| 摘要 |
A multimode fiber lightwave communication system using pulses of center wavelength in the region of anomalous dispersion of the fiber material. For instance, in silica-based fiber, this implies a wavelength greater than about 1.3 mu m. In such a system, modal dispersion can be reduced by using the nonlinear properties of the fiber material. In particular, by adjusting the pulse amplitude to satisfy the expression <IMAGE> where vgj is the group velocity of the j-th mode, vo is the group velocity of the pulse, fo is the center frequency of the pulse, no is the field-independent effective refractive index of the fiber at fo, n2 is the quadratic coefficient of the refractive index of the fiber at fo, ¦ phi ¦ is the absolute magnitude of the peak electric field in the pulse averaged over the cross-section of the guiding region, and alpha is a constant approximately equal to 1/2, all modes whose group velocity satisfy the expression are "trapped", i.e., are prevented from spreading. The reduced mode dispersion permits e.g., operation of lightwave communication systems at increased data rates.
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