if you've ever built a tree fort you've probably also tried to send a secret
message to your friend using morse code and a flashlight and fundamentally fiber
optic networking works in the same way encoding data in pulses of light that
travel around the world carrying our phone calls business conferences and
important internet data but now hold on
a second how exactly do you send light
over great distances and still manage to extract information from it i mean fiber
optic cables have to carry light for literally thousands of miles like across
oceans yet if you've ever shined a flashlight down a long hallway you'll
know that over any more than a short distance the light scatters and
eventually becomes too dim to make out well that is where optical fibers come
in those really skinny tubes that make your christmas tree look nice without
having to string up any messy lights have some special characteristics that
allow them to work over incredible distances
the main way that fiber optics behave differently than your flashlight is that
they take advantage of a physical phenomenon called total internal
reflection you see a fiber optic system doesn't
just shine light down any random hollow tube instead optical cables are made up
of a core of glass or plastic surrounded
by an outer layer called cladding both the glass and the cladding have an
inherent property called a refractive index which is basically a measure of
how fast light can travel through something
for the system to work properly the cladding needs to have a slightly lower
index of refraction than the core now sometimes this is achieved by using pure
glass that is silicon dioxide for the core and then doping the cladding with
chemicals to lower its refractive index while other times the core itself can be
doped to raise the same value either way this different means that if
light hits the cladding at a shallow enough angle it will be completely
reflected at the same angle instead of
passing through the cladding that means that it can continue on down the fiber
in a zigzag pattern indefinitely yeah well not quite
although in theory the optical signal should just keep going all the way until
it reaches the other end of the fiber the pesky
real world always has a way of throwing a wrench in the pudding
no matter how high end and pure an optical cable is there will always be
some imperfections even if they're so small that you could
only see them at the molecular level and these will cause some of that light to
scatter weakening the signal over distance until eventually it can't be
understood by the equipment at the other end so to combat this long distance
fiber runs are assisted by repeaters or amplifiers
a repeater gets placed at a point down the fiber where the signal will have
weakened significantly but it's still strong enough to be red once the light
hits the repeater it's turned into the corresponding electronic signal which is
then turned back into light much as it was at the origination point and then
sent along on its merry way repeaters come with a latency and a
complexity cost though so many modern long distance systems now use amplifiers
instead these gadgets have optical fibers which
are doped with chemicals that directly amplify light when the weakened signal
hits them so the ions in the fibers themselves
will re-emit the same signal but much more strongly than what came in and
it continues down the cable in this way optical fiber runs can be
designed to be really long making them a more viable choice for long distance
communication than copper optical fiber is not only more cost
effective than copper wiring it's more power efficient and it even goes farther
without requiring a boost also because it's thinner and doesn't
cause electromagnetic interference to the cables around it it's common to
bundle a bunch of optical fibers each of which can carry multiple wavelengths of
light into one large cable making it possible to transmit enormous amounts of
data without taking up too much space
this versatility means that fiber optics have found uses outside of just
communication such as an endoscopy where their flexibility allows a user to light
up and view inside very hard to reach spaces this is useful in fields like
engineering plumbing and even medicine
speaking of which i gotta run and get to a doctor's appointment that hopefully
doesn't involve sticking a fiber optic scope up somewhere embarrassing
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