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What is the difference between single-mode fiber and multi-mode fiber?

2021-08-09
Optical fiber is a communication line that uses optical signal transmission. In general use, a certain number of optical fibers are combined into optical cables in a certain way for use in engineering. The core of an optical fiber is very thin, a glass filament about the thickness of a human hair.

The advantage of optical fiber is that it transmits signals through light guide, it is not conductive, and it is not afraid of lightning strikes, so it does not need to use grounding protection.

According to the transmission mode of light in the optical fiber, we can divide it into multi-mode optical fiber and single-mode optical fiber. For our users, you only need to remember the origin of the multi-mode and single-mode names.

Multimode fiber: It can transmit multiple modes of light.

Single-mode fiber: Only one mode of light can be transmitted. The middle core wire of multimode fiber is thicker, and the middle core wire of single mode fiber is thinner, but the two are relatively speaking, the multimode fiber is 50 microns, and the single mode fiber is 10 microns. If you forget the unit conversion of micrometers, 1 millimeter = 1000 micrometers. The transmission distance of multimode fiber is relatively short, generally only a few kilometers. The transmission distance of single-mode fiber is much longer, and it can usually reach several tens of times that of multi-mode fiber. Single-mode fiber is generally more expensive than multi-mode fiber. The color of the outer sheath of the single-mode fiber is generally yellow. The outer color of multimode fiber is generally orange-red.


The advantages of using optical fiber also include:

1. When the transmission distance of the information point is greater than 100m, if you choose to use copper cable. It is necessary to add repeaters or increase network equipment and weak current rooms, thereby increasing costs and potential failures. The use of optical fibers can easily solve this problem.

2. There are a large number of electromagnetic interference sources in specific working environments (such as factories, hospitals, air-conditioning rooms, electric computer rooms, etc.). Optical fibers can be free from electromagnetic interference and operate stably in these environments.

3. There is no electromagnetic leakage in the optical fiber, and it is very difficult to detect the signal transmitted in the optical fiber. It is a good choice in places with high confidentiality requirements (such as military, research and development, auditing, government and other industries).

4. In environments with high bandwidth requirements, up to 1G or more, optical fiber is a good choice.

In the actual application process, single-mode fiber is used if the distance is far away; multi-mode fiber can be used if the distance is short. In addition, fiber optic transceivers are required for fiber transmission, single-mode fiber uses single-mode transceiver, and multi-mode fiber uses corresponding The price of single-mode fiber transceivers is higher than that of multi-mode transceivers.