When many friends are wiring, some friends may have little knowledge about optical fiber, so today ZR Cable has a detailed understanding of optical fiber through this article.
1. Multimode fiber
When the geometric size of the fiber is much larger than the wavelength of the light wave, 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 widening of optical pulses after long-distance transmission. This phenomenon is called modal dispersion of the fiber.
Modal dispersion will narrow the bandwidth of multimode fiber and reduce its transmission capacity, so multimode fiber is only suitable for small-capacity fiber communication.
2. Single-mode fiber
When the geometric size of the fiber can be similar to the wavelength of light, the fiber only allows one mode to propagate in it, and the rest of the higher-order modes are all cut off. Such a fiber is called a single-mode fiber.
Since it has only one mode of propagation, the problem of modal dispersion is avoided, so the single-mode fiber has a very wide bandwidth, which is especially suitable for large-capacity optical fiber communication.
3. What are the advantages of using optical fibers?
1) The passband of the optical fiber is very wide, and the theoretical value can reach 30T.
2) The length of support without repeater can reach dozens to hundreds of kilometers, and the copper wire is only a few hundred meters.
3) Unaffected by electromagnetic fields and electromagnetic radiation.
4) Light weight and small size.
5) Optical fiber communication is not electrified, and can be used in flammable and violent places for safe use.
6) Wide range of ambient temperature for use.
7) Long service life.
4. How to choose optical cable?
The selection of optical cables is not only based on the number of optical fibers and the type of optical fibers, but also the structure and outer sheath of the optical cable according to the use environment of the optical cable.
1. When the outdoor optical cable is directly buried, loose armored optical cable should be used. For overhead use, a loose-sheathed fiber optic cable with black PE outer sheath with two or more reinforcing ribs can be used.
2. When selecting the optical cable used in the building, the tight sleeve optical cable should be selected and attention should be paid to its flame retardant, toxic and smoke characteristics. Generally, the flame-retardant but smoke-free type (Plenum) or the flammable and non-toxic type (LSZH) can be used in the pipeline or forced ventilation, and the flame-retardant, non-toxic and smoke-free type (Riser) should be used in the exposed environment.
3. When cabling vertically or horizontally in the building, you can choose the tight-sleeve optical cable, distribution optical cable or branch optical cable that is common in the building.
4.Select single-mode and multi-mode optical cables according to network application and optical cable application parameters. Usually indoor and short-distance applications are dominated by multi-mode optical cables, and outdoor and long-distance applications are dominated by single-mode optical cables.
