#TechExchange: Fiber Optic Cables In Detail

Currently fiber broadband is the hottest Internet service in Africa and across all other continents. The robust and fierce network speeds offered by fibre optic cables is the main reason for everyone to switch to fibre broadband ISP’s such as ZOL. Today we are looking deeper into the finer optic cable infrastructure so that we demystify the supremacy behind the fierce optical networks.

By Engineer Shingie Lev Muringi

These cables permit long range transmission of data far much better than any other network media such as Copper. Optical fibres are very flexible but extremely thin transparent strands made of pure glass called silica and are of the same size with human hair.

Looking into the mechanism of data transmission using fibre cables, its optical structure acts as a waveguide or “light pipe” to carry network traffic between two end points with minimal loss of signal. The main merit of using Fiber Optic cables over Copper is their ability to transmit data signals with less attenuation aided by their complete immune to Electrical Magnetic Interference (EMI) and Radio Frequency Interference (RFI).

Fiber Strands

Fiber Optic Cross Section during data transmission

Fiber Optic cables are now being deployed on various enterprise levels which include Fiber-to-the-Home, Enterprise Networks for Backbone Support, Long-Haul Networks and Submarine Networks which are used to provide inter-continental connectivity. Recently, Liquid Telecom announced its plans to start deploying submarine optical cables aimed to give direct connectivity between Africa and the  Far East.

These cables are capable of producing reliable high speed bandwidth, and can carry mega data under harsh sea conditions over very long transoceanic distances. Within regions, fiber cables are deployed to support backbone enterprise networks where they connect huge infrastructure devices such as data center switches such as the Cisco Nexus 7000 Series to enterprise routers.

Fiber Infrastructure

Fiber Optic Infrastructure after deployment

Fiber Optic cables are classified into two broad categories, Single Mode Fiber (SMF) and Multi-Mode Fiber (MMF). Singe Mode fiber consists of a very small core and uses expensive laser technology to send data in a single ray of light. Engineers deploy this fiber cable mode in long-distance situations spanning hundreds of kilometers. Single Mode Fiber is highly suitable for long-haul telephony and cable TV Applications.

Multi-Mode Fiber consists of a larger core and uses LED emitters to transmit data in light pulses. This fiber cable type is popular in Local Area Networks (LANs) where it is used to provide high bandwidth in compass networks. Currently MMF provides speeds close to 10Gbls over a link length of up to 550 meters.

Fiber MM

Multi-Mode Fiber Patch Code

The only major difference between SMF and MMF is that Multi-Mode Fiber allows greater dispersion resulting in attenuation. Attenuation is phenomenon which results in loss of signal strength after data has traversed a long distance limited to the media capacity. Attenuation is solved by installing Repeaters or Regenerators after every 100km for single mode fiber and around 500m for multi-mode fiber.

For in-house connections, Fiber optic connectors are used to connect devices, whether wifi-routers to switches, switches to routers, routers to firewalls or switches to any other end devices. These fiber connectors terminate the end of an optical fiber. The connectors vary according to dimensions and methods used for mechanical coupling.

Fiber Patch Codes

Single Mode Fiber Patch Codes

Accounting all the generations of these fiber optic connectors, about 70 types of connectors are in use today. The popular used here in Zimbabwe and around Africa include the Subscriber Connector (SC), Straight Tip (ST), Lucent Connector (LC), and Ferule Connectors. The connectors are coupled into patch codes to provide two way connectivity when transmitting data.

The Fiber Optic cables are classified under the TIA 598 Standards which recommends the use of Yellow jackets for Single Mode Fiber and Orange or Aqua jackets for Multi-Mode Fiber.

To be Continued …….

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