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25 Mar 2016

When designing a structured optical cabling system, the most basic question is inevitably: what fiber type to use. These are two standards for single mode fiber optic cabling from a total of six types of fiber that are generically used today known of “OF types” (OM1, OM2, OM3, OM4 for multimode and OS1, OS2 for single mode.) There is a great deal of confusion about the purpose and meaning of cabled single mode optical fiber Categories OS1 and OS2. So here is the explanation of the differences between the specifications of OS1 and OS2.

The difference between OS1 and OS2 fiber optic cables mainly lie in the performance due to cable construction. The performance is less dependent on optical fiber performance and more dependent on how the cable is constructed and designed in the device. Every designer must make the decision to find out about how the cables will improve the functionality of the device. Here is some information related to the differences between the cable construction.


Category OS1 and Category OS2 are the two types of cable construction. Category OS1 is recommended for internal tight buffered cable construction, and Category OS2 is recommended for loose tube or blown fiver solution. The loose tube cable is made from optical fiber and gives the best installed performance of 0.4db per km.

Category OS1 cable is designed for use in internal situations where the maximum distance is 2km. The cable type will allow speeds of over one to 10 gigabit Ethernet. By contrast, category OS2 cable is designed for maximum distance of 5 km to 10 km. This cable type will also allow a distance of one to 10 gigabit Ethernet.

There are numerous similarities between cable construction. In general, experts recommend that any of their solutions be constructed from B1.3 optical fiber. The maximum attenuation allowed per km for an installed cable is 1.0 db for OS1 that transmits signals between 1310 nm and 1550 nm. The maximum attenuation allowed per kilometer is 0.4db between 1310 nm and 1550 nm.

Slight interoperabilty will be experienced if either the OS1 SM fiber cable or OS2 SM fiber cable is created by splicing or patching. Replacement may be a better option if you decide to incorporate either of these standard fiber optic cable options into your design.

OS1 is for indoor use such as in campus or data centers where universal tight buffered cable constructions exist. Category OS2 is appropriate to outdoor and universal loose tube solutions where the cabling process applies no stress to the optical fibers. Indoor fiber is more tolerant of bending (called B1.3). The fiber is more plastic and able to bend plus the buffered cable reduces the risk of catastrophic damage. Outdoor fibers are bend sensitive and thus more likely to break during install unless care is taken.

After learning about the differences between OS1 and OS2 fiber optic cable, are you clear about which cable should you choose? First, if you want to use for indoor application, OS1 is better for you. However, if used for outdoor application, you should choose OS2. Second, there is no benefit to be gained in using OS2 cable if under 2 km. OS2 is best for distance over 2 km. Finally, you should note that OS1 is much cheaper than OS2. Fiberstore offers both single mode fiber cables (like OS2 duplex single mode fiber patch cables) and multimode fiber cables (like OM4 duplex multimode fiber patch cables). All these cables can be customized to meet your special requirements.


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