As is known to all, silica fiber with its attenuation is small, the advantages of wide frequency band, but because of the required purity of raw materials, manufacturing process of complex, expensive, in place of difficulties, to a large number of used for short distance access of optical transmission medium is not cost-effective. The plastic fiber (POF) was born to reduce the cost of optical fiber to connect the clients in the network. The following sections describe the structure and advantages and disadvantages of the plastic optical fiber POF.
The structure and type of plastic optical fiber POF
The plastic fiber is composed of a low refraction fiber core and a lower refractive index. Requirements to make use of plastic optical fiber material has good pervious to light, the refractive index of a uniform optical properties, suitable and easy to adjust, convenient processing, chemistry, physics, stable performance, price cheap, etc. The materials used for plastic fiber core are: polymethyl methacrylate, polystyrene polycarbonate, fluorinated polymethacrylate and perfluororesin.
The distribution of the refractive index of plastic fiber can be divided into two categories: the step type plastic optical fiber (SI - POF) and the graded plastic fiber (GI - POF).
Advantages and disadvantages of POF
POF plastic optical fiber POF is a transmission medium with low development cost, good light transmittance, light quality, soft and easy to install.
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Compared with copper cable, the advantages of plastic fiber are:
(1) the bandwidth is large: within the range of l00m ~ 1000m, the bandwidth can be up to several GHz.
(2) anti-electromagnetic interference; The POF is not sensitive to electromagnetic interference, nor does it occur. The attenuation of different data rates is constant, and the error rate can be predicted, which can be used in the electric noise environment.
(3) low price: cost of POF is symmetrical cable and the cost of POF and its accessories and plastic optical fibers are down, and the copper cost reduce to a great extent by the copper, drop space is limited
Compared with quartz fiber, the advantages of plastic fiber are:
(1) the plastic optical fiber core diameter thick, large numerical aperture NA: big core diameter (0.3 ~ 1.0 mm), in the place can use simple POF connector, even in the center alignment of optical fiber producing (including 30 m deviation will not affect the coupling loss; Large numerical aperture (0.3 ~ 0.5 mm), by light Angle can reach 60 °, can use cheap LED, and high coupling efficiency.
(2) flexural good, easy to process and use, small bending radius.
(3) the separation is simple and easy to operate: it can be connected directly by the injection molding connector.
Of course, there are some disadvantages to plastic optical fiber, mainly including:
(1) attenuation: the typical attenuation coefficient of POF at the wavelength of 850nm is approximately 100 ~ 200 dB/km, compared with the typical attenuation coefficient of G.652 fiber at 1.31. 35 dB/km, there is a big gap.
(2) narrow band: PMMA GT - POF even in the case of the optimal refractive index profile, the bandwidth at 650nm wavelength is only 3GHz 100m.
(3) poor heat resistance: the plastic optical fiber POF only at work - 40 ~ 85 ° C, is a bit poor heat resistance.