Multimode fiber cable is a type of optical cable used for high-speed data transmission over short distances. It is widely used in local area networks, data centers, and other applications where high-bandwidth connectivity is required. In this blog post, we will discuss the key features and advantages of multimode fiber cable.

What is Multimode Fiber Cable?

Multimode fiber allows multiple modes or paths of light to travel through the fiber core. Multimode fiber can only support transmission over short distances. At longer distances, light traveling in different modes will interfere with each other, causing signal degradation and bit errors. The core diameter of multimode fiber is typically larger than that of single-mode fiber, allowing more light to be transmitted.
Multimode fiber cables are commonly used in local area networks (LANs) ,data centers, and other applications that require high-bandwidth transmission over short distances. It is also used in applications such as video transmission and security systems.
Compared to single-mode fiber cable, multimode fiber cable has a shorter maximum transmission distance and lower maximum bandwidth. but is generally easier to install. For short-distance applications, the overall cost of a multimode system will usually be less than that of a single-mode transmission system.


Multimode Optical Fiber

Structure of an optical fiber

Difference between Multimode and Single-mode fiber

Here are some key differences between multimode and single-mode fiber and cable:

  • Core Diameter: The core diameter of multimode fiber is usually 50 microns, although 62.5 microns is found in some legacy applications. In contrast, the core diameter of single-mode fiber is usually 9 microns.
  • Distance: Single-mode fiber cable can transmit data over much longer distances than multimode fiber cable. Multimode fiber cable is generally used for distances of less than 300m and can support transmission up to 2 km at relatively low data transmission rates. Single-mode fiber can transmit data over distances of up to 40 km or more, with very high transmission rates possible when wavelength-division multiplexing is used.
  • Light Source: Multimode fiber cable is typically used with low-cost LED or VCSEL (vertical cavity surface-emitting laser) light sources, while single-mode fiber cable is exclusively used with laser light sources.
  • Cost: Due to the relative cost of the light sources, for short-distance applications, multimode fiber cable systems are generally less expensive than single-mode fiber cable systems.
  • Applications: Multimode fiber cable is commonly used in LANs, data centers, and CCTV systems, where the overall cost of a multimode system is less than that of singlemode. Single-mode fiber cable is typically used for long-distance applications, such as telecommunication networks and cable TV systems, with transmission distances beyond the range of multimode fiber.

How Do Multimode Fiber Work?

Multimode fiber works by using multiple paths or modes to transmit light signals over short distances. The fiber consists of a core, which is the central part of the cable where the light travels, a cladding layer, which surrounds the core and helps to keep the light confined within the core, and a coating to cushion and protect the fiber.
When light is transmitted through a multimode fiber, it enters the core at one end of the cable and is reflected off the walls of the core at different angles. These multiple angles cause the light to take multiple paths, or modes, through the core, hence the name "multimode" fiber. The light signals are transmitted over these multiple modes simultaneously, allowing for multiple signals to be transmitted at the same time.
However, because the light takes multiple paths through the core, the signals tend to degrade as they travel farther down the fiber. This is known as modal dispersion, and it limits the range of multimode fiber compared to single-mode fiber.
To compensate for this degradation, multimode fibers are typically designed with a larger core diameter, which allows for more modes to be transmitted at the same time, increasing the bandwidth of the cable. Additionally, multimode fiber cables may be used with specialized transceivers or other equipment that can help reduce modal dispersion and increase the range of the cable.
Multimode fibers are commonly used in LANs, data centers, and campus applications where the cables containing and protecting the fiber are completely or partially run within buildings. As a result, multimode fiber cables are often flame-retardant to protect human life and safety.

Conclusion

Multimode fiber cable is an excellent cost-effective choice for high-speed data transmission in a variety of applications where the transmission distance is relatively short. Its ability to carry multiple modes of light launched by low-cost LED and VCSEL sources allows for fast and efficient data transfer. With its relatively low system cost and easy installation and maintenance, it's no wonder that multimode fiber cable is a popular choice for many businesses and organizations.

FAQs

The range of multimode fiber cable varies depending on the specific type of cable, as well as the equipment used in the transmission system. Generally, multimode fiber can transmit data up to distances of around 550 meters for 10 Gigabit Ethernet transmissions, and up to 2 kilometers for Gigabit Ethernet transmissions.
However, there are different types of multimode fiber, such as OM1, OM2, OM3, and OM4, with varying bandwidth and distance capabilities. For example, OM1 has a bandwidth of 200 MHzkm and a distance range of up to 33 meters for 10 Gigabit Ethernet, while OM4 has a bandwidth of 4700 MHzkm and can transmit data up to 400 meters for 10 Gigabit Ethernet.
It's important to note that single-mode fiber has a much greater range than multimode fiber, making it a better choice for long-distance transmissions. Single-mode fiber can transmit data up to distances of tens or even hundreds of kilometers, depending on the transmission equipment used.

Multimode fiber is commonly used in local area networks (LANs), data centers, and other applications where data needs to be transmitted over relatively short distances. Some specific examples of where multimode fiber is used include:

  • Campus networks: Multimode fiber is often used to connect buildings on a college or university campus, where the distances are relatively short.
  • Data centers: Multimode fiber is widely used in data centers to connect servers, switches, and other networking equipment within the same data center.
  • LANs: Multimode fiber is used in LANs to connect computers and other devices within a building or office.
  • CCTV: Multimode fiber is sometimes used for CCTV systems, where it can transmit video signals over relatively short distances.
  • Audiovisual systems: Multimode fiber can be used to transmit high-quality audio and video signals over short distances in auditoriums, theaters, and other venues.

Multimode fiber is typically used for short distance applications, such as in buildings or campuses, where data is transmitted over relatively short distances. It is commonly used for LANs, data centers, and security systems, as it can transmit multiple signals simultaneously.

Multimode fiber transmits data by using multiple modes of light that travel through the fiber's larger core. A light source injects light into the fiber at an angle, causing the light to bounce off the core/cladding boundary at different angles, resulting in multiple modes of light traveling through the fiber. Different levels of attenuation or loss can occur, so multimode fibers may use various techniques to mitigate these effects. Overall, multimode fiber allows for the transmission of higher amounts of data over shorter distances.