WEBVTT

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if you've ever built a tree fort you've probably also tried to send a secret

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message to your friend using morse code and a flashlight and fundamentally fiber

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optic networking works in the same way encoding data in pulses of light that

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travel around the world carrying our phone calls business conferences and

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important internet data but now hold on

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a second how exactly do you send light

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over great distances and still manage to extract information from it i mean fiber

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optic cables have to carry light for literally thousands of miles like across

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oceans yet if you've ever shined a flashlight down a long hallway you'll

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know that over any more than a short distance the light scatters and

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eventually becomes too dim to make out well that is where optical fibers come

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in those really skinny tubes that make your christmas tree look nice without

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having to string up any messy lights have some special characteristics that

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allow them to work over incredible distances

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the main way that fiber optics behave differently than your flashlight is that

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they take advantage of a physical phenomenon called total internal

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reflection you see a fiber optic system doesn't

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just shine light down any random hollow tube instead optical cables are made up

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of a core of glass or plastic surrounded

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by an outer layer called cladding both the glass and the cladding have an

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inherent property called a refractive index which is basically a measure of

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how fast light can travel through something

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for the system to work properly the cladding needs to have a slightly lower

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index of refraction than the core now sometimes this is achieved by using pure

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glass that is silicon dioxide for the core and then doping the cladding with

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chemicals to lower its refractive index while other times the core itself can be

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doped to raise the same value either way this different means that if

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light hits the cladding at a shallow enough angle it will be completely

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reflected at the same angle instead of

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passing through the cladding that means that it can continue on down the fiber

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in a zigzag pattern indefinitely yeah well not quite

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although in theory the optical signal should just keep going all the way until

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it reaches the other end of the fiber the pesky

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real world always has a way of throwing a wrench in the pudding

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no matter how high end and pure an optical cable is there will always be

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some imperfections even if they're so small that you could

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only see them at the molecular level and these will cause some of that light to

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scatter weakening the signal over distance until eventually it can't be

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understood by the equipment at the other end so to combat this long distance

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fiber runs are assisted by repeaters or amplifiers

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a repeater gets placed at a point down the fiber where the signal will have

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weakened significantly but it's still strong enough to be red once the light

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hits the repeater it's turned into the corresponding electronic signal which is

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then turned back into light much as it was at the origination point and then

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sent along on its merry way repeaters come with a latency and a

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complexity cost though so many modern long distance systems now use amplifiers

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instead these gadgets have optical fibers which

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are doped with chemicals that directly amplify light when the weakened signal

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hits them so the ions in the fibers themselves

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will re-emit the same signal but much more strongly than what came in and

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it continues down the cable in this way optical fiber runs can be

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designed to be really long making them a more viable choice for long distance

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communication than copper optical fiber is not only more cost

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effective than copper wiring it's more power efficient and it even goes farther

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without requiring a boost also because it's thinner and doesn't

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cause electromagnetic interference to the cables around it it's common to

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bundle a bunch of optical fibers each of which can carry multiple wavelengths of

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light into one large cable making it possible to transmit enormous amounts of

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data without taking up too much space

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this versatility means that fiber optics have found uses outside of just

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communication such as an endoscopy where their flexibility allows a user to light

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up and view inside very hard to reach spaces this is useful in fields like

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engineering plumbing and even medicine

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speaking of which i gotta run and get to a doctor's appointment that hopefully

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doesn't involve sticking a fiber optic scope up somewhere embarrassing

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oh i know what the doctor ordered this message from our sponsor becoming

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thanks for watching guys like dislike leave a comment if you have a suggestion

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for a future fast as possible and i will see you next time