revision to a commonly used ITU-T Recommendation will extend use of fibre
previously used mainly in core networks to metropolitan or regional networks.
Crucially it also has the potential to greatly reduce operating costs for
for non-zero dispersion-shifted fibre (NZDSF) was originally designed to
support DWDM long distance core, it was designed to reduce a phenomenon called
four wave mixing (an interaction between wavelengths that generates additional
optical channels). The impressive improvement in dispersion profiles afforded
by G.655 fibre together with the development of the G.692 standard for optical
interfaces for multichannel systems with optical amplifiers led to an explosion
in the market for DWDM systems experts say.
dispersion allows sending signals over greater distances without dispersion
compensation, meaning that operators will be able to avoid using a compensator
and amplifier as well as the costs associated with this; power, protection,
housing and security.
revision to G.655 (full title, Characteristics of a non-zero dispersion-shifted
single-mode optical fibre and cable) deals with chromatic dispersion, a
phenomenon which at low levels counteracts distortion, but at high-levels can
make a signal unusable. The management of chromatic dispersion is crucial as
the number of wavelengths used in WDM systems increases. ITU has a history of
providing the specifications that allow operators to most efficiently handle
this. The revision allows more efficient use of the properties of chromatic
dispersion by more stringently defining its existence. It defines chromatic
dispersion in two new categories that can be exploited by systems designers as
need for the work stemmed from systems' designers want to better understand
dispersion. And a result is that experts saw a use for G.655 cable in metro or
regional networks where it had previously only been used in core networks.