SFP-10G-SR vs. SFP-10G-LR

 With the development of technology, from the original GBIC, XENPAK, X2 to the current SFP28, QSFP2 optical modules are used in different application scenarios. However, based on the market analysis, the 10G SFP+ optical modules are still the most in demand, especially SFP-10G-SR and SFP-10G-LR.

SFP-10G-SR and SFP-10G-LR have different wavelengths, transmission distances, fiber types and laser types：

Module	SFP-10G-SR	SFP-10G-LR
Wavelength	850nm	1310nm
Transmission Distance	300m	10km
Fiber Type	MMF	SMF
Laser Type	VCSEL	DFB
DOM	Support	Support

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

Data Rate	Fiber Type	Model Bandwidth @850nm (MHz-km)	Distance Range(m)
9.83-11.3Gb/s	62.5/125um MMF	160	26
9.83-11.3Gb/s	62.5/125um MMF	200	33
9.83-11.3Gb/s	50/125um MMF	400	66
9.83-11.3Gb/s	50/125um MMF	500	82
9.83-11.3Gb/s	50/125um MMF	2000	100

SFP-10G-LR optical module, where LR refers to the long range (Long Range), the center wavelength is 1310nm, it is used with 9/125um single-mode fiber, and the effective transmission is 2km to 10km.

Applications of SFP-10G-SR & SFP-10G-LR
Comparison of the characteristics of the two modules shows that the advantages and applications are as follows: SFP-10G-SR optical module has the characteristics of miniaturization and low power consumption. The TOSA laser used is a VCSEL laser, and the cost is low. The short transmission distance is suitable for short-distance application scenarios, such as enterprises, hospitals and data centers. SFP-10G-LR optical module has the characteristics of miniaturization, low power consumption and long transmission distance. It is suitable for medium and long-distance application scenarios, such as campus, industrial districts, and operator customers, big data centers, etc.

When using these two types of optical modules with optical fibers, should be paid attention to the fact that single-mode optical fibers cannot be inserted into multi-mode optical modules, because the divergence angle of the optical signal sent by the multi-mode optical module is large, while the aperture of single-mode optical fibers is small. Too little light enters the fiber to travel long distances. Meanwhile, it is not recommended to multi-mode optical fiber into the single-mode optical module, because although the light emitted by the single-mode optical module can all enter the optical fiber, it is transmitted in multi-mode mode in the optical fiber, and the dispersion is large, so it can only be transmitted over a short distance. And in this case, the optical power of the receiving end will increase, which will cause the optical power over"" of the receiving end. Therefore, it is not recommended to use multi-mode optical fibers with single-mode optical modules.

Application Scenarios of CFP Transceiver Modules

 CFP optical transceiver modules are mainly used in switches, routers, converters, OTN optical transmission platforms and other equipment for line-side optical transmission of 100G wavelength division systems. Compared with other forms of line-side optical modules, It has good OSNR performance, sensitivity, dispersion tolerance, and DGD tolerance. At the same time, CFP coherent optical modules using wavelength division multiplexing technology are widely used in 100G metropolitan area networks to meet their high-capacity and long-distance requirements.

100G Multi-channel DWDM Transmission Network
Since 100G is more susceptible to dispersion, it is necessary to dispersion and improve optical power. First, a 100GHz DWDM multiplexer is used to combine all 100Gs, and then the dispersion compensation and amplification of the whole combination are performed. This architecture supports "pay-as-you-grow" service providers. Existing legacy 10G channels can be seamlessly swapped with 100G services when bandwidth is exhausted. The rest of the same components can even be reused to extend the data rate to 2.4Tb/s.

This solution requires 24 color CFP optical transceiver modules and a 48-channel 100GHz DWDM multiplexer. First, all 100G lines are multiplexed together, and then only one dispersion compensation and amplification is required. Obviously, such a network structure can provide higher density at a reasonable cost, and has the ability to flexibly reuse the existing infrastructure.

100G Distance Extension Solution
SFP + OEO Optical amplification repeaters can be used in conjunction with switches to achieve distance extension. After the 100G output signal of the switch is converted into a DWDM signal, it can realize longer distance transmission. This solution eliminates the distance limitation problem by using CFP coherent optical transceiver modules to connect the output signal to the line fiber to achieve longer distance signal transmission.

The above architecture achieves longer-distance signal transmission by adding MTP branch cables and WDM SFP + OEO converters, 6-channel dual-fiber DWDM dense wavelength division multiplexers and 8-channel dual-fiber CWDM coarse wavelength division multiplexers. The role of OEO is to convert conventional SR wavelengths to DWDM wavelengths. Therefore, the 100G CFP coherent optical module is an effective solution for building a 2500km long-distance DWDM network.