A new generation of multimode fiber type

A new generation of multimode fiber Is a new generation of multimode fiber 50/125μm, graded-index multimode fiber distribution. 50μm core diameter is used because the number of optical fiber transmission mode is about 62.5μm multimode fiber transmission mode of 1/2.5. This can effectively reduce the multi-mode fiber mode dispersion and increase bandwidth. Of 850nm wavelength, 50/125μm multimode fiber bandwidth than 62.5/125μm increase three times (500MHz.km than 160MHz.km). Standards recommended by IEEE802.3z at 1Gbit / s rate, 62.5μm core diameter multimode fiber can transmit 270 meters; and 50μm core diameter multimode fiber can transmit 550 meters. In fact recent experiments confirmed: use of 850nm vertical-cavity surface-emitting laser (VCSEL) light source, the 1Gbit / s rate, 50μm core diameter multimode fiber standard can be error-free transmission 1750 m (lines with 5 of the connector), 50μm core diameter multimode fiber to a new generation of error-free transmission 2000 m (line contains two pairs of connectors). At 10Gbit / s under, 50μm core diameter multimode fiber can transmit a new generation of 600 meters and has 200/500MHz.km over into full-bandwidth standard 62.5μm core diameter multimode fiber can transmit 35 meters.

Using 50μm core diameter is another reason the past people saw 62.5μm core diameter multimode fiber benefits, with the advances in technology have become irrelevant. In the middle period of the eighties, LED light source output power is low, a large divergence angle, connector loss, using a large core diameter and numerical aperture of optical fiber in order to make more power into that must be considered. At that time, no one seems to think the LAN rate may exceed 100Mbit / s, that is, the bandwidth performance of multimode fiber is not prominent. Now that the LED output power and divergence angle of the improvements, the connector performance improvements, particularly the use of a VCSEL, optical power injected is not a problem. Core diameter and numerical aperture is no longer so important as before, and 10Gbit / s transmission rate became the principal contradiction, can provide higher bandwidth 50μm core diameter multimode fiber is acclaimed.