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Analysis: How to choose single mode fiber and multimode fiber correctly
release time:2021-04-29
Author: Lu Bai

With the rapid development of information network, people's requirements for data transmission are more and more high, and optical fiber with its transmission speed, long distance, security and stability, anti-interference, convenient expansion and other advantages become more and more people's first choice in cabling construction.As we all know, fiber is widely used in the integrated cabling scene. Many people will encounter the choice of single-mode fiber and multi-mode fiber. Today, we will understand the choice of single-mode fiber and multi-mode fiber together.

Classification of optical fibers

Optical fiber can be divided into single mode and multi-mode according to the transmission mode of light in it.

Multi-mode fiber: When the geometrical size of the fiber (mainly the core diameter D1) is much larger than the wavelength of the light wave (about 1μm), there will be dozens or even hundreds of propagation modes in the fiber.Different propagation modes have different propagation velocities and phases, resulting in time delay and broadening of optical pulses after long-distance transmission.This phenomenon is called mode dispersion of optical fibers.Mode dispersion can narrow the bandwidth of multimode fiber and reduce its transmission capacity. Therefore, multimode fiber is only suitable for communication of fiber with small capacity. The core diameter of multimode fiber is 50 or 62.5μm, and the outer diameter of cladding is 125μm, which is expressed as 50/125μm or 62.5/125μm.

Single mode fiber:When the geometrical size (mainly core diameter) of the fiber can be close to the wavelength, such as the core diameter D1 in the range of 5 ~ 10μm, only one mode (fundamental mode HE11) is allowed to propagate in the fiber, and the other high order modes are all cut off, such fiber is called single-mode fiber. The core diameter of single-mode fiber is 8.3μm, and the outer diameter of the cladding is 125μm.Represented as 8.3/125 microns

The transmission distance between single-mode fiber and multimode fiber

Single-mode optical fiber: according to the core diameter and outer envelope diameter of the single-mode optical fiber mentioned above, and the working wavelength of the single-mode optical module is 1310nm and 1550nm.Compared with multimode fiber, single-mode fiber can support longer transmission distance, from 100Mbps Ethernet to 1G gigabit network, single-mode fiber can support more than 5000M transmission distance.

Multi-mode fiber: Compared with twisted pair, multi-mode fiber can support longer transmission distance;In 10Mbps and 100Mbps Ethernet, multimode fiber can support up to 2000 meters of transmission distance;In a 1Gbps gigabit network, the multimode fiber can support a transmission distance of up to 550 meters.In 10Gbps 10,000MB network, the multi-mode fiber OM3 can reach 300m and OM4 can reach 500m

The operating wavelengths of the fiber are 850nm for short wavelength, 1310nm for long wavelength and 1550nm for long wavelength.The optical fiber loss generally decreases with the lengthening of the wavelength. The loss of 850nm is 2.5dB/km, and the multi-mode optical fiber works at this wavelength, so the loss is too large.The loss at 1310nm is 0.35dB/km, and the loss at 1550nm is 0.20dB/km. The operating wavelength of single-mode fiber is also the lowest loss of fiber.Therefore, considering various factors, the transmission distance of single-mode fiber is better than that of multi-mode 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 fiber and multimode fiber

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 Aidetai Technology Co., Ltd. is a high-tech enterprise and a leading OEM manufacturer and exporter of optical fiber communication devices, including optical fiber jumpers, MPO jumpers, WDM wavelength division multiplexers, optical fiber distribution frame, AOC jumpers, etc.....Through continuous innovation and development, Aidetai has a strong technical strength and strong productivity, to ensure the reliability and stability of each product, to provide excellent products for our customers