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Single Mode vs Multimode Fiber – Whats the Difference?

What Are the Differences Between Single Mode and Multimode Fiber?

A fiber optic cable, which is a network cable created using glass fiber strands, is useful for telecommunications and high-performance data networking over long distances. Governments, businesses, and individuals around the world use fiber optics for operating telephone systems, cable television, and of course, the internet. Fiber optic cables are available in two types: single mode or multimode. There are some key differences between the two. 

Fiber Cable Bandwidth

Bandwidth is an important factor when choosing which type of cable is best for your needs. For most people, single mode cables are the best option. They support more powerful, brighter light sources at lower attenuation. Additionally, in theory, a single mode fiber’s bandwidth is unlimited. Multimode’s use of multiple light modes means a higher attenuation that isn’t as bright. There are five different grades of multimode fiber cables, but none of them offer the unlimited bandwidth you can get with single mode. 

Fiber Cable Distance

Although fiber transmission technically depends on the electronics using it and their individual light output, most users agree that single mode is the better bet. Single mode works to transmit both long and short distances and does so regardless of the resolution of the device. A single mode fiber optic cable allows most devices to transmit more than six miles. Multimode fiber has a maximum distance of only about 1,800 feet. 

If you are running low-distance applications, it can still be beneficial to choose multimode cables. The key is to choose the correct ones. Multimode fiber cables are available in five different grades: OM1, OM2, OM3, OM4, and OM5. OM1 works over the shortest distances and has the lowest bandwidth, while OM5 offers the most bandwidth over the longest distances. Typically, a project that works with a multimode option will use OM3. Keep in mind that OM1 has a different core (62.5 µm) and cannot be used for patching any other multimode cable systems.

Fiber Cable Construction

A single mode fiber cable has an optical core that is 9µm, while modern multimode cables use 50µm. The single mode’s smaller core size means it has lower attenuation and transmits at higher bandwidths and over longer distances. Simply put, single mode propagates a single light mode while a multimode can support simultaneous light modes.

Despite their stark difference in size, you wouldn’t be able to tell just by looking at the cables, as they are both smaller than the width of a human hair. If you could view the cable, you mostly see the protective coating and the cladding, not the cable itself. Additionally, the terms “single” and “multi” don’t describe how many cables there truly are within the coating. A single coating can hold more than 100 of either type of fiber. 

Fiber Cable Cost

Typically, when something is more efficient, it is also more expensive. That isn’t the case when it comes to the battle between single mode and multimode fiber. Since single mode fiber is easier to manufacture, it also tends to be more affordable. Going with the single mode cable will typically save you about 30 percent over multimode. There is one downside, though. Because single mode electronics have more intricate optical processors to make strong light sources, they are often about 30 percent more expensive than other electronics. This means that in reality, the costs are about the same. 

When it comes to choosing the right fiber optics bandwidth for your project, it depends on what that project is. Consider the need for high speeds and whether your data networking will be over short or long distances. If you aren’t sure where to begin, don’t worry. Contact V1 Fiber to have experienced fiber engineers help you choose correctly and get your project up and running.

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