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Question:

What are the principles and functions of optical fiber cables?

What are the principles and functions of optical fiber cables?

Answer:

Cable fibre (optical) is a communication cable consisting of two or more glass or plastic fiber cores, which are located in protective coatings and covered by plastic PVC outer sleeves. Signal transmission along an internal optical fiber generally uses infrared light.
Compared with radio communication, optical fiber communication can provide more communication channels and meet the needs of large capacity communication systems. Optical fiber generally consists of two layers, the inner layer is called the inner core, the diameter is tens of microns, but the refractive index is higher. The outside layer is called the cladding, and the refractive index is low. The light incident at one end of the optical fiber is transmitted to the end by repeated refraction of the inner core, and the light entering the inner core is always transmitted in the inner core due to the difference in the refractive index of the two layers. The transmission distance of light is related to the optical loss of optical fiber. The optical loss is small and the transmission distance is long. Otherwise, the attenuation signal should be amplified by repeaters. Optical fibers made from the latest fluoro glass can transmit light signals to the Pacific Ocean without any relay stations. In actual use, thousands of optical fibers are often combined and reinforced to form optical cables like imaging cables, which improves the strength of the optical fiber and greatly increases the communication capacity.
Fiber transmission is based on the principle that total reflection occurs at two dielectric interfaces based on available light. The mutant fiber, N1 fiber core refractive medium refractive index cladding rate, N2 medium rate, N1 is greater than N2, into the core of the light reaching the core and cladding interface (the core packet interface) when the incident angle is greater than the critical angle of total reflection C, total reflection can occur no light energy through the core, the incident light can be through countless times of total reflection at the interface of forward transmission. It turns out that when the fiber bends, the normal interface turns and the angle of incidence is small, so the incident angle of a part of the light becomes less than theta C instead of total reflection. But the light of the incident angle is still total reflection, so the fiber bending time can still be transmitted, but it will cause energy loss. Generally, when the bending radius is greater than 50~100 mm, the loss is negligible. Slight bending will cause severe "slight bending loss"".

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