Non-zero dispersion-shifted fiber (NZDSF), specified in ITU-T G.655, is a type of
single-mode optical fiber
In fiber-optic communication, a single-mode optical fiber (SMF), also known as fundamental- or mono-mode, is an optical fiber designed to carry only a single mode of light - the transverse mode. Modes are the possible solutions of the Helmholtz ...
which was designed to overcome the problems of
dispersion-shifted fiber Dispersion-shifted fiber (DSF) is a type of optical fiber made to optimize both low dispersion and low attenuation.
Dispersion Shifted Fiber is a type of single-mode optical fiber with a core-clad index profile tailored to shift the zero-dispersion ...
. NZDSF is available in two primary flavours: NZD+ and NZD-, which differ in their
zero-dispersion wavelength
In a single-mode optical fiber, the zero-dispersion wavelength is the wavelength or wavelengths at which material dispersion and waveguide dispersion cancel one another. In all silica-based optical fibers, minimum material dispersion occurs natural ...
s. These are typically around 1510 nm and 1580 nm, respectively. Because the zero-dispersion point of NZDSF is outside of the normal communications window,
four-wave mixing Four-wave mixing (FWM) is an intermodulation phenomenon in nonlinear optics, whereby interactions between two or three wavelengths produce two or one new wavelengths. It is similar to the third-order intercept point in electrical systems. Four-wave ...
and other non-linear effects are minimized. Other types of NZDSF include which has a reduced slope in its change of dispersion and large core NZDSF which further reduces residual non-linear distortion under high launch power.
Some long-haul fiber paths will alternate NZD+ and NZD- segments to provide self-dispersion compensation with uniformly low dispersion across the minimum-loss window at 1550 nm.
References
Optical fiber
{{Optics-stub