# How does light carry data and information, i.e in fiber optic cables?

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How does light carry data and information, i.e in fiber optic cables?

In: Physics

Light is either on or off. Light or dark. So let’s say that in normal computer(binary) code you have 1 representing the light being on and 0 being the light off. Light is shot through the fiber optic in a series of on/off 1/0 and picked up on the other end and converted into binary code.

Digital information is transmitted in binary, that is, 0s and 1s, you have a medium that let light travel through it (fiber optic) if there’s light it’s a 1 if there’s not, it’s a 0. (Is this simplified enough?)

There is a light in one end which is switched on and off in a pattern and a light sensor in the other end to detect this pattern. This is just a modern version of the ancient signalling system of showing or hiding a torch from the recipient or the more recent signalling lamps used to communicate between ships. But modern technology means we can switch the light billions of times a second.

So everyone has already more or less summed it up as On vs Off, zeroes and ones, all that good stuff.

but if you want to get really interesting: we can actually do multiple “streams” of data on the same piece of fiber. How? *Different colors of light.*

We do the same on/off thing described by other commenters, but with light of different wavelenths (colors) on the same piece of fiber optic cable, at the same time.

It’s called Wavelength Division Multiplexing, multiplexing means sending more than one stream of information, so Wavelenth Division Multiplexing is sending multiple streams of information, divided by using different wavelengths/colors.

I know it’s not directly answering your question, but it’s a pretty cool thing we can do!

Think of it like more code data is sent by a laser at 1 end turning data into light and a receiver at another turning that light back into data

Light doesn’t carry data. Light **is** the data.

You need only come up with a standard method to represent data using the light, that can be encoded at one end and decoded at the other end using purpose-built hardware. Light has multiple properties you could use to convey information. That could be as simple as using blinking the light on and off in a certain pattern, to using varying levels of intensity (amplitude), or using certain wavelengths/frequencies or combinations of wavelengths/frequencies.