Why is Optical Fibre faster?

Boris Dosen

What am I hoping to achieve?• …that we jointly come to a conclusion why we like optical fibre more than

coaxial or Ethernet (copper) cables.

• …that we become a step closer to the ENGINEERING UTOPIA, where everyone knows the answer to THIS question.

Why should we all care?

• Because we use the Internet everyday.• Because we sell “this thing” for a living.• Because Optical Fibre has enable services such as iPlayer, allowing you

to watch “Snog, Marry, Avoid” at your convenience• If you have no idea what I am talking about, than because it also enables you

to Google what iPlayer is and what “Snog, Marry, Avoid” is

Coaxial Cable vs Fibre Cable

• Made out of copper• Used to send electric signals

• If your router is connected tothe local exchange via a CoaxialCable, your internet connection isprobably around 8 Mbit/s

• Made out of glass• Used to send light signals

• If your router is connected tothe local exchange an Optical Fibre,your internet connection is20 Mbit/s plus…

Coaxial Cable vs Fibre Cable

SLOWER FASTER

WHY?

Let’s Look at This Example

TRANSMITTER

I just send signals that represent

zeroes and ones down the wire

COAXIAL CABLERECEIVER

I will make a beeping sound as soon as I realise

that I am receiving a signal

Transmitter starts sending some data down the wire. The receiver beeps after 2μs.

TRANSMITTER RECEIVERFANCY OPTICAL FIBRE

Transmitter starts sending some data down the optical fibre. Optical fibre is of thesame length as the coaxial cable.

a) It will take less than 2μs until receiver makes the beeping soundb) It will take exactly 2μs until receiver makes the beeping soundc) It will take more than 2μs until receiver makes the beeping sound ?

Who travels Faster?

FANCY OPTICAL CABLE

I am a light signal. I travel at the Speed of

Light!! Whoosh!

COAXIAL CABLE

I am an electrical signal. And guess

what? I travel at the Speed of Light too!

Let’s Look at This Example

TRANSMITTER

I just send signals that represent

zeroes and ones down the wire

COAXIAL CABLERECEIVER

I will make a beeping sound as soon as I realise

that I am receiving a signal

Transmitter starts sending some data down the wire. The receiver beeps after 2μs.

TRANSMITTER RECEIVERFANCY OPTICAL FIBRE

Transmitter starts sending some data down the optical fibre. Optical fibre is of thesame length as the coaxial cable.

b) It will take exactly 2μs until receiver makes the beeping sound

Coaxial Cable vs Fibre Cable

SLOWER FASTER

So signal will propagate down the wire and down the optical fibre at the SAME speed-the speed of light

Here’s Why…

TRANSMITTER RECEIVERFANCY OPTICAL CABLE

OMG!This optical cable is sooo FANCY!

I can hear perfectly what the transmitter is telling me

Here’s Why…

TRANSMITTER RECEIVER

OMG!This coaxial cable is HORRIBLE!!

I can barely hear what the transmitter is saying!

COAXIAL CABLE

Here’s Why…

TRANSMITTER RECEIVER

YO! Transmitter!Change between your zeroes and ones

more slowly, so that I can hear you better!

COAXIAL CABLE

Signals do not travel faster down the fibre cable!

They just stay more preserved. Hence, if you are using fibre you can have your transmitter switching between ones and zeroes faster! Hence, the faster Internet!

Why Else is Fibre cool

TRANSMITTER RECEIVERFANCY OPTICAL CABLE

You know what!? I can send light signals

of different colours!

So,… We are playing the colour game

now!? Bring it on!

1010010110100110001011010100000101010100011010101110100111010011101010

Wavelength Division Multiplexing (WDM)

Because both the Business people and the Engineers like names that make them look smart, and both have an unhealthy obsession with three letter acronyms.