Fiber Optics are so much cooler than I thought（原声文稿）
In 1887, a young physics teacher attached a thin glass rod to the end of an era and. loaded it into his homemade crossbow.
He torched the rod's end into a molten glass bead, roughly the size of a pin's.
head was barely hanging on, and then he fired the arrow.
Bright sunlight streaming into the room glinted off a tiny glass fiber. At its.
thinnest, it was less than a tenth of the diameter of a human hair.
Now, legally, we cannot shoot a crossbow indoors. Luckily, I am pretty quick.
That's cool. Look at that. Look how thin we got it.
The physics teacher was using these fibers to measure very small forces, but in the.
decades that followed, other researchers found a different use for them.
Sending light signals. Glass fibers can carry light even through bends. Like it's. like that's 90 degrees. And during the 1960s, the telecoms industry was desperate for a better way to.
carry more information. As one American engineer said, it should be possible to. transmit all of the.
conversations going on anywhere in the world simultaneously over a single thread. of light.
But these glass fibers were terrible. The light faded so much that you couldn't.
decode a signal after just one kilometer. No one thought they'd be practical. Except.
one man. His own boss called his dream a wild goose chase. But if he was right.
If you could prove that fiber optics were in fact viable, and if someone could then.
figure out how to make them at scale, well, eventually they could connect. continents.
How much is in this warehouse? There's millions of kilometers here that we're.
pushing through here every month. It's approximately three times as hot at the. surface of the top.
That's crazy. And one day, it could build the internet.
All that was unimaginable in the 1960s, but even then, telecom companies wanted a. our communication system, just for phone calls.
Between 1960 and 1973, the number of daily calls doubled in the US, from $285 million. to $576 million.
In that same time period, NASA sent people to the moon for a total cost of $26. billion.
while AT&T had to spend nearly triple that amount just to install new telephone.
infrastructure. They just couldn't keep up with the demand.
At the time, phone calls were mostly transmitted over copper wires. Now imagine. I'm trying to phone my buddy Gregor.
Now when I pick up, a constant current immediately flows through the wire to.
supply power to the phone. When I speak, my voice vibrates a tiny diaphragm in the. mouthpiece that modulates the current.
The louder I am, the bigger the current swing, and my voice's pitch changes how.
fast the current oscillates. At Gregor's end, that current reaches a speaker that. turns it back into sound.
Now this works for one call on one line, but phone companies aren't gonna install.
wires between every single house. One cable needs to carry multiple calls. So phone companies figure out a neat little trick.
Even though humans can hear frequencies up to 20 kilohertz, you're really between 300.
and 3,400 hertz to understand what someone's saying.
So phone companies drop frequencies above four kilohertz or anything outside the. voice band.
But if everyone used that zero to four kilohertz band on the same line, well then.
all the conversations would be on top of each other and you wouldn't be able to. hear the person that you're talking to.
Luckily, we can shift those electrical signals, so my conversation can use 0-4kHz.
while another person can use 4-8, and so on all the way down the same copper wire.
At the other end, a filter separates out the different frequency bands, similar to. how a radio can tune into one station.
Then the signal is shifted back down to the 0-4kHz range before it hits the. speaker, so it sounds like a normal voice.
But as phone companies started using higher and higher frequencies, they. started running into problems. That oscillating current carrying the signal generates additional fields, a. magnetic field shown here in red and little loops of current called eddy. currents which are shown here in blue.
Now because of their shape those loops resist. changes to the current at the center of the wire and they reinforce.
changes along the surface. But eddy currents get stronger the faster the.
signal changes and if you want more calls you need more bands which use.
higher and higher frequencies. So soon the eddy currents are strong enough to to.
cancel out the oscillation in the center of the wire.
But if the signal can only travel along the wire surface, it's limited to a.
smaller cross-section. So resistance goes up and higher frequency signals can't. travel very far before they're absorbed.
For a while, telephone companies were able to work around the high loss by boosting. signals every few kilometers.
But past 65 megahertz, well, the high frequencies died off in less than two. kilometers. So they were too impractical to use.
And this trade-off between signal power and data rate was actually discovered back.
in 1948. The Shannon-Hartley theorem described the maximum capacity of a.
communication channel based on the signal power, noise, and bandwidth, or the.
difference between the highest and lowest frequencies. The best way to increase. capacity is to increase the bandwidth.
But they'd already reached the limit for copper. The telecom's industry didn't have.
another alternative. But then they saw the light. Visible light has frequencies in.
hundreds of terahertz. As one researcher for Bell Labs put it, the possibility of. extremely.
high frequencies, and accordingly, vastly wider bands of frequencies, appeared as a.
fabulous El Dorado, always beckoning us onward.
But if you're going to use light, there are two problems. First, there wasn't a.
strong enough light source to send a signal. A light bulb couldn't produce. enough power. There just weren't any options.
A science fiction weapon that melts steel, a death ray that could be more deadly than.
a nuclear bomb. It's a beam of light. This is called a laser.
There's a running joke that the laser was a solution looking for a problem. But. that's not really true.
That rejuvenated the interest in possible optical communications. change. As one.
Bell Labs engineer said, think of all this bandwidth.
But they couldn't figure out the second problem. Glass is not as clear as it.
looks. Only a small amount of light actually makes it through.
In fact, only a year after the laser's invention, a Bell Labs scientist started. looking into fiber optics.
His boss told him to check its loss, or how much a light signal weakens as it. travels through the glass.
Now, signal loss is measured with decibels, similar to how you measure audio. volume. Both are on a logarithmic scale.
But while volume uses sound pressure, loss uses signal power. His boss said it would.
only be worthwhile if the loss was less than 20 decibels a kilometer, so it was. comparable to copper.
But when he checked the loss for the best fibers, a thousand decibels a kilometer.
To understand just how bad that was, imagine a leaky truck carrying sand over 1. kilometer.
If the truck starts with 100 kilograms and it ends up with 1, well that represents a.
loss of 20 decibels per kilometer. That's only one percent of the signal left. It's. what was.
happening with copper. Bad, but still manageable. A loss of a thousand decibels. a kilometer is.
like starting with the mass of the observable universe and ending up with.
less than the mass of a single atom. To be practical, these fibers we need to improve. by a factor of 10 to the 98th.
and sounded impossible. It would have to be one of the most absurd engineering.
improvements in history." So Bell Labs gave up, and fiber optics might have died. right there, if it wasn't for one man.
Charles Cow. In 1960, he started working for an English telecoms lab that was.
looking for a way to communicate with higher frequencies. But not with fiber. optics. Cow's boss said.
that it was a wild goose chase, and the rest of the lab agreed. But Cow kept.
coming back to it, asking, why is glass so lossy? And can we remove those factors? Or. are they intrinsic to the.
material. If it was the latter, then fiber would be dead in the water. But if not. then maybe it had a chance. So the question was, why was the loss so high?
Well, you might think it's because. light is exiting through the sides of this fiber, but glass is really good at. trapping light.
even through bends. Here's how. I've got a bucket of propylene glycol here and a. green laser. When I remove.
the tape, the laser bounces one, two, three times. And there are two things. working.
together here that actually trapped the light. See light travels slower in some. materials than.
others, and it travels as a wave, shown here as a line of crests, with the beam.
always pointing perpendicular to that line. When the wave meets a boundary at an. angle, one end of the crest.
crosses into the new material first, and it changes speed before the rest. If light. travels.
slower in that new material, then that end drags behind, and the beam bends or. refracts away from the boundary.
How much it bends depends on the angle it hits the boundary, and on how much each.
material slows light down, which is described by their index of refraction. This relationship is defined by Snell's law.
Now if light is moving from a material with a higher index of refraction, into.
one with a lower index, like propylene glycol to air, well then one part of the.
wave crest speeds up, and the beam bends toward the boundary.
But as you increase the angle of the light, the refracted beam gets closer and.
closer to the boundary until it's running right along it. That's the critical angle. A little bit more. and all the light reflects back into the glycol. That's total internal reflection.
and you get the exact critical angle by setting the angle of refraction to 90. degrees and then rearranging.
Snell's law. The key of it is the bigger the difference in index of refraction, the. more powerful.
this effect is. If I have a really subtle difference between these two, then the.
amount of bending that takes place will be smaller.
You can do the same demo with water, but propylene glycol works a bit better.
because it has a higher refractive index, 1.43 compared with 1.33.
See, once the liquid is low enough for the angle of the stream to be much sharper.
the light breaks through the water stream, but it stays trapped in the propylene. glycol.
And if you use something with an even higher refractive index, like the glass.
type cow was investigating, well then the critical angle decreases even more, which. traps Perhaps the light signals through even sharper turns.
Okay, but the light has to move from a high refractive index to a low one. An.
error that works right up until something touches the glass.
If you disturb that boundary, well light can leak out the side. So about a decade.
before a cow, researchers realized that a fiber needed to have two types of glass.
The middle, the core, has the higher refractive index. And around it goes a.
second glass, the clatic, with a lower refractive index. Together, they keep the. light trapped.
Now the fiber could be touched, coated in plastic, buried in a cable, bent around.
things, and the light would still travel down the core and come out the other end.
So Kao knew that if the high loss wasn't from light leaking out the sides, well it.
had to be from something else. He spoke with material scientists and glass. experts, but no one seemed to know what was really causing it.
He kept looking, and eventually he landed on two potential sources, scattering and. and absorption. Scattering and absorption.
If you shine light through a perfect crystal that's transparent, there's going.
to be a little bit of reflection, but almost all of the electromagnetic energy. will keep going down in the same direction that it started.
But glass isn't a crystalline solid. The basic building block is silica, or silicon. dioxide.
One silicon atom connected to four oxygen atoms, in a tetrahedron, or pyramid shape.
In the glass, the pyramids are connected at the corners, so every oxygen is shared.
with another silicon. That's why it's called silicon dioxide. For every two. oxygens, there's one.
silicon atom. This isn't amorphous solid. Unlike a crystal, its atoms have no. long-range order.
Instead, its disordered liquid-like structure locks in as it cools, and with.
the exact arrangement depending on the glass type and cooling speed.
For example, if you quench the glass really fast, the structure locks at a.
higher temperature. The final solid has lots of dense regions, which re-radiate. more light than the sparse ones.
The light scatters, which weakens the signal. This is called Rayleigh. scattering, and you can't get rid of it completely.
But if you cool the glass slowly, those pyramids have more time to settle and pack.
together evenly. The structure locks in at a lower temperature, and light scatters. less.
But how needed to know the minimum scattering? Was it 10 decibels a. kilometer, 100, a thousand? He needed something concrete. Finally, he stumbled.
on a paper by Robert Maurer, a scientist from corn and glass who measured the. Rayleigh scattering across several glass types and cooling rates.
Kao used his calculations to estimate that if the glass's structure was locked at a.
thousand degrees Celsius, well its scattering loss would be around 1 decibel. a kilometer.
He was surprised, he expected scattering loss to increase with higher temperatures. that's what causes more density fluctuations.
But a thousand degrees Celsius was pretty hot compared to other glass types. So.
then scattering couldn't be behind those crazy high losses. Absorption had to be. the problem.
But cow didn't know what exactly was absorbing so much light. Was it the glass. itself, or something else?
Absorption works like this. In a single atom, electrons sit at discrete energy.
levels, and there are usually some empty spaces in the upper ones.
But pack atoms together into a solid, and those levels smear up, into a wide band.
separated by gaps. Now when light hits the surface, it can excite an electron to a. higher band.
But only if the photon has at least as much energy as this bandgap. If it does.
the photon is absorbed, and eventually it releases that energy as heat.
In something like silicon, that bandgap is very small. It's only around 1.12 electron.
volts. Visible light is between 1.63 to 3.26.
It's got plenty of energy, so it gets absorbed. That's why pure silicon looks. opaque to us.
But the silicon and glass is connected to oxygen atoms that pull more on the shared. electrons.
Now it takes a lot more energy to excite an electron the band gap is much larger.
around nine electron volts Visible light doesn't have enough energy. So it passes. right through and that's why glass looks clear to us.
But most glass types aren't pure silica the raw materials for glass sand soda lime. and other ingredients.
Well, they contain impurities like trace metals, and these metals absorbed far more. light than silicon did.
One of the worst impurities in glass is iron.
Inside the glass structure, iron atoms form positive ions that strongly absorb. violet bluish and infrared wavelengths.
Of the visible light spectrum, impure glass doesn't absorb green light as much. And you can even see this in a regular glass plane.
Looking at it from the edge, light travels down the entire width of the glass, so by.
by the time it reaches your eye, only green light is left.
So if you can see this attenuation after just a few centimeters, imagine a glass. fiber trying to carry light for kilometers and kilometers. Now wonder it at a crazy. loss. Cow spoke with more experts who estimated that without those metal ions.
the loss would drop to around 20 decibels a kilometer.
Copper will the copper just by removing impurities.
It was all theoretical at this point, but it was enough for cow.
In 1966, his team published a paper on their theories, concluding with, The.
crucial material problem appears to be one which is difficult but not impossible.
But nobody really paid attention to his paper because it really seemed impossible.
A 10 to the 98 times improvement was unprecedented.
And Kao didn't actually measure the loss in glass. He didn't have anything. concrete. So he needed proof.
Cal needed to prove that his theoretical low-loss glass was really possible, so he.
decided to measure the purest glass anyone had ever made, Fusilica.
The reason glass manufacturers had added all those extra ingredients was to bring. sans melting point down to around 1400 degrees Celsius.
Celsius. But few silica was pure silicon dioxide, melted at over 2,000 degrees.
Celsius, so it was a lot harder to make. And that meant that Kao couldn't get his. hands on much of it.
Measuring loss normally takes hundreds of meters of cable, if not kilometers. But he.
only had pieces less than 30 centimeters long. To measure the loss in something. that.
small, he and his colleagues invented a new, very precise instrument. Kao spent.
the next three years working on it. But when he finally measured a sample, he. found that Fuse-Silica.
had zero loss. That couldn't be right. In a panic, Cal ran his experiment again. It. turned.
out that the loss was so low that it was within their margin of error, a mere plus. or minus four decibels a kilometer. He spent months fine-tuning his equipment. and in 1969 he.
finally reported that Fuse-Silica had a loss of less than five decibels a. kilometer. Now, that got everyone's attention. One scientist at Bell Labs said, How gave. everyone a jolt?
That was the first practical measurement which said, Hey. you're not just whistling Dixie. Now everyone was interested. Telecom labs. around the planet rushed to fund fiber optics groups.
But, coward only worked. with small samples. Nobody knew whether kilometers of low-loss fiber were even. possible. The problem caught the attention of one Robert Mauer, courting researcher.
and author of the scattering paper that Cow had referenced. To make a practical. fiber he saw three major problems to tackle. First he needed to decide.
which glass to use. He could try purifying raw materials for normal glass, or he.
could try using fused silica, which cow had already proven to be very pure. Most. labs were avoiding. fused silica because of how hard it was to work with. But luckily, corning had a.
secret technique. Back in the 1930s, another corning scientist had ran silicon. tetrachloride gas through an oxygen flame. In the heat, water vapor from the flame. would break silicon tetrachloride into hydrogen chloride gas and silicon dioxide.
The latter would then start clicking together in a fine glassy silica powder. Then the powder would be pressed into shape and melted to make...few silica. Corning was one of the few companies in the world using this technique, called. flame hydrolysis, to make ultra pure glass. So they had the supply, but there.
was a bigger problem with fused silica. It has a refractive index of 1.46, which is. the lowest of any glass, but for total internal reflection to work, the core. needs to have a higher refractive index than the cladding. So if Maurer wanted to.
use a Fusilica core, well then finding another glass with a lower refractive. index for the cladding, well that'd be a nightmare, it simply didn't exist. So. everyone abandoned Fusilica, except for Maurer. He said, I had no reason to think.
Fusilica was any better, but nobody else was working on it. If you do something. that's different from what everybody else is doing, you've got two advantages.
One is you may succeed where they fail, of course, but even if you fail, you will.
gather information that they don't gather. All the other labs were thinking of using. a fused silica core.
After all, that's where the light travels. But Maurer decided to use fused silica for.
the cladding. Then he could easily raise the refractive index of the core by. batting some impurities. or dopants. But that would mean adding titanium right where light needed to.
travel. Cal worked hard to prove that glass could be pure enough. All the other. labs were trying to get rid of impurities, and Maur wanted to add some back in. But.
he wasn't completely crazy. Easy. Like silicon, the titanium and glass can easily. share electrons with four oxygen atoms, forming the same pyramid shape, so it. wouldn't disrupt the overall glass structure too much.
Now that he had the. composition, Maurer needed to tackle that second problem. How do you make a tiny. fiber with that perfect core and cladding cross-section? To help, he hired two more.
scientists, Peter Schultz, a ceramics engineer, and Donald Keck, a physicist. To. understand their technique, I went to the Bay Area Glass Institute for some hands-on. demos. Here our instructor Aaron is taking a colored rod of glass and then dipping it.
in a bowl of clear molten glass. In fiber optics, this large cylinder is called a. preform. We have two colors of glass here. we have a color core and a clear outside.
that if you want your inner rod to say be a quarter of the diameter of your outer. one, you just set that in the preform and then all the length.
along your pull, the cross-section is going to be identical. This is pretty. similar to how hard candies with patterns are made. This sugar is an amorphous. solid, just like glass, so the process is the same, just at a lower temperature.
But. there is one problem with this method, resting glass on a surface like this. introduces is a ton of stress and impurities.
But when I try and suspend it in the air, well, it sags.
But yeah, from all that movement it did create stress, so now it's a curved piece. of glass. Thankfully there's another option.
Now gravity is pulling our glass for us and the surface tension is keeping it. together.
So now we get a much more straight and consistent fiber. That's awesome.
With their drawing technique sorted, the cording team could tackle the final.
problem. How do you actually make the preform? How do you actually make the. preform?
Instead of starting with a core and adding the cladding, Schultz and Keck decided to. start from the cladding and work in.
They used the flame hydrolysis technique to make titanium-doped silica powder, or. soot as they called it.
Next, they took a pure fused silica tube and tried spreading soot down the inside.
If they could get an even layer, well then they could melt and collapse the tube into. a solid rot, a perfect preform. But the soot collected at one end, no matter how they sprayed it. So one of the. technicians grabbed a vacuum cleaner from the corner of the room and he held it up.
to the backside of this tube and it sucked a stream of titanium dope silica glass. down through the center of the tube, coated it just like we'd hoped it would.
The vacuum did not survive that experiment. But they tinkered with a new.
setup until they got the gas flow just right.
All through the summer of 1969, their furnace burned hotter than Hades. They.
drew kilometers of fiber from preform after preform, testing various. compositions.
But none of it was good enough. Titanium was breaking down in the high heat and. absorbing too much light.
They ran the finished fibers through a second heat treatment in an oxygen.
environment before where they finally started seeing results.
A year later, on July 22nd of 1970, a preform slipped against the furnace wall. after Keck only got a few meters of fiber.
The preform was ruined, but he decided to test the short fiber anyway after its heat. treatment.
When I slid it across and the laser light hit the core of the fiber, all of a sudden. I had another beam coming back in my face.
The core was brightly lit and it took a while to realize the light was going all.
the way to the other end of the fiber and reflecting off the far end and coming back. into my eye.
The loss was 17 decibels a kilometer. The only word I could come up with for this.
auspicious moment in history was whoopee.
So that's what's in my lab notebook whoopee. But the fiber was much shorter.
than usual, only 29 meters to their typical 200.
He added a careful, must-remeasure in his notebook. team quickly remade the preform.
but it took almost a month to get 210 meters of finished fiber.
It was finally done by late afternoon of Friday, August 21st. It was a gorgeous.
summer day, and almost everyone left early, but Keck didn't want to wait.
The fiber was so fragile, small temperature changes might break it over. the weekend.
So alone in the lab, he anxiously measured the loss, 16.9 decibels per kilometer.
Mauer published their results that fall. As Schultz described it, no one believed.
The telephone companies all demanded to see the fibers first hand, so Mauer hand.
carried a spool of fiber to all the big telephone laboratories.
He would literally guard to make sure that they didn't snip pieces off and keep them.
For two years, they refined their methods. And to make the fiber stronger, they. switched to a germanium dopant.
Like titanium, it easily swaps with silicon while still raising the refractive. index.
But unlike titanium, germanium fibers didn't break down in the heat, so they.
could skip the second heat treatment. When they drew their first germanium fiber, the. end lit up with the light from the furnace.
Even when it reached the bottom and wound up around a large drum, the fiber stayed. bright.
And we kept winding and winding and winding and thinking the light was gonna. go out and it never went out.
The loss was only four decibels per kilometer with excellent strength Keck.
considers that the very first truly practical low-loss fiber.
By 1977 AT&T trialed a fiber system underneath Chicago.
Two years later a fiber team from Japan was able to get a loss of just 0.2.
decibels a kilometer The standard up to today.
Fiber networks continued to grow, with the first transatlantic fiber optic cable.
installed by 1988. It transmitted those phone calls differently than in copper.
The audio wave was split up, or sampled into discrete values, and then converted. into binary to get a long string of 1's and 0's.
Then the laser flashed on for 1 and off for 0, 280 million times a second. These.
pulses of light traveled down the fiber, but that wasn't all.
Well, multiple conversations could now be weaved together. One bit from one.
conversation, then from another, and so on, slotting it together like a zipper.
As long as the receiver knew the timing of each conversation and the sampling rate. well they could reconstruct the original waves.
So this first intercontinental cable could carry 40,000 simultaneous calls, 10 times. more than the previous copper version.
This insane capacity opened up a whole new world, and with digital signals people. people realized that they weren't limited to phone calls.
It was easier than ever to send text, images, videos. All building up to the.
internet. And since then, demand has only increased. This reel right here, yeah, 50.477 kilometers, so 50 kilometers, so it's. about 30 miles.
That's crazy. Like how much is in this warehouse? Oh, there's millions of.
kilometers here that we're pushing through here every month.
To see how modern fibers are made, we visited Prismian's North Carolina factory. It all starts with the preform.
Each pass of this microwave source ignites a mixture of gases into a plasma which.
deposits a thin layer of glass on the inside of the tube. And you see when it. turns purple, that's when we're making a plasma with that gas.
So how thick are these deposition legs? Like how many times are you doing this.
how thick are you doing this? Thousands of passes. Thousands of passes.
Several thousand times it's doing this. Every time we make go back and forth we. could change the composition of that if we wanted to.
After all the interlayers are done the tube has a thicker wall, but there's still.
a gap down the middle So we want to collapse that channel upon itself.
So what we do is we heat it up. We have a furnace that goes back and forth Just by a.
surface tension it collapses upon itself Interesting, I would have thought maybe.
you'd like pull it or so I asked this exact question It said are you pulling a. vacuum in there? What's making that thing shrink? It's really just a glass phenomena where the molecules are trying to pull together. you heat it up You lower the viscosity of the glass it just Now they need to add.
more silica on the outside to get the preform to the right proportions The core. is very small just seven point two percent of the total diameter, and you have a. several thousand C Plume of plasma right there. There's grains of silica that's. flowing into that plume and and effectively melting it and spraying it.
onto that rod. Wow. That plasma torch is approximately three times as hot at the. surface of the pond. Plasma always bugs my mind.
This is absurd. Once the preform's. done, it goes to the top of the draw tower, seven stories up to start making. fiber. Really looks like some sort of steam punk thing, you know?
All these. coils and this hot glass going down. The bottom of the preform is tapered to a. point and heated to over 2,000 degrees celsius. It's like, there's some heat.
coming up this. The end of the taper slowly drops down to the floor below. We. call it a gob, but it looks like a teardrop. The fiber is a little thick, so.
it'll be thinned down to the final 125 microns before it passes to the next. level. I didn't expect it to be so violent. If the drawing, like the pull. down to that final diameter, happens in such a short amount of time.
And a few. meters, let's call it. A few meters. Then why do you need six more floors?
You've got to cool the glass before you can apply the coating, and if you cool the. glass too quickly, it'll have residual stress and then have optical loss. attenuation. Once the fibers are cool enough, they are dipped in two protective. plastic coatings.
At the bottom of the draw tower, the fiber is wound onto. massive spools, each capable of carrying hundreds of kilometers at over 50 meters a. second. Next the finished fiber is tested for loss and strength. Next, fiber is.
stronger than a steel wire of the same thickness. If I guess if I try to do it. like, if you just try to do it like that, it's really hard to break it. First of. all, it just slides down my hand.
And that's a glass fiber with two coatings on. it. Ah, it's just hurting my hand. Oh my God. Yeah, not easy.
Definitely not easy. Ow! But it's weak to sharp turns. Tighter than not. Tighter than not?
Well, watch what happens. And see how much you can get before it breaks. Yeah. because the angle is so great, you can break it. But after testing, fiber is.
bundled and wrapped into thicker cables so that it's harder for them to knot and. break. These cables will join the more than 8 billion kilometers of fiber already. installed that carry information around the world, powering the internet and. letting you watch this video.
But some experts argue that even with fiber, the. internet would not be possible without another key invention. The amplifier. That's what boosts signals across long stretches, and it revolutionized fiber. capacity on land and sea.
So, if you'd like to see a video about submarine cables. and fiber amplifiers, well, let us know in the comments. As for Cao, his dream went. further than he ever thought. When he received the Nobel Prize in 2009 for his.
work, he said, the information revolution that started in the 1990s could not have. happened without optical fibers.
It is beyond the dreams of the first serious concept of optical communication. in 1966, when even 1 gigahertz was only a hope.
For me, one of the things I kept on coming back to in this story is that Kao was not. a material scientist.
He was an electrical engineer, and it was only because he was an outsider that he.
was able to ask the questions that nobody was asking. He was able to push the status. quo.
But he was not the only one. Maurer's team were also working with a very unintuitive.
idea that by making something seemingly worse, they actually were making it. better.
As Kao said, who knows what other forward thinkers will dream of in the future.
Granted he was talking about bandwidth, but I think it applies anywhere, where.
people are able to question why things are the way they are, and whether that's. really the limit.
One last thing. These videos are only possible because of the incredible work. done by our team behind the scenes.
We have world-class editors, animators, researchers, and writers that make these. videos possible.
We'd love to shine more of a light on their work, so we organized a Q&A with the. writer of today's video, Sully.
She discusses the fascinating things she learned while researching this topic, and. things that didn't make the cut but that are really interesting.
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