fiber optic systems, tx , rx, fiber, connectors and types

7/30/2019 fiber optic systems, tx , rx, fiber, connectors and types

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Introduction

[1] Fiber optics has many advantages over copper. You can build much longer point to pointlinks using fiber than is possible with conventional wire cables, the bandwidth is much wider, it is lighterand it occupies less space. By careful adoption of the available tools, you can also multiplex many signals

of different types onto a single fiber link. The link can even be bi-directional.

[2] Fiber optic cable is available in single-mode and multi-mode types. Multi-mode cable has alarger core diameter (50um or 62.5um) than single-mode fiber (9um core diameter). When light travelsdown multi-mode fiber it is reflected at different angles as it propagates down the transmission path.These multiple reflections cause the light to spread out in time as it propagates down the fiber, makingit more difficult for the receiver to recover the data. Single-mode fiber being much narrower, confinesthe optical signal to a straighter path with fewer reflections. As a result, optical signal dispersion issignificantly reduced, which translates into a cleaner signal. Longer transmission lengths can thereforebe achieved with single mode cable. It is also a bonus that single-mode fiber can now be purchased forthe same or less than multi-mode fiber. Single-mode and multi-mode cable should not be mixed in thesame system. However, if really necessary, it is possible to use multi-mode fiber downstream of single-mode fiber, as the larger diameter multi-mode fiber will collect most of the light emitted from the singlemode fiber.


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System Design

The basic elements found in fiber optic systems are: Transmitter, Fiber optic cable, Receiver, andConnectors. These elements are the foundations to make possible and efficient fiber optic system/

optical transmission/reception system.

1. Transmitter

Converts an electrical signal to a light signal, consists of a driver and a source. The source is either a LEDor a Laser Diode.


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2. Fiber Optic Cable

This is a medium for carrying the light signal. The optical fiber contains two concentric layers called thecore and the cladding. The main parts of a fiber cable are the optical fiber, cladding, buffer jacket,buffer, strength members, and jacket.

2.1 Hybrid or Composite Optical Cables

When single mode and multimode cables is packet together in a single tube then this type oroptical cable is known as hybrid optical cable. This kind of cable can be constructed with differentcombinations of single and multimode cables. Like 4 multimode and 4 single mode cables can be twistedtogether as single cable and packed in a protective plastic tube.

2.2 Fiber Optic Cable Color

For data center premise cables, the jacket color depends on the fiber type in the cable. Forcables containing single mode fibers, the jacket color is typically yellow, whereas for cables containingmultimode fibers, the jacket color is typically orange. For outside plant cables, the standard jacket coloris typically black.


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2.3 Types of Fiber Optic Cable (Most Popular Fiber Optic Cable Types)

1. Indoor Cables1.1.1 Simplex Fiber Cables

A single cable structure with a single fiber. Simplex cable varieties include

1.6mm and 3mm jacket sizes.1.1.2 Duplex Fiber Cable

cable contains two optical fibers in a single cable structure. Light is not coupledbetween the two fibers; typically one fiber is used to transmit signals in onedirection and the other receives.

1.1.3 Ribbon Fiber CablesConsist of up to 12 fibers contained side by side within a single jacket. Often

used for network applications and data centers.1.1.4 LSZH Fiber Cables

Low Smoke Zero Halogen cables are offered as an alternative for halogen freeapplications. Less toxic and slower to ignite, they are a good choice for manyinternal installations. They are available as simplex, duplex, and 1.6mm designs. Thiscable may be run through risers directly to a convenient network or splicing closetfor interconnection.

2. Outdoor Fiber Cable2.2.1 Outdoor Loose Tube Fiber Optic Cables

Tube encloses multiple coated fibers that are surrounded by a gel compound thatprotects the cable from moisture in outside environments. Cable is restricted from indoor use,typically allowing not to exceed 50 feet.

2.2.2 Indoor/Outdoor Tight buffered Fiber Cables

Indoor/outdoor rated tight buffered cables have riser and plenum rated versions. Thesecables are flexible, easy to handle and simple to install. Since they do not use gel, the connectorscan be terminated directly onto the 900um fiber without difficult to-use kits. This provides aneasy and overall less expensive installation.

2.2.3 Indoor/Outdoor Dry Loose Tube Fiber Optic

This cable is suitable for both indoor and outdoor applications. One advantage of thiscable is that it eliminates of this cable is that it eliminates the need for a splice or connector at

the point where the cable transitions between an outdoor and indoor environment.

3. Aerial/Self-SupportingAerial/self-supporting fiber cables are designed to be strung from poles outdoors and most canalso be installed in underground ducts. They have internal stress members of steel of steel oraramid yarn that protect fibers from stress.


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4. Direct-buried4.4.1 Armored Fiber Optic CableArmored cables are similar to outdoor cables but include an outer armor layer for mechanicalprotection and to prevent damage. They can be installed in ducts or aerially or directly buriedunderground. Armor is surrounded by a polyethylene jacket. Armored cable can be used for

rodent protection in direct burial if required. This cable is non-gel filled and can also be used inaerial applications. The armor be removed leaving the inner cable suitable for anyindoor/outdoor use. Temperature rating -40 to +85 *C.

5. Submarine Fiber Optic Cable (Undersea Fiber Optic Cable)Submarine cables are used in fresh or salt water. To protect them from damage by fishingtrawlers and boat anchors they have elaborately designed structures and armors. Long distancesubmarine cables are especially complex designed.

2.4 Receiver

Accepts the light signal and converts it back to an electrical signal. Contains a detector,amplifier, and output section. Connectors is a disconnectable device used to connect a fiber to asource, detector or another fiber

2.5 Connectors

is a disconnectable device used to connect a fiber to a source, detector or another fiber.

fiber optic systems, tx , rx, fiber, connectors and types

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