OS1 vs OS2 Fiber, What is the Difference?

Initial Published: March 15, 2023

We have discussed the differences between single mode and multimode fiber in the earlier post. But did you know single mode is also classified as OS1 and OS2 fiber? As part of our series of fiber optic guides, we will focus on this topic in today’s post. 

In this post, we are going to discuss the below topics.

Let’s go on.

What is OS1 Fiber?

OS1 generally refers to a single mode fiber whose mechanical, optical, and environmental characteristics conform to the ITU-T G.652A and ITU-T G.652B standards (conventional). However, the low water peak fibers classified as ITU-T G.652C and G.652D also belong to the usual OS1 fibers.

It is a tightly buffered fiber with 1.0 dB/km attenuation, mainly for short-distance transmission in indoor plants, usually up to 2 km under 10 Gigabit Ethernet. As an old legacy fiber, OS1 has lower performance requirements than OS2, is easier to manufacture, and is less costly than OS2 fiber.

What is OS2 Fiber?

Unlike OS1, OS2 fiber refers to single mode low-water peak fibers that comply with ITU-T G.652C and ITU-T G.652D specifications. In the real world, OS2 fiber usually refers to the G.652D. ITU-T G.652A or G.652B fibers, which are unsuitable for 1383nm transmission due to their high attenuation characteristics. The G.652D fiber enhances this performance to support full-spectrum transmission with low attenuation values in this band. 

Therefore, this fiber can be used for full-band CWDM and DWDM applications, thus maximizing fiber utilization. With a maximum of 0.4dB/km attenuation, this fiber is primarily suitable for long-distance transmission in outdoor applications. It can typically support network throughputs of up to 100 Gbit/s and a maximum distance of about 200 km.

OS1 vs OS2 Fiber, What is the Difference?

After discussing the single mode fiber basics, let’s quickly examine their differences. The simple comparison chart is below.

Comparison	OS1	OS2
Standards	ITU-T G.652A/B/C/D	ITU-T G.652C/G.652D
Cable Construction	Tight Buffer	Loose Tube
Application	Indoor	Outdoor
Attenuation	1.0dB/km	0.4dB/km
Wavelength	1310nm, 1550nm	1310nm, 1383nm, 1550nm
Max. Distance	10 km	200 km
Price	Low	High

1. Cable Construction

OS1 fibers are encased in a thick polymer jacket and are typically used in cable constructions with tightly buffered interiors. This construction is particularly suitable for indoor applications. However, the OS2 fiber is ideal for loose tubes or blown fibers and is particularly appropriate for outdoor use (In this case, no pressure is exerted on the fiber, and the cable can be extended without stretching the fiber itself).

2. Attenuation and Distance

The attenuation of OS2 fiber is much lower than that of OS1. In general, OS1 has a maximum attenuation of 1.0dB/km, while OS2’s attenuation is only 0.4dB/km. The difference in attenuation results in different transmission distances. OS1 single-mode fiber has a maximum transmission distance of 10 km, while OS2 can reach a maximum transmission distance of 200 km – far more than another. Due to this advantage, OS2 is widely used in practical fiber optic cabling.

3. Cost

Since OS2 fiber requires better performance on the attenuation and full wavelength support, it increases the manufacturing difficulty and, finally, impacts the cost. Typically, OS2 fiber cost more than OS1. 

FAQ

Q: Is OS2 fiber better than OS1?

A: In terms of performance, OS2 fiber is better than OS1. However, OS1 fiber price is lower than OS2, so it is still applicable for some short-distance applications.

Q: Are OS1 and OS2 fiber compatible?

A: The answer is no. Since they have different features and parameters for various applications, you should use them mixed. However, sometimes, you may mate or splice them together when not used for a WDM multiplexer.

Q: Can OS1 fiber support 40G & 100G?

A: No, OS1 can not support 40G&100G. It only supports a max of 10G speed. 

Q: What is Polarization-mode dispersion?

A: Also called PMD, it refers to a dispersion effect, where parts of the light in different polarization directions travel at different phase speeds, causing the beam to be dispersed as it travels along the fiber.

Q: What are the typical OS2 fiber applications?

A: OS2 fiber is ideal for long-distance and high-bandwidth applications, including campuses, enterprises, Large-scale data centers, and backbone networks.

Q: Can you mix OS1 and OS2 fiber?

A: Yes, you can mix OS1 and OS2 cables. However, remember that OS2 provides better performance, so you should prefer the OS2 cable for long-distance fiber cabling to maximize the transmission.

Q: What single-mode fiber cable do you provide?

A: We can provide both OS1 and OS2 fiber optic cable. However, we usually offer products with OS2 as the default. If you need the OS1 type, don’t hesitate to contact us for custom service.

Conclusion

After reading this post, do you know about OS1 and OS2 fiber? Can you tell their difference and application? Let us know if any information is missed. As a professional fiber optic vendor, Optcore provides all single mode cables made of OS2 fiber with superior performance and affordable pricing.

Reference:

• https://www.itu.int/rec/T-REC-G.652/en

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• Fiber Connector Types: A Complete Guide