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Do You Know This Basic Knowledge Of Optical Fiber?

Views: 0     Author: Site Editor     Publish Time: 2022-11-29      Origin: Site

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According to the transmission mode of light in the fiber: single-mode fiber and multi-mode fiber

The core diameter of the multimode fiber is 50-62.5 μm, the outer diameter of the cladding is 125 μm, the core diameter of the single-mode fiber is directly 9 μm, the outer diameter of the cladding is 125 μm, and the working wavelength of the optical fiber is a short wavelength, 0.85 μm, long Wavelengths 1.31 μm and 1.55 μm. The fiber loss generally decreases with the wavelength. The loss of 0.85 μm is 2.5dB/km, the loss of 1.31 μm is 0.35dB/km, and the loss of 1.55 μm is 0.20dB/km, which is the lowest loss of optical fiber.

Multimode fiber

Multimode fiber: The central glass core is thicker (50 or 62.5 μm), and can transmit light in multiple modes, but its inter-mode color is large, which limits the frequency of transmitting digital signals, and it will become more serious with the increase of distance. For example, 600MB/KM fiber has only 300MB bandwidth at 2KM, so the transmission distance of multimode fiber is relatively short, generally only a few kilometers.

Single-mode fiber:

Single-mode fiber: The central glass core is very thin (the core diameter is generally 9 to 10 μm), and only one mode of light can be transmitted. Therefore, its intermodal dispersion is very small, which is suitable for long-distance communication, but there are also material dispersion and waveguide dispersion, so single-mode fiber has higher requirements on the spectral width and stability of the light source. Be good. It was later found that at the wavelength of 1.31 μm, the material dispersion and the waveguide dispersion of the single-mode fiber are positive and negative, and the magnitudes are exactly the same. This means that at a wavelength of 1.31 μm, the total dispersion of a single-mode fiber is zero. From the loss characteristics of the fiber, 1.31 μm is just a low-loss window of the fiber. In this way, the 1.31 μm wavelength region has become an ideal working window for optical fiber communication, and it is also a low-loss window for practical optical fibers. The main parameters of 1.31 μm conventional single-mode fiber are determined by the International Telecommunication Union TTU-T in the G652 recommendation, so this fiber is also called G652 fiber.


Core Nominal Diameter

Transmission distance

Jumper Color


8/125 μm  or 9/125 μm  or 10/125 μm

Long distances, up to hundreds of kilometers

Generally yellow, the connector box protective cover is blue


50/125 μm  European standard

Short distance, generally within 2KM

Generally orange, some use gray, and the connector box protective sleeve is beige or black



1. Do not bend and loop the optical fiber excessively during use, which will increase the attenuation of light during transmission and break the pigtail at the tip of the nose.

2. After using the optical fiber jumper, be sure to protect the optical fiber connector with a protective sleeve, the return trip, and oil pollution will lose the coupling of the optical fiber.

3. The transceiver wavelengths of the optical modules at both ends of the fiber jumper must be the same, that is to say, the two ends of the optical fiber must be optical modules with the same wavelength. The simple way to distinguish is that the colors of the optical modules should be the same.

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