applications are dominated by multi-mode fiber, while outdoor and long-distance applications are dominated by single-mode fiber

Based on the above analysis, have you learned how to choose between single-mode fiber and multi-mode fiber?

Shenzhen ADTEK Technology Co., Ltd. is a high-tech enterprise and a leading OEM manufacturer and exporter of fiber optic communication devices, with products covering fiber optic patch cords, MPO patch cords, WDM wavelength division multiplexers, fiber optic patch panels, AOC patch cords, etc. …. Through continuous innovation and development, Edeltek has strong technical strength and powerful productivity to ensure the reliability and stability of each product and provide excellent products for our customers.


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