When optical fiber is needed to monitor integrated wiring, at least we should understand what optical fiber is and how to distinguish between single-mode and multi-mode. We try to use popular text in this article to make it clear to novices. In fact, every professional book contains the knowledge of fiber optics, but it seems that there are not many that can be remembered after reading it, because it is still too professional and uncommon for most non-professional people.
Take a section to explain the single-mode fiber and show it to everyone: "When the geometrical size of the fiber is mainly that the core diameter can be close to the wavelength of the light, such as the core diameter D1 in the range of 5-10 µm, the fiber only allows the fundamental mode HE11 to propagate in it. , The remaining high-order modes are all cut off. Such fibers are called single-mode fibers."
Optical fiber is a communication line that uses optical signal transmission. For the first time, Kao Kun, former president of the Chinese University of Hong Kong, and a foreign scientist who does not remember his name proposed that optical fibers can be used to transmit communications. For this reason, Kao Kun won the 2009 Nobel Prize in Physics.
In normal 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, is not conductive, and is not afraid of lightning strikes, so it does not need to be grounded.
According to the transmission mode of light in the optical fiber, we divide it into multi-mode optical fiber and single-mode optical fiber. For our users, just 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 the multimode fiber is thicker, and the middle core wire of the 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 microns, 1 millimeter = 1000 microns. The transmission distance of multimode fiber is relatively short, generally only a few kilometers. The transmission distance of single-mode fiber is much longer, usually 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, above 1G, optical fiber is a good choice.
In the actual application process, if the distance is far, single-mode fiber can be used; if the distance is short, multi-mode fiber can be used. In addition, fiber optic transceivers are required for fiber transmission. Single-mode fiber uses single-mode transceivers, and multi-mode fiber uses corresponding multimode fibers. Mode transceivers, single-mode fiber transceivers are more expensive than multi-mode transceivers.
