Nonzero dispersion shifted fiber
Encyclopedia
Non-zero dispersion-shifted fiber (NZDSF), specified in ITU-T G.655, is a type of single-mode optical fiber
which was designed to overcome the problems of dispersion-shifted fiber. NZDSF is available in two primary flavors: NZD+ and NZD-, which differ in their zero-dispersion wavelength
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
and other non-linear effects are minimized. Other types of NZDSF include RS-NZDSF 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.
Single-mode optical fiber
In fiber-optic communication, a single-mode optical fiber is an optical fiber designed to carry only a single ray of light . Modes are the possible solutions of the Helmholtz equation for waves, which is obtained by combining Maxwell's equations and the boundary conditions...
which was designed to overcome the problems of dispersion-shifted fiber. NZDSF is available in two primary flavors: NZD+ and NZD-, which differ in their zero-dispersion wavelength
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 naturally at a wavelength of approximately 1300nm...
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
Four-wave mixing is an intermodulation phenomenon in optical systems, whereby interactions between 3 wavelengths produce a 4th wavelength in the signal. It is similar to the third-order intercept point in electrical systems...
and other non-linear effects are minimized. Other types of NZDSF include RS-NZDSF 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.