Difference Between Single Mode Fibers And Multi-mode Fiber

Single Mode Fibers

In fiber optic communication, a single-mode optical fiber is an optical fiber designed to carry only a single mode of light, the transverse mode. Single –mode fibers achieve large transmission capacities, transports coherent light and maintain state of polarization over a longer distance and can be used for a variety of sensing applications.

 Single-mode optical fiber can also refer to as fundamental or mono-mode fiber, Uni-mode fiber or Single mode optical waveguide. Single mode fiber provides users with a greater transmission rate in addition to nearly 50 times longer distance as opposed to multimode fiber. In this regard, single mode fibers will require single mode transmitters which use solid-state laser diodes.  The cost of this transmitter equipment may be 5 or 6 times more than that of multimode equipment.

The optical fiber itself has three most important parts, the core, the cladding and the coating or buffer. The most central part is the core through which light travels. Single mode fiber optic cable has a small diameter core that only allows one mode of light ray to propagate. Also due to single core in single mode fiber, the light reflections will be less and hence attenuation is lower which makes light signal to reach on the other end faster. It is also important to note that, a single-mode fiber with an ideal circular core has no polarization dispersion.

Single mode fibers can be classified depending on operating wavelengths, distance and transmission link architecture which include various amplification methods. Types of single mode fibers include:

• Standard single mode fiber (G.652)
• Cutoff shifted fiber (G.654)
• Low water peak fiber (G.652)
• Dispersion shifted fiber (G.653)
• Non-zero dispersion shifted fiber (G.655).

What You Need To Know About Single Mode Fibers

1. Single mode fiber optic cable has a small diameter core that only allows one mode of light ray to propagate. The core is usually between 8 and 10 microns in diameter.
2. Due to single core in single mode fiber, the light reflections will be less and hence attenuation is lower which makes light signal to reach on the other end faster.
3. Signal transmission capacity in single mode fibers is less.
4. Single mode fibers are suitable for long distance communication and for carrying high bandwidth signal with the help of laser diode as optical transmission system equipment.
5. Single mode step index fibers have less core diameter (<10µm) and the difference between refractive indices of the core and cladding is very small.
6. In single mode fibers, there is no signal dispersion and distortion.
7. Single mode fibers provide higher performance but building the network is relatively expensive.
8. Broadband Radio Frequency (RF) signals can be propagated through single mode fiber optical cable.
9. Major applications of single mode are CATV, Telcos, universities as well as collages.
10. Single mode fiber is usually yellow in color.

Multimode Fibers

Multimode optical fiber is a type of optical fiber mostly used for communication over short distances such as within a building or on campus. Multimode links can be used for data rates up to 100 Gbits/s. multimode fiber optic cable is made of glass fibers and has a large diameter core that allows multiple modes of light to propagate. Because of this, the number of light reflections created as the light passes through the core increases, creating the ability for more data to pass through at a given time.

However, due to a relatively large light carrying core usually 62.5 microns, the light reflections in multimode fiber are more and hence attenuation is higher which makes light signal to reach the other end slower. In this regard, due to large dispersion and attenuation, multimode fibers are suitable for short distance communication with LED based fiber optic equipment.  Multimode will allow transmission distances of up to about 10 miles and will allow the use of relatively inexpensive fiber optic transmitters and receivers.

There are two major types of multimode fiber, which include step-index and graded-index multimode fiber. Other types include OM1, OM2, OM3, OM4 and OM5 which vary in terms of core diameter and bandwidth.

What You Need To Know About Multimode Fibers

1. Multimode fiber optic cable has a large diameter core that allows multiple modes of light to propagate. The core is usually 62.5 microns or larger in diameter.
2. Due to multiple cores in multimode fiber, the light reflections will be more and hence attenuation is higher which makes light signal to reach the other end slower.
3. Signal transmission capacity is more in multimode fibers.
4. Due to large dispersion and attenuation, multimode fibers are suitable for short distance communication with LED based fiber optic equipment.
5. Multimode step index fibers have larger core diameter (50 to 200 µm) and the difference between the refractive indices of the core and cladding is large.
6. In multimode fibers, there is signal distortion and dispersion.
7. Fabrication of the multimode fiber is more costly, however, the deployment of the network is relatively inexpensive.
8. Broadband Radio Frequency (RF) signals cannot be propagated through multimode fiber optical cable.
9. Multimode fiber is used for short distance communication mainly for video/audio/data based wireless LAN application.
10. The color of multimode fibers depends on the type of the fiber. OM1 and OM2 fibers are usually orange, OM3 aqua, OM4 aqua or pink and OM5 light green.

Also Read: Difference Between Step Index Fiber And Graded Index Fiber

Difference Between Single Mode Fibers And Multimode Fiber In Tabular Form