The bandwidth with much fiber-optic model

From;  Author:Stand originally
The parameter of a lot of cable products is at present medium, often fiber-optic bandwidth this one noun, and use MHz.km is an unit. Theoretic, the bandwidth of cable can accomplish infinity, why fiber-optic bandwidth says even? Is the unit common MHz however the product of MHz and length Km?

Fiber-optic the carrier that transmits as a kind, the advantage that its itself has tall bandwidth, low weight, Sunday run but fiber-optic main material is 2 oxidation silicon, with common glass it is same kind of material, compare with vacuum photograph, the transmission method with different wavelengh, different course, the affirmation when arriving at sink can have time to differ, the influence that this time difference brings is chromatic dispersion, the rainbow after rain also is same argument. Much model is fiber-optic with Chan Moguang fine photograph is compared, have thicker fine core diameter, the transmission way that means smooth signal is more, brought result is serious mode chromatic dispersion, the smooth emitter smooth wavelengh with much fiber-optic model is wider, chromatic dispersion is more serious, transmission distance is accordingly closer. The fine core diameter with single fiber-optic standard is lesser, the transmission way of smooth signal is very few, mode chromatic dispersion is lesser, the smooth purity of laser emitter is taller, transmission distance is accordingly further. The transmission distance that considers much model cable and smooth emitter, insert receive a low cost factor that waits for fiber-optic accessory, in intelligent architectural indoor in applying outdoor with stone's throw, much model cable holds very large proportion.

Illuminant place gives ejaculation energy coupling to enter the process with much fiber-optic model to be become smooth infuse means. Have commonly full infuse and be restricted modular infuse two kinds of means. Become full infuse is when use LED illuminant, namely illuminant goes out shooting facula size and the fine core size with many fiber-optic model match, at this moment pulse is in fiber-optic inside the conduction with much fiber-optic model will be aroused completely when transmitting mode, energy is centered at intermediate mode group, high-ranking mode group and low rank mode group the impact is very little. And be restricted when modular infuse, because incident facula covered partial fine core only, when its are conducted, just also aroused a part to conduct pattern group. It is when incident facula when the different position of fine core, arouses mode group different also, the difference that causes the chromatic dispersion between the model and make transmit fiber-optic bandwidth performance change. Because this loves to amount to dispatch wiring engineer to think to be in,be restricted when modular infuse, must define incident position and point of view, otherwise the transmission distance of fiber-optic support will produce change.

Radial bandwidth is the product of the modulation frequency of the pulse of frequency of the biggest modulation that one Duan Guang fine can pass and fiber-optic length, it is much model of a token the integrated index with fiber-optic characteristic optics, for instance the smooth emitter of common cable is LED commonly (glow diode) , requirement cable is in the should achieve 200MHz at least bandwidth of 850nm, the smooth emitter of OM3 cable is VCSEL (perpendicular antrum face launchs laser) , requirement cable should achieve 2000MHz when 850nm. Get the influence of a lot of element, be like illuminant, coupling means, wave guide structure, and the influencing factor with the other bypass such as receiver function, to fiber-optic itself character, the itself element that decides its bandwidth is the chromatic dispersion character with much fiber-optic model. Consider optical transmission track is very few inside Chan Moguang fine, the chromatic dispersion between the model is lesser, negligible even not plan, to it the laser chromatic dispersion of suitable LD smooth emitter is lesser, accordingly fiber-optic bandwidth is restricted to be much model only at present fiber-optic, the transmission bandwidth with single fiber-optic standard is understandable be is infinite, but its itself accepts a demand to inserting tall, because this is odd,modular cable serves as the choice of the communication of Sunday run commonly. (1000 nets)
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