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  • This episode of DNews is brought to you buy LG G3

  • Researchers have found a way to make glass tubes a tenth the thickness of your hair send

  • cat videos around the world. Better. They found a way to do all that but better.

  • HI! Julian here for DNews. Your smartphone is super cool, youve got all the DNews

  • you could possibly want, anywhere. But youre not really totally wireless. Youre within

  • a few miles of a cell phone tower, but the tower may be hundreds of miles from the servers

  • where all that juicy knowledge is stored. So how do you connect the two? Why with laser

  • beams, of course!

  • Let’s begin at the beginning, which is all the way back in the 1840’s when Swiss Physicist

  • Daniel Colladon noticed he could shine a light in one end of a water pipe and it would come

  • out the other side. 170 years later, modern optic fibers are basically the same thing,

  • but they use optically pure glass and are 9 thousandths of a millimeter thick instead.

  • You may be wondering, how does light travel inside water or glass without just bouncing

  • out and being lost? The answer is it all has to do with the angle the light is shone in.

  • If the light is hitting the walls of the glass at a shallow angle, less than 42 degrees,

  • itll experience total internal reflection and bounce back and forth down the glass.

  • This property of light is the same reason you can look out over a lake and see a beautiful

  • reflection, but when you look straight down you can see into the water.

  • To make sure none of that light does leak out, the optical glass is encased in a cladding

  • with a higher refraction index that can bend light back into the glass, then that’s put

  • in a buffer coating. Each one of these fibers can carry the equivalent data of 10 million

  • phone calls, and hundreds of thousands are bundled together and stuffed in a jacket to

  • make a fiber optic cable. Because of them you can send a beam of light to the other

  • side of the planet in a seventh of a second.

  • Being able to shoot light through a glass tube to China is all well and good, but you

  • still need a way to send information, and that’s where modulation comes in.

  • Modulation is when you vary some property of a wave to encode information. Then when

  • it gets to the destination, it’s demodulated to separate the carrier from the message.

  • Youve been dealing with it a lot and you might not even know it. FM radio uses frequency

  • modulation, which is when a wave’s length is altered. AM is when a wave’s Amplitude

  • is changed. and the Modem in your house is short for Modulator Demodulator.

  • In fiber optics there are a lot of ways to modulate the beam and send information. There’s

  • AM, Sine wave FM, Square wave FM, pulse frequency modulation, which is basically turning the

  • beam on and off so it can be interpreted as ones and zeroes. All of these methods need

  • costly external modulators, which are costly and inefficient.

  • But Dr. Radan Slavik, who is a research fellow at the Optoelectronic Research Centre and

  • probable Jame Bond nemesis, has improved another method. Theyve devised a way of adjusting

  • the current of the laser beams so they can have better control of the optical field and

  • send more information. Actually the words Dr. Radan Slavik used were, “Exquisite control

  • over the optical field generated directly from a current-modulated semiconductor laser.”

  • Tell me he’s not a Bond villain!

  • There was another awesome breakthrough in sending wireless signals a few months ago.

  • I talk about that and a bit more about Fiber Optics over here.

  • If you know of some interesting tech in the pipeline and want us to cover it, let us know

  • in the comments and I’ll see you next time on DNews.

This episode of DNews is brought to you buy LG G3

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B1 中級

是什麼讓互聯網快速發展? (What Makes The Internet Fast?)

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    稲葉白兎 發佈於 2021 年 01 月 14 日
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