Advantages of fiber optics

The interest of this method of transmission through optical fiber, a priori exotic, are numerous:
signal loss over long distances much smaller than in an electric conductor in a metal
transmission speeds very high,
low weight per meter (this is important, both to reduce the weight exerted the complex installations in buildings to reduce the traction of long cables at their ends),
insensitivity to external interference (near a neon or a high-voltage cable, for example)
no heating (high frequency copper boiler, it must be cool to get high data rates).
A case of mode
Optical mode is the number of paths (for simplicity).
In a multimode fiber, light can take many paths (see diagram). In a fiber, it is trapped in a direct way. It retains speed and consistency. The fiber is a fiber better than multimode fiber, but requires the use of light sources (laser) very powerful.




Multimode fiber

Multimode fiber, or MMF (MultiMode Fiber) is mainly used in local area networks (a few hundred meters). Its diameter is relatively large (50 to 85 microns). It uses an LED to generate the signal.
The establishment of this type of transmission poses few problems and does not require expensive equipment or complex to implement.
We distinguish fibers low or step index (flow rate limited to 50 Mb / s) and fiber graded index (flow rate limited to 1 Gb / s).
See the file "Fiber optic local area network."
Singlemode optical fiber
The fiber or SMF (Single Mode Fiber) is used for metropolitan networks or long-distance operators. His heart is extremely thin (a few microns). The data transmission is ensured by lasers emitting wavelengths from 1300 to 1550 nanometers and optical amplifiers at regular intervals.
We can distinguish several categories of more efficient, both in speed that distance:
• G.652 - fiber dispersion shifted not the most common. It enables transmission to 2.5 Gbps maximum.
• G.653 - dispersion shifted fiber: for submarine cables.
• G.655 - fiber to non-zero dispersion (NZDF: Non Zero Dispersion Fiber): designed for applications such as WDM (Wavelength Division Multiplexing) amplified (see below).
• G.692 - more recent, it is compatible with DWDM multiplexing. It helps to support the high speeds over distances of 600 to 2000 km (submarine cables).
It should be noted that over the distance is, the less the flow may be high.