CommScope® Enterprise Data Center Design Guide - Public ...

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TABLE 9: TIA 568C LOMMF AND ISO’S OM PERFORMANCE STANDARDS
Fiber Type or Name
(ISO OM designation)
Loose Tube Fiber Optic Cable Construction
Fiber cable starts with optical fiber. Optical fiber consists of a germanium doped silica core
within a concentric layer of silica cladding that is 125 µm in diameter. The core and cladding
are covered by two or three concentric layers of acrylate coatings which provide physical
protection. The outer acrylate layer is typically colored for identification. The coated fiber
diameter is approximately 250 µm.
Figure 18: Optical Fiber Cross Section
Optical fiber
cross section
Core
Cladding
Acrylate coatings
Bandwidth (MHz•km)
850/1300 nm 1 Gb/s Range 10 Gb/s Range
OM4 50 μm 4700*/500 1100 m 550 m
OM3 50 μm 2000*/500 1000 m 300 m
OM2+ 50 μm 950*/500 800 m 150 m
OM2 50 μm 500/500 600 m 82 m
OM1 62.5 μm 200/500 300 m 33 m
OS2 8.3 μm Single-mode NA 40 km** 40 km**
* OFL bandwidth
** using 1310 & 1550 nm lasers
Loose tube construction places several fibers in a small-diameter plastic buffer tube. Multiple buffer
tubes can be cabled together around a central strength member for higher fiber-count cables.
High-strength yarn is placed over the buffer tubes, and a jacket is applied. A variant of loose tube
design is called central tube that uses a single large diameter tube to contain all the fibers.
Loose tube designs have lower attenuation than tight buffered cables and are used for longer
distance single-mode cables. Loose tube cables offer optimum performance in campus subsystems.
Loose tube design also helps fiber performance in areas with extremes of temperature.
Indoor/outdoor cables
Indoor/outdoor cables are NEC listed (and sometimes LSZH) cables that meet environmental
requirements for outdoor usage. Indoor/outdoor cables can operate as underground or aerial
links between buildings without a transition to a listed indoor cable. They are protected against
moisture like outside plant cables.
Outside plant
Outside plant cables are designed specifically for outdoor usage. They do not carry NEC
listings and are not intended for indoor use except when placed in rigid or intermediate metal
conduit (check local codes). Outdoor plant cables come in specialized constructions (armored,
multiple jackets, special chemical-resistant jacket compounds) to help them withstand severe
environments such as heat/cold, sunlight, petrochemical exposure and rodent attack.
Moisture ingress is addressed with either a water-blocking material in the buffer tubes, or with
water-swellable tapes and binding threads that incorporate super-absorbent polymers (SAPs). These
cables are intended for single-pass installation, whereas other aerial cables first require installation
of a supporting messenger wire and subsequent overlashed installation of the fiber optic cable.