Optical Fiber Cables – Construction and Application

Optical Fiber Cables – Construction and Application

Fiber Cables

Glass fiber is coated with a protective plastic covering called the “primary buffer coating” that protects it from moisture and other damage. More protection is provided by the “cable” which has the fibers and strength members inside an outer protective covering called a “jacket”. Most indoor fiber optic cables are tight-buffer design, usually, they consist of the following components:

  • Tight buffer optical fiber
  • Kevlar which is used to further strengthen the cable structure, making it resist high tension
  • FRP which is non-metallic strengthen member
  • Cable outer jacket

simplex fiber optic cable structure

So, based on these basic components, indoor fiber cables are available with following standard structures:

  • 900um Buffer cable

Tight Buffered Fiber features a secondary layer of coating applied directly to their initial 250mm layer(bare fiber). The second layer acts as reinforcement to the individual fibers and makes them easier to handle and terminate. Tight buffer fibers are indoor used or outdoor used in fiber enclosures.

  • Simplex fiber cable

Simplex Fiber Cable is a cable contains a single tight buffer fiber inside and is used in applications that only require one-way data transmission. Simplex fibers are available in single-modemultimode, laser-optimized 10 Gigabit OM3, OM4 types.

  • Duplex Fiber Cable

Duplex Fiber Cable consists of two separate Tight buffer fibers. Duplex fiber cables are formatted in the ‘zipcord’ styling, where each fiber has independent coatings that are linked together with a thin layer of coating material. This design can allow for a duplex cable to be pulled apart and used as two simplex cables.  Duplex is most used where require simultaneous, bi-directional data transmission, i.e. one fiber transmits in one direction while the other fiber transmits in the opposite direction.

  • Distribution fiber trunk Cable

multi core/strand fiber optic trunk cable OM3Distribution Fiber Cable usually bundles 2 to 24 fibers(tight buffered) into one cable jacket with only a single aramid strength member around all the fibers. For cable with 24 fiber or more, the tight buffer fibers will be bundled into subunits of 6 fibers, 8 fibers or 12 fibers, and each subunit with its own aramid yarns, then the subunits were bundled into total 24, 36, 48, 72, 96 or 144 fibers with taps and outer jacket.  Distribution cables are popular indoor use cables in backbone cabling in dater centers, FTTH and are available plenum and riser rated.

  • Breakout Fiber Cablebreakout fiber optic cable, single mode, multimode OM1 OM2 OM3 OM4

Breakout Cables contains individual fiber with its own aramid strength aramid yarns and jacket. Beyond this, breakouts are known for their rugged and tough design, considerable crush resistance, and tensile strength. Because each fiber is reinforced, breakout cables allow users to “breakout” inner fibers directly at any point along the run and continue to route the remainder to another point.

  • Ribbon Fiber Cable

ribbon indoor fiber optic cable 12 cores single modeTo meet different installation environment, the cable jackets will be flame retardant and built with LSZH, riser(OFNR) or Plenum(OFNP) rated PVC materials.

Indoor Optical Fiber Cables are mainly used in building wiring applications. Act as patch cables, they could be installed in network racks, cabinet, patch panels, and other fiber enclosures. As backbone fiber cables, they could be installed in walls, between floors, in plenum air handling ducts, and under data center floors.


Fibers – Single-mode or Multimode? 50/125 or 62.5/125?

For identification purposes, multimode fiber, and also single-mode fiber, is often referred to by its performance level identified by ISO/IEC (International Organization of Standards and International Electrotechnical Committee), which is based on the fibers bandwidth capabilities.

 Fiber Types and Typical Specifications
(OM/OS refers to TIA types, B refers to IEC types, G refers to ITU types)
 Core/Cladding AttenuationBandwidth Applications/Notes
Multimode Graded-Index
@850/1300 nm
 50/125 microns (OM2)3/1 dB/km500/500 MHz-kmLaser-rated for GbE LANs
 50/125 microns (OM3)3/1 dB/km2000/500 MHz-kmOptimized for 850 nm VCSELs
 50/125 microns (OM4)3/1 dB/km3600/500 MHz-kmOptimized for 850 nm VCSELs, higher speed
 62.5/125 microns (OM1)3/1 dB/km160-200/500 MHz-kmLAN fiber
 100/140 microns3/1 dB/km150/300 MHz-kmObsolete
@1310/1550 nm
 9/125 microns (OS1 B1.1 or G.652) 0.4/0.25 dB/km HIGH! Singlemode fiber,  most common  for  Telco/CATV/high speed LANs
~100 Terahertz
 9/125 microns (OS2, B1.2 or G.652) 0.4/0.25 dB/km HIGH! Low water peak fiber
~100 Terahertz
 9/125 microns (B2 or G.653) 0.4/0.25 dB/km HIGH! Dispersion shifted fiber
~100 Terahertz
 9/125 microns (B1.2 or G.654) 0.4/0.25 dB/km HIGH! Cutoff shifted fiber
~100 Terahertz
 9/125 microns (B4 or G.654) 0.4/0.25 dB/km HIGH! Non-zero dispersion shifted fiber
~100 Terahertz
Multimode Step-Index
@850 nm
 200/240 microns 4-6 dB/km 50 MHz-km Slow LANs & links
POF (plastic optical fiber)
 @ 650 nm  @ 650 nm
 1 mm ~ 1 dB/m ~5 MHz-km Short Links & Cars
  • OM3 fiber is designed to accommodate 10 Gigabit Ethernet up to 300 meters, and OM4 can accommodate it up to 550 meters. Therefore, many users are now choosing OM3 and OM4 over the other glass types. In fact, nearly 80% of 50-micron fiber sold is OM3 or OM4.Single-mode 9/125 fiber is refered to as OS1 or OS2, now commonly used is OS2 type.
  • Multimode 62.5/125 fiber is referred to as OM1.
  • Multimode 50/125 fiber is referred to as OM2, OM3, and OM4. OM4 has greater bandwidth than OM3, and OM3 has greater bandwidth than OM2.

If you require higher data rates or plan on upgrading your network in the near future, laser optimized 50-micron (OM3 or OM4) would be the logical choice.

Fibers And Cables

Leave a Reply

error: Content is protected !!