How a Fiber Optic Cable Works

How a Fiber Optic Cable Works

Light pulses move easily down the fiber-optic line because of a principle known as total internal reflection. "This principle of total internal reflection states that when the angle of incidence exceeds a critical value, light cannot get out of the glass; instead, the light bounces back in. When this principle is applied to the construction of the fiber-optic strand, it is possible to transmit information down fiber lines in the form of light pulses. The core must a very clear and pure material for the light or in most cases near infrared light (850nm, 1300nm and 1500nm). The core can be Plastic (used for very short distances) but most are made from glass. Glass optical fibers are almost always made from pure silica, but some other materials, such as fluorozirconate, fluoroaluminate, and chalcogenide glasses, are used for longer-wavelength infrared applications.

There are three types of fiber optic cable commonly used: single mode, multimode and plastic optical fiber (POF).

Transparent glass or plastic fibers which allow light to be guided from one end to the other with minimal loss.

Single Mode cable is a single stand (most applications use 2 fibers) of glass fiber with a diameter of

8.3 to 10 microns that has one mode of transmission. Single Mode Fiber with a relatively narrow diameter, through which only one mode will propagate typically 1310 or 1550nm. Carries higher bandwidth than multimode fiber, but requires a light source with a narrow spectral width. Synonyms mono-mode optical fiber, single-mode fiber, single-mode optical waveguide, uni-mode fiber.

Single Modem fiber is used in many applications where data is sent at multi-frequency (WDM Wave-Division-Multiplexing) so only one cable is needed - (single-mode on one single fiber)

Single-mode fiber gives you a higher transmission rate and up to 50 times more distance than multimode, but it also costs more. Single-mode fiber has a much smaller core than multimode. The smallcore and single light-wave virtually eliminate any distortion that could result from overlapping light pulses, providing the least signal attenuation and the highest transmission speeds of any fiber cable type.

Single-mode optical fiber is an optical fiber in which only the lowest order bound mode can propagate at the wavelength of interest typically 1300 to 1320nm.

Multi-Mode cable has a little bit bigger diameter, with a common diameters in the 50-to-100 micron range for the light carry component (in the US the most common size is 62.5um). Most applications in which Multi-mode fiber is used, 2 fibers are used (WDM is not normally used on multi-mode fiber). POF is a newer plastic-based cable which promises performance similar to glass cable on very short runs, but at a lower cost.

Multimode fiber gives you high bandwidth at high speeds (10 to 100MBS - Gigabit to 275m to 2km) over medium distances. Light waves are dispersed into numerous paths, or modes, as they travel through the cable's core typically 850 or 1300nm. Typical multimode fiber core diameters are 50, 62.5,and 100 micrometers. However, in long cable runs (greater than 3000 feet [914.4 meters), multiple paths of light can cause signal distortion at the receiving end, resulting in an unclear and incomplete data transmission so designers now call for single mode fiber in new applications using Gigabit and beyond.

Distribution Cable (compact building cable) packages individual 900µm buffered fiber reducing size and cost when compared to breakout cable. The connectors may be installed directly on the 900µm buffered fiber at the breakout box location. The space saving (OFNR) rated cable may be installed where ever breakout cable is used. FIS will connectorize directly onto 900µm fiber or will build up ends to a 3mm jacketed fiber before the connectors are installed.

FIS now offers indoor/outdoor rated tight buffer cables in Riser and Plenum rated versions. These cables are flexible, easy to handle and simple to install. Since they do not use gel, the connectors can be terminated directly onto the fiber without difficult to use breakout kits. This provides an easy and overall less expensive installation. (Temperature rating -40ºC to +85ºC).

FIS indoor/outdoor rated breakout style cables are easy to install and simple to terminate without the need for fanout kits. These rugged and durable cables are OFNR rated so they can be used indoors, while also having a -40c to +85c operating temperature range and the benefits of fungus, water and UV protection making them perfect for outdoor applications. They come standard with 2.5mm sub units and they are available in plenum rated versions.

Corning Cable Systems FREEDM® LST™ cables are OFNR-rated, UV-resistant, fully waterblocked indoor/outdoor cables. This innovative DRY™ cable with water blocking technology eliminates the need for traditional flooding compound, providing more efficient and craft-friendly cable preparation. Available in 62.5µm, 50µm, Singlemode and hybrid versions.

KRONE’s innovative line of indoor/outdoor loose tube cables are designed to meet all the rigors of the outside plant environment, and the necessary fire ratings to be installed inside the building. These cables eliminate the gel filler of traditional loose tube style cables with super absorbent polymers.

Loose Tube Cable

`Loose tube cable is designed to endure outside temperatures and high moisture conditions. The fibers are loosely packaged in gel filled buffer tubes to repel water.Recommended for use between buildings that are unprotected from outside elements. Loose tube cable is restricted from inside building use, typically allowing entry not to exceed 50 feet .

Aerial Cable/Self-Supporting

Aerial cable provides ease of installation and reduces time and cost. Figure 8 cable can easily be separated between the fiber and the messenger. Temperature range ( -55ºC to +85ºC) Hybrid & Composite Cable

Hybrid cables

Hybrid cables offer the same great benefits as our standard indoor/outdoor cables, with the convenience of installing multimode and singlemode fibers all in one pull. Our composite cables offer optical fiber along with solid 14 gauge wires suitable for a variety of uses including power, grounding and other electronic controls.

Armored Cable

Armored cable can be used for rodent protection in direct burial if required. This cable is non-gel filled and can also be used in aerial applications. The armor can be removed leaving the inner cable suitable for any indoor/outdoor use. (Temperature rating -40ºC to +85ºC)

Low Smoke Zero Halogen (LSZH)

Low Smoke Zero Halogen cables are offered as as alternative for halogen free applications. Less toxic and slower to ignite, they are a good choice for many international installations. We offer them in many styles as well as simplex, duplex and 1.6mm designs. This cable is riser rated and contains no flooding gel, which makes the need for a separate point of termination unnecessary. Since splicing is eliminated, termination hardware and labor times are reduced, saving you time and money. This cable may be run through risers directly to a convenient network hub or splicing closet for interconnection.

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