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What OS1 and OS2 represent

Optical fiber is the most widely used transmission medium in optical transmission today, and can be divided into single-mode optical fiber and multi-mode optical fiber. The international wiring standard ISO/IEC 11801 divides single-mode fiber into two types: OS1 and OS2 single-mode fiber. They have different characteristics and application environments, and they cannot be connected to each other, otherwise it will lead to problems such as weak transmission signals. So what is the difference between OS1 and OS2 single-mode fiber? This article will detail the differences between the two, and provide guidance for your installation and purchase.

What is the difference between OS1 and OS2 single-mode fiber?

OS1 single-mode fiber optic jumper complies with ITU-T G.652 standards, including ITU-T G.652.A and ITU-T G.652B standards (regular), ITU-T G.652C and G.652D standards (low water peak). However, OS2 single-mode fiber refers to the fiber that meets the fiber standard G.652C or G.652D, also known as single-mode zero-water peak fiber or single-mode low-water-peak fiber. These low-water-peak fibers are usually used in CWDM (coarse wavelength division multiplexing) use) application. In addition, the new cabling standard G.657.A1 is released for bending-insensitive single-mode optical fiber jumpers to optimize the cost performance of optical fiber products. Today, there are also OS2 single-mode cables that meet this standard on the market. mode fiber.

cable structure

OS1 singlemode fiber is typically in a tight tube construction and is designed for indoor applications. It usually has a protective cover on the outside, and a bundle of flexible fiber polymers (such as aramid yarn) is wrapped in the middle. The core and cladding of OS1 single-mode fiber are made of glass, which cannot be bent and is fragile. The coating protects and prolongs the service life of the fiber. OS2 single-mode fiber is usually designed with a loose tube, which is more suitable for outdoor applications. When deployed in some extreme environments, more robust cable construction is required. The OS2 single-mode fiber is helically placed in a semi-rigid tube so that the OS2 can stretch without bending the inner fiber, which would otherwise break the fiber under extreme tension.

Attenuation value

The attenuation value of OS1 single-mode fiber is greater than that of OS2 single-mode fiber. Generally, the maximum attenuation value of OS1 single-mode fiber in the 1310nm and 1550nm bands is 1.0db/km, while the maximum attenuation of OS2 is 0.4db/km. In addition, their transmission distances are also different. The maximum transmission distance of OS1 single-mode fiber is 10km, while the maximum transmission distance of OS2 single-mode fiber can reach 200km. Both OS1 and OS2 single-mode fibers can achieve transmission rates from 1 to 10GbE at different transmission distances. In addition, OS2 type single-mode fiber can also be used for 40G/100G Ethernet transmission.


OS1 and OS2 single-mode fiber: how to choose?

When choosing a suitable single-mode fiber for your network, you must be clear about your needs, and you can choose the appropriate OS1 or OS2 single-mode fiber according to the link length. OS1 single-mode fiber is very suitable for indoor applications, such as internal buildings/campus networks and internal wiring systems in data centers. OS2 single-mode fiber is more suitable for outdoor applications, such as factory wiring and backhaul networks in extreme external environments.


Why OS2 single-mode fiber is the general trend?

After the above comparison, we know that OS2 single-mode fiber has better performance and lower link loss, is more suitable for long-distance transmission, and is also very suitable for today’s high-speed network cabling systems to provide higher and more reliable performance.

In fact, OS1 single-mode fiber used to be the only standard for single-mode fiber, and the maximum link length it supports is about 10km, which is far from meeting the growing demand for transmission distance. However, as fiber technology and technology become more mature, OS2 single-mode fiber will gradually replace OS1 single-mode fiber and become an ideal choice for connecting 1G/10G/40G/100G Ethernet connections to meet high-performance long-distance transmission requirements.