What Is SFP?

SFP stands for Small Form-Factor Pluggable. It is a compact, hot-pluggable transceiver used for both telecom and datacom applications.

SFP module has two ports, one port has laser inside, which is the transmitter side. The other port has a photodetector inside, which is the receiver side. So basically, SFP is a transceiver module, since it has transmitter and receiver in a single unit.

Which Components Make Up the SFP Optical Module?

The SFP optical module is composed of laser, circuit board IC and external accessories. The external accessories include shell, unlocking part, buckle, base, gripper, rubber plug, PCBA, and the color of gripper can help you to identify the parameter type of the module. For the types of SFP module, there are many types for SFP module such as BIDI-SFP, Electrical interface SFP, CWDM SFP, DWDM SFP, SFP+ transceivers and so on. In addition, for the same type of XFP, X2, XENPAK optical transceivers, SFP optical transceivers can not only be directly connected with it, but also have the feature of lower cost than it.

How Are the SFP modules used on the PCB board?

The following picture shows a perspective view of the SFP module, so you can clearly see its mechanical outlines.

Gigalight 10G SFP+

SFP module's mechanical interface and electrical interface are specified by a multi-source agreement, also called MSA.

MSA is an industrial group composed of many network component vendors, such as Finisar, Fujikura, Lucent, Molex, Tyco, etc.

Engineers from these major vendors came together and made a design that everybody agreed upon. So based on this MSA specification agreement, these companies can make products that can work together in a system without compatibility issues. It is almost like an industry standard.

SFP was designed based on the bigger GBIC interface, but SFP has a much smaller footprint in order to increase port density. That is why SFP is also called mini-GBIC.

SFP modules are classified based on the working wavelength and its distance reach. Let's take a look at the list here.

For multimode fibers, the SFP module is called SX. SX modules use 850nm wavelength. The distance that the SX module supports depends on the network speed. For 1.25 Gbps, the reach is 550 meters. For 4.25 Gbps, SX modules support 150 meters.

For single mode fibers, there are a lot of choices. I am listing the most common types here.

LX modules use 1310nm wavelength laser and support up to 10km reach. ZX modules use 1550nm wavelength laser, and supports reach up to 80km. ZX modules also use 1550nm laser but support up to 120km reach.

There are also CWDM and DWDM SFP modules, which use multiple wavelengths in the module to support even more bandwidth and distance.

And don't forget, the MSA also defined a SFP module based on the UTP twisted pair copper cables. But this SFP module currently only supports Gigabit Ethernet.

Traditional SFP modules support the speed up to 4.25 Gbps. But an enhanced version, which is called SFP+, supports up to 10Gbps, and is becoming more popular on 10Gigabit Ethernet and 8Gbit Fibre Channel.

SFP transceivers are used on all types of network applications, including telecommunication, data communication, Storage Area Network.

On the protocol side, there are SFP modules that support SONET/SDH, Gigabit Ethernet, Fibre Channel, Optical Supervisory Channel, and more.

Conclusion

Gigalight is committing to providing cost-effective products for customers. 10G optical modules such as 10G SFP+, 10G CWDM SFP+, 10G DWDM SFP+ can be provided by Gigalight. Gigalight has been investing in the development of colored (CWDM/DWDM) transceivers which have been widely sold around the world. You can find more relevant information from Gigalight’s official website.