Basic knowledge of fiber optic cable cabling and system design. As a high-bandwidth, high-security data transmission medium, optical fiber is widely used in various large and medium-sized networks.
Due to the high cost of cables and equipment, optical fibers are mostly only used in network backbones, that is, system cabling used in vertical backbone subsystems and building group subsystems to realize connections between buildings and floors. , is currently also used in horizontal cabling subsystems that have higher requirements for transmission rate and security.
The wavelength range of visible light is: 390~760nm (nanometer).
The part greater than 760nm is infrared light, and the part less than 390nm is ultraviolet light.
There are three types of optical fibers used: 850, 1300, and 1550.
Because the propagation speed of light in different materials is different, so When light passes from one substance to another, it is refracted and reflected at the interface between the two substances.Moreover, the angle of refracted light changes with the angle of incident light.
When the angle of the incident light reaches or exceeds a certain angle, the refracted light will disappear and all the incident light will be reflected back. This is the total reflection of light.
Different substances have different refractive angles for light of the same wavelength (that is, different substances have different refractive indexes), and the same substance also has different refractive angles for light of different wavelengths.
Optical fiber communication is based on the above principles.
Bare optical fibers are generally divided into three layers: a central high-refractive index glass core (the core diameter is generally 50 or 62.5 μm), a middle low-refractive index silica glass cladding (the diameter is generally 125 μm), and an outer It is a reinforced resin coating.
