Multimode SFP vs Single Mode SFP：What's the difference?

SFP transceivers, otherwise called small form-factor pluggable or mini GBIC, is a hot-pluggable optical transceiver module which is regularly utilized for both media transmission and data communications applications. As indicated by the link type it utilized together with, SFP transceivers are separated into single mode SFP and multimode SFP. Single mode SFP works with single mode fiber, while multimode SFP works with multimode fiber. This article will give you information about the differences between single and multimode.

SFP Single Mode  vs Multimode –

Choosing between a multimode SFP and a single mode SFP can be crucial when setting up an effective network operation. These SFPs differ largely in the type of fiber cable they use, their distance capabilities, and their costs. Let’s understand the differences in detail:

Type of Fiber:

1. Multimode SFP transceivers are designed to be used with multimode fiber optic cables, which have a larger core diameter that allows multiple paths or modes for light to travel. This leads to more data being carried in a given time frame, but increases the signal distortion and attenuation over long distances.

2. Single mode SFP transceivers, on the other hand, are used with single mode fiber cables, which have a much smaller core diameter that allows light to travel in a single path. This eliminates signal dispersion, but also reduces the amount of data that can be carried in a given time frame.

Distance:

1. Multimode SFPs are ideal for short-distance applications, typically covering distances up to 2 kilometers.

2. Single mode SFPs are designed for long-distance transmissions, capable of carrying signals over dozens of kilometers up to hundreds of kilometers.

Cost:

1. Multimode SFPs and multimode cables are generally less expensive to produce, because the larger core is more forgiving with alignment during connection, thus requiring less sophisticated and costly equipment.

2. Single mode SFPs and their cables are typically more costly due to the precision required in aligning the smaller core size. The manufacturing of single mode fibers involves more complicated processes, resulting in higher costs.

In summary, the right transceiver hinges on the specific requirements of your network such as: the distance that the signal needs to travel, the data transmission rate, and your budget. Multimode SFPs and their associated fiber are often the chosen solution for entities like data centers, where high-capacity, short-distance connections are the norm. Meanwhile, single mode SFPs are more commonly used in telecommunications and larger networks where data must travel long distances with minimal signal loss.

 

What do multimode sfp and single mode sfp represent respectively?

What is multimode sfp ?

Multimode SFP, or Small Form-factor Pluggable, is a type of optical transceiver module designed for use with multimode fiber optic cables. These multimode fiber optic cables have a larger core diameter than single mode fibers, allowing multiple light paths or modes (hence the term "multimode") to propagate within the same cable.

Multimode SFP modules typically operate at an 850nm wavelength and are designed for short-range data communication and interconnect applications, handling data rates typically ranging from 100 Mbps to 10 Gbps. 

Given the nature of the multimode fibers, these SFPs are capable of transmitting data over short distances, generally up to 2 kilometers or about 1.2 miles. This makes them the ideal choice for local data traffic, such as within a single building or on a campus.

Despite their limitation in distance, Multimode SFPs are a cost-effective option due to the lower cost of the multimode fiber itself, and the associated components. They are commonly used in applications like Ethernet, Fiber Channel, InfiniBand, and ATM.

 

What is single mode sfp?

Single mode SFP, or Small Form-factor Pluggable, is a type of optical module transceiver designed to work with single mode fiber optic cables.

Single mode fiber optic cables feature a smaller core diameter than multimode fibers and are engineered to carry only a single path, or mode, of light. This 'single mode' design allows for the transmission of light directly down the fiber, reducing signal loss and enabling data transmission over significantly longer distances than multimode fibers.

Operating typically at wavelengths of 1310nm or 1550nm, Single mode SFPs are designed for long-haul network connections, capable of reaching distances from 10 kilometers up to 120 kilometers or more, depending on the specific module type.

While single mode fibers and their associated SFPs are usually more expensive due to the cost of the high-precision lasers they employ, the trade-off is their capability for significantly longer transmission distances and higher bandwidth, hence often used in metropolitan, access networks, and long-haul telecommunications.

 

How to purchase and use them

When we purchase single mode SFP or multimode SFP in the market, we should affirm the transmission distance and wavelength we need. This will assist us with choosing the ideal SFP types. The expense for transceiver module is likewise a huge factor considered by numerous clients. Tthe compatible SFP moduleshould be recommended as a simple and convenient choice. Since it forfeits no quality or dependability as well as has a low cost.

 

Tips on utilizing Single Mode SFP and Multimode SFP

Single mode SFP and multimode SFP modules are both utilized in the switch slot and support data communication over either fiber optic or copper cable. When you utilize single mode SFP or multimode SFP, you would be advised to remember these tips:

• Ensure that SFPs have identical wavelength and color coding at the two end points of the fiber patch cord.

• To guarantee the data accuracy, short-wave SFP modules are commonly used with multimode fibers, while long-wave SFP modules with single mode fiber.

• Secure the optical port by plugging the dust plug in when not utilizing the SFP.
  
   

Single-Mode SFP with Multimode Fiber

Can I use single-mode SFP with a multimode cable? My answer is - YES. Single-mode SFP works with multimode fiber for short-range transmission within 100 meters. However, it should be treated as a solution of a last resort.

In principle, it is feasible. To understand this point, you need to dive into the difference between single-mode and multimode fiber.

First, identify the light source of single-mode vs multimode fiber. Interfaces that use multimode fiber generally use LEDs as light sources, while interfaces using single-mode fiber uses Laser as the light source.

Second, distinguish the fiber core diameter of single-mode vs multimode fiber. Single-mode fiber has a very narrow fiber core - 9um/7um/5um, while multimode fiber has a wide fiber core - 62.5um (OM1)/50um (OM2/OM3/OM4/OM5). 

Third, get to know the transmission mode of single-mode vs multimode fiber. The transmission mode of single-mode fiber is along the axis of the fiber core, which avoids dispersion and power loss. The transmission mode of multimode fiber is refraction. The light signal will be continuously reflected along the edge wall of the fiber core, hence there is a lot of dispersion and waste of light energy.

The fiber core diameter of the multi-mode patch cable is wide, so it is conditioned to connect the light source to this very wide fiber core, but the transmission is not far due to the multimode fiber transmission mode. 

As for the real-life experience, our expert has done corresponding tests in the lab. Used product portfolios are 2× Cisco GLC-LH-SM Compatible 1000BASE-LX/LH SFP, 1× 100m OM3 MMF fiber patch cable, and 2× Cisco SG110 gigabit switch. The result shows it's indeed feasible to use single-mode SFP with multimode fiber in short-range transmission. However, due to the characteristics of the multi-mode fiber, it is not recommended to use this method for transmission in long-distance applications. One should judge based on the actual situation. Here are real feedbacks by other users in the Spiceworks community: power loss, CRC fails and link flapping, etc. If it is an extremely urgent situation, such as the degree of fire burning eyebrows, you can try, maybe it can adapt to your short-term emergency.

 

Multimode SFP with Single-Mode Fiber

Can I use a multimode transceiver with single-mode fiber? My answer is – it is possible but not recommended. We do see the green light when connecting multimode SFP with single-mode fiber, but technically here are some issues.

As we mentioned above, the fiber core diameter of the single-mode patch cable is very narrow. Besides,the LED light source of the multi-mode module is very divergently. Hence when we use single-mode fiber with multimode SFP, only a fraction of the signal emitted by LED should get into the narrow single-mode fiber core. Meanwhile, great signal loss, attenuation, and serious modal dispersion also occur when it enters the single-mode fiber core. 

This is why I do not recommend you to do so. Irregular use is always risky, which will lead to uncertain fault. I bet you don't want to live with the anxiety that the link may fail at any time every day, especially for commercial use in SMB, enterprise, and data centers. If you do need to interconnect multimode SFP with single-mode fiber, a more secure solution is to use mode conditioning patch cables or single-mode to multimode media converters.

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.

Conclusion

Single-mode vs multimode SFP refers to SFP module type breakdown by the fiber optic cable worked with them. How to identify single-mode and multimode SFP? An easy and quick way is to distinguish the color of the SFP module Bale Clasp. SFP with black color-coded Bale Clasp stands for multimode SFP, while SFP Bale Clasp in blue, yellow, red refers to single-mode SFP. Other major differences between the two SFP module types are transmitter type, working central wavelength, max transmission distance, single-mode vs multimode SFP price, etc. For the topic of mixed-use of single-mode SFP with multimode fiber, it is feasible for urgent use but not reliable. For multimode SFP with single-mode fiber, remember not to do so, it is a matter of principle and technology. Finally, for achieving the best connection performance the author strongly recommends using single-mode SFP with single-mode fiber and multi-mode SFP with multimode fiber.