about a guy who works in the communication industry, so you can expect some technical

language. Remember, you can turn captions on to get subtitles so you can listen and

read at the same time. As you are listening think about these three questions and we'll

look at the answers together at the end of the video.

Hi, My name's Sam and I work in the fibre optic cable industry. So, my job is, as a

physicist, to think about the design of lasers and equipment called modulators which are

used to turn data, that is everything which you use on the internet: video, voice, everything

that powers our modern electrical world gets turned into pulses of light which we send

down optical fibres and that light can be transmitted everywhere around the world. So

if you imagine that I'd like to talk to my friend on the other side of the world, my

voice gets turned into a series of pulses of light which get transmitted down an optical

fibre which runs underneath the sea and reappears on the other side of the Atlantic and gets

converted then back into voice and that is a means of communicating with people not just

by voice but also by text and internet and everything else. My job specifically involves

designing lasers which are the sources of the light and we work with special materials

called semi-conductors. Semi conductors have very special properties between what we call

conductors and insulators and they allow us in a very large variety of ways to convert

electrical energy into light energy. Now the laser is the most efficient means by which

we can do that and the laser must be designed very carefully with a colour, a colour of

light what we call a wavelength, very specifically designed for the type of optical fibre we

transmit the light down. It 's important that a wavelength of light is chosen that it is

not absorbed within the fibre since the length of the fibre, which would typically be going

underneath the Atlantic ocean from the United Kingdom to the USA, would be typically many

thousands of kilometres long. And it is important that when we shine our laser in one end of

the fibre that we get something at the other end that we are able to detect. So, that wavelength

must be very specifically chosen so that the absorption within that fibre is kept to a

minimum and that we can actually measure something at the other end. But the optical fibre industry,

the communication industry, is evolving very quickly the modern demands of the internet,

the rise of YouTube and Facebook and all these social media which we rely on so much more

every day, continuously are driving up the need for capacity within optical fibres. There

is a certain limit on how much you can transmit through a fibre, the rate of 1s and 0s which

we call the bit rate which you can transmit through a fibre is currently limited at the

moment to about 10 billion bits per second. Now, that may seem like a lot but a bit of

information carries very little. If you think about typical examples, for instance an Mp3,

an audio file of length say 3 minutes that is 3 megabytes, that is 3 million bytes and

there are 8 bits in a byte which means 3 x 8 that 24 million bits of information just

in 3 minutes of audio and the same would be for a phone call, a phone call would require

several minutes minimum, maybe up to an hour, and that's a lot of information to transmit.

If you think about video for instance, video files these days are several gigabytes in

size and that's billions of bytes. So, if everyone on the internet was watching a video,

say on YouTube, or, you know, in Britain we have BBC iplayer which allows us to watch

information streamed on the BBC. All that data from every single user needs to be transmitted

through the fibre. Now that puts huge demands and strain on the capacity of the fibres.

So my job, as working in the fibre optic communications industry, is to do research into how we can

improve the capacity of those fibres on a daily basis. Now we are working on technology

at the moment that will hopefully allow us to multiply that by ten. So, to go from 10

gigabits per second, 10 billion bits per second, up to 100 billion bits per second. But this

is real technology now and we are really pushing the limits of what we can do with optical

fibres at the present time. And these demands are continuously being driven by the industry

who demand faster and faster speeds every day. So we accept these challenges and we

move forward and this is the very largest part of my work at the moment: understanding

these challenges and overcoming them. Ok, I hope you understood all that, but if

not, go back, listen again and this time turn on the captions so you can listen and read

at the same time. But for now, let's look at these questions. Number 1, what does his

job involve? Well, he mentioned that his job involves designing the lasers that they use

with fibre optic cables. Number 2, How do fibre-optic cables work? Well, as Sam explained,

information is transformed into pulses of light which are created by a laser. This laser

sends the pulses of light down a cable and the modulator collects these pulses at the

other end and turns them back into data. And finally, question 3, why is his job so important?

Well, we are a very good example. You are watching a YouTube video and, like the rest

of society, many people are using the internet to share videos, to share ideas, to watch

TV, to listen to the radio and so the amount of information that needs to be transmitted

is going up all the time. So his job is so important because he keeps the infrastructure

able to cope with the amount of information that is being sent along it. OK guys, so we

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Thank you for watching, see you next time. This is Dave saying goodbye for now.