Statistical analysis of conditioned launch for Gigabit Ethernet links using multimode fiber

This paper reports, what is believed to be the first statistical analysis of restricted launch schemes. This is achieved by a detailed theoretical study of a large range of perturbed multimode optical fibers (MMF's) that are believed to be representative of those currently in use. It is shown that radial `offset' launches allow a robust and reliable solution to bandwidth collapse that occurs when standard laser sources are used with multimode fibers. Using such an approach, it is shown that gigabit per second link lengths using the offset launch technique can be increased to 550 m at an operating wavelength of 1300 nm using 62.5-μm diameter MMF. These link lengths are greater than those achievable with conventional techniques. The approach is also used to indicate the tolerance on alignment precision required for successful operation and to suggest a simple measurement for the assessment of link performance. Finally, the use of angled launching into MMF is shown to allow enhanced operating bandwidths.