Core diameter 50 or 62,5 micron. Lower cost of LED sources and lasers operation at 850nm and 1300nm.

• OM1 62.5/125um (up to 622Mbit / 10Gbit @33 meters) - obsolete
• OM2 50/125 um (up to 622Mbit / 10Gbit @82 meters) - popular
• OM3 50/125 um (850nm laser optimized up to 10Gbit/s / 10 Gbit @300 meters)
• OM4 50/125 um (850nm laser optimized up to 100Gbit/s / 10 Gbit @550 meters)

Wavelength 1310 or 1550 nm.

• OS1 ITU-T G.652A or ITU-T G.652B
  • Indoor (tight-buffered construction)
  • max att 1.0 db/km
  • max distance 1km
  • cheaper

• OS2
  • Outdoor (loose-tube design)
  • are only compliant with ITU-T G.652C or ITU-T G.652D standards.
  • which means OS2 is explicitly applied to the low-water-peak fibers. These low-water-peak fibers are usually used for CWDM (Coarse Wavelength Division Multiplexing) applications.
  • appropriate for outdoor cases like street, underground and burial
  • max att 0.4db/km.
  • max distance 10 km

• G.652D
  • full spectrum fibers (no high loss in 1360 – 1460 nm)
  • suitable for WDM

• 850 nm - I (MM)
• 1300 nm - II (MM)
• 1310 nm - II (SM)
• 1550 nm - III (SM)
• 1625 nm - IV

• Yellow - single mode
• White - for end user home installation - single mode
• Orange - multimode OM1/OM2
• Turquoise - multimode OM3
• Turquoise / Violet - multimode OM4

Square Connectors:

• ST - obsolete - looks like RF BNC connector. Push and rotate to lock.
• SC - bigger (more popular, older)
• LC - smaller, half size of SC (Lucent, less popular, license fees)
  • popular for SFP adapters as full fuplex pairs with plastic lock mechanism
• E2000

Fiber polishing:

• APC (Angled Physical Contact) - face of fiber is filed by 8 or 9 degree. Less attentuation. (-70dB)
  • Marking (plug) color: GREEN.
• UPC/PC (Ultra Physical Contact) - polished diagonally (-40dB).
  • Marking (plug) color BLUE or BEIGE.

End user:

• green rectangle plugs - FO SM SC/APC-SC/APC SIMPLEX

End user (Orange):

• green rectangle plugs and yellow cable - single mode, APC polishing