A singlemode optical fiber designed to reduce chromatic dispersion. The fiber core is fabricated in several layers with different refractive indices running in parallel throughout its length.
Nonzero vs. Zero Dispersion
Nonzero-dispersion-shifted fiber is designed for wavelength division multiplexing (WDM). It has no dispersion near 1500 nm and beyond 1600 nm, which provides lower dispersion in the 1550 nm range. In contrast, zero-dispersion-shifted fiber has zero chromatic dispersion at 1550 nm but causes interference in WDM transmission and is no longer made. See
graded-index fiber,
step index fiber and
dispersion.