SFP single mode vs multimode : What's the difference?

Single Mode SFP vs Multimode SFP: What’s the Difference?

PARAMETER	SM SFP	MM SFP
Abbreviation for	Single Mode SFP	Multimode SFP
Distance Supported	Can Support Greater distance than MM Fiber. SM Fiber can support distance value as high as 80 km or even 120 km	Used for short distance transmission reaching 100 m and 500 m
Cost	SM SFP is costly	MM SFP is cheaper than SM SFP
Core Size	Single-mode fiber has a smaller core (9 micron)	Multi-mode fiber has a broader core (62.5 and 50 micron)
Wavelength supported	works mainly in 1310nm and 1550nm wavelength	Works mainly in 850nm wavelength
Preferential usage	Used inside LAN for Switch ,Router and Server connectivity inside Building or Data Center	Required on WAN connectivity like Service provider Handoff to office/Data Center or connectivity between offices.
Colour schema	The colour coded bale clasp and colour arrow on label are generally blue, yellow or purple. And the colour of compatible fiber optic patch cord is yellow.	Their colour coded bale clasp and colour arrow on label are black and the used fiber optic patch cord is usually orange.

 

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

Single Mode SFP vs Multimode SFP: Working Wavelength
Single mode SFP module has a narrower laser wavelength, which works mainly in 1310nm and 1550nm wavelength. Whereas multimode SFP module works in 850nm wavelength due to the larger core size.

Single Mode SFP vs Multimode SFP: Color Coding

The color coded bale clasp and color arrow of single mode SFP modules are generally designed in blue, yellow or purple. Blue is the 1310nm module, yellow is the 1550nm module and purple is the 1490nm module. And the color of compatible fiber optic patch cord is yellow. While the color coded bale clasp and color arrow on the label of multimode SFP modules are black and the used fiber optic patch cord is usually orange.

Single Mode SFP vs Multimode SFP: Transmitter

Single mode SFP and multimode sfp use different types of transmitters. VCSELs are typically used in multimode SFP transceivers. They can be tested on the wafer level and don’t need a hermetic package. Edge-emitting lasers, such as Fabry–Pérot, DFB and DBR lasers, are utilized in single mode SFP modules for different reaches and applications. They have complex layer structures and often require a hermetic package to achieve higher emission power and stable single mode operation. Therefore, Edge-emitting lasers are more costly than VCSELs.

Single Mode SFP vs Multimode SFP: Cost

When comparing single mode SFP vs multimode SFP in terms of cost, single mode SFP is more expensive than multimode SFP. The cost difference between single mode SFP and multimode SFP mainly arises from the different transmitters they use. As mentioned above, the transmitter of single mode SFP is more costly than that of multimode SFP. Hence, multimode SFP module is cheaper.
 
 

Singlemode SFP

Singlemode fiber has much tighter tolerances for optics used. The core is smaller and the laser wavelength is narrower. This means that SMF has the capability to carry a higher bandwidth at much longer transmission distances. Singlemode SFPs work mainly in the 1310nm and 1550nm wavelengths and is mostly used in a long distances transmission environment reaching 2km, 10km, 40km, 60km, 80km and 120km.

SINGLEMODE SFP COLOR CODING

SFPs are identified by the color of the Bale Clasp. Though there is still a lack of total conformity; generally speaking, Singlemode SFPs use this color coding:
· Gray color coded bale clasp designates the 1470 nm SFP
· Violet color coded bale clasp designates the 1490 nm SFP
· Blue color coded bale clasp designates the 1510 nm SFP
· Green color coded bale clasp designates the 1530 nm SFP
· Yellow color coded bale clasp designates the 1550 nm SFP
· Orange color coded bale clasp designates the 1570 nm SFP
· Red color coded bale clasp designates the 1590 nm laser SFP
· Brown color coded bale clasp designates the 1610 nm SFP
· The color of the compatible fiber optic patch cord or pigtail is yellow

Multi-mode SFP

Multi-mode fiber uses a much bigger core and usually uses a longer wavelength of light. Because of this, the optics used in Multi-mode have a higher capability to gather light from the laser. In practical terms, this means the optics are cheaper. The common Multi-mode SFPs work in 850nm wavelength and is only used for short distance transmission reaching 100m and 500m. Though it’s not able to transport for long distance, it can transport many kinds of optical signals.
As with Singlemode SFPs, Multi-Mode SFPs are identified by the color of the Bale Clasp:
· Black color coded bale clasp designates a Multi-mode SFP
· The color of the compatible fiber optic patch cord or pigtail is orange
 
 

What Should We Notice When Using Singlemode SFP & Multimode SFP

· Ensure that the SFPs in both ends of the fiber patch cord are of the same wavelength. A simple method is that the color of the modules must be consistent.
· In general, to ensure the data accuracy, short-wave SFP modules use with multimode fibers (ie. orange fiber patch cord), while long-wave SFP modules use with single-mode fiber (ie. yellow fiber patch cord).
· Do not over bend or winding fiber optic cables when using them. This will increase the attenuation of light in transit.
· If you don’t use the SFP, you must use the dust plug to protect the optical bore.
 
 

Frequently Asked Question about Single Mode vs Multimode Fiber Optic Cable

Q: What is better single mode or multimode fiber type?

A: As has been mentioned above, single mode fiber and multimode fiber cable have their own advantages on cost and applications. There is no such thing that single mode optical fibers are better than multimode ones. Just choosing the best-fit one for your applications is ok.

Q: Can I mix single mode and multimode fiber type?

A: This answer for this question is “no”. Multimode fiber and single mode fiber have different core sizes, and the number of light modes that they transmit is also different. If you mix the two fibers, or connect them together directly, you’ll lose a large amount of optical loss, resulting in a link flapping or being down. Keep in mind that never mix different types of cabling randomly.

Q: Can I use a multimode transceiver on single mode fiber optic cable?

A: Generally speaking, the answer is "no". Large optical loss will occur if a multimode transceiver is connected with single mode fiber. However, the opposite will work. For example, 1000BASE-LX single mode SFP can work on multimode fiber cable by using mode conditioning fiber cable. Sometimes, fiber media converters also can be used to solve such problems between single mode transceivers and multimode transceivers.

Q: Single mode vs multimode fiber optic cable type: which should I choose?

A: When making a decision between single mode and multimode fiber cables, the first factor to consider is the fiber distance which you need actually. For example, in a data center, multimode fiber cables are enough for the distance of 300-400 meters. While in applications that require distance up to several thousands of meters, the single mode fiber is the best choice. And in applications that can use single mode and multimode fiber, other factors like cost and future upgrade requirements should be taken into consideration for your choice.

Summary

From the comparison between single mode vs multimode fiber optic cable, it can conclude that single-mode fiber cabling system is suitable for long-reach data transmission applications and widely deployed in carrier networks, MANs and PONs. Multimode fiber cabling system has a shorter reach and is widely deployed in enterprise, data centers and LANs. No matter which one you choose, on the basis of total fiber cost, choosing the one that best suits your network demands is an important task for every network designer.