NEW CABLOFIL® ACCESSORIES FOR
FIBER OPTIC INSTALLATIONS.
Poly accessories speed installation times and protects fiber
optic cables better. Cable exits, crossovers, corner shields,
flexible inserts and more, make for smooth transitions to protect
sensitive cable sheathings. Installation is easy – most parts just
snap in place. For more information on our products,
designed to be better.™
criterion. Specifically, OM1’s 850-nm
bandwidth is 200 MHz.km; OM2’s is 500;
OM3’s is 1,500.
The aforementioned bandwidth
performance levels are measured using what is known as the overfilled
launch (OFL) method. Another band-width-measurement method, called effective modal bandwidth (EMB), is a calculated measurement. EMB bandwidth
exists for OM3 fiber, but not for OM1
or OM2. OM3 fiber’s minimum EMB is
As a practical matter for user organizations, OM1 fiber can support
1000Base-SX—the 850-nm variant of
Gigabit Ethernet—to 275 meters. OM2
provides 550 meters of support. When
speeds go up to 10 Gbits/sec in the form
of 10GBase-SR, OM1 supports 33 meters,
OM2 supports 82 meters and OM3 supports 300 meters.
Notably, however, the ANSI/
TIA-568.3-D Optical Fiber Cabling
Components Standard was approved
and released for publication in February.
Table 1 in that standard no longer includes OM1 or OM2 fiber performance
grades. They have been moved to the
standard’s annex and are no longer recommended for use in fiber-optic installations. OM3 is now the minimum recommended performance grade.
That relegation to the standard’s annex is unlikely to prevent users from
continuing to purchase and use OM1
or OM2 fiber-optic cable. OM3 is back-ward-compatible with OM2 and could
be placed into an existing OM2 cabling
plant without sacrificing performance.
However, OM1 fiber, with its 62.5-mi-
cron core, cannot be combined with
a higher grade of multimode fiber because that higher grade’s 50-micron
core means high losses will be induced
when a signal crosses from the 62.5-mi-
cron to the 50-micron portion of the
To some extent the technological development that led to OM3’s development
repeated itself and resulted in the introduction of OM4 fiber. After OM3 fiber was established and its guaranteed
10GBase-SR distance was specified, fi-
ber manufacturers developed better-per-
forming fibers with higher bandwidth,
better loss performance, and therefore
the ability to support longer-distance
10G. With OM3 being the highest-per-forming standardized multimode fiber,
vendors, users and others in the industry frequently used the term “OM3+” to
refer to fibers with bandwidth and performance levels that exceed those specified for OM3.