Multimode fiber optic cable is the backbone of most modern corporate networks. Multimode fiber optic networks are more efficient, easier to install, and significantly cheaper than single mode systems — making them the top choice for everyone from small businesses to large enterprises.
There’s just one thing preventing multimode fiber from being the perfect network solution: multimode fiber distance limits.
Single mode fiber networks can’t compete with multimode systems on price, but multimode fiber has a much shorter data transmission range. As networks grow and required data transmission speeds and volume increase, network designers and integrators like you must figure out how to manage multimode fiber distance limits to build and maintain fiber optic networks that meet your company’s needs and fit your budget.
We’ve put together this short guide to help you better understand multimode fiber distance limits and how you can manage them to ensure your company network is optimized for performance, efficiency, and cost.
A Quick Intro to Multimode Fiber Distance Limits
Multimode fiber is designed to transmit multiple rays of light simultaneously. It has a larger core than single mode fiber (50 - 62.5 μm vs 9 μm) which allows light to bounce off the walls of the fiber as it travels. This larger core enables multimode fiber to support multiple data protocols and transmit multiple signals at the same time, but it also limits the signal transmission range.
As light travels along a fiber optic cable, a phenomenon called modal dispersion occurs. Modal dispersion is a technical way of saying the optical energy gets spread out and the signal loses integrity. It’s worse in multimode fiber because of the more jagged path light takes as it travels.
Modal dispersion gets worse the further the light travels. After a certain distance, the signal gets so spread out that it’s no longer distinguishable by the devices it’s being transmitted to. As a result, multimode fiber distance limits are determined by how far the fiber can transmit data before modal dispersion degrades the signal.
Three Ways You Can Manage Multimode Fiber Distance Limits
There’s no way to completely eliminate multimode fiber distance limits, but there are ways to manage them and maximize the range of your multimode fiber network. Let’s take a look at the three most effective strategies.
1. Choose the Best Fiber for Your Application
The most basic way to manage multimode fiber distance limits is to choose the best multimode fiber for your application. There are five industry-standard multimode fiber grades.
As you can see from the table below, they differ in size, optical source, bandwidth, and distance limits at various speeds. They also differ in price — with OM5 being the most expensive and OM1 the least expensive.
In general, OM1 should only be used to patch or repair existing networks. OM3, OM4 and OM5 offer higher bandwidths and longer distance limits due to their use of advanced VSCEL (LASER) sources instead of traditional LED sources.
OM3 is a good choice for most corporate applications, while OM4 features increased bandwidth and data transmission ranges if you need them. OM5 is best for data centers and other high speed applications.
Don’t forget to think ahead and consider both your current and future bandwidth and distance needs when choosing your multimode fiber.
|Multimode Fiber Type||Core/Cladding Diameter (μm)||Jacket Color||Optical Source Type||Bandwidth @ 850 nm (MHz·km)|
|Multimode Fiber Type||Fast Ethernet (100 Mb) Distance Limit||1 Gigabit Ethernet Distance Limit||10 Gigabit Ethernet Distance Limit||40 Gigabit Ethernet Distance Limit||100 Gigabit Ethernet Distance Limit|
|OM1||2 km||275 m||33 m||-||-|
|OM2||2 km||550 m||82 m||-||-|
|OM3||2 km||800 m||300 m||100 m||100 m|
|OM4||2 km||1100 m||400 m||150 m||150 m|
|OM5||2 km||1100 m||400 m||150 m||150 m|
2. Consider Using Higher Wavelengths
Industry-standard multimode fiber bandwidth and distance limits are based on a wavelength of 850 nm, but modern fiber optic cables and devices can efficiently transmit signals using three wavelengths: 850 nm, 1300 nm, and 1550 nm.
Higher wavelengths can actually be transmitted more efficiently, meaning you get less modal dispersion and longer effective transmission distances. Fiber optics that use 1300 nm and 1550 nm are more expensive than devices operating at 850 nm, but the difference is usually not prohibitive, and the extra range is often worth the extra cost.
3. Take Advantage of Technology
Scientists and engineers haven’t figured out how to change the laws of physics and eliminate model dispersion, but they have developed technology to help mitigate the effects and extend the data transmission range of multimode fiber networks.
With the help of technology such as Wavelength Division Multiplexing (WDM) and advanced small form-factor pluggable (SFP) optical fiber transceivers, you can achieve Gigabit Ethernet multimode fiber path lengths of up to 2 km — a significant increase from the industry standard limits.
Let ComNet Help Optimize Your Multimode Fiber Use
As you can see, there are several things you can do to maximize and manage multimode fiber distance limits, but it’s not easy. Choosing the right fiber, wavelength, and technology requires a high level of technical expertise and professional judgment.
Fortunately, you don’t have to figure it out alone. Our ComNet Design Team is ready and willing to help. We offer a wide range of technology designed to help you maximize your multimode fiber range — including an extensive selection of SFPs and WDM optics. We also offer advanced design support from the experts in our ComNet Design Center.
Click the button below to see our SFP Modules or contact us to learn more about how we can help you with your multimode fiber network.