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The Truth About OS1 and OS2 Optical Fiber

Several years ago, OS1 fiber optic cable was the only one standard for single-mode fiber with the maximum link length for campus cabling around 10km, but 10km can no longer satisfy people’s increasing needs nowadays. Therefore, OS2 fiber that can support much longer distance than 10km has been widely utilized in telecommunication industry. But there has been some debate and confusion as to the differences between OS1 and OS2 fiber types and what the terminology actually means. Thus, the following article is provided to assist the users in understanding the differences between OS1 and OS2 fiber types. The following image shows the LC to LC fiber patch cable single mode plugging in a switch.

single-mode-fiber

OS1 and OS2 Single-mode Fibers

Firstly, OS in the term OS1 and OS2 specifications refers to the Optical Single-mode fiber. Single-mode OS1 is indoor tight buffered fiber. An OS1 cable could be a micro-core LSZH indoor cable that consists of 250 micron fibers, with the fibers being tightly enclosed in a cable with aramid strengthening yarn and a LSZH jacket. The attenuation of a OS1 fiber is higher than an OS2 fiber. From the above table, the maximum attenuation allowed per km of installed cable is 1.0 dB for OS1 for 1310nm and 1550nm, while the maximum attenuation allowed per km of installed cable is 0.4 dB for OS2 for 1310nm and 1550nm.

os1-and-os2-maximum-attenuation

Single-mode OS2 is an outdoor loose tube optical fiber cable, which is suitable for outdoor applications where the cabling process applies no stress to the optical fibers. For instance, a 250 micron coated multi-fiber, which is loose inside an enclosure or tube and/or is free to move, is classified as OS2.

OS1 or OS2 performance cables are constructed from B1.3 optical fibers (or ITU specification G.652D). Furthermore, OS1 and OS2 cable types can also include cables manufactured from B6_A fiber, which is commonly known as bend insensitive single-mode optical fiber, or ITU specification G657A2 (compatible with B1.3 optical fiber). OS1 or OS2 single mode fiber performance, does not relate to ITU specification G.655 (Non-dispersion shifted single mode optical fibers.

Why Should We Use OS2 Over OS1 Fiber?

Single-mode fiber was mainly used for long-hual applications but not marked as a cost-effective investment for future application in building. One reason is that the single-mode related products like cables and optical transceivers are offered with high price. The other is that with the price decrease of the VCSEL or laser power source, the performance gap (namely link length) between multimode or single-mode fiber is smaller everyday.

Considering this, why not use the best single-mode fiber (OS2) to create better performance and ready for high speed data networks? Besides the difference in link distance, OS1 and OS2 fibers have different attenuation—OS2 has two times less losses than OS1 fibers.  And in CWDM or DWDM network, OS1 has poor result in the wavelength range called E-band or water peak band, which makes it not suitable for the WDM-based network.

cwdm-allocation-and-fiber-loss

Figure 3: CWDM wavelength allocation and fiber loss. The solid line represents OS2 fibers. The dotted line represents the water peak.

Another good news is that if you use OS2 fiber, it will be more suitable for you to support the IEEE 802.3 multiplexed series (40G BASE-LR4 and 100G BASE-ER4). You even don’t need to change your existing OS1 fibers, as the OS2 can be mixed with OS1 in the same link. What’s more, active or passive component for OS1 like connectors, adapters also works with OS2.

Conclusion

To sum up, OS1 optical fiber is appropriate for indoor and universal tight buffered cable constructions, which are mainly deployed in internal building/campus networks, as well as internal cabling within telecommunication exchanges and data centers. While OS2 optical fiber is appropriate for outdoor and universal loose tube solutions, which would include external plant and most back-haul networks. Therefore, when deciding which single-mode optical fiber type to specify, consider the application as well as how and where the cable will be installed. For further information on optical fiber products, please contact FS.COM. Our fiber optic cable price is the cheapest with great feedback.

Guide to Several Materials in Fiber Optic Cable Construction

Fiber optic cable is considered as one of the most effective transmission medium today for safe, and long-reach communications, and it also offers a number of advantages over copper. In general, fiber optic cable consists of a core, cladding, coating, strengthening fibers, and a cable jacket, which has been clearly introduced in the previous article. Today’s article will focus on the several materials in fiber optic cable construction, as well as their features and applications.

PVC (Polyvinyl Chloride)

Polyvinyl Chloride (PVC) is one of the most commonly used thermoplastic polymers in the world. The PVC cable is typically used for patch connections in the data center, wiring closet, and at the desktop. PVC is produced in two general forms, first as a rigid or unplasticized polymer (RPVC or uPVC). The following image shows a ST single-mode pre-Terminated cable (0.9mm PVC Jacket).

2m-upc-singlemode-48-fiber-multi-fiber-pre-terminated-cable-0-9mm-pvc-jacket

Features:

  • Good resistance to environmental effects. Some formulations are rated for -55 to +55.
  • Good flame retardant properties. Can be used for both outdoor and indoor fiber optic cables.
  • PVC is less flexible than PE (Polyethylene).

PE (Polyethylene)

Polyethylene is a kind of polymer that commonly categorized into one of several major compounds of which the most common include LDPE, LLDPE, HDPE, and Ultrahigh Molecular Weight Polypropylene. Polyethylene fiber has a round cross section and has a smooth surface. Fibers made from low molecular weight polyethylene have a grease like handle.

Features:

  • Popular cable jacket material for outdoor fiber cables
  • Very good moisture and weather resistance properties
  • Very good insulator
  • Can be very stiff in colder temperatures
  • If treated with proper chemicals, PE can be flame retardant.

Kevlar (Aramid Yarn)

The word Aramid is a generic term for a manufactured fiber in which the fiber forming substance is a long chain synthetic polyamide in which at least 85% of the amide linkages are attached directly to the two aromatic rings as defined by the U.S. federal trade commission. Kevlar fiber is based on poly (P-phenylene terephthalamide). Aramid yarn is the yellow fiber type material found inside cable jacket surrounding the fibers. It can also be used as central strength members.

Features:

  • Aramid yarn is very strong and is used in bundle to protect the fibers.
  • Kevlar is a brand of aramid yarn. Kevlar is often used as the central strength member on fiber cables which must withstand high pulling tension during installation.
  • When Kevlar is placed surrounding the entire cable interior, it provides additional protection for the fibers from the environment.

Steel Armor

The steel armored fiber cable, using light-steel tube, can provide maximum bend radius, strong protection and flexible cabling. Steel armor jacket is often used on direct burial outdoor cables and it provides excellent crush resistance and is truly rodent-proof. Since steel is a conductor, steel armored cables have to be properly grounded and loss fiber optic cable’s dielectric advantage. Armored fiber optic cable are often used in the outdoor direct burial cables and for the industrial environment where cables are installed without conduits or cable tray protection. The following image shows a single-mode armored fiber optic cable.

1m-lc-upc-to-lc-upc-duplex-3-0mm-pvcofnr-smf-armored-fiber-patch-cable

Various types of these light-steel armored fiber cables are in stock in FS.COM, including pre-terminated armored fiber patch cables, armored fiber trunk cables and field-terminated armored fiber cables for both indoor and outdoor applications.

Features:

  • Provides excellent crush resistance for outdoor direct burial cables
  • Protects cables from rodent biting
  • Decreases water ingress into the fiber which prolongs the fiber cable’s life expectancy

Central Strength Member

Strength member is used to increase the tensile force that will be applied on the cable during installation. Strength member will take the pulling force and will keep the fibers safe during installation. For large fiber count cables, a central strength member is often used.

The central strength member provides strength and support to the cable. During fiber optic cable installation, pulling eyes should always be attached to the central strength member and never to the fibers. On fiber splice enclosure and patch panel installations, the cable central strength member should be attached to the strength member anchor on the enclosure or patch panel.

Conclusion

When you choose to use which type of the fiber optic cables, the fiber optic cable construction, along with the mechanical and environment requirements should all be taken into account. All the above materials in the fiber optic cable construction are specifically required to meet the network infrastructure. FS.COM fiber optic cables come in various types with detailed specifications displayed for your convenient. These quality cables are designed with best-in-class performance. For more information about fiber optic cables or patch cords, you can visit fs.com.