1. Overview

With the development of science and technology, the development of optical modules is also changing day by day, from the initial GBIC, XENPAK, X2 to the hot SFP28, QSFP28 in recent years, all kinds of optical modules are used in different application scenarios. However, analyzing the domestic and international markets, the most demanded optical modules are still 10G SFP+ optical modules, especially SFP-10G-SR and SFP-10G-LR optical modules.

Introduction of SFP-10G-SR and SFP-10G-LR

SFP-10G-SR and SFP-10G-LR have different wavelengths, transmission distances, types of fibers used and types of lasers, as shown below:

Figure 1 Comparison of basic information between SFP-10G-SR and SFP-10G-LR Figure 1 Comparison of basic information between SFP-10G-SR and SFP-10G-LR

SFP-10G-SR optical module, in which SR means Short Range, the center wavelength is 850nm, can be used with 62.5/125um multimode fiber and 50/125um multimode fiber, and its transmission distance will be affected by the type of fiber, as follows (refer to IEEE Standard 802.3)

Figure 2 Different fiber types correspond to different transmission distances 

SFP-10G-LR optical module, where LR refers to Long Range, the center wavelength of 1310nm, with the use of 9/125um single-mode fiber, effective transmission for 2km to 10km.

3. SFP-10G-SR and SFP-10G-LR applications

By comparing the characteristics of the two modules, we can see the advantages and applications of the two optical modules are as follows: SFP-10G-SR optical module has a miniaturization, low power consumption, the use of TOSA lasers for the VCSEL lasers, the cost is lower. The short transmission distance is suitable for short-distance application scenarios, such as enterprises, small hospitals and data center rooms.SFP-10G-LR optical module has the characteristics of miniaturization, low power consumption and long transmission distance. SFP-10G-LR optical modules have the characteristics of miniaturization, low power consumption and long transmission distance, which are suitable for medium and long-distance application scenarios, such as universities, industrial parks, as well as carrier customers, large-scale data centers.

When using these two types of optical modules with optical fiber, special attention needs to be paid to the single-mode fiber can not be inserted in the multi-mode optical module, because the multi-mode optical module sends out a large dispersion angle of the optical signal, the single-mode optical fiber aperture is small, into the optical fiber light is too small, can not be transmitted over long distances. At the same time, multi-mode fiber is not recommended to be inserted in the single-mode optical module, because although all the light from the single-mode optical module can enter the fiber, but the light is transmitted in the fiber in multi-mode mode, the dispersion is large, and can only be transmitted over short distances. And in this case, the optical power at the receiving end will increase, which will lead to optical power overload at the receiving end, so it is also not recommended to use multi-mode fiber with single-mode optical module.