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Voice Through the wire of light: Fiber optics

 Voice Through the wire of light: Fiber optics

God Rays

About Bifröst of Com. engineering


Optical fiber cables or fiber optics transmit data/information as light pulses/beams along a thin plastic or glass fiber. Consisting of few to a few hundred at fibers in a bundle covered by another layer called the cladding and finally surrounding it with a protective plastic/rubber jacket called the …. Jacket :D .

Cross section
Detailed Cross section








    So these fibers transport data at the speed of Light, but does not reach the destination as fast it is transmitted, because the total internal reflection[1] increases the length of which the light beam should travel anddd because glass has a higher refractive index[2] than air (therefore light travels slower). So roughly the speed is cut down to 1/3rd of the original speed. 




So there are 2 main types of FO cables


2 Types of FOC



1.Single Mode Fiber: In the industry we can identify it with the signature yellow color, this beautifully colored lemony cables are used at long distances which dont require much booster/repeaters. Having a small diameter reduces the attenuation and gives a direct route to travel.


2.Multi Mode Cables: Uses larger cores enabling a multitude of beams to enter (of multiple frequencies) and  more bandwidth. But downsides is that it requires the use of multiple repeaters. And all these frequencies are mixed in when inputting and requires a seperator in the end, these components are called multiplexer and demultiplexer respectively. More on that on the next topic

  • Multimode step: Contains layers of glass/plastic of different RI which gives better and clearer signal but scattering occurs to much and diffraction so the signal disrupts due to latency.

  • Multimode Graded: Layers are varied gradually making even waveforms throughout the fiber. Chromatic aberration occurs due to that(Splitting of light into different colours)  



How light travels through it

Core Diameters

Ray diagrams of the main types of FOC




"UNLIMITED POWER!.." MUX/ DEMUX


Emperor Palpatines famous words.

So the Multi mode cables require a component called a multiplexer which mixes all these different frequency beams together into a band of beams.



MUX/DEMUX


 And a demulter uses reverse combination of optics(mirrors, lenses, prisms) to separate each beam from the band. Usually the client and server both contain this demux/mux setup.

On our field visit SLT’s submarine base station , the engineers there taught us about the functions and setups used by Sri Lanka. Here we saw these expensive units.

Location: https://www.submarinenetworks.com/stations/asia/sri-lanka


So according to the engineers in Matara the optical fibers can handle 100 or 1000 times more traffic and data through them till saturation . The speed and amount of data transported through the fiber depends on the mux and demux used, thereby making them capable of transporting unlimited amount of data(as long as technology improves) in the same fiber.

Imagine the small fiber microns width is capable of transporting more data without replacement.




Good ol' reliable


  • Due to the application of Lasers and EM radiation there is no interference from electric and magnetic fields.

  • They support high bandwidth (data rate)

  • Does Not require much repeaters like its copper counterparts.

  • They can be submerged in water.

  • Fiber optic cables are stronger, thinner and lighter than copper wire cables.

  • They do not need to be maintained or replaced as frequently.



Examples

From Endoscopes to Networking

Endoscopes                                     Commmunication


Note worthy


Engineers in Japan achieved a record-breaking internet speed of 319 terabits per second (Tb/s). That is about 7.6 million times faster than the average home internet speed in the U.S. To achieve the speed, researchers developed an experimental optical fiber with four cores.




[1]Total internal reflection

When light moving from a denser medium(higher refractive index) to a rarer refractive index(low RI) after a certain angle incidenting the medium, the ray will reflect into its own entering medium(denser medium)




[2]Refractive index

The ratio between the speeds of light in different media.1= air, Every other media >1





Manupa Wickramasinghe