Theoptical fiber technology has made a significant contribution towardsthe revolution of the communication industry. The main objective ofadvancing the fiber technology has been to resolve the challenges(such as transmission losses and the speed of transmission) thatreduce efficiency in communication. 1Currently, the fiber technology is being applied in many industries,including the medical and communication. This paper will discuss thesingle-mode and the multi-mode fibers with a focus on the features,benefits, and major applications.
Themulti-mode fiber optic is a type of optic fiber cable with a largercore that has the capacity to permit the multiple modes to bepropagated. This creates a scenario in which the numbers ofreflections of light that occur as the light go through the coreincrease. This increases the possibility for more data to be passedthrough at any given time. 2The high dispersion coupled with the high rate of attenuation leadsto a decline in the quality of the signal over a long distance. Thislimits the application of the multi-mode optic fiber to audio / videoand short distance applications since the RF broadband that is usedby large cable companies may not be transmitted over the multi-modeoptic fiber. In most cases, the construction of the multi-mode opticfiber is classified as 62.5 / 125 and 50 /125. 3This means that its core to the cladding diameter ration should be 50microns – 125 microns and 62.5 microns – 125 microns.
Figure1: Multi-mode fiber
Source:ARC Electric (2015)
Althoughthe application of the multi-mode fiber optic is limited by highrates of dispersion, it has several uses. Multi-mode optic fiber isused in communication equipments that require a speed limit of about100 Mbit/s and a maximum distance of 2 km, 1 Gbits/s for a maximumdistance of 1 km, or 10 Gbits / s for a maximum distance of 550 m. 4In addition, multi-mode fiber optic has a backbone application inlarge buildings due to its high reliability and high capacity.Moreover, the multi-mode fiber has made it possible to centralize allelectronics within the communication room instead of allowing activeelectronics on each of the floors of a given building. Otherapplications of multi-mode fiber include the plain energy transport,delivery of high laser power in medical applications, and studyingcoupling characteristics.
Single-modefibers are designed to allow one propagation mode for eachpolarization direction and a given wavelength. Single-mode fibershave a relatively small core as well as the refractive indexdifference between the cladding and the core. 5One of its distinguishing features is the existence of transverseintensity at the fiber output that has fixed shape that isindependent of the properties of light, launch conditions. The launchcondition can only influence the efficiency of coupling light intosome guided mode. The key advantage of the single-mode fiber is thatit does not allow intermodal dispersion to occur. This allows for theapplication of the single-mode fiber in high data rate and longdistance transmissions. In addition, single-mode fiber is known forits low propagation losses, which facilitates its use in long-haultransmission of data as well as outdoor applications for shortdistances. 6
Figure2: Single-mode fiber
Source:ARC Electric (2015)
Thereare three major conditions for efficient launching of light into thesingle mode fiber. First, the source of light should have a highquality beam. Secondly, the light should have a focus at the inputend of the fiber in order to ensure that the plane wavelengths arematched. 7Lastly, the beam profile should have the correct shape and size andbe precisely aligned to the core. This means that the error inpositioning should be less than the radius of the beam and theangular misalignment kept smaller compared to the beam divergence ofthe transmission mode.
Thesingle-mode fiber has many applications, all of which can beattributed to its transmission efficiency. For example, single-modefiber is used in amplifiers and fiber lasers where its guidance isused as the basis for attaining a high quality beam as the output. 8Single-mode fibers are used in communication systems because itsguidance reduces the challenge of intermodal dispersion, which wouldotherwise result in the occurrence of many input signals at thereceiver. In addition, single-mode fibers are used in interferometerswhere different components are connected in the fiber optic setups.For this application to be accomplished, the fiver can be appliedtogether with the fiber connectors or be fusion-spliced.
Thefiber technology has helped scientists have a significantbreakthrough, especially in the communication sector. For example,multi-mode fiber facilitates the installation of short distance (suchas within the building) communication systems. The single-mode fiber,on the other hand, allows a long distance and efficienttransmissions. Single-mode fiber is mainly preferred forlong-distance transmission because it has less transmission lossesand it does not allow intermodal transmissions. Multi-mode fiber, onthe other hand, lacks these qualities, which limits its applicationto short-distance transmissions.
1.Paschotta (2014) explains the benefits that fiber technology hasbrought to different industries
2.See Multicom, Inc. (2015) for the key features of the multi-modefiber.
3.Multicom, Inc. (2015) explains different sizes of the multi-modefiber.
4.See Irujo (2011) for the key applications of the multi-mode fiber.
5.Paschotta (2014) explains different features of the single-modefiber.
6.See Paschotta (2014) for the key reasons for the application of thesingle-mode fiber in long-haul transmission.
7.Paschotta (2014) explains the major conditions for efficientlaunching of light into the single mode optic fiber.
8.See Paschotta (2014) for the key applications of the single-modefiber.
ARCElectric (2015). Fiber optics: Brief overview of fiber optic cableadvantages over copper. ARCElectric.Retrieved August 4, 2015, from http://www.arcelect.com/fibercable.htm
Irujo,T. (2011). Thenext generation of multi-mode fiber.Tokyo: Furukawa Electronic North America.
Multicom,Inc. (2015). Single-mode versus multi-mode fiber optic cable.Multicom.Retrieved August 4, 2015, fromhttp://www.multicominc.com/training/technical-resources/single-mode-vs-multi-mode-fiber-optic-cable/
Paschotta,R. (2014). Single-mode fiber. RPPhotonics.Retrieved August 4, 2015, fromhttp://www.rp-photonics.com/single_mode_fibers.html