Comparison Between MMF and SMF Optical Cables

According to different standards, fiber optic cables can be categorized into different classifications. One way is to classify the cable into single-mode fiber (SMF) and multimode fiber (MMF). The comparison between these two types of optical cables can assist you in choosing the most suitable cable for device. This article will compare the two kinds of cables from cable path, distance, precision termination, cost and color. Hope you can find some useful information from the article.

Single Path Vs. Multiple Paths

SMF uses laser light which usually follows a single path through the fiber. MMF takes multiple paths, which may result in a differential mode delay. Each type of fiber can be applied for different equipment. It’s important to know which application is more suitable for practical use. Otherwise, it will not operate at optimal levels.

SMF-and-MMF-paths

Short Distances Vs. Long Distances

SMF is used for long distance communication, and MMF is used for distances of 500m or less. Each type is equally as effective when chosen for the proper communication device. Make sure to check the ratings to determine which type is best for your application. The distances should be clearly marked.

Thick Core Size Vs. Thin Core Size

SMF typically has a smaller core size of 8.3 to 10 microns in diameter which is more precise for signal transmission in long distance, while the core size of MMF is much larger than SMF from 50 to100 microns in diameter which is more suitable for short distance transmission owing to the signal distortion. With a thinner core size, SMF is only allowed to carry a single light-wave along a single path, while the thick core size makes MMF able to carry different light-waves along numerous paths without modal dispersion limitation.

SMF-and-MMF-core-size

Low Cost Vs. High Cost

MMF is typically a lower cost solution than SMF. Limited budget may prompt designers to seek solutions with MMF fiber optic cables. The equipment that’s used for communications over MMF is usually less expensive than SMF. But the typical transmission speed and distance of MMF have limitations of 100 Mbit/s for distances up to 2 km.

Color Differences

MMF and SMF cables can also be distinguished by color. Usually, yellow is used for SMF cable color and orange or aqua is used for MMF cables. It is much easier to distinguish them just by their appearance color.

SMF-and-MMF

Other Primary Differences

MMF is typically characterized by having a larger core diameter. In most cases, it’s larger than the wavelength of light it supports. Therefore, MMF has more capacity to gather light than SMF. A larger core size means that designers can create a lower cost electronic device and offer a lower price to the public. Also, by using light-emitting diodes (LEDs) and vertical-cavity surface-emitting lasers (VCSELs), the costs can be driven down even more.

Conclusion

SMF and MMF are two different optic cables which have their own separate application fields. It is terribly wrong for not selecting suitable SMF or MMF patch cables according to the application. Think twice before you are certain that the cable is the best choice for your project. If you want to know more details about SMF and MMF fiber optic cables, FS.COM can solve all your problems.

In-depth Understanding of Fiber Optic Cables

The commitment to fiber optic technology has spanned more than 30 years, and nowadays a high level of glass purity, fiber optic cable, has been achieved owing to the continuous research and development. This purity, combined with improved system electronics, enables to transmit digitized light signals over hundreds of kilometers with high performance, offering many advantages in fiber optic systems. This text provides an overview of the construction, categories, and working principles of this fiber optic cable.

Construction of Fiber Optic Cable

Fiber optic cable generally consists of fiver elements : the optic core, optic cladding, a buffer material, a strength material and the outer jacket. Here, much more detailed information is attributive to the optic core and optic cladding which are both made from doped silica (glass).

The Optic Core and Cladding Details

The optic core is the light-carrying element at the center of the cable, and the optic cladding surrounds the optic core. Their combination makes the principle of total internal reflection possible. Besides, a protective acrylate coating then surrounds the cladding. In most cases, the protective coating is a dual layer composition: a soft inner layer that cushions the fiber and allows the coating to be stripped from the glass mechanically, and a harder outer layer that protects the fiber during handling, particularly the cabling, installation, and termination processes. This coating protects the glass from dust and scratches that can affect fiber strength.

Optic Core and Cladding, makes reflection possible

Categories of Fiber Optic Cable

There are two general categories of fiber optic cable: single-mode fiber (SMF) and multi-mode fiber (MMF).

MMF was the first type of fiber to be commercialized. It has a core of 50 to 62.5 µm in diameter much larger than SMF, allowing hundreds of modes of light to propagate through the fiber simultaneously. Additionally, the larger core diameter of MMF facilitates the use of lower-cost optical transmitters (such as light emitting diodes or vertical cavity surface emitting lasers) and connectors, more suitable for relatively shorter-reach application. Take 1 Gigabit Ethernet (GbE) applications for example, MMF is deployed to establish 550m link length with 1000BASE-SX SFPs (eg. Cisco Meraki MA-SFP-1GB-SX).

SMF, in contrast, has a much smaller core, approximately 8 to 10 µm in diameter, which allows only one mode of light at a time to propagate through the core. It’s designed to maintain spatial and spectral integrity of each optical signal over longer distances, permitting more information to be transmitted. Similarly, as for 1GbE applications, SMF is able to realize 70km reach with 1000BASE-ZX SFPs, like GLC-ZX-SM, a product compatible with Cisco listed in Fiberstore.

GLC-ZX-SM, 1000BASE-ZX SFP

Working Principles of Fiber Optic Cable

The operation of a fiber optic cable is based on the principle of total internal reflection. Light reflects (bounces back) or refracts (alters its direction while penetrating a different medium), depending on the angle at which it strikes a surface.

This principle comes at the center of how fiber optic cable works. Controlling the angle at which the lightwaves are transmitted makes it possible to control how efficiently they reach their destination. Lightwaves are guided through the core of the fiber optic cable in much the same way that radio frequency (RF) signals are guided through coaxial cable. The lightwaves are guided to the other end of the fiber being reflected within the core. The composition of the cladding glass related to the core glass determines the fiber’s ability to reflect light. That reflection is usually caused by creating a higher refractive index in the core of the glass instead of in the surrounding cladding glass, creating a waveguide. The refractive index of the core is increased by slightly modifying the composition of the core glass, generally by adding small amounts of a dopant. Alternatively, the waveguide can be created by reducing the refractive index of the cladding using different dopants.

Conclusion

In fiber optic cables, the light can carry more information over longer distances than the amount carried in a copper or coaxial medium or radio frequencies through a wireless medium. With few transmission losses, low interference, and high bandwidth, fiber optic cables are the ideal transmission medium. Fiberstore offers various kinds of fiber optic cables, including SMF and MMF types, simplex and duplex fiber optic cables, indoor distribution cables and outdoor loose tube cables, etc. For more information about fiber optic cables, you can visit Fiberstore.

FAQs About Laser-Optimized Fiber

Fiber optical networks have dominated for long-haul communications for years, increasingly used in short distance applications, such as local area networks (LANs). And the Ethernet data-rate needed for these high-performance fiber optic networks increases from 1Gbps to 10Gbps, to 40Gbps, to 100Gbps, or even higher. Together with this speed increase, a term, laser-optimized fiber, has crept into the telecommunication market. What is laser-optimized fiber? How much do you know about it? Knowing answers to these frequently asked questions (FAQs) about laser-optimized fiber will help you prepare for the latest wave in optical communication networks.

FAQ 1: What Is Laser-Optimized Fiber?

Laser-optimized multi-mode fiber (LOMMF: OM3 & OM4) differs from standard MMF (OM1 & OM2), because the former has graded refractive index profile fiber optic cable in each assembly. This means that the refractive index of the core glass decreases toward the outer cladding, so the paths of light towards the outer edge of the fiber travel quicker than the other paths. This increase in speed equalizes the travel time for both short and long light paths, ensuring accurate information transmission and receipt over much greater distances up to 300 meters (OM3) and 400 meters (OM4) at 10Gbps, while OM1 and OM2 can only realize 26 meters and 33 meters link length respectively at the same data rate. And when 1000BASE-SX SFP transceivers transmit and receive signals over LOMMF and standard MMF at 1Gbps, the possible link lengths achieved are also different, with OM1 275-meter reach, OM2, OM3, and OM4 up to 550-meter reach. Take MGBSX1 for example, this compatible Cisco 1000BASE-SX SFP listed in Fiberstore supports up to 550-meter link length over OM2.

MGBSX1, 550m link length over MMF

FAQ 2: Why Have MMF Been “Optimized” for Use with Lasers?

As the demand for bandwidth and higher throughput increased, especially in building and campus backbones, LEDs, short for Light Emitting Diodes, that are used as light sources in fiber optic systems could not keep pace. With a maximum modulation rate of 622Mb/s, LEDs would not support the 1 Gb/s and greater transmission rates required. The use of traditional lasers (Fabry-Perot, Distributed Feedback) typically used over single-mode fiber (SMF) could accommodate this problem. However, it’s very expensive due to the higher performance characteristics required for long-distance transmission on SMF. As such, a high-speed laser light source, a Vertical Cavity Surface Emitting Laser (VCSEL) was developed. These VCSELs are inexpensive, suited for low-cost 850nm multi-mode transmission systems, allowing for data rates up to 100Gbps in the enterprise. With the emergence of these VCSELs, MMFs have been “optimized” for operation with lasers.

FAQ 3: Why Are LOMMFs the Best Choice for Use with VCSELs?

After VCSELs appears, to fully capitalize on the benefits that VCSELs offer, LOMMFs have been specifically designed, fabricated, and tested for efficient and reliable use with VCSELs.

LOMMF,specifically designed, fabricated, and tested

LOMMFs have a well-designed and carefully controlled refractive index profile to ensure optimum light transmission with a VCSEL. Precise control of the refractive index profile minimizes the modal dispersion, also known as Differential Mode Delay (DMD). This ensures that all modes, or light paths in the fiber arrive at the receiver at about the same time, minimizing pulse spreading and, therefore, maximizing bandwidth.

LOMMF is completely compatible with LEDs and other fiber optic applications. LOMMFs can be installed at slower data rates or higher data rate. When there occurs the data rate migration from 10Gbps to 40Gbps, there is no need to pull new cable. You only need to upgrade the optics modules to VCSEL-based transceivers, avoiding infrastructure redesign.

Conclusion

LOMMFs are the suitable medium for short-wave 10G optical transmission. Their great bandwidth- and information-carrying capacity make them more popular among consumers than standard MMFs especially in 10GbE systems. Fiberstore supplies countless OM3 and OM4, as well as OM1 and OM2 for your network projects. Besides, other kinds of fiber optic cables, like MTP cable and SMF, are also available in Fiberstore. For more information about fiber optic cables, please visit Fiberstore.