Single-mode SFP VS Multimode SFP: What’s the Difference?

What is Single-mode SFP?

Single-mode SFP (SMF SFP) operates on single-mode fibers with a typical core diameter of 9 microns and a cladding diameter of 125 microns. SMF SFP primarily operates at wavelengths of 1310 nanometers and 1550 nanometers. Therefore, it is suitable for long-distance data transmission applications such as 2 kilometers, 10 kilometers, 40 kilometers, 60 kilometers, 80 kilometers, and 120 kilometers. There are various types of single-mode SFP modules available, such as 1000BASE-LX and 1000BASE-EX.

What is Multimode SFP?

Multimode SFP (MMF SFP) operates on multimode fibers with core diameters of 50 microns and 62.5 microns, and a cladding diameter of 125 microns. Common multimode SFP works at a wavelength of 850 nanometers and is used for short-distance transmission, reaching distances of 100 meters and 550 meters. There are various types of multimode SFP modules available, including SFP1G-SX-85.

Single-mode SFP VS Multimode SFP: What’s the Difference?

There are several main differences between single-mode SFP and multimode SFP:

Working Wavelength

Single-mode SFP module has a narrower laser wavelength, which works essentially in 1310nm and 1550nm wavelength. However, the multimode SFP module works in 850nm wavelength because of the bigger core size.

Color Coding

The color coding for single-mode SFP modules typically includes blue, yellow, or purple. The color blue is used for 1310 nanometer modules, yellow for 1550 nanometer modules, and purple for 1490 nanometer modules. The compatible fiber patch cords for single-mode SFP modules are usually yellow. On the other hand, the color-coding for multimode SFP modules includes black for the label's color-coding and arrow, and orange for the fiber patch cords used.

Transmitter

Single-mode SFP and multimode SFP utilize various transmitters. VCSELs (Vertical Cavity Surface Emitting Lasers) are commonly used in multimode SFP transceivers. They can be tested at the wafer level and do not require hermetic packaging. Edge-emitting lasers such as Fabry-Perot, DFB (Distributed Feedback), and DBR (Distributed Bragg Reflector) lasers are used in single-mode SFP modules for various spans and applications. They have complex layer structures and typically require hermetic packaging to achieve higher output power and stable single-mode operation. Therefore, edge-emitting lasers are more expensive than VCSELs.

Cost

From a cost perspective, single-mode SFP is more expensive than multimode SFP. The cost difference between single-mode SFP and multimode SFP is largely reflected in the various transmitters they use. As mentioned earlier, the transmitters used in single-mode SFP are more expensive compared to those used in multimode SFP. Therefore, multimode SFP modules are generally cheaper.

Tips on Utilizing Single-mode SFP and Multimode SFP

Single-mode SFP and multimode SFP modules are used in switch slots and support communication through fiber optic or copper network cables. When using single-mode SFP or multimode SFP, it is important to keep the following points in mind:

• Make sure that SFPs at both ends of the fiber patch cord are of the same wavelength and consistent in color coding.

• To ensure data accuracy, shortwave LC SFP transceivers are typically used with multimode fiber (orange-colored fiber patch cords), while longwave LC SFP transceivers are used with single-mode fiber (yellow-colored fiber patch cords).

• When not using an LC SFP transceiver, protect the optical port with a dust cap.

Conclusion

After comparing single-mode SFP and multimode SFP, we can see that single-mode SFP is suitable for long-distance data transmission applications, while multimode SFP is typically used for short-distance transmission. The choice depends on the specific requirements. FS offers a variety of single-mode and multimode optical transceivers. If you have any needs, feel free to visit FS.COM.