Advanced User Stuff: What exactly is LiFi?

LiFi has become a big deal in the tech world, and a big buzzword as far as ‘The Next Big Thing’ goes. ‘LiFi’ is a term a that was adapted from ‘WiFi’ to try to describe a network between the lights above you and other electronic devices. While the term is not really accurate, and pretty vague, the idea of a ‘Light Network’ is very exciting. Combined with emerging IoT ideas and the capability of modern cellphones, LiFi can quickly become an important technology in our everyday lives.

The Past:

In the past, light was used to transmit data, but it was done in a rather passive way. Light wasn’t exactly used to transmit the data itself, but rather the presence of the light was used as a signal.

Car dashboards are a prime example of a light transmitting data to you. When your car needs fuel.. a light come on telling you the fuel tank is empty. Probably the most straightforward network ever.

If you’ve ever walked into a store and been greeted with a loud chime that announced your entry, you have demonstrated another way light is used. Your legs broke a light beam that was shining across the doorway, and triggered a sensor to become aware of a customer walking into the store.

The Present:

The idea of light being modulated to transmit data is far from new. Fiber optic communications have used this strategy since the early 70’s. The advent of the compact and affordable laser driver made this possible. The laser was used to provide a focused, high energy beam with the advantage of being able to be turned on and off very quickly. It wasn’t really practical to transmit laser data across the open air, so the laser output was channelled into a fiber optic light pipe. Over time, data transmission rates climbed and climbed, and become so reliable that we take it for granted.

Most recently, engineers have begun to take advantage of the coherent nature of laser light to allow multiple wavelengths of laser light to be transmitted within the same fiber optic strand. Coherent light will not mix when put together; if you put a ‘Red’ wavelength and a ‘Blue’ wavelength together, ‘Red’ and ’Blue’ will be present at the other end, rather than mixing into ‘Purple’.

Today most communication companies commonly squeeze 88 different wavelengths into the same fiber-optic strand. This has pushed data transmission rates into and above the 100 Gb/Sec ranges—even over long distances!

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